This is ./p/doc/info/gpc.info, produced by makeinfo version 4.8 from
gpc.texi.

INFO-DIR-SECTION GNU programming tools
START-INFO-DIR-ENTRY
* GPC: (gpc).                   The GNU Pascal Compiler.
END-INFO-DIR-ENTRY
INFO-DIR-SECTION Individual utilities
START-INFO-DIR-ENTRY
* GPC: (gpc)Invoking GPC.       The GNU Pascal Compiler.
END-INFO-DIR-ENTRY

   This file documents the GNU Pascal Compiler.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Copyright (C) 1988-2006 Free Software Foundation, Inc.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the sections entitled "GNU General Public License", "The GNU
Project", "The GNU Manifesto" and "Funding for free Software" are
included exactly as in the original, and provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that the sections entitled "GNU General Public
License", "The GNU Project", "The GNU Manifesto" and "Funding for Free
Software" and this permission notice, may be included in translations
approved by the Free Software Foundation instead of in the original
English.


File: gpc.info,  Node: Top,  Next: Welcome,  Up: (dir)

GNU Pascal
**********

This manual documents how to run, install and maintain the GNU Pascal
Compiler (GPC), as well as its new features and incompatibilities, and
how to report bugs. It corresponds to GPC 20060325 (GCC 2.8.1, 2.95.x,
3.2.x, 3.3.x or 3.4.x).

* Menu:

Introduction:

* Welcome::           Welcome to GNU Pascal ...
* Highlights::        Some of GPC's most interesting features.
* News::              New Features of GNU Pascal.
* FAQ::               The GNU Pascal Frequently Asked Questions List.

Installation:

* Installation::      How to download, compile and install GNU Pascal.

Using GNU Pascal:

* Invoking GPC::      Command Line Options supported by GNU Pascal.
* Programming::       The Programmer's Guide to GPC.
* Borland Pascal::    A QuickStart Guide from Borland Pascal to GNU Pascal.
* Reference::         The Alphabetical GPC Language Reference.
* Keywords::          Pascal keywords and operators supported by GNU Pascal.
* Support::           Where to get support for GNU Pascal; how to report bugs.

Development:

* To Do::             The GNU Pascal To-Do List.
* Internals::         How to get more information from the GPC source itself.

Licenses:

* Copying::           The GNU General Public License -- Your rights and
                      duties when using GPC.
* Library Copying::   The GNU Lesser General Public License -- Your rights
                      and duties when using certain libraries.
* Demo Copying::      GPL with exception -- Your rights and duties when
                      using or modifying the demo programs.

Appendix:

* Acknowledgments::   Contributors to GNU Pascal.
* Resources::         Resources For Use With GPC.
* GNU::               The GNU Project.
* Index-GPC::         Index of concepts and symbol names (incomplete).


File: gpc.info,  Node: Welcome,  Next: Highlights,  Prev: Top,  Up: Top

Welcome to GNU Pascal ...
*************************

...  the free 32/64-bit Pascal compiler of the GNU Compiler Collection
(GNU CC or GCC). It combines a Pascal front-end with the proven GCC
back-end for code generation and optimization.  Other compilers in the
collection currently include compilers for the Ada, C, C++, Objective
C, Chill, FORTRAN, and Java languages. Unlike utilities such as p2c,
this is a true compiler, not just a converter.

   This version of GPC corresponds to GCC version 2.8.1, 2.95.x, 3.2.x,
3.3.x or 3.4.x.

   The purpose of the GNU Pascal project is to produce a Pascal
compiler (called GNU Pascal or GPC) which

   * combines the clarity of Pascal with powerful tools suitable for
     real-life programming,

   * supports both the Pascal standard and the Extended Pascal standard
     as defined by ISO, ANSI and IEEE (ISO 7185:1990, ISO/IEC
     10206:1991, ANSI/IEEE 770X3.160-1989),

   * supports other Pascal standards (UCSD Pascal, Borland Pascal,
     parts of Borland Delphi, Mac Pascal and Pascal-SC) in so far as
     this serves the goal of clarity and usability,

   * may be distributed under GNU license conditions, and

   * can generate code for and run on any computer for which the GNU C
     compiler can generate code and run on.

   Pascal was originally designed for teaching. GNU Pascal provides a
smooth way to proceed to challenging programming tasks without learning
a completely different language.

   The current release implements Standard Pascal (ISO 7185, levels 0
and 1), most of Extended Pascal (ISO 10206, aiming for full
compliance), is highly compatible to Borland Pascal (version 7.0), has
some features for compatibility to other compilers (such as VAX Pascal,
Sun Pascal, Mac Pascal, Borland Delphi and Pascal-SC).

   It provides a lot of useful GNU extensions not found in other Pascal
compilers, e.g. to ease the interfacing with C and other languages in a
portable way, and to work with files, directories, dates and more,
mostly independent of the underlying operating system.

   Included units provide support for regular expressions, arithmetic
with integer, rational and real numbers of unlimited size,
internationalization, inter-process communication, message digests and
more. Demo programs show the usage of these units and of many compiler
features.

   This manual contains

   * an overview of some of GPC's most interesting features, see *Note
     Highlights::,

   * a list of new features since the last release, see *Note News::,

   * the GNU Pascal Frequently Asked Questions List, see *Note FAQ::,

   * installation instructions, see *Note Installation::,

   * a QuickStart Guide for programmers used to the Turbo Pascal/Borland
     Pascal compiler, see *Note Borland Pascal::,

   * a list of command-line options to invoke the compiler, see *Note
     Invoking GPC::,

   * the Programmer's Guide to GPC, describing the Pascal programming
     language in general and GPC specifc aspects, see *Note
     Programming::,

   * the alphabetical GPC language reference, see *Note Reference::,

   * a list of keywords and operators supported by GNU Pascal, see
     *Note Keywords::,

   * information on how to report bugs in GNU Pascal and how to get
     support, see *Note Support::,

   * the list of known bugs and things to do, also listing bugs fixed
     and features implemented recently, see *Note To Do::,

   * some information for those who are interested in how GNU Pascal
     works internally, see *Note Internals::,

   * a list of contributors which tells you who developed and is
     maintaining GNU Pascal, see *Note Acknowledgments::,

   * the GNU General Public License which informs you about your rights
     and responsibilites when using, modifying and distributing GNU
     Pascal, see *Note Copying::,

   * and other texts about Free Software and the GNU Project intended to
     answer questions like "what is GNU?" you might have in mind now,
     see *Note GNU::.

   If you are familiar with Standard Pascal (ISO 7185) programming, you
can probably just go ahead and try to compile your programs. Also, most
of the ISO Extended Pascal Standard (ISO 10206) is implemented into GNU
Pascal. The Extended Pascal features still missing from GPC are set
types with variable bounds and discriminated ordinal schema as schema
discriminants.

   If you are a Borland Pascal programmer, you should probably start
reading the QuickStart guide from BP to GNU Pascal, see *Note Borland
Pascal::. If you are curious about the new features GPC offers, you can
get an idea in the overview of GPC highlights (*note Highlights::), and
read in more detail about them in the Programmer's Guide to GPC (*note
Programming::) and in the alphabetical GPC Language Reference (*note
Reference::).

   And, please, think about how you can contribute to the GNU Pascal
project, too. Please support our work by contributing yours in form of
example programs, bug reports, documentation, or even actual
improvements of the compiler.

   All trademarks used in this manual are properties of their
respective owners.


File: gpc.info,  Node: Highlights,  Next: News,  Prev: Welcome,  Up: Top

1 Some of GPC's most interesting features.
******************************************

The GNU Pascal Compiler (GPC) is, as the name says, the Pascal compiler
of the GNU family (`http://www.gnu.org/software/gcc/').  This means:

   * GPC is a 32/64 bit compiler,

   * does not have limits like the 64 kB or 640 kB limit known from
     certain operating systems - even on those systems -,

   * runs on all operating systems supported by GNU C, including

        - GNU Hurd (http://www.gnu.org/software/hurd/),

        - Linux (http://www.linux.org) on Intel, AMD64, Sparc, Alpha,
          S390, and all other supported types of hardware,

        - the BSD family: FreeBSD (http://www.freebsd.org), NetBSD
          (http://www.netbsd.org), OpenBSD (http://www.openbsd.org),

        - DOS with 32 bits, using DJGPP (http://www.delorie.com/djgpp/)
          or EMX,

        - MS-Windows 9x/NT, using CygWin (http://cygwin.com) or mingw
          (http://www.mingw.org) or MSYS
          (http://www.mingw.org/msys.shtml),

        - OS/2 with EMX,

        - Mac OS X,

        - MIPS-SGI-IRIX,

        - Alpha-DEC-OSF,

        - Sparc-Sun-Solaris,

        - HP/UX,

     and more (note: the runtime system only supports ASCII based
     systems; that includes almost all of today's systems, but a few
     IBM machines still use EBCDIC; on those, the compiler might run,
     but the runtime support might need major changes),

   * can act as a native or as a cross compiler between all supported
     systems,

   * produces highly optimized code for all these systems,

   * is Free Software (http://www.gnu.org/philosophy/free-sw.html)
     (Open-Source Software (http://www.opensource.org)) according to the
     *GNU General Public License*
     (http://www.gnu.org/copyleft/gpl.html),

   * is compatible to other GNU languages and tools such as GNU C and
     the GNU debugger.

   The compiler supports the following language standards and
quasi-standards:

   * ISO 7185 Pascal (*note Resources::),

   * most of ISO 10206 Extended Pascal,

   * Borland Pascal 7.0,

   * parts of Borland Delphi, Mac Pascal and Pascal-SC (PXSC).

   Some highlights:

   * From Standard Pascal: Many popular Pascal compilers claim to
     extend Standard Pascal but miss these important features.

        - Conformant array parameters - the standardized and
          comfortable way to pass arrays of varying size to procedures
          and functions.  [Example (conformantdemo.pas)]

        - Passing local procedures as procedural parameters - with full
          access to all variables of the "parent" procedure.  [Example
          (iteratordemo.pas)]

        - Automatic file buffers and standard `Get' and `Put'
          procedures. Read ahead from files without temporary variables.
          [Example (filebuf1demo.pas)] This allows you, for instance, to
          validate numeric input from text files before reading without
          conversion through strings. [Example (filebuf2demo.pas)]

        - True packed records and arrays. Pack 8 Booleans into 1 byte.
          [Example (packdemo.pas)]

        - Internal files. You don't have to worry about creating
          temporary file names and erasing the files later.  [Example
          (intfiledemo.pas)]

        - Global `goto'. (Yes, `goto' has its place when it is not
          restricted to the current routine.) [Example (parserdemo.pas)]

        - Automatically set discriminants of variant records in `New'.
          [Example (variantdemo.pas)]

        - Sets of arbitrary size. [Example (bigsetsdemo.pas)]

   * From Extended Pascal:

        - Strings of arbitrary length. [Example (stringschemademo.pas)]

        - `ReadStr' and `WriteStr'. Read from and write to strings with
          the full comfort of `ReadLn'/`WriteLn'.  [Example
          (rwstringdemo.pas)]

        - System-independent date/time routines.  [Example
          (datetimedemo.pas)]

        - Set member iteration:
          `for Ch in ['A' .. 'Z', 'a' .. 'z'] do ...' [Example
          (bigsetsdemo.pas)]

        - Set extensions (symmetric difference, `Card')

        - Generalized `Succ' and `Pred' functions
          (`foo := Succ (bar, 5);').

        - Complex numbers. [Example (mandelbrot.pas)] [Example
          (parserdemo.pas)]

        - Exponentiation operators (`pow' and `**') for real and
          complex numbers.

        - Initialized variables. [Example (initvardemo.pas)]

        - Structured value constructors - build array or record values
          without using temporary variables.

        - Functions can return array or record values.

        - Result variables. [Example (resultvardemo.pas)]

        - Modules.

        - Non-decimal numbers in base 2 through 36: `base#number'.

        - `MinReal', `MaxReal', `EpsReal', `MaxChar' constants.

        - Schemata - the Pascal way to get dynamic arrays without dirty
          tricks. [Example (schemademo.pas)]

        - Local variables may have dynamic size.  [Example
          (dynamicarraydemo.pas)]

        - Array Slice Access - access parts of an array as a smaller
          array, even on the left side of an assignment [Example
          (arrayslicedemo.pas)]

   * Compatible to Borland Pascal 7.0 with objects (BP):

        - Supports units, objects, ..., and makes even things like
          `absolute' variables portable. [Example (absdemo.pas)]

        - Comes with portable versions of the BP standard units with
          full source.

        - True network-transparent CRT unit: You can run your CRT
          applications locally or while being logged in remotely,
          without any need to worry about different terminal types.
          Compatible to BP's unit, but with many extensions, such as
          overlapping windows.  [Example (crtdemo.pas)]

        - Fully functional GUI (X11) version of CRT (also completely
          network transparent).

        - The `Random' function can produce the same sequence of
          pseudo-random numbers as BP does - if you need that instead
          of the much more elaborate default algorithm.

        - Supports BP style procedural variables as well as Standard
          Pascal's procedural parameters. [Example (procvardemo.pas)]

        - A `Ports' unit lets you access CPU I/O ports on systems where
          this makes sense. [Example (portdemo.pas)]

        - Special compatibility features to help migrating from BP to
          GPC, like a `GPC for BP' unit which provides some of GPC's
          features for BP, and some routines to access sets of large
          memory blocks in a uniform way under GPC and BP (even in real
          mode).  [Example (bigmemdemo.pas)]

        - Comes with a BP compatible `binobj' utility.  [Example
          (binobjdemo.pas)]

   * From Borland Delphi:

        - `abstract' object types and methods

        - classes

        - `is' and `as' operators to test object type membership

        - Comments with `//'

        - Empty parameter lists with `()'

        - Assertions

        - A `SetLength' procedure for strings makes it unnecessary to
          use dirty tricks like assignments to the "zeroth character".

        - `Initialize' and `Finalize' for low-level handling of
          variables.

        - `initialization' and `finalization' for units.

   * From Pascal-SC (PXSC):

        - User-definable operators. Add your vectors with `+'.

   * Carefully designed GNU extensions help you to make your real-world
     programs portable:

        - 64-bit signed and unsigned integer types.

        - Special types guarantee compatibility to other GNU languages
          such as GNU C. Directives like `{$L foo.c}' make it easy to
          maintain projects written in multiple languages, e.g.,
          including code written in other languages into Pascal programs
          [Example (Pascal part) (c_gpc.pas)] [Example (C part)
          (c_gpc_c.c)],

        - or including Pascal code into programs written in other
          languages.  [Example (Pascal part) (gpc_c_pas.pas)] [Example
          (Pascal unit) (gpc_c_unit.pas)] [Example (C part) (gpc_c_c.c)]

        - Extensions like `BitSizeOf' and `ConvertFromBigEndian' help
          you to deal with different data sizes and endianesses.
          [Example (endiandemo.pas)]

        - Little somethings like `DirSeparator', `PathSeparator',
          `GetTempDirectory' help you to write programs that look and
          feel "at home" on all operating systems.

        - The `PExecute' routine lets you execute child processes in a
          portable way that takes full advantage of multitasking
          environments.  [Example (pexecutedemo.pas)] [Example
          (pexec2demo.pas)]

        - The GNU GetOpt routines give you comfortable access to
          Unix-style short and long command-line options with and
          without arguments.  [Example (getoptdemo.pas)]

        - Routines like `FSplit' or `FSearch' or `FExpand' know about
          the specifics of the various different operating systems.
          [Example (fexpanddemo.pas)]

        - The `FormatTime' function lets you format date and time
          values, according to various formatting rules.  [Example
          (formattimedemo.pas)]

   * Useful and portable GNU standard units:

        - A `Pipes' unit gives you inter-process communication even
          under plain DOS. [Example (pipedemo.pas)] [Demo process for
          the example (demoproc.pas)]

        - With the `RegEx' unit you can do searches with "regular
          expressions". [Example (regexdemo.pas)]

        - The GNU MultiPrecision (`GMP') unit allows you to do
          arithmetics with integer, real, and rational numbers of
          arbitrary precision.  [Example: factorial (factorial.pas)]
          [Example: fibonacci (fibonacci.pas)] [Example: power
          (power.pas)] [Example: real power (realpower.pas)] [Example:
          pi (pi.pas)]

        - Posix functions like `ReadDir', `StatFS' or `FileLock'
          provide an efficient, easy-to-use and portable interface to
          the operating system. [Example (readdirdemo.pas)] [Example
          (statfsdemo.pas)] [Example (filelockdemo.pas)]

        - A `DosUnix' unit compensates for some of the incompatibilities
          between two families of operating systems.  [Example
          (dosunixdemo.pas)]

        - An `MD5' unit to compute MD5 message digests, according to RFC
          1321. [Example (md5demo.pas)]

        - A `FileUtils' unit which provides some higher-level file and
          directory handling routines. [Example (findfilesdemo.pas)]

        - A `StringUtils' unit which provides some higher-level string
          handling routines. [Example (stringhashdemo.pas)]

        - An `Intl' unit for internationalization.  [Example
          (gettextdemo.pas)] [Example (localedemo.pas)]

        - A `Trap' unit to trap runtime errors and handle them within
          your program. [Example (trapdemo.pas)]

        - A `TFDD' unit that provides some tricks with text files, e.g.
          a "tee" file which causes everything written to it to be
          written to two other files. [Example (tfdddemo.pas)]

        - A `HeapMon' unit to help you find memory leaks in your
          programs.

   The demo programs mentioned above are available both on the WWW and
in GPC source and binary distributions.

   Disadvantages:

   * The GNU debugger (GDB) still has some problems with Pascal debug
     info.

   * Compilation with GPC takes quite long.

   *Co-workers welcome!*

   Able, committed programmers are always welcome in the GNU Pascal
team. If you want to be independent of companies that you have to pay
in order to get a compiler with more restrictive licensing conditions
that only runs on _one_ operating system, be invited to join the
development team, *Note Acknowledgments::.


File: gpc.info,  Node: News,  Next: FAQ,  Prev: Highlights,  Up: Top

2 New Features of GNU Pascal.
*****************************

   GPC's new or changed features since the last (non alpha/beta) GPC
release are listed here. Items without further description refer to new
routines, variables or options.

   Features implemented for compatibility to other compilers are marked
with, e.g., `(B)' for BP compatibility.

   A few old and obsolete features have been dropped or replaced by
cleaner, more flexible or otherwise more useful ones. This might lead
to minor problems with old code, but we suppose they're rare and easy
to overcome. Backward-incompatible changes are marked with `(@)'.

   * preliminary support for gcc-4.0.x

   * handle named exit from a method

   * check string parameters more strictly (@)

   * use at least integer precision for arithmetic (@)

   * refuse `--executable-file-name' on names without a suffix

   * do not create `.gpi' files from incorrect input

   * `CWordBool' type

   * allow passing variant selector by reference in default mode

   * `noinline' attribute

   * check for identifier redeclaration in records and parameter lists
     (@)

   * set constants are compatible with packed sets

   * `ReadString' and `StringOf' predefined routines (M)

   * pass discriminated string schema by value (@)

   * `const var' parameters

   * preliminary support for OOE class views (test/view1[a-g].pas)

   * `--iso-goto-restrictions' option

   * `--preprocessed' option

   * integrated preprocessor (@)

   * `--longjmp-all-nonlocal-labels' is on by default on Darwin/PPC

   * preliminary support for Delphi classes and Mac objects (D) (M)
     (delphi1[bc].pas, peter5[a-g].pas)

   * new options `--[no]-objects-require-override',
     `--[no]-delphi-method-shadowing', `--[no]-objects-are-references'
     (off by default) (D) (M)

   * new options `--gnu-objects' (default), `--ooe-objects',
     `--mac-objects', `--borland-objects' which choose object model

   * `uses' can not directly follow `import' (@)

   * handle `+' and `-' as Mac Pascal does (M) (@)

   * new options `--[no]-nonlocal-exit' (default in `--ucsd-pascal' and
     `--mac-pascal') (fjf988[fijk].pas, fjf1062*.pas) (U) (M)

   * new options `--[no]-object-checking' (on by default) to check on
     virtual method calls if VMT pointer is not nil and has matchin
     `Size' and `NegatedSize' entries, new options
     `--[no]-range-and-object-checking' which are now equivalent to
     `$R[+-]' (fjf1053*.pas) (B)

   * new options `--[no]-pointer-checking',
     `--[no]-pointer-checking-user-defined'; new variable
     `ValidatePointerPtr' (fjf1052*.pas, pcerrorc.pas) (these options
     are _off_ by default!)

   * new options `--[no]-implicit-result' (fjf1022*.pas) (on by default
     *only* in `--delphi' mode!) (D) (@)

   * new options `--{en,dis}able-predefined-identifier' (fjf1037*.pas)

   * `import' within a routine (mod15[c-e].pas)

   * the option `--no-debug-info' was renamed to
     `--disable-debug-info', and `--no-default-paths' was renamed to
     `--disable-default-paths' (@)

   * qualified identifiers (chief18.pas, fjf260*.pas, fjf921*.pas,
     grp1.pas, kurzw1.pas, mod{9,10,13..17}*.pas) (@)

   * with `-Wnested-comments' and without `--nested-comments' warn
     about comment openers found within comments (fjf1017*.pas)

   * new options `--[no-]case-value-checking' (fjf1012*.pas)

   * optimize arithmetic with a complex and a real operand
     <20020118143553.B28837@artax.karlin.mff.cuni.cz>

   * range checking
     <Pine.LNX.4.21.0012091605570.8168-100000@rusty.russwhit.com>
     (chuck5.pas, fjf446.pas, fjf989*.pas, fjf992*.pas,
     fsc{01..37}*.pas, miklos1[bc].pas,
     mir{016,021..028,030..047}*.pas, ole[12]*.pas, russ4*.pas)

   * `Exit' with an argument (non-local exits not yet supported)
     (fjf988*.pas) (U) (M)

   * new options `--[no-]propagate-units' (on by default with
     `--mac-pascal', off in other dialects) (fjf987*.pas) (M); this
     also covers the item "unit inheritance"

   * enable `Pointer' in `--mac-pascal' mode (Mac Pascal has a
     `Pointer' function which does the same as a type-cast to
     `Pointer'; though adding `Pointer' as a type allows more, it's
     backward-compatible) (M)

   * `&' and `|' (shortcut `and' and `or') (fjf981*.pas) (M)

   * `Leave' and `Cycle' (equivalent to `Break' and `Continue')
     (avo3.pas) (M)

   * optimize `WriteLn (... STRING_CONSTANT)' and `Write (...
     STRING_CONSTANT, STRING_CONSTANT ...)'

   * `BindingType' is now a packed record as EP demands (fjf975a.pas)
     (E)

   * EP structured initializers (fjf964*.pas, fjf967*.pas, fjf968*.pas)
     (E)

   * EP record, array, set values (constdef.pas, fjf966*.pas,
     fjf971*.pas) (E)

   * `gp': `PC' now sets the compiler for both Pascal and C unless `CC'
     is set explicitly

   * `Discard'

   * `Integer', `Word', `Cardinal' are now equivalent to `PtrInt',
     `PtrWord', `PtrCard', no more (necessarily) to C's `int' and
     `unsigned int' (@)

   * new types `CInteger', `CWord', `CCardinal'

   * new make variable `GPC_PAGESIZE' to set the page size when
     building the manual (PDF, PostScript, DVI)

   * `qualified' and import lists are no more allowed after `uses'
     (only after `import', as EP demands) (@)

   * the `GMP' unit doesn't support gmp-2.x anymore (if you used it,
     just upgrade to a newer GMP version) (@)

   * conflicts between object fields/methods and ancestor type names
     are detected as required by OOE (fjf945*.pas) (@) (O)

   * repeated function headings (in `forward' declarations and
     interfaces) are checked stricter: if one has a result variable, so
     must the other (according to the OOE draft) (@) (O)

   * the `Pipe' unit was renamed to `Pipes' because of a name conflict
     (@)

   * empty parameter lists can be written as `()' (chief54*.pas,
     delphi6*.pas) (D)

   * GMP unit: `mpf_sin', `mpf_cos'

   * the test suite output is now by default stored in DejaGnu
     compatible files `gpc.log' and `gpc.sum' in the `p/test/'
     directory; other available test targets are `pascal.check-short'
     and `pascal.check-long' (@)

   * new options `-W[no-]dynamic-arrays' (fjf931*.pas)

   * new argument to `_p_initialize' (@)

   * `UMask'

   * new option `--no-debug-source'

   * new lexer (no directly user-visible difference, but should allow
     for better handling of lexer-based problems in the future)

   * `CompilerAssert' (fjf904*.pas)

   * options `--[no]-assert' renamed to `--[no]-assertions' (necessary
     to avoid a conflict with GCC) (@)

   * new options `--[no-]range-checking', also as short compiler
     directives `{$R+}'/`{$R-}' (default is on) (C, E, B, @)

   * new options `--[no-]methods-always-virtual' (fjf903*.pas) (M)

   * new options `--[no-]pointer-arithmetic',
     `--[no-]cstrings-as-strings', `-W[no-]absolute' (all of which
     `--[no-]extended-syntax' implies)

   * `Integer2StringBase', `Integer2StringBaseExt'

   * new constants `NumericBaseDigits', `NumericBaseDigitsUpper'

   * allow assigning, passing by value and returning objects, with
     assignments of an object of derived type to one of a base type
     (chief35[ab].pas, fjf451*.pas, fjf696[ef].pas, fjf884*.pas), BP
     compatible except for a bug in the BP feature itself (see the
     comment in `p/test/fjf451h.pas') (B)

   * new options `-W[no-]object-assignment'

   * warn (except in `--borland-pascal') if a virtual method overrides
     a non-virtual one (chief52*.pas)

   * warn when an non-abstract object type has virtual methods, but no
     constructor (chief51*.pas)

   * `--maximum-field-alignment' does not apply to `packed' records

   * `ArcSin', `ArcCos'

   * trimming string relations as functions (`EQPad' etc.) (fjf873.pas)

   * new options `-W[no-]interface-file-name'

   * `SeekEOF' and `SeekEOLn' use `Input' implicitly when no file is
     given (fjf871.pas) (B)

   * tagging feature for `with' statements (tom6.pas)
     <200012022215.eB2MFD614424@wsinpa16.win.tue.nl> (Sun Pascal)

   * new option `--sun-pascal'

   * field names and array indices in initalizers are recognized
     (waldek5*.pas) (options `-W[no-]field-name-problem' removed, @)

   * object directives `published', `public' (both equivalent),
     `protected' (scope limited to object type and derived object
     types), `private' (scope limited to current unit/module)
     (fjf864*.pas) (options `-W[no-]object-directives' removed, @)

   * the operator precedence and associativity of `+' and `-' is now as
     defined in EP by default (and as in BP with `--borland-pascal')
     <Pine.LNX.4.44.0210251249500.6181-100000@duch.mimuw.edu.pl>
     (fjf863*.pas) (@)

   * `Integer (16)' etc. changed to `Integer attribute (Size = 16)'
     (works for integer and Boolean types) (fjf861.pas) (@)

   * types can have attributes (note: no preceding `;') (fjf860*.pas)

   * dynamic object methods (fjf859.pas) (B)

   * in `--borland-pascal' mode, `Assign' unconditionally
     (re-)initializes its file parameter (fjf858.pas) (B)

   * GPC doesn't use `gpm' files anymore (instead, each module has an
     implicit `MODULENAME-all.gpi' interface which is a regular `gpi'
     file)

   * make the program/module/unit finalizers non-public (`static' in C
     sense), omit them if easily possible

   * new options `-W[no-]parentheses' (fjf848*.pas)

   * non-`interface' modules with empty implementation part (pmod1.pas,
     fjf843.pas)

   * `maximum-field-alignment' and `[no-]field-widths' work as local
     compiler directives now (fjf842.pas)

   * dropped `{$debug-statement}' (should not be necessary anymore, now
     that debug info mostly works)

   * new options `--[no-]longjmp-all-nonlocal-labels'

   * object methods can have attributes (fjf826*.pas)

   * new attributes `iocritical' (fjf824*.pas), `ignorable'
     (fjf839*.pas) for routines

   * dropped computed `goto' (never worked for nonlocal `goto' into the
     main program, implementing it would be quite difficult, probably
     not worth it) (@)

   * new type `AnyFile' for parameters and pointer targets (fjf821*.pas)

   * `TimeStamp' is now a packed record as EP demands (fjf975b.pas) (E)

   * Mac Pascal specific features are supported according to the
     dialect options (M)

   * `--interface-only' does not require `-S' or `-c' anymore (and does
     not create an object file)

   * `initialization', `finalization' (D)

   * `TimeZone' in `TimeStamp' counts seconds _east_ of UTC now (not
     west, as before) (datetimedemo.pas) (@)

   * `export FOO = all (...)' (fjf811*.pas)

   * new options `-W[no-]local-external' (implied by `-Wall')

   * type-casts are BP compatible now, in particular, value type-casts
     between ordinal and real or complex types don't work anymore (B)
     (@)

   * all non-ISO-7185 keywords can be used as identifiers (with two
     small exceptions) (fjf440.pas)

   * `pack-struct' does not imply bit-level packing anymore (only
     explicit `packed' records and arrays do) (@)

   * new options `--[no-]ignore-packed' (`--ignore-packed' is the
     default in BP mode) (fjf796*.pas) (B) (@)

   * new option `--maximum-field-alignment=N'

   * new options `{$[no-]pack-struct}' as a compiler directive

   * `attribute' for routines doesn't imply `forward' anymore (so you
     don't have to declare routines twice in a program or
     implementation part when setting the linker name or some other
     attribute) (@)

   * `static', `volatile' and `register' for variables and `inline' for
     routines are no prefix-directives anymore, but `attribute's (@)

   * combining several dialect options (such as `--extended-pascal
     --borland-pascal') doesn't work anymore (what should this mean,
     anyway? Combine the features, but also the warnings from
     both!?!?!?) (@)

   * `external' without `name' defaults to all-lowercase now (@)

   * `c', `c_language' and `asmname' are deprecated (@)

   * `external name 'foo'' (fjf780.pas), `external 'libname' name
     'foo'' (where `libname' is ignored) (B)

   * Mac Pascal directives `definec', `macro', `undefc', `ifc',
     `ifoptc', `elsec', `elifc', `endc', `errorc' (treated as
     equivalent to the corresponding existing ones) (M)

   * units without `implementation' part (M)

   * new options `--vax-pascal', `--mac-pascal'

   * attributes `const' for variables and `name' for variables,
     routines and modules; assembler names and module/unit file names
     can now be expressions (which must yield string constants)
     (fjf781*.pas, fjf809*.pas)

   * the utilities `gpidump' and `binobj' are installed with GPC (B)

   * new options `-W[no-]identifier-case',
     `-W[no-]identifier-case-local' (fjf751*.pas)

   * new compiler directive `$R foo', equivalent to `$L foo.resource'
     (B)

   * dropped `--[no-]borland-char-constants' (now simply coupled to
     dialect options) (@)

   * test suite: support progress messages (`TEST_RUN_FLAGS=-p' from
     the Makefile; `-p' in testgpc); see
     `http://fjf.gnu.de/misc/progress-messages.tar.gz'

   * `=' and `<>' comparisons of structures (arrays, records, ...)
     except strings and sets are forbidden now (@) (E)

   * irrelevant operands and arguments (e.g.: `foo in []'; `bar * []';
     `Im (baz)' if `baz' is of real type) are not necessarily evaluated
     anymore (which is allowed by the standard); instead, a warning is
     given if they have side-effects (@)

   * accept only one program, unit, module interface or implementation
     or a module interface and the implementation of the same module in
     one file; new options `--[no-]ignore-garbage-after-dot'
     (fjf735*.pas) (@)

   * new options `-W[no-]implicit-io' (fjf734*.pas)

   * new options `--enable-keyword', `--disable-keyword' (fjf733*.pas)

   * `CBoolean' (fjf727.pas)

   * dropped the usage of `GetMem' as a function with one parameter
     (only the BP compatible usage as a procedure with two parameters
     remains) (@)

   * accessing the variable `FileMode' now requires using the `GPC'
     (or, for BP compatibility, the `System') unit (@)

   * `DupHandle'

   * dropped the predefined dialect symbols `__CLASSIC_PASCAL__',
     `__STANDARD_PASCAL__', `__EXTENDED_PASCAL__', `__OBJECT_PASCAL__',
     `__UCSD_PASCAL__', `__BORLAND_PASCAL__', `__DELPHI__',
     `__PASCAL_SC__' and `__GNU_PASCAL__' (one can use `{$ifopt
     borland-pascal}' etc. instead) (@)

   * `Succ', `Pred', `Inc', `Dec' for real numbers (fjf714*.pas)

   * use environment variables `GPC_UNIT_PATH', `GPC_OBJECT_PATH'

   * new options `-W[no-]float-equal'

   * new option `--ucsd-pascal'

   * dropped the syntax `type foo = procedure (Integer, Real)' (i.e.,
     without parameter names) (@)

   * CRT: new argument `On' to `CRTSavePreviousScreen'

   * `SetUserID', `SetGroupID'

   * `HeapChecking'

   * new built-in procedure `Assert'; new options `--[no]-assert' (also
     `{$C+}', `{$C-}' for Delphi compatibility) (fjf665*.pas) (D)

   * `ProcessGroup'

   * StringUtils: `QuoteEnum'

   * `CurrentRoutineName' (fjf752.pas)

   * TFDD: new unit

   * gpc-run: new options `-e FILE' and `-E FILE' (redirect/append
     standard error)

   Have fun,

   The GNU Pascal Development Team


File: gpc.info,  Node: FAQ,  Next: Installation,  Prev: News,  Up: Top

3 The GNU Pascal Frequently Asked Questions List.
*************************************************

   This is the Frequently Asked Questions List (FAQ) for GNU Pascal. If
the FAQ and the documentation do not help you, you have detected a
*bug* in it which should be reported, *Note Mailing List::.  Please
really do it, so we can improve the documentation.

* Menu:

* GNU Pascal::          GNU Pascal
* Installing GPC::      Installing GPC
* GPC on DJGPP::        GNU Pascal on the DJGPP (MS-DOS) platform
* Strings in GPC::      Strings
* Getting Help::        Getting Help
* Miscellaneous FAQ::   Miscellaneous


File: gpc.info,  Node: GNU Pascal,  Next: Installing GPC,  Up: FAQ

3.1 GNU Pascal
==============

* Menu:

* What and why::                What and why?
* Current version::             What is the current version?
* Turbo Pascal compatibility::  Is it compatible with Turbo Pascal (R)?
* Supported platforms::         Which platforms are supported by GNU Pascal?


File: gpc.info,  Node: What and why,  Next: Current version,  Up: GNU Pascal

3.1.1 What and why?
-------------------

The purpose of the GNU Pascal project is to produce a Pascal compiler
(called GNU Pascal or GPC) which

   * combines the clarity of Pascal with powerful tools suitable for
     real-life programming,

   * supports both the Pascal standard and the Extended Pascal standard
     as defined by ISO, ANSI and IEEE (ISO 7185:1990, ISO/IEC
     10206:1991, ANSI/IEEE 770X3.160-1989),

   * supports other Pascal standards (UCSD Pascal, Borland Pascal,
     parts of Borland Delphi, Mac Pascal and Pascal-SC) in so far as
     this serves the goal of clarity and usability,

   * may be distributed under GNU license conditions, and

   * can generate code for and run on any computer for which the GNU C
     compiler can generate code and run on.

   Pascal was originally designed for teaching. GNU Pascal provides a
smooth way to proceed to challenging programming tasks without learning
a completely different language.

   The current release implements Standard Pascal (ISO 7185, levels 0
and 1), most of Extended Pascal (ISO 10206, aiming for full
compliance), is highly compatible to Borland Pascal (version 7.0), has
some features for compatibility to other compilers (such as VAX Pascal,
Sun Pascal, Mac Pascal, Borland Delphi and Pascal-SC).

   It provides a lot of useful GNU extensions not found in other Pascal
compilers, e.g. to ease the interfacing with C and other languages in a
portable way, and to work with files, directories, dates and more,
mostly independent of the underlying operating system.

   Included units provide support for regular expressions, arithmetic
with integer, rational and real numbers of unlimited size,
internationalization, inter-process communication, message digests and
more. Demo programs show the usage of these units and of many compiler
features.


File: gpc.info,  Node: Current version,  Next: Turbo Pascal compatibility,  Prev: What and why,  Up: GNU Pascal

3.1.2 What is the current version?
----------------------------------

The current version is 20060325.

   Releases are available as a source archive and precompiled binaries
for several common platforms from the GPC web site,
`http://www.gnu-pascal.de'.

   For details about new features, see the section `News' on the web
site. On bugs fixed recently, see the `Done' section of the To-Do list
(on the same web site).

   GPC uses GCC as a back-end. It supports GCC version 2.8.1, 2.95.x,
3.2.x, 3.3.x or 3.4.x. (The newest supported GCC version is usually
preferable, unless it contains serious bugs in itself.)

   There are no fixed time frames for new releases. Releases are made
when enough interesting changes have been made and the compiler is
somewhat stable.


File: gpc.info,  Node: Turbo Pascal compatibility,  Next: Supported platforms,  Prev: Current version,  Up: GNU Pascal

3.1.3 Is it compatible with Turbo Pascal (R)?
---------------------------------------------

GPC is not a drop-in replacement for Borland's Turbo Pascal (R).
Almost all BP language features are supported. Notable exceptions are
the string format (as discussed below), or the `Mem' and `Port' pseudo
arrays, though replacement functions for the latter on IA32 platforms
exist in the `Ports' unit.

   Almost all of BP's run time library is supported in GPC, either by
built-in compiler features or in units with the same names as their BP
counterparts.

   For details about the compatibility, the few remaining
incompatibilities and some useful alternatives to BP features, see the
`Borland Pascal' chapter in the GPC Manual.  (*note Borland Pascal::)


File: gpc.info,  Node: Supported platforms,  Prev: Turbo Pascal compatibility,  Up: GNU Pascal

3.1.4 Which platforms are supported by GNU Pascal?
--------------------------------------------------

GPC uses the GCC backend, so it should run on any system that is
supported by GNU CC. This includes a large variety of Unix systems,
MS-DOS, OS/2 and Win32. A full list of platforms supported by GCC can
be found in the file `INSTALL' of the GCC distribution. Not all of
these have actually been tested, but it is known to run on these
platforms:

ix86-gnu                      (GNU Hurd)
ix86-linux                    (Linux 2.x, ELF)
Linux/AMD64                   
i486-linuxaout                
i486-linuxoldld               
i386-freebsd1.2.0             
AIX 4.2.1                     
AIX 4.3                       
DJGPP V2                      (Dos)
EMX 0.9B                      (OS/2, Dos)
Cygwin32 beta20 and higher    (MS-Windows95/98, MS-Windows NT)
mingw32                       (MS-Windows95/98, MS-Windows NT)
MSYS                          (MS-Windows)
Mac OS/X 10.3                 
mips-sgi-irix5.3              
mips-sgi-irix6.5              
sun-sparc-sunos4.1.4          
sparc-sun-solaris2.x          
sun-sparc-solaris 2.5.1       
sun-sparc-solaris 2.6         
sun-sparc-solaris 7           
sun-sparc-solaris 8           
alpha-unknown-linux           
alpha-dec-osf4.0b             
s390-ibm-linux-gnu            

   *OK people - send us your success stories, with canonical machine
name!*


File: gpc.info,  Node: Installing GPC,  Next: GPC on DJGPP,  Prev: GNU Pascal,  Up: FAQ

3.2 Installing GPC
==================

You find the most up-to-date installation instructions in the GPC
Manual or the file `INSTALL' in source distributions, or on the GPC web
site.  (*note Installation::)

   The following sections describe things you might need or want to
install besides GPC itself.

* Menu:

* Documentation files::  What to read next
* Components::           Which components do I need to compile Pascal code?
* Debugger::             How do I debug my Pascal programs?
* Libraries::            What additional libraries should I have?
* Contributed units::    Contributed units
* IDE::                  Can you recommend an IDE?


File: gpc.info,  Node: Documentation files,  Next: Components,  Up: Installing GPC

3.2.1 What to read next
-----------------------

After installing GPC, please check the files in the directory
`/usr/local/doc/gpc':

`README'           General Information about GPC
`FAQ'              This FAQ :-)
`NEWS'             Changes since the last release
`BUGS'             How to report bugs, about the Test Suite
`AUTHORS'          List of GPC authors
`COPYING'          The GNU General Public License
`COPYING.LIB'      The GNU Lesser General Public License


File: gpc.info,  Node: Components,  Next: Debugger,  Prev: Documentation files,  Up: Installing GPC

3.2.2 Which components do I need to compile Pascal code?
--------------------------------------------------------

A complete Pascal compiler system should at least have:

  1. The actual compiler, GPC.

  2. An editor, assembler, linker, librarian and friends.

  3. A C library. If you have a working C compiler, you already have
     this.

  4. A debugger, if you want to debug your programs.

   For most people, the GNU binutils and GNU debugger (`gdb') are a
good choice, although some may prefer to use vendor specific tools.


File: gpc.info,  Node: Debugger,  Next: Libraries,  Prev: Components,  Up: Installing GPC

3.2.3 How do I debug my Pascal programs?
----------------------------------------

To debug your programs, (a) GNU Pascal must be able to generate
executables with debug info for your platform, and (b) you must have a
debugger which understands this.

   * If `gpc -g -o hello hello.p' says:
          gpc: -g not supported for this platform
     then GPC is unable to generate debugging info. Usually, installing
     `gas' (part of GNU binutils) instead of your system's assembler
     can overcome this. When you configure the GCC used for GPC, specify
     `--with-gnu-as', and possibly `--with-gnu-ld' and/or
     `--with-stabs'. More information can be found in the `INSTALL'
     file in the GNU CC source directory.

   * Your system's debugger may not understand the debug info generated
     by GNU tools. In this case, installing `gdb' may help.

   The bottom line: if you can debug GCC compiled programs, you should
be able to do this with GPC too.

   The GNU debugger (`gdb') currently does not have a "Pascal" mode, so
it is unable to display certain Pascal structures etc. When debugging,
please note that the Initial Letter In Each Identifier Is In Upper Case
And The Rest Are In Lower Case. If you want to display variable `foo'
in the debugger, type `show Foo' or `display Foo' instead.

   Although `gdb' is an excellent debugger, it's user interface is not
everybody's preference. If you like to debug under X11, please refer to
the comp.windows.x FAQ: "Where can I get an X-based debugger?" at:
`http://www.faqs.org/faqs/x-faq/part6/section-2.html'

   Some useful frontends include: XXGDB, tGDB and XWPE. See:
`http://www.ee.ryerson.ca:8080/~elf/xapps/Q-IV.html'

   Very nice, but resource consuming is the Motif based DDD:
`http://sol.ibr.cs.tu-bs.de/softech/ddd/'

   Furthermore, RHIDE (*note IDE::) contains built-in debugging suport,
similar to the IDE of BP.


File: gpc.info,  Node: Libraries,  Next: Contributed units,  Prev: Debugger,  Up: Installing GPC

3.2.4 What additional libraries should I have?
----------------------------------------------

You will need certain additional libraries when you compile some of the
units. These can be found in the directory
`http://www.gnu-pascal.de/libs/'.

   Currently, there are the following libraries:

gmp
     Arithmetic for integers, rationals and real numbers with arbitrary
     size and precision. Used by the GMP unit.

rx
     Regular expression matching and substitution. Used by the RegEx
     unit.

ncurses
PDCurses
     Screen handling. Used by the CRT unit. Depending on your system,
     you have the following choices:

     Unix: You can compile terminal applications with ncurses and
     applications that run in an X11 window with PDCurses (though
     terminal applications can, of course, also run in an xterm under
     X11). ncurses is used by default. If you want to use PDCurses
     (a.k.a. XCurses), give the option `-DX11' when compiling CRT.

     Dos with DJGPP and MS-Windows with mingw: Only PDCurses is
     available and will be used by default.

     MS-Windows with Cygwin: PDCurses and ncurses are available.
     PDCurses is used by default. If you want to use ncurses, give the
     option `-DUSE_NCURSES' when compiling CRT.

     Other systems: Please see the `README's and installation
     instructions of PDCurses and ncurses to find out which one(s) can
     be built on your system. See the conditionals at the end of
     crt.inc and crtc.h (and change them if necessary) on which library
     is used by default.

intl
     Internationalization. Used by the Intl unit. On some systems, it is
     part of the system library (libc).

ElectricFence
     This library is not used by any GPC unit. It is a debugging tool to
     assist you in finding memory allocation bugs. To use it, just link
     it to your program, either on the command line (`-lefence') or in
     the source code (`{$L efence}') which you might want to put into
     an `{$ifdef DEBUG}' or similar since using libefence is only
     recommended for debugging.

   The source code of the libraries is available in the main `libs'
directory. Most libraries come with one or several patches which should
be applied before compiling them.

   Binaries for some platforms are available in the `binary/PLATFORM'
subdirectories. If you compile the libraries for other platforms, be
invited to make the binaries available to us for distribution on the
web site.

   There are also the following files:

`terminfo-linux.tar.gz'
     This is a patch to enable ncurses programs to make use of the
     ability of Linux 2.2 and newer kernels to produce a block cursor
     when needed. The present patch can be installed without recompiling
     anything, just by copying some files into place. More details can
     be found in the `README' file included in this archive. The patch
     will not do any harm on older kernels. Please note that *not* only
     on Linux machines it is useful to install the patch. Installing
     them on any other machine will allow users who telnet in from a
     Linux console to profit from the block cursor capability. Besides,
     some Unix systems have installed older Linux terminfo entries or
     none at all, so it's a good thing, anyway, to give them a current
     version. The patch is included in the terminfo database of ncurses
     5.0, so if you install ncurses 5.0 (source or binary), you don't
     need to get the patch separately. But you can install it on a
     system with an older ncurses version if you don't feel like
     upgrading ncurses altogether.

`tsort-2.9i.zip'
     A little utility (extracted from util-linux-2.9i, but not Linux
     specific), needed for the configuration of the rx library. You
     need it only if you compile rx yourself (and if it's not already
     present on your system), not when using a rx binary.


File: gpc.info,  Node: Contributed units,  Next: IDE,  Prev: Libraries,  Up: Installing GPC

3.2.5 Contributed units
-----------------------

Several people have contributed units for GPC. They are usually
announced on the mailing list, *Note Mailing List::. Most of them can
be found in `http://www.gnu-pascal.de/contrib/'.


File: gpc.info,  Node: IDE,  Prev: Contributed units,  Up: Installing GPC

3.2.6 Can you recommend an IDE?
-------------------------------

Users of Borland Pascal may wonder if there's a replacement for the IDE
(Integrated Development Environment). Here's a few suggestions:

   * (X)Emacs. Some people think it's the answer to the question of
     Life, the Universe and Everything, others decide it's uGNUsable.
     Available from your friendly GNU mirror and most distributions.

   * PENG. It's not free software, but it was written with GPC.  It's
     very similar to Borland's IDE, but with many extensions.  Binaries
     for DJGPP, Linux and Solaris can be downloaded from
     `http://fjf.gnu.de/peng/'.

   * RHIDE. DJGPP users might want to try RHIDE. The latest (beta)
     release is compatible with GNU Pascal and allows stepping, tracing
     and watching like Borland's IDE. It can be downloaded from
     `http://www.rhide.com'.

   * DevPascal. DevPascal is a Free Software IDE for mingw32. It can be
     downloaded from `http://www.gnu-pascal.de/contrib/chief/' or
     `http://www.bloodshed.net/devpascal.html'

   * XWPE is another imitation of the Borland IDE, so users of Borland
     Pascal may find it a good alternative.


File: gpc.info,  Node: GPC on DJGPP,  Next: Strings in GPC,  Prev: Installing GPC,  Up: FAQ

3.3 GNU Pascal on the DJGPP (MS-DOS) platform
=============================================

This chapter discusses some potential problems with GNU Pascal on
MS-DOS, using DJGPP.

* Menu:

* What is DJGPP::            What is DJGPP?
* DJGPP FAQ::                If you need more information
* DJGPP download::           What do I download?
* Installing GPC on DJGPP::  How do I install the compiler?
* DJGPP Info reader::        I cannot read the Info documentation!
* DJGPP DPMI server::        GPC says: no DPMI
* Assembler syntax::         I have troubles with assembly code
* DJGPP specific code::      Tell me how to do DPMI, BIOS and
                             other DOS related things.
* Stack size::               I got an exception when accessing an
                             `array [1 .. 4000000] of Byte'.


File: gpc.info,  Node: What is DJGPP,  Next: DJGPP FAQ,  Up: GPC on DJGPP

3.3.1 What is DJGPP?
--------------------

The following paragraph is from the site
`http://www.delorie.com/djgpp/':

   DJGPP is a complete 32-bit C/C++ development system for Intel 80386
(and higher) PCs running DOS. It includes ports of many GNU development
utilities. The development tools require a 80386 or newer computer to
run, as do the programs they produce. In most cases, the programs it
produces can be sold commercially without license or royalties.


File: gpc.info,  Node: DJGPP FAQ,  Next: DJGPP download,  Prev: What is DJGPP,  Up: GPC on DJGPP

3.3.2 If you need more information
----------------------------------

GPC/DJGPP is a DJGPP V2 application, and most of the DJGPP
documentation applies for GPC too. A great source of information is the
DJGPP FAQ: `http://www.delorie.com/djgpp/v2faq/230b.zip'

   Another place to look for DJGPP documentation is the DJGPP Knowledge
Base, at this URL: `http://www.delorie.com/djgpp/doc/kb/'


File: gpc.info,  Node: DJGPP download,  Next: Installing GPC on DJGPP,  Prev: DJGPP FAQ,  Up: GPC on DJGPP

3.3.3 What do I download?
-------------------------

As discussed in *Note Components::, other than GPC itself, you need an
assembler, linker and friends, a C library and possibly a debugger.
The site `http://www.delorie.com/djgpp/' recommended the following
files and they will help you find a mirror:

`v2/djdev203.zip'       (C library)
`v2gnu/bnu2951b.zip'    (assembler, ...)
`v2gnu/gcc2952b.zip'    (gcc)
`v2gnu/gdb418b.zip'     (debugger)
`v2gnu/mak379b.zip'     (make)
`v2gnu/txi40b.zip'      (texi)

   This list is about 10 MB not counting GPC. You can use a binary
version of GPC from the web site.


File: gpc.info,  Node: Installing GPC on DJGPP,  Next: DJGPP Info reader,  Prev: DJGPP download,  Up: GPC on DJGPP

3.3.4 How do I install the compiler?
------------------------------------

If you don't have DJGPP installed on your harddisk, create a directory
for GNU Pascal (`c:\gpc'), and unzip the archives.  Make sure you
preserve the directory structure (use `pkunzip -d'). Now, add the
directory where `gpc.exe' lives (`c:\gpc\bin') to your path and set the
DJGPP environment variable to point to your `djgpp.env' file:

     set DJGPP=c:\gpc\djgpp.env

   Then, add this to your `djgpp.env' file:

     ---------------------------------------------------------
     [gpcpp]
     C_INCLUDE_PATH=%/>;C_INCLUDE_PATH%%DJDIR%/lang/pascal;%DJDIR%/include

     [gpc]
     COMPILER_PATH=%/>;COMPILER_PATH%%DJDIR%/bin
     LIBRARY_PATH=%/>;LIBRARY_PATH%%DJDIR%/lib;%DJDIR%/contrib/grx20/lib
     ---------------------------------------------------------

   The GPC online documentation is in GNU info format; you need the
Info reader (`txi390b.zip') to read it, or use the built-in Info reader
of the RHIDE or PENG IDE. To add the GPC documentation to the info
directory file, edit the `c:\gpc\info\dir' file, and locate this
section:

     ---------------------------------------------------------
     * GCC: (gcc.inf).
     The GNU C, C++, and Objective-C Compiler

     * GDB: (gdb.inf).
     The GNU Debugger (gdb and gdb-dpmi).

     ---------------------------------------------------------

   To add GPC, change it to look like this:

     ---------------------------------------------------------
     * GCC: (gcc.inf).
     The GNU C, C++, and Objective-C Compiler

     * GPC: (gpc.inf).
     The GNU Pascal Compiler

     * GDB: (gdb.inf).
     The GNU Debugger (gdb and gdb-dpmi).

     ---------------------------------------------------------

   Specific information for low-memory conditions and more can be found
in the DJGPP FAQ and documentation.


File: gpc.info,  Node: DJGPP Info reader,  Next: DJGPP DPMI server,  Prev: Installing GPC on DJGPP,  Up: GPC on DJGPP

3.3.5 I cannot read the Info documentation!
-------------------------------------------

To read the Info documentation, you need the `info' program from
`txi390b.zip' or an IDE like RHIDE or PENG.


File: gpc.info,  Node: DJGPP DPMI server,  Next: Assembler syntax,  Prev: DJGPP Info reader,  Up: GPC on DJGPP

3.3.6 GPC says: no DPMI
-----------------------

You don't have a DPMI server installed, and DJGPP v2 requires it to
run. You can either use one of the commercial DPMI servers (e.g., run
`gpc' in a DOS box under MS-Windows) or download and install CWSDPMI
(`csdpmi3b.zip') which is a free DPMI server written for DJGPP.


File: gpc.info,  Node: Assembler syntax,  Next: DJGPP specific code,  Prev: DJGPP DPMI server,  Up: GPC on DJGPP

3.3.7 I have troubles with assembly code
----------------------------------------

The GNU Assembler (`as.exe'), or `gas', called by GCC accepts "AT&T"
syntax which is different from "Intel" syntax.  Differences are
discussed in section 17.1 of the DJGPP FAQ.

   A guide is available which was written by Brennan Mr. Wacko
Underwood <brennan@mack.rt66.com> and describes how to use inline
assembly programming with DJGPP, at this URL:
`http://www.delorie.com/djgpp/doc/brennan/brennan_att_inline_djgpp.html'

   There's also a GPC assembler tutorial at
`http://www.gnu-pascal.de/contrib/misc/gpcasm.zip'

   Section 17.3 of the DJGPP FAQ discusses some methods to convert
"Intel" syntax to "AT&T" syntax.

   However, please note that assembler code is unportable, i.e. it will
work on IA32 ("x86") and compatible processors if written for them, but
will not even compile for other processors. So by writing assembler
code in your programs, you will limit their usefulness substantially.

   If you think you "need" assembler code for speed - and you've
checked that your assembler code actually runs faster than Pascal code
compiled with suitable optimizations - you might want to put both
Pascal and assembler versions of the critical sections in your program,
and let, e.g., an `{$ifdef i386}' decide which one to use. This way,
your program will at least compile on all processors.


File: gpc.info,  Node: DJGPP specific code,  Next: Stack size,  Prev: Assembler syntax,  Up: GPC on DJGPP

3.3.8 Tell me how to do DPMI, BIOS and other DOS related things.
----------------------------------------------------------------

DPMI, BIOS and other functions are no different than other system
functions. Refer to the GPC Manual on how to access your system's
C-library. This small example shows how to use DPMI, copying some
structures and function prototypes of `<dpmi.h>':

     program DPMIDemo;

     { Only for DJGPP }

     {$X+}

     { `Byte' is `unsigned char' in C,
       `ShortCard' is `unsigned short' in C,
       `MedCard' is `unsigned long' in C,
       `Word' is `unsigned' in C,
       etc. (all these types are built-in). }

     type
       TDpmiVersionRet = record
         Major     : Byte;
         Minor     : Byte;
         Flags     : ShortCard;
         CPU       : Byte;
         Master_PIC: Byte;
         Slave_PIC : Byte;
       end;

     type
       TDpmiFreeMemInfo = record
         LargestAvailableFreeBlockInBytes,
         MaximumUnlockedPageAllocationInPages,
         MaximumLockedPageAllocationInPages,
         LinearAddressSpaceSizeInPages,
         TotalNumberOfUnlockedPages,
         TotalNumberOfFreePages,
         TotalNumberOfPhysicalPages,
         FreeLinearAddressSpaceInPages,
         SizeOfPagingFilePartitionInPages,
         Reserved1,
         Reserved2,
         Reserved3: MedCard;
       end;

     function DpmiGetVersion (var Version: TDpmiVersionRet): Integer;
              external name '__dpmi_get_version';

     function DpmiGetFreeMemoryInformation
              (var MemInfo: TDpmiFreeMemInfo): Integer;
              external name '__dpmi_get_free_memory_information';

     var
       Version: TDpmiVersionRet;
       MemInfo: TDpmiFreeMemInfo;

     begin
       if DpmiGetVersion (Version) = 0 then
         begin
           WriteLn ('CPU type:       ', Version.CPU, '86');
           WriteLn ('DPMI major:       ', Version.Major);
           WriteLn ('DPMI minor:       ', Version.Minor);
         end
       else
         WriteLn ('Error in DpmiGetVersion');
       if DpmiGetFreeMemoryInformation (MemInfo) = 0 then
         WriteLn ('Free DPMI memory: ',
                  MemInfo.TotalNumberOfFreePages, ' pages.')
       else
         WriteLn ('Error in DpmiGetMemoryInformation');
     end.


File: gpc.info,  Node: Stack size,  Prev: DJGPP specific code,  Up: GPC on DJGPP

3.3.9 I got an exception when accessing an `array [1 .. 4000000] of Byte'.
--------------------------------------------------------------------------

Per default, the maximum stack size of a DJGPP application is 256K.  If
you need more, you have to adjust it with the stubedit program, i.e.:

     stubedit your_app.exe minstack=5000K

   Another way is to add the following code to your program to define a
minimum stack size (here: 2 MB). This value will be honored even if a
user sets a lower value by using stubedit, so this method might be a
little safer. (The linker name `_stklen' is essential; the Pascal
identifier doesn't matter. The constant doesn't have to be used
anywhere in the program. It is recommended to put this declaration in
the main program file, not in any unit/module, so programs using a
unit/module can set whatever limit they need.)

     {$ifdef __GO32__}
     const
       MinStackSize: Cardinal = $200000; attribute (name = '_stklen');
     {$endif}

   Still, it might be a good idea to use pointers for large structures,
and allocate the memory at runtime.

   DJGPP has to allocate the stack in physical memory at program
startup, so one might have to be careful with too large stack limits.
Most other systems allocate stack pages on demand, so the only reason
to set a limit at all might be to prevent a runaway recursion from
eating up all memory ...

   On Unix-like systems, you can set a resource limit, but you usually
don't do it in normal programs, but rather in the shell settings (bash:
`ulimit'; csh: `limit'; syscall: `setrlimit'(2)).


File: gpc.info,  Node: Strings in GPC,  Next: Getting Help,  Prev: GPC on DJGPP,  Up: FAQ

3.4 Strings
===========

* Menu:

* String schema::                What's this confusion about strings?
* Strings in variant records::   Overlaying strings in variant records
* Length byte::                  Why does `s[0]' not contain the length?
* Strings as value parameters::  Watch out when using strings as parameters
* Short strings::                Support for BP compatible short strings
* C strings::                    What about C strings?


File: gpc.info,  Node: String schema,  Next: Strings in variant records,  Up: Strings in GPC

3.4.1 What's this confusion about strings?
------------------------------------------

Turbo Pascal strings have a length byte in front. Since a byte has the
range 0 .. 255, this limits a string to 255 characters. However, the
Pascal string schema, as defined in section 6.4.3.3.3 of the ISO 10206
Extended Pascal standard, is a schema record:

     type
       String (Capacity: Integer) = record
         Length: 0 .. Capacity;
         String: packed array [1 .. Capacity + 1] of Char
       end;

   The `+ 1' is a GPC extension to make it feasible to automatically
add the `#0' terminator when passing or assigning them to CStrings.
Thus at the expense of a little added complexity (must declare
capacity, don't use `GetMem' without explicit initialization of the
`Capacity' field, and the additional space requirement) you can now
have very long strings.


File: gpc.info,  Node: Strings in variant records,  Next: Length byte,  Prev: String schema,  Up: Strings in GPC

3.4.2 Overlaying strings in variant records
-------------------------------------------

Q: Should the different variants in a variant record overlay in the
same memory? Previous Pascals I have used have guaranteed this, and
I've got low-level code that relies on this. The variants are not the
same length, and they are intended not to be.

   A: No, this is intentional so that the discriminants are not
overwritten, and they can be properly initialized in the first place.
Consider:

     record
     case Boolean of
       False: (s1: String (42));
       True:  (s2: String (99));
     end;

   If the strings would overlay, in particular their discriminants
would occupy the same place in memory. How should it be initialized?
Either way, it would be wrong for at least one of the variants ...

   So, after a discussion in the ISO Pascal newsgroup
(news:comp.lang.pascal.ansi-iso) where this topic came up concerning
file variables (which also require some automatic initialization and
finalization), we decided to do this in GPC for all types with
automatic initialization and finalization (currently files, objects and
schemata, including strings, in the future this might also be Delphi
compatible classes and user-defined initialized and finalized types),
since the standard does not guarantee variants to overlay, anyway ...

   There are two ways in GPC to get guaranteed overlaying (both
non-standard, of course, since the standard does not assume anything
about internal representations; both BP compatible), `absolute'
declarations and variable type casts. E.g., in order to overlay a byte
array `b' to a variable `v':

     var
       b: array [1 .. SizeOf (v)] of Byte absolute v;

   Or you can use type-casting:

     type
       t = array [1 .. SizeOf (v)] of Byte;

   then `t (v)' can be used as a byte array overlayed to `v'.


File: gpc.info,  Node: Length byte,  Next: Strings as value parameters,  Prev: Strings in variant records,  Up: Strings in GPC

3.4.3 Why does `s[0]' not contain the length?
---------------------------------------------

Q: In standard Pascal you expect `s[1]' to align with the first
character position of `s' and thus one character to the left is the
length of `s'. Thus `s[0]' is the length of `s'.  True?

   A: This holds for UCSD/BP strings (which GPC does not yet implement,
but that's planned). The only strings Standard Pascal knows are arrays
of char without any length field.

   GPC also supports Extended Pascal string schemata (*note String
schema::), but they also don't have a length byte at "position 0", but
rather a `Length' field (which is larger than one byte).


File: gpc.info,  Node: Strings as value parameters,  Next: Short strings,  Prev: Length byte,  Up: Strings in GPC

3.4.4 Watch out when using strings as parameters
------------------------------------------------

Q: Any "gotchas" with string parameters?

   A: Be careful when passing string literals as parameters to routines
accepting the string as a value parameter and that internally modify
the value of the parameter. Inside the routine, the value parameter
gets a fixed capacity - the length of the string literal that was
passed to it. Any attempt to assign a longer value will not work.

   This only applies if the value parameter is declared as `String'. If
it is declared as a string with a given capacity (e.g., `String
(255)'), it gets this capacity within the routine.


File: gpc.info,  Node: Short strings,  Next: C strings,  Prev: Strings as value parameters,  Up: Strings in GPC

3.4.5 Support for BP compatible short strings
---------------------------------------------

Q: Two different kinds of strings with the same name - `String' - does
make a bit of confusion. Perhaps the oldstyle strings could be renamed
`short string' ?

   A: When we implement the short strings, we'll have to do such a
distinction. Our current planning goes like this:

   `String (N)': string schema (EP compatible)

   `String [N]': short string (UCSD/BP compatible, where N must be <=
255)

   `String': dependent on flags, by default undiscriminated schema, but
in BP mode (or with a special switch) short string of capacity 255
(UCSD/BP compatible).

   Q: So when will these short strings be available?

   A: It's been planned for some years. The delay has been caused by
more pressing problems.


File: gpc.info,  Node: C strings,  Prev: Short strings,  Up: Strings in GPC

3.4.6 What about C strings?
---------------------------

A C string (`char *') is an array of char, terminated with a `#0' char.

   C library functions require C, not Pascal style string arguments.
However, Pascal style strings are automatically converted to C style
strings when passed to a routine that expects C style strings. This
works only if the routine reads from the string, not if it modifies it.

   E.g., this is how you could access the `system()' call in your C
library (which is not necessary anymore, since `Execute' is already
built-in):

     program SysCall;

     function System (CmdLine: CString): Integer; external name 'system';

     var
       Result: Integer;

     begin
       Result := System ('ls -l');
       WriteLn ('system() call returned: ', Result)
     end.

   You could use the type `PChar' instead of `CString'. Both `CString'
and `PChar' are predefined as `^Char' - though we recommend `CString'
because it makes it clearer that we're talking about some kind of
string rather than a single character.

   A lot of library routines in Pascal for many applications exist in
the GPC unit and some other units. Where available, they should be
preferred (e.g. `Execute' rather than `system()', and then you won't
have to worry about `CString's.)

   Do *not* pass a C style string as a `const' or `var' argument if the
C prototype says `const char *' or you will probably get a segfault.


File: gpc.info,  Node: Getting Help,  Next: Miscellaneous FAQ,  Prev: Strings in GPC,  Up: FAQ

3.5 Getting Help
================

Please read the GPC Manual (info files or other formats) as well as the
`README' and `BUGS' files that come with GPC (usually installed in
directory `/usr/local/doc/gpc'), plus other docs that might help (the
DJGPP FAQ if you use DJGPP, etc.) before you send email to the
maintainers or mailing list.

   In particular, the `BUGS' file contains information on how to submit
bug reports in the most efficient way.

   The `Support' chapter of the GPC Manual tells you where to find more
information about GPC and how to contact the GPC developers.  (*note
Support::)


File: gpc.info,  Node: Miscellaneous FAQ,  Prev: Getting Help,  Up: FAQ

3.6 Miscellaneous
=================

* Menu:

* Contributing::   I want to contribute; where do I start?
* GPC web site::   Where is the GNU Pascal web site?
* About the FAQ::  About this FAQ


File: gpc.info,  Node: Contributing,  Next: GPC web site,  Up: Miscellaneous FAQ

3.6.1 I want to contribute; where do I start?
---------------------------------------------

If you want to contribute, please write to the mailing list, *Note
Mailing List::.


File: gpc.info,  Node: GPC web site,  Next: About the FAQ,  Prev: Contributing,  Up: Miscellaneous FAQ

3.6.2 Where is the GNU Pascal web site?
---------------------------------------

The GPC homepage on the web, for information and downloads, is
`http://www.gnu-pascal.de'.

   The GPC To-Do list, listing the latest features and fixed bugs can
also be found there.


File: gpc.info,  Node: About the FAQ,  Prev: GPC web site,  Up: Miscellaneous FAQ

3.6.3 About this FAQ
--------------------

Current Maintainer: Russ Whitaker, <russ@ashlandhome.net>

   This is the second incarnation of the GNU Pascal FAQ list, based on
the previous FAQ by J.J. van der Heijden. Comments about, suggestions
for, or corrections to this FAQ list are welcome.

   Please make sure to include in your mail the version number of the
document to which your comments apply (you can find the version at the
beginning of this FAQ list).

   Many people have contributed to this FAQ, only some of them are
acknowledged above. Much of the info in, and inspiration for this FAQ
list was taken from the GPC mailing list traffic, so you may have
(unbeknownst to you) contributed to this list.


File: gpc.info,  Node: Installation,  Next: Invoking GPC,  Prev: FAQ,  Up: Top

4 How to download, compile and install GNU Pascal.
**************************************************

* Menu:

* Download::              Where and what to download
* Binary Distributions::  How to install a binary distribution
* Compiling GPC::         How to compile GPC
* Compilation Notes::     Compilation notes for specific platforms
* Cross-Compilers::       Building and Installing a cross-compiler
* Crossbuilding::         Crossbuilding a compiler


File: gpc.info,  Node: Download,  Next: Binary Distributions,  Up: Installation

4.1 Where and what to download
==============================

You can download the source code of the current GNU Pascal release from
     `http://www.gnu-pascal.de/current/'
   and binaries for some platforms from
     `http://www.gnu-pascal.de/binary/'

   The binary archive files are named `gpc-VERSION.PLATFORM.EXTENSION'
- for example `gpc-2.1.alpha-unknown-linux-gnu.tar.gz' for GPC version
2.1 on an Alpha workstation running the Linux kernel with GNU C
Library, or `gpc-20000616.i386-pc-msdosdjgpp' for GPC version 20000616
on an Intel IA32 compatible PC running DOS with DJGPP.

   After you have downloaded the correct archive file for your
platform, please read the installation notes on how to install such a
binary distribution.

   If you are running Dos or MS Windows, you will need additional tools
- see "What else to download and where" below.

Current snapshots
-----------------

GNU Pascal is subject to steady development. Alpha and beta snapshots
(source only, use at your own risk) can be found at:

     `http://www.gnu-pascal.de/alpha/'
     `http://www.gnu-pascal.de/beta/'

What else to download and where
-------------------------------

When you are using GNU Pascal on a DOS system, you will need either the
DJGPP or the EMX development environment (see below). On an OS/2
system, you will need EMX. On an MS Windows 95/98/NT system you will
need either the CygWin or the mingw32 ot the MSYS environment.

   GNU Pascal uses the compiler back-end from the GNU Compiler
Collection, GNU CC or GCC. If you want to compile GPC, you will need
the source of GCC as well as the source of GPC itself. From the same
place as GPC, please download GCC `2.8.1, 2.95.x, 3.2.x, 3.3.x or
3.4.x'. (It is also available from any GNU mirror; see
`http://www.gnu.org/software/gcc/'.)

Libraries
---------

For some of GPC's units, you will need some standard libraries. In
particular:

Unit             Platform              Library
CRT              Unix/terminal         ncurses >= 5.0 (1), (2)
CRT              Unix/X11              PDCurses (2)
CRT              Dos, MS-Windows       PDCurses (3)
GMP              any                   gmp
RegEx            any                   rx
(debugging)      Unix, MS-Windows      ElectricFence (4)

   Notes:

   (1) ncurses version 5.0 or newer is strongly recommended because
older versions contain a bug that severely affects CRT programs.

   (2) You can install both ncurses and PDCurses on a Unix system, and
choose at compile time whether to generate a terminal or X11 version of
your program.

   (3) ncurses also runs under MS-Windows with CygWin (not mingw32,
however), but doesn't appear to behave much differently from PDCurses
on that platform.

   (4) ElectricFence is not used by any unit, but can be used for
debugging memory allocation bugs by simply linking it (see the
accompanying documentation).

   You can find those libraries on many places on the Net. Also, many
GNU/Linux distributions, DJGPP mirrors and other OS distributions
already contain some of the libraries. In any case, you can find the
sources of the libraries (sometimes together with patches that you
should apply before building if you choose to build from the sources)
and binaries for some platforms in

     `http://www.gnu-pascal.de/libs/'

   For more information and descriptions of these libraries, see *Note
Libraries::.

DJGPP
-----

DJGPP (http://www.delorie.com/djgpp/) is available from any SimTel
mirror in the `gnu/djgpp' subdirectory; for addresses look into the
DJGPP FAQ (http://www.delorie.com/djgpp/v2faq/).  To use GNU Pascal you
need at least

   - the C library, `v2/djdev201.zip', and

   - `binutils' (assembler, etc.), `v2gnu/bnu270b.zip'.

   We also recommend you to get:

   - the `make' utility, `v2gnu/mak375b.zip'

   - the GNU debugger, `v2gnu/gdb416b.zip'

   - the DJGPP FAQ, `v2faq/faq211b.zip'

   - the GRX graphics library, `http://www.gnu.de/software/GRX/'

   - PENG, `http://fjf.gnu.de/peng/', an integrated development
     environment, similar to BP's one, written in GNU Pascal, or

   - RHIDE, `v2app/rhide.zip', another integrated development
     environment, or

   - DevPascal, `http://www.bloodshed.net/devpascal.html', an
     integrated development environment for mingw32.

EMX
---

EMX is an environment for creating 32-bit applications for DOS and OS/2.
To develop EMX programs with GNU Pascal you need at least

   - the EMX runtime package, `emxrt.zip',

   - the EMX development system, `emxdev*.zip', and

   - the GNU development tools, `gnudev*.zip'.

   If your DOS box has DPMI (it does if you are using MS Windows or
OS/2) you will also need RSX, available from the same sites as EMX in
the subdirectory `rsxnt'.

   The GNU development tools contain the GNU C compiler which is in fact
not needed to use GNU Pascal. However, the C library _is_ needed.

CygWin
------

CygWin is an environment which implements a POSIX layer under MS
Windows, giving it large parts of the functionality of Unix. CygWin
contains development tools such as an assembler, a linker, etc. GPC
needs for operation. More information about CygWin can be found at
     `http://cygwin.com'

mingw32
-------

The Minimalists' GNU Win32 environment, mingw32, allows a large number
of Unix programs - including GPC and GCC - to run under MS Windows
95/98/NT using native MS libraries. mingw32 ressources can be found at
     `http://www.mingw.org'


File: gpc.info,  Node: Binary Distributions,  Next: Compiling GPC,  Prev: Download,  Up: Installation

4.2 Installation instructions for a GPC binary distribution
===========================================================

To install a binary distribution, `cd' to the root directory and unpack
the archive while preserving the stored directory structure. Under a
Unix compatible system with GNU `tar' installed, the following
(performed as `root') will do the job:

     # cd /
     # tar xzf ARCHIVE.tar.gz

   If you are using a `tar' utility other than GNU `tar', it might be
necessary to do the above in an explicit pipe:

     # cd /
     # gzip -c -d ARCHIVE.tar.gz | tar xf -

   Some binary distributions are now distributed packed with `bzip2'.
You can recognize them by their file name suffix `.bz2' instead of
`.gz'. For such archives, make sure you have `bunzip2' installed and
then use the following command:

     # cd /
     # tar xjf ARCHIVE.tar.bz2

   Or:

     # cd /
     # bunzip2 -c -d ARCHIVE.tar.bz2 | tar xf -

   If you want to install a GPC binary distribution in another directory
than it was prepared for (for example, if you do not have root access
to the computer and want to install GPC somewhere under your home
directory), you can do the following:

   - Unpack the archive file in a directory of your choice (see above).

   - `cd' to the "prefix" directory of the distribution (for instance
     `usr/local').

   - Run the script `install-gpc-binary', available from
     `http://www.gnu-pascal.de/binary/'.

   - Follow the instructions in the script.

   To install a ZIP archive under DOS with `PKunzip', `cd' to the
appropriate directory (usually `\' for EMX, `\DJGPP' for DJGPP), then
call `PKunzip' with the `-d' option:

     C:\> cd djgpp
     C:\DJGPP> pkunzip -d ARCHIVE.zip

   where `ARCHIVE.zip' is the name of the distribution file.

   For DJGPP you must edit your `djgpp.env' in the `DJGPP' directory to
complete the installation: Please copy the entries from `[gcc]' to
create a new `[gpc]' section. The result may look as follows:

     [gcc]
     COMPILER_PATH=%/>;COMPILER_PATH%%DJDIR%/bin
     LIBRARY_PATH=%/>;LIBRARY_PATH%%DJDIR%/lib

     [gpc]
     COMPILER_PATH=%/>;COMPILER_PATH%%DJDIR%/bin
     LIBRARY_PATH=%/>;LIBRARY_PATH%%DJDIR%/lib

   If you are using the DJGPP version of GPC but do not have a `DJGPP'
directory, please download and install DJGPP (*note Download::).

   Binary distributions include `libgcc.a' and `specs', files that are
normally part of GCC. If you have GCC installed, they will be replaced
unless you manually install the archive.


File: gpc.info,  Node: Compiling GPC,  Next: Compilation Notes,  Prev: Binary Distributions,  Up: Installation

4.3 Compiling GPC
=================

The preferred way to distribute GNU software is distribution of the
source code. However, it can be a non-trivial exercise to build GNU
Pascal on some non-Unix systems, so we also provide ready-to-run
binaries for a number of platforms. (See *Note Binary Distributions::
for how to install a binary distribution.)

   GPC is based on the GNU Compiler Collection, GNU CC or GCC. You will
need the GCC sources to build it. It must be the same version as the
one GPC is implemented with - `2.8.1, 2.95.x, 3.2.x, 3.3.x or 3.4.x' as
of this writing. Although you need GCC to build the GNU Pascal
compiler, you don't need GCC to compile Pascal programs once GNU Pascal
is installed. (However, using certain libraries will require compiling
C wrappers, so it is a good idea to install the C compiler as well.)

   Because GNU Pascal shares its back-end with GCC, it should run on any
system supported by GCC. A full list of platforms supported by GCC can
be found in *Note the GCC installation instructions: (gcc)Installation.

   The GCC source can be obtained from any mirror of the GNU FTP site,
`ftp://ftp.gnu.org/gnu/gcc/'. The "core" distribution is sufficient for
GPC.

   Here is the generic procedure for installing GNU Pascal on a Unix
system. See *Note Compilation Notes:: for extra information needed to
install GPC on DOS-like platforms.

  1. Checking the prerequisites

     Make sure that GNU make is installed and that you use it in the
     following steps. When unsure, you can try `make --version' and/or
     `gmake --version'. It should tell you that it is GNU make. If you
     don't have it, you can obtain it from
     `http://www.gnu.org/software/make/'.

     (In the following, we will simply speak of `make' when invoking
     GNU make; you might need to call `gmake' instead.)

     You also need a `patch' program. If such a program is not
     installed on your system, you can get GNU patch from
     `http://www.gnu.org/directory/patch.html'.

     For extracting the example programs from the documentation to the
     `doc/docdemos' directory a non-crippled `sed' is needed.  GNU sed
     is known to work.

     If you have downloaded a "minimal" source distribution, most
     derived files have to be rebuilt. This is done automatically when
     building GPC, but you need additional tools:

     `bash', `bzip2', *GNU* `sed', GNU `awk', GNU `m4', `bison' (at
     least version 2.1), `flex' (version 2.5.27), `autoconf' (version
     2.12), `texinfo' (at least version 4.2), `help2man'.

     Make sure that these are installed. The minimal distributions are
     compressed with `bzip2' instead of `gzip', so substitute it in the
     instructions below.

     If your bison and flex programs are installed under different
     names, you may have to set some or all of the following environment
     variables before running `configure':

          FLEX=/path/to/flex
          LEX=/path/to/flex
          BISON=/path/to/bison
          YACC=/path/to/bison
          INTLBISON=/path/to/bison

     If you want to build the GPC WWW pages you will also need a TeX
     distribution (including `pdftex' and `dvips').

     If you run into trouble during the installation process, please
     check whether you are using outdated versions of the required
     utilities and upgrade if necessary.

     The GNU versions of the packages above are available from
     `http://www.gnu.org/software/', in a subdirectory whose name is
     the name of the package.

  2. Unpacking the source

     From a directory of your choice (e.g. `/home/fred'), unpack the
     GCC and GNU Pascal source distributions. This will create separate
     subdirectories for GCC and GPC. Let us assume `gcc-3.4.3' and
     `gpc-20041218' in this example.
          % cd /home/fred
          % bzip2 -d < gcc-core-3.4.3.tar.bz2 | tar xf -
          % gzip -c -d gpc-20041218.tar.gz | tar xf -

     `cd' to the GPC directory and move the contents (a subdirectory
     `p') to the subdirectory `gcc' of the GCC directory:

          % mv /home/fred/gpc-20041218/p /home/fred/gcc-3.4.3/gcc/

     Instead of moving the directory, it is now also possible to make a
     symbolic link (if the OS supports symlinks). This is useful if you
     want to build GPC with several different GCC versions:

          % ln -s /home/fred/gpc-20041218/p /home/fred/gcc-3.4.3/gcc/p

     It is recommended, though not required, to use a separate
     directory for building the compiler, rather than compiling in the
     source directory. In this example, let us create
     `/home/fred/gpc-build' for this purpose:

          % mkdir /home/fred/gpc-build

     If you use a separate directory, you do not need to write into the
     GCC source directory once you have patched the GCC source (see
     below), and can build GPC for more than one platform from the same
     source tree.

     In case you are re-using a directory where you have already built
     GCC and/or GPC for a different target machine, do `make distclean'
     to delete all files that might be invalid. One of the files this
     deletes is `Makefile'; if `make distclean' complains that
     `Makefile' does not exist, it probably means that the directory is
     already suitably clean.

  3. Configuring and building GCC

     GNU Pascal is automatically configured with GCC. Configuration of
     GCC is treated in depth in *Note the GCC installation
     instructions: (gcc)Installation.  The normal procedure is as
     follows:

     `cd' to the GPC build directory. From there, run the `configure'
     script in the GCC source directory:

          % cd /home/fred/gpc-build
          % /home/fred/gcc-3.4.3/configure --enable-languages=pascal

     This creates all the necessary config files, links and Makefile in
     the GCC object directory.

     Note 1: The configuration will prompt you for patching the GCC
     source for GPC support, so you need write access to that
     directory. All changes to GCC are surrounded by `#ifdef GPC ...
     #endif', so they should not interfere when you build a C compiler
     from this source tree.

     Note 2: The `--enable-languages=pascal' option means that we only
     want to build the Pascal compiler and not, for instance, the C++
     compiler.

     Note 3: The standard base directory for installing GCC and GPC is
     `/usr/local'. If you want to install files to an alternate
     directory DIR, specify `--prefix=DIR' when you run `configure'.
     For installing into a system directory such as `/usr/local' you
     will, of course, need appropriate permissions (often root).
     Therefore, if you want to install GPC on a system where you don't
     have those permissions, you must specify a prefix (e.g.,
     `$HOME/usr').

  4. Putting other GNU tools in place

     Some environments require other GNU tools (such as the GNU
     assembler or linker) instead of the standard system tools for GCC
     to work. (See the GCC installation instructions for details.) If
     this is the case for your system, install the required tools in
     the GPC build directory under the names `as', `ld', or whatever is
     appropriate. This will enable the compiler to find the proper
     tools for compilation of the program `enquire' (a part of GCC) and
     to install the GNU tools to a place where they are found by GCC
     but do not interfere with the standard system tools.

     Alternatively, you can do subsequent compilation using a value of
     the `PATH' environment variable such that the necessary GNU tools
     come before the standard system tools.

  5. Compiling GPC

     Once you are satisfied with the configuration as determined by
     `configure', you can build the compiler:

          % make

     Notice that this procedure will build the C compiler (and maybe
     some other compilers) too, because that is used to compile the GPC
     runtime library.

     Optionally, you may supply CFLAGS, LDFLAGS or RTSFLAGS. CFLAGS is
     used for compiler and RTS, RTSFLAGS are for RTS only, i.e.: `make
     CFLAGS="-O2" RTSFLAGS=-Wall'

     *Note*: The documentation may fail to build from *.texi sources if
     GCC 2.95.x tries to use an older version of `makeinfo' supplied in
     GCC package itself. This can be prevented by supplying explicit
     instruction to use your system's `makeinfo':

          % make MAKEINFO=`which makeinfo`

     optionally followed by the rest of arguments.

  6. Completing the installation

     When everything has been compiled, you can check the installation
     process with:

          % make -n install

     To complete the installation, run the command `make install'. You
     need write access to the target directories (`/usr/local/bin',
     `/usr/local/lib', `/usr/local/info', `/usr/local/doc', and
     `/usr/local/man' in this example), so this is usually done as
     `root':

          % su -c "make install"

     If you want to install _only_ the Pascal compiler (for example if
     you already have the correct version of GCC installed), `cd' to the
     `gcc' subdirectory of the build directory (e.g.
     `/home/fred/gpc-build/gcc') and run `make pascal.install'. This
     installation process does *not* overwrite existing copies of
     `libgcc.a' or `specs', should they exist.

     However, if you do not have the exactly matching GCC version
     installed, you might need some additional files (otherwise GPC will
     complain about missing files at runtime). You can install them by
     doing `make pascal.install-with-gcc' in the `gcc' subdirectory of
     the build directory.

     There is a (partial) translation of the GPC manual into Croatian
     available now. It is not installed by default. If you want to
     install it, do a `pascal.install-hr' in the `gcc' directory. This
     will install the manpage `gpc-hr.1' and the info documentation
     `gpc-hr.info*'. Other formats like PS, PDF and HTML can be built
     manually (it's also easy to add appropriate make targets for them
     when needed).

     Also from the `gcc' subdirectory you can do some more "exotic"
     builds. For instance, you can build the GPC WWW pages by typing
     `make pascal.html' or a binary distribution by typing `make
     pascal.bindist'. See the `Makefile' in that directory for more
     examples.


File: gpc.info,  Node: Compilation Notes,  Next: Cross-Compilers,  Prev: Compiling GPC,  Up: Installation

4.4 Compilation notes for specific platforms
============================================

* Menu:

* MS-DOS with DJGPP::        The DJGPP port of GNU compilers to MS-DOS.
* MS-DOS or OS/2 with EMX::  The EMX port of GNU compilers to MS-DOS and OS/2.
* MS Windows 95/98/NT::      Installation on a Windows 95/98/NT system.


File: gpc.info,  Node: MS-DOS with DJGPP,  Next: MS-DOS or OS/2 with EMX,  Up: Compilation Notes

4.4.1 MS-DOS with DJGPP
-----------------------

The only compiler that is capable of compiling the GNU Compiler
Collection (GNU CC or GCC) under MS-DOS is GCC itself. In order to
compile GPC or GCC for MS-DOS with DJGPP you will therefore need either
a working copy of DJGPP installed, or you will have to cross-build from
a non-MS-DOS system.

   Building GPC under MS-DOS with DJGPP follows the same scheme as
building GPC under a Unix-like system: Place the `p' subdirectory in the
`gcc' directory and follow the instructions for compiling GCC. This
requires `bash' and many other tools installed, and you must be very
careful at many places to circumvent the limitations of the DOS
platform.

   Our preferred way to build GPC for DJGPP is to cross-build it from a
Unix-like platform - which is much easier. For instructions, see *Note
Cross-Compilers:: and *Note Crossbuilding::.


File: gpc.info,  Node: MS-DOS or OS/2 with EMX,  Next: MS Windows 95/98/NT,  Prev: MS-DOS with DJGPP,  Up: Compilation Notes

4.4.2 MS-DOS or OS/2 with EMX
-----------------------------

EMX is a free 32-bit DOS extender which adds some properties of Unix to
MS-compatible DOS and IBM's OS/2 operating systems.

   As of this writing, we are not aware of current versions of GCC for
EMX, and EMX support in GPC has not been maintained. Please contact us
if you know about recent development in EMX and are interested in
continuing EMX support in GPC.


File: gpc.info,  Node: MS Windows 95/98/NT,  Prev: MS-DOS or OS/2 with EMX,  Up: Compilation Notes

4.4.3 MS Windows 95/98/NT
-------------------------

There are two ports of the GNU development tools to MS Windows
95/98/NT: CygWin and mingw32.

   The CygWin environment implements a POSIX layer under MS Windows,
giving it large parts of the functionality of Unix. Thus, compiling GCC
and GPC under the CygWin environment can be done following the
instructions for compiling it under a Unix-like system (see *Note
Compiling GPC::).

   The Minimalists' GNU Win32 environment, mingw32, uses the native
`crtdll.dll' library of MS Windows. It is much smaller than CygWin, but
it is not self-hosting and must be crossbuilt from another system (see
*Note Crossbuilding::).


File: gpc.info,  Node: Cross-Compilers,  Next: Crossbuilding,  Prev: Compilation Notes,  Up: Installation

4.5 Building and Installing a cross-compiler
============================================

GNU Pascal can function as a cross-compiler for many machines.
Information about GNU tools in a cross-configuration can be found at
`ftp://ftp.cygnus.com/pub/embedded/crossgcc/'.

   If you want a cross-compiler targetting Linux you may use Dan Kegel's
crosstool from `http://www.kegel.com/crosstool/'

   Since GNU Pascal generates assembler code, you need a cross-assembler
that GNU Pascal can run, in order to produce object files. If you want
to link on other than the target machine, you need a cross-linker as
well. It is straightforward to install the GNU binutils to act as
cross-tools - see the installation instructions of the GNU binutils for
details.

   You also need header files and libraries suitable for the target
machine that you can install on the host machine. Please install them
under `PREFIX/PLATFORM/include/', for instance
`/usr/local/i386-pc-msdosdjgpp/include/' for a cross-compiler from a
typical Unix-like environment to MS-DOS with DJGPP.

   Configuration and compilation of the compiler can then be done using
the scripts `cfgpc' and `mkgpc' which are included in the source
distribution in the subdirectory `p/script'. Please call them with the
`-h' option for instructions.


File: gpc.info,  Node: Crossbuilding,  Prev: Cross-Compilers,  Up: Installation

4.6 Crossbuilding a compiler
============================

Using a cross-compiler to build GNU Pascal results in a compiler binary
that runs on the cross-target platform. This is called "crossbuilding".
A possible reason why anybody would want to do this, is when the
platform on which you want to run the GNU Pascal compiler is not
self-hosting. An example is mingw32.

   To crossbuild GNU Pascal, you have to install a cross-compiler for
your target first, see *Note Cross-Compilers::.

   As when building a cross-compiler, configuration and compilation of
the compiler can be done using the scripts `cfgpc' and `mkgpc' which
are included in the source distribution in the subdirectory `p/script'.
Please call them with the `-h' option for instructions.


File: gpc.info,  Node: Invoking GPC,  Next: Programming,  Prev: Installation,  Up: Top

5 Command Line Options supported by GNU Pascal.
***********************************************

GPC is a command-line compiler, i.e., to compile a program you have to
invoke `gpc' passing it the name of the file you want to compile, plus
options.

   GPC supports all command-line options that GCC knows, except for
many preprocessor options. For a complete reference and descriptions of
all options, see *Note GCC Command Options: (gcc)Invoking GCC. Below,
you will find a list of the additional options that GPC supports, and a
list of GPC's most important options (including some of those supported
by GCC as well).

   You can mix options and file names on the command line. For the most
part, the order doesn't matter. Order does matter, e.g., when you use
several options of the same kind; for example, if you specify `-L' more
than once, the directories are searched in the order specified. _Note:_
Since many options have multiletter names; multiple single-letter
options may _not_ be grouped as is possible with many other programs:
`-dr' is very different from `-d -r'.

   Many options have long names starting with `--' or, completely
equivalent `-f'. E.g., `--mixed-comments' is the same as
`-fmixed-comments'. Some options tell GPC when to give warnings, i.e.
diagnostic messages that report constructs which are not inherently
erroneous but which are risky or suggest there may have been an error.
Those options start with `-W'.

   Most GPC specific options can also be changed during one compilation
by using compiler directives in the source, e.g. `{$X+}' or
`{$extended-syntax}' for `--extended-syntax' (*note Compiler
Directives::).

   GPC understands the same environment variables GCC does (*note
Environment Variables Affecting GCC: (gcc)Environment Variables.).  In
addition, GPC recognizes `GPC_EXEC_PREFIX' with the same meaning that
`GCC_EXEC_PREFIX' has to GCC. GPC also recognizes `GCC_EXEC_PREFIX',
but `GPC_EXEC_PREFIX' takes precedence.

   Some of the long options (e.g., `--unit-path') take an argument.
This argument is separated with a `=' sign, e.g.:

     --unit-path=/home/foo/units

* Menu:

* GPC Command Line Options::  GPC options besides those of GCC.
* GPC Options::               The most commonly used options to GPC.


File: gpc.info,  Node: GPC Command Line Options,  Next: GPC Options,  Up: Invoking GPC

5.1 GPC options besides those of GCC.
=====================================

The following table lists the command line options GPC understands in
addition to those understood by GCC.

`--debug-tree'
     (For GPC developers.) Show the internal representation of a given
     tree node (name or address).

`--debug-gpi'
     (For GPC developers.) Show what is written to and read from GPI
     files (huge output!).

`--debug-automake'
     (For GPC developers.) Give additional information about the
     actions of automake.

`--debug-source'
     Output the source while it is being processed to standard error.

`--no-debug-source'
     Do not output the source while it is being processed (default).

`--disable-debug-info'
     Inhibit `-g' options (temporary work-around, this option may
     disappear in the future).

`--progress-messages'
     Output source file names and line numbers while compiling.

`--no-progress-messages'
     Do not output source file names and line numbers while compiling
     (default).

`--progress-bar'
     Output number of processed lines while compiling.

`--no-progress-bar'
     Do not output number of processed lines while compiling (default).

`--automake-gpc'
     Set the Pascal compiler invoked by automake.

`--automake-gcc'
     Set the C compiler invoked by automake.

`--automake-g++'
     Set the C++ compiler invoked by automake.

`--amtmpfile'
     (Internal switch used for automake).

`--autolink'
     Automatically link object files provided by units/modules or `{$L
     ...}' (default).

`--no-autolink'
     Do not automatically link object files provided by
     units/modules/`{$L ...}'.

`--automake'
     Automatically compile changed units/modules/`{$L ...}' files and
     link the object files provided.

`--no-automake'
     Same as `--no-autolink'.

`--autobuild'
     Automatically compile all units/modules/`{$L ...}' files and link
     the object files provided.

`--no-autobuild'
     Same as `--no-autolink'.

`--maximum-field-alignment'
     Set the maximum field alignment in bits if `pack-struct' is in
     effect.

`--ignore-packed'
     Ignore `packed' in the source code (default in `--borland-pascal').

`--no-ignore-packed'
     Do not ignore `packed' in the source code (default).

`--ignore-garbage-after-dot'
     Ignore anything after the terminating `.' (default in
     `--borland-pascal').

`--no-ignore-garbage-after-dot'
     Complain about anything after the terminating `.' (default).

`--extended-syntax'
     same as `--ignore-function-results --pointer-arithmetic
     --cstrings-as-strings -Wno-absolute' (same as `{$X+}').

`--no-extended-syntax'
     Opposite of `--extended-syntax' (same as `{$X-}').

`--ignore-function-results'
     Do not complain when a function is called like a procedure.

`--no-ignore-function-results'
     Complain when a function is called like a procedure (default).

`--pointer-arithmetic'
     Enable pointer arithmetic.

`--no-pointer-arithmetic'
     Disable pointer arithmetic (default).

`--cstrings-as-strings'
     Treat CStrings as strings.

`--no-cstrings-as-strings'
     Do not treat CStrings as strings (default).

`-Wabsolute'
     Warn about variables at absolute adresses and `absolute' variable
     with non-constant addresses (default).

`-Wno-absolute'
     Do not warn about variables at absolute adresses and `absolute'
     variable with non-constant addresses.

`--short-circuit'
     Guarantee short-circuit Boolean evaluation (default; same as
     `{$B-}').

`--no-short-circuit'
     Do not guarantee short-circuit Boolean evaluation (same as
     `{$B+}').

`--mixed-comments'
     Allow comments like `{ ... *)' as required in ISO Pascal (default
     in ISO 7185/10206 Pascal mode).

`--no-mixed-comments'
     Ignore `{' and `}' within `(* ... *)' comments and vice versa
     (default).

`--nested-comments'
     Allow nested comments like `{ { } }' and `(* (* *) *)'.

`--no-nested-comments'
     Do not allow nested comments (default).

`--delphi-comments'
     Allow Delphi style `//' comments (default).

`--no-delphi-comments'
     Do not allow Delphi style `//' comments.

`--macros'
     Expand macros (default).

`--no-macros'
     Do not expand macros (default with `--ucsd-pascal',
     `--borland-pascal' or `--delphi').

`--truncate-strings'
     Truncate strings being assigned to other strings of too short
     capacity.

`--no-truncate-strings'
     Treat string assignments to other strings of too short capacity as
     errors.

`--exact-compare-strings'
     Do not blank-pad strings for comparisons.

`--no-exact-compare-strings'
     Blank-pad strings for comparisons.

`--double-quoted-strings'
     Allow strings enclosed in "\" (default).

`--no-double-quoted-strings'
     Do not allow strings enclosed in "\" (default with dialect other
     than `--mac-pascal').

`--longjmp-all-nonlocal-labels'
     Use `longjmp' for all nonlocal labels (default for Darwin/PPC).

`--no-longjmp-all-nonlocal-labels'
     Use `longjmp' only for nonlocal labels in the main program
     (default except for Darwin/PPC).

`--iso-goto-restrictions'
     Do not allow jumps into structured instructions (default).

`--no-iso-goto-restrictions'
     Allow jumps into structured instructions (default in
     `--borland-pascal').

`--nonlocal-exit'
     Allow non-local `Exit' statements (default in `--ucsd-pascal' and
     `--mac-pascal').

`--no-nonlocal-exit'
     Do not allow non-local `Exit' statements (default).

`--io-checking'
     Check I/O operations automatically (same as `{$I+}') (default).

`--no-io-checking'
     Do not check I/O operations automatically (same as `{$I-}').

`--pointer-checking-user-defined'
     Use user-defined procedure for validating pointers.

`--no-pointer-checking-user-defined'
     Do not use user-defined procedure for validating pointers
     (default).

`--pointer-checking'
     Validate pointers before dereferencing.

`--no-pointer-checking'
     Do not validate pointers before dereferencing (default).

`--object-checking'
     Check for valid objects on virtual method calls (default).

`--no-object-checking'
     Do not check for valid objects on virtual method calls.

`--range-checking'
     Do automatic range checks') (default).

`--no-range-checking'
     Do not do automatic range checks (same as `{$R-}').

`--range-and-object-checking'
     Same as `--range-checking --object-checking', same as `{$R+}'.

`--no-range-and-object-checking'
     Same as `--no-range-checking --no-object-checking', same as
     `{$R-}'.

`--case-value-checking'
     Cause a runtime error if a `case' matches no branch (default in
     ISO Pascal modes).

`--no-case-value-checking'
     Do not cause a runtime error if a `case' matches no branch
     (default).

`--stack-checking'
     Enable stack checking (same as `{$S+}').

`--no-stack-checking'
     Disable stack checking (same as `{$S-} (default)').

`--read-base-specifier'
     In read statements, allow input base specifier `n#' (default).

`--no-read-base-specifier'
     In read statements, do not allow input base specifier `n#'
     (default in ISO 7185 Pascal).

`--read-hex'
     In read statements, allow hexadecimal input with `$' (default).

`--no-read-hex'
     In read statements, do not allow hexadecimal input with `$'
     (default in ISO 7185 Pascal).

`--read-white-space'
     In read statements, require whitespace after numbers.

`--no-read-white-space'
     In read statements, do not require whitespace after numbers
     (default).

`--write-clip-strings'
     In write statements, truncate strings exceeding their field width
     (`Write (SomeLongString : 3)').

`--no-write-clip-strings'
     Do not truncate strings exceeding their field width.

`--write-real-blank'
     Output a blank in front of positive reals in exponential form
     (default).

`--no-write-real-blank'
     Do not output a blank in front of positive reals in exponential
     form.

`--write-capital-exponent'
     Write real exponents with a capital `E'.

`--no-write-capital-exponent'
     Write real exponents with a lowercase `e'.

`--transparent-file-names'
     Derive external file names from variable names.

`--no-transparent-file-names'
     Do not derive external file names from variable names (default).

`--field-widths'
     Optional colon-separated list of default field widths for Integer,
     Real, Boolean, LongInt, LongReal.

`--no-field-widths'
     Reset the default field widths.

`--pedantic'
     Reject everything not allowed in some dialect, e.g. redefinition
     of its keywords.

`--no-pedantic'
     Don't give pedantic warnings.

`--typed-address'
     Make the result of the address operator typed (same as `{$T+}',
     default).

`--no-typed-address'
     Make the result of the address operator an untyped pointer (same
     as `{$T-}').

`--enable-keyword'
     Enable a keyword, independently of dialect defaults.

`--disable-keyword'
     Disable a keyword, independently of dialect defaults.

`--implicit-result'
     Enable implicit `Result' for functions (default only in
     `--delphi').

`--no-implicit-result'
     Disable implicit `Result' for functions.

`--enable-predefined-identifier'
     Enable a predefined identifier, independently of dialect defaults.

`--disable-predefined-identifier'
     Disable a predefined identifier, independently of dialect defaults.

`--assertions'
     Enable assertion checking (default).

`--no-assertions'
     Disable assertion checking.

`--setlimit'
     Define the range for `set of Integer' etc..

`--gpc-main'
     External name for the program's entry point (default: `main').

`--propagate-units'
     Automatically re-export all imported declarations.

`--no-propagate-units'
     Do not automatically re-export all imported declarations.

`--interface-only'
     Compile only the interface part of a unit/module and exit (creates
     `.gpi' file, no `.o' file.

`--implementation-only'
     Do not produce a GPI file; only compile the implementation part.

`--executable-file-name'
     Name for the output file, if specified; otherwise derive from main
     source file name.

`--unit-path'
     Directories where to look for unit/module sources.

`--no-unit-path'
     Forget about directories where to look for unit/module sources.

`--object-path'
     Directories where to look for additional object (and source) files.

`--no-object-path'
     Forget about directories where to look for additional object (and
     source) files.

`--executable-path'
     Path where to create the executable file.

`--no-executable-path'
     Create the executable file in the directory where the main source
     is (default).

`--unit-destination-path'
     Path where to create object and GPI files of Pascal units.

`--no-unit-destination-path'
     Create object and GPI files of Pascal units in the current
     directory (default).

`--object-destination-path'
     Path where to create additional object files (e.g. of C files, not
     Pascal units).

`--no-object-destination-path'
     Create additional object files (e.g. of C files, not Pascal units)
     in the current directory (default).

`--disable-default-paths'
     Do not add a default path to the unit and object path.

`--gpi-destination-path'
     (Internal switch used for automake).

`--uses'
     Add an implicit `uses' clause.

`--init-modules'
     Initialize the named modules in addition to those imported
     regularly; kind of a kludge.

`--cidefine'
     Define a case-insensitive macro.

`--csdefine'
     Define a case-sensitive macro.

`--big-endian'
     Tell GPC that the system is big-endian (for those targets where it
     can vary).

`--little-endian'
     Tell GPC that the system is little-endian (for those targets where
     it can vary).

`--print-needed-options'
     Print the needed options.

`-Wwarnings'
     Enable warnings (same as `{$W+}').

`-Wno-warnings'
     Disable all warnings (same as `{$W-}').

`-Widentifier-case-local'
     Warn about an identifier written with varying case within one
     program/module/unit.

`-Wno-identifier-case-local'
     Same as `-Wno-identifier-case'.

`-Widentifier-case'
     Warn about an identifier written with varying case.

`-Wno-identifier-case'
     Do not warn about an identifier written with varying case
     (default).

`-Winterface-file-name'
     Warn when a unit/module interface differs from the file name.

`-Wno-interface-file-name'
     Do not warn when a unit/module interface differs from the file
     name (default).

`--methods-always-virtual'
     Make all methods virtual (default in `--mac-pascal').

`--no-methods-always-virtual'
     Do not make all methods virtual (default).

`--objects-are-references'
     Turn objects into references (default in `--mac-pascal').

`--no-objects-are-references'
     Do not turn objects into references (default).

`--objects-require-override'
     Require override directive for objects (default in `--mac-pascal').

`--no-objects-require-override'
     Do not require override directive for objects (default).

`--delphi-method-shadowing'
     Redefining methods silently shadows old definition (default in
     `--delphi').

`--no-delphi-method-shadowing'
     Do not silently shadow method definitions (default).

`--borland-objects'
     Choose Borland object model.

`--mac-objects'
     Choose Mac object model.

`--ooe-objects'
     Choose OOE object model.

`--gnu-objects'
     Reset object model to default state.

`--preprocessed'
     Treat the input file as already preprocessed.

`-nostdinc'
     Do not search standard system.

`-remap'
     Remap file names when including files.

`-A'
     Ignored.

`-E'
     Preprocess only.

`-H'
     Print the name of include files as they are used.

`-P'
     Do not generate #line directives.

`-Wimplicit-abstract'
     Warn when an object type not declared `abstract' contains an
     abstract method (default).

`-Wno-implicit-abstract'
     Do not warn when an object type not `declared' abstract contains
     an abstract method.

`-Winherited-abstract'
     Warn when an abstract object type inherits from a non-abstract one
     (default).

`-Wno-inherited-abstract'
     Do not warn when an abstract object type inherits from a
     non-abstract one.

`-Wobject-assignment'
     Warn when when assigning objects or declaring them as value
     parameters or function results (default).

`-Wno-object-assignment'
     Do not warn when assigning objects or declaring them as value
     parameters or function results (default in `--borland-pascal').

`-Wimplicit-io'
     Warn when `Input' or `Output' are used implicitly.

`-Wno-implicit-io'
     Do not warn when `Input' or `Output' are used implicitly (default).

`-Wfloat-equal'
     Warn about `=' and `<>' comparisons of real numbers.

`-Wno-float-equal'
     Do not warn about `=' and `<>' comparisons of real numbers.

`-Wtyped-const'
     Warn about misuse of typed constants as initialized variables
     (default).

`-Wno-typed-const'
     Do not warn about misuse of typed constants as initialized
     variables.

`-Wnear-far'
     Warn about use of useless `near' or `far' directives (default).

`-Wno-near-far'
     Do not warn about use of useless `near' or `far' directives.

`-Wunderscore'
     Warn about double/leading/trailing underscores in identifiers.

`-Wno-underscore'
     Do not warn about double/leading/trailing underscores in
     identifiers.

`-Wsemicolon'
     Warn about a semicolon after `then', `else' or `do' (default).

`-Wno-semicolon'
     Do not warn about a semicolon after `then', `else' or `do'.

`-Wlocal-external'
     Warn about local `external' declarations.

`-Wno-local-external'
     Do not warn about local `external' declarations.

`-Wdynamic-arrays'
     Warn about arrays whose size is determined at run time (including
     array slices).

`-Wno-dynamic-arrays'
     Do not warn about arrays whose size is determined at run time
     (including array slices).

`-Wmixed-comments'
     Warn about mixed comments like `{ ... *)'.

`-Wno-mixed-comments'
     Do not warn about mixed comments.

`-Wnested-comments'
     Warn about nested comments like `{ { } }'.

`-Wno-nested-comments'
     Do not warn about nested comments.

`--classic-pascal-level-0'
     Reject conformant arrays and anything besides ISO 7185 Pascal.

`--standard-pascal-level-0'
     Synonym for `--classic-pascal-level-0'.

`--classic-pascal'
     Reject anything besides ISO 7185 Pascal.

`--standard-pascal'
     Synonym for `--classic-pascal'.

`--extended-pascal'
     Reject anything besides ISO 10206 Extended Pascal.

`--object-pascal'
     Reject anything besides (the implemented parts of) ANSI draft
     Object Pascal.

`--ucsd-pascal'
     Try to emulate UCSD Pascal.

`--borland-pascal'
     Try to emulate Borland Pascal, version 7.0.

`--delphi'
     Try to emulate Borland Pascal, version 7.0, with some Delphi
     extensions.

`--pascal-sc'
     Be strict about the implemented Pascal-SC extensions.

`--vax-pascal'
     Support (a few features of) VAX Pascal.

`--sun-pascal'
     Support (a few features of) Sun Pascal.

`--mac-pascal'
     Support (some features of) traditional Macintosh Pascal compilers.

`--gnu-pascal'
     Undo the effect of previous dialect options, allow all features
     again.


File: gpc.info,  Node: GPC Options,  Prev: GPC Command Line Options,  Up: Invoking GPC

5.2 The most commonly used options to GPC
=========================================

As the most simple example, calling

     gpc foo.pas

   tells GPC to compile the source file `foo.pas' and to produce an
executable of the default name which is `foo.exe' on EMX, `a.exe' on
Cygwin, both `a.out' and `a.exe' on DJGPP, and `a.out' on most other
platforms.

   Users familiar with BP, please note that you have to give the file
name extension `.pas': GPC is a common interface for a Pascal compiler,
a C, ObjC and C++ compiler, an assembler, a linker, and perhaps an Ada
and a FORTRAN compiler. From the extension of your source file GPC
figures out which compiler to run. GPC recognizes Pascal sources by the
extension `.pas', `.p', `.pp' or `.dpr'. GPC also accepts source files
in other languages (e.g., `.c' for C) and calls the appropriate
compilers for them. Files with the extension `.o' or without any special
recognized extension are considered to be object files or libraries to
be linked.

   Another example:

     gpc -O2 -Wall --executable-file-name --automake --unit-path=units foo.pas

   This will compile the source file `foo.pas' to an executable named
`foo' (`--executable-file-name') with fairly good optimization (`-O2'),
warning about possible problems (`-Wall'). If the program uses units or
imports modules, they will be searched for in a directory called `units'
(`--unit-path') and automatically compiled and linked (`--automake').

   The following table lists the most commonly used options to GPC.

`--automake'
     Check whether modules/units used must be recompiled and do the
     recompilation when necessary.

`--unit-path=DIR[:DIR...]'
     Search the given directories for units and object files.

`--object-path=DIR[:DIR...]'
     Search the given directories for object files.

`--unit-destination-path=DIR'
     Place compiled units (GPI and object files) into the directory
     DIR. The default is the current directory.

`--object-destination-path=DIR'
     Place compiled object files (e.g., from C files, but not from
     Pascal units) into the directory DIR. The default is the directory
     given with `--unit-destination-path'.

`--executable-path=DIR'
     Place the executable compiled into the directory DIR. The default
     is the main source file's directory.

`-o FILE'
     Place output in file FILE. This applies regardless to whatever
     sort of output is being produced, whether it be an executable file,
     an object file, an assembler file, etc.

     Since only one output file can be specified, it does not make sense
     to use `-o' when compiling more than one input file, unless you
     are producing an executable file as output.

`--executable-file-name[=NAME]'
     Derive the executable file name from the source file name, or use
     NAME as the executable file name. The difference to the `-o'
     option is that `--executable-file-name' considers the
     `--executable-path', while `-o' does not and accepts a file name
     with directory. Furthermore, `--executable-file-name' only applies
     to executables, not to other output formats selected.

`-LDIR'
     Search the directory DIR for libraries. Can be given multiple
     times.

`-IDIR'
     Search the directory DIR for include files. Can be given multiple
     times.

`-lLIBRARY'
     Search the library named LIBRARY when linking. This option must be
     placed on the command line _after_ all source or object files or
     other libraries that reference the library.

`-O[N]'
     Select the optimization level. Without optimization (or `-O0'
     which is the default), the compiler's goal is to reduce the
     compilation time and to make debugging produce the expected
     results.  Statements are independent: if you stop the program with
     a breakpoint between statements, you can then assign a new value to
     any variable or change the program counter to any other statement
     in the same routine and get exactly the results you would expect
     from the source code.

     With optimization, the compiler tries to reduce code size and
     execution time. The higher the value of N, the more optimizations
     will be done, but the longer the compilation will take.

     If you use multiple `-O' options, with or without N, the last such
     option is the one that is effective.

`-g'
     Produce debugging information suitable for `gdb'. Unlike some
     other compilers, GNU Pascal allows you to use `-g' with `-O'. The
     shortcuts taken by optimized code may occasionally produce
     surprising results: some variables you declared may not exist at
     all; flow of control may briefly move where you did not expect it;
     some statements may not be executed because they compute constant
     results or their values were already at hand; some statements may
     execute in different places because they were moved out of loops.
     Nevertheless it proves possible to debug optimized output. This
     makes it reasonable to use the optimizer for programs still in the
     testing phase.

`-s'
     Remove all symbol table and relocation information from the
     executable. Note: this has no influence on the performance of the
     compiled executable.

`-Wall'
     Give warnings for a number of constructs which are not inherently
     erroneous but which are risky or suggest there may have been an
     error. There are additional warning options not implied by
     `-Wall', see the GCC warning options (*note Options to Request or
     Suppress Warnings: (gcc)Warning Options.), while `-Wall' only
     warns about such constructs that should be easy to avoid in
     programs. Therefore, we suggest using `-Wall' on most sources.

     Note that some warnings (e.g., those about using uninitialized
     variables) are never given unless you compile with optimization
     (see above), because otherwise the compiler doesn't analyze the
     usage patterns of variables.

`-Werror'
     Turn all warnings into errors.

`-S'
     Stop after the stage of compilation proper; do not assemble. The
     output is in the form of an assembler code file for each source
     file. By default, the assembler file name for a source file is made
     by replacing the extension with `.s'.

`-c'
     Compile and assemble the source files, but do not link. The output
     is in the form of an object file for each source file. By default,
     the object file name for a source file is made by replacing the
     extension with `.o'.

`-static'
     On systems that support dynamic linking, this prevents linking with
     the shared libraries, i.e. forces static linking. On other systems,
     this option has no effect.

`-DMACRO[=DEF]'
     Define the macro and conditional symbol MACRO as DEF (or as `1' if
     DEF is omitted).

`-b MACHINE'
     The argument MACHINE specifies the target machine for compilation.
     This is useful when you have installed GNU Pascal as a
     cross-compiler.

`-v'
     Print (on standard error) the commands executed to run the stages
     of compilation. Also print the version number of the compiler
     driver program and of the preprocessor and the compiler proper.

`--classic-pascal-level-0'
`--classic-pascal'
`--extended-pascal'
`--object-pascal'
`--ucsd-pascal'
`--borland-pascal'
`--delphi'
`--pascal-sc'
`--mac-pascal'
     GNU Pascal supports the features of several different Pascal
     standards and dialects. The intention is to have common language,
     where features off all dialects are available.  As result, the
     defualt language is the biggest dialect, with most features.
     Sometimies features of different dialect conflict (in such cases
     we usually provide more detailed switches to choose desired
     behaviour). These switches turn on maximal compatiblity with given
     dialect. In particular they tell GPC to restrict itself to the
     features of the specified standard.  Warnings about certain
     dangerous constructs which would be valid in the specified dialect
     (e.g., assignment to a typed constant with `--borland-pascal') are
     suppressed.

     By default, GNU Pascal allows the redefinition of some keywords.
     Each of these switches causes GNU Pascal to forbid the redefinition
     of keywords of the specified standard.

     Most ISO 7185 Pascal programs should compile properly with or
     without `--classic-pascal'. However, without this option, some
     constructs behave in non-standard way. Moreover, certain GNU
     extensions and Pascal features from other dialects are supported
     as well. With this option, they are rejected.

     These options are not intended to be useful; they exist only to
     satisfy pedants who would otherwise claim that GNU Pascal fails to
     support the ISO Standard or is not really compatible to Borland
     Pascal, or whatever. We recommend, rather, that users take
     advantage of the extensions of GNU Pascal and disregard the
     limitations of other compilers.

`-pedantic-errors'
     Produce errors rather than warnings for portability violations.
     Unlike in C, this does _not_ imply the `-pedantic' option, so you
     can, for instance, use `-pedantic-errors' without `-pedantic', but
     with `--extended-pascal'.

`--gpc-main=NAME'
     Name the entry point of the main program `NAME' instead of `main'
     on the linker level. This is useful, e.g., when working with some
     C libraries which define their own `main' function and require the
     program's main entry point to be named differently. (This option
     should preferably be used as a compiler directive in the unit or
     module which links to that strange C library, rather than be given
     on the command-line.)



File: gpc.info,  Node: Programming,  Next: Borland Pascal,  Prev: Invoking GPC,  Up: Top

6 The Programmer's Guide to GPC
*******************************

*This chapter is still under development.*

   This chapter tells you how the source of a valid GNU Pascal program
should look like.  You can use it as tutorial about the GNU Pascal
language, but since the main goal is to document all special GPC
features, implementation-dependent stuff, etc., expect a steep learning
curve.

   This chapter does _not_ cover how to compile your programs and to
produce an executable - this is discussed above in *Note Invoking GPC::.

* Menu:

* Source Structures::    Programs, Units and Modules.
* Data Types::           Standard and non-standard data types.
* Operators::            Built-in and user-definable operators.
* Parameters::           Procedure And Function Parameters
* Pointer Arithmetics::  How pointer arithmetics works in Pascal.
* String Slice Access::  Accessing parts of strings (and other arrays)
* Type Casts::           Explicit and emulated type casting in GPC.
* OOP::                  How object-oriented programming is implemented.
* Compiler Directives::  Compiler Directives And The Preprocessor
* Library Routines::     Routines Built-in or in the Run Time System
* Other Languages::      How to share libraries with other languages.
* Notes for Debugging::  Problems and caveats when debugging GPC programs.
* I18N::                 How to use Internationalization in your programs
* Run Time System::      Pascal declarations for GPC's Run Time System library.
* GPC Units::            Units included with GPC


File: gpc.info,  Node: Source Structures,  Next: Data Types,  Up: Programming

6.1 Source Structures
=====================

A source file accepted by GNU Pascal may contain up to one program,
zero or more ISO-style modules, and/or zero or more UCSD-style units.
Units and modules can be mixed in one project.

* Menu:

* The Program::             The Source Structure of Programs
* Label Declaration::
* Constant Declaration::
* Type Declaration::
* Variable Declaration::
* Subroutine Declaration::  Procedures, Functions and Operators
* Statements::              Loops and Conditional Statements
* Modules and Units::       Import Part and Module/Unit Concept

   One trivial example for a valid GPC source file follows. Note that
the code below may either be in one source file, or else the unit and
the program may be in separate source files.

     unit DemoUnit;

     interface

     procedure Hello;

     implementation

     procedure Hello;
     begin
       WriteLn ('Hello, world!')
     end;

     end.

     program UnitDemo;

     uses
       DemoUnit;

     begin
       Hello
     end.


File: gpc.info,  Node: The Program,  Next: Label Declaration,  Up: Source Structures

6.1.1 The Source Structure of Programs
--------------------------------------

A generic GNU Pascal program looks like the following:

     program NAME (Input, Output);

     IMPORT_PART

     DECLARATION_PART

     begin
       STATEMENT_PART
     end.

   The `program' headline may be omitted in GPC, but a warning will be
given except in `--borland-pascal' mode.

   While the program parameters (usually `Input', `Output') are
obligatory in ISO Pascal if you want to use `ReadLn' and `WriteLn',
they are optional in GNU Pascal. GPC will warn about such missing
parameters in `--extended-pascal' mode. However if you give parameters
to the program headline, they work like ISO requires.

   The IMPORT_PART consists either of an ISO-style `import'
specification or a UCSD/Borland-style `uses' clause. While `import' is
intended to be used with interfaces exported by ISO 10206 Extended
Pascal modules, and `uses' is intended to be used with units, this is
not enforced. (See also *Note uses::, *Note import::.)

   The DECLARATION_PART consists of label, constant, type, variable or
subroutine declarations in free order. However, every identifier must
be declared before it is used. The only exception are type identifiers
pointing to another type identifier which may be declared below.

   The STATEMENT_PART consists of a sequence of statements.

   As an extension, GPC supports a "declaring statement" which can be
used in the statement part to declare variables (see *Note var::).


File: gpc.info,  Node: Label Declaration,  Next: Constant Declaration,  Prev: The Program,  Up: Source Structures

6.1.2 Label Declaration
-----------------------

A label declaration has the following look:

     label
       LABEL_NAME, ..., LABEL;

   A label declaration part starts with the reserved word `label',
which contains a list of labels.

See also
--------

*Note label::, *Note goto::


File: gpc.info,  Node: Constant Declaration,  Next: Type Declaration,  Prev: Label Declaration,  Up: Source Structures

6.1.3 Constant Declaration
--------------------------

A constant declaration has the following look:

     const
       CONSTANT_IDENTIFIER = CONSTANT_EXPRESSION;
       ...
       CONSTANT_IDENTIFIER = CONSTANT_EXPRESSION;

   A constant declaration part starts with the reserved word `const'.
It declares a CONSTANT_IDENTIFIER which is defined by
CONSTANT_EXPRESSION. This expression has to be evaluatable during
compilation time, i.e. it can include numbers, parentheses, predefined
operators, sets and type casts (the last, however, is a Borland
extension).  In ISO 7185 Pascal, CONSTANT_EXPRESSION must be a constant
or a set. All Pascal Dialects but ISO-Pascal allow the use of these
intrinsic functions in CONSTANT_EXPRESSION:

   *Note Abs::, *Note Round::, *Note Trunc::, *Note Chr::, *Note Ord::,
*Note Length::, *Note Pred::, *Note Succ::, *Note SizeOf::, *Note Odd::.

   In Borland Pascal, in the constant declaration part variables can be
declared as well, which are given an initial value. These variables are
called "typed constants". It is good style to avoid this use,
especially since Extended Pascal and GNU Pascal allow to initialize a
variable in variable declaration part or give a type a preset value on
declaration.

     const
       FiveFoo      = 5;
       StringFoo    = 'string constant';
       AlphabetSize = Ord ('Z') - Ord ('A') + 1;

     type
       PInteger     = ^Integer;     { Define a pointer to an Integer }

     const
       { Constant which holds a pointer to an Integer at address 1234 }
       AddressFoo   = PInteger (1234);

   * BP does not know initialized variables, only typed constants. Even
     worse, it allows them to be misused as variables, without even
     warning. GPC supports this (unwillingly ;-), and warns unless in
     `--borland-pascal' mode.

     An example of a typed constant:

          const
            i: Integer = 0;

     If you want to use it as a constant only, that's perfectly fine.
     However, if you modify `i', we suggest to translate the
     declaration to an initialized variable. The EP syntax is:

          var
            i: Integer value 0;

     GPC supports this as well as the following mixture of dialects:

          var
            i: Integer = 0;

     Furthermore, you can also assign initialization values to types:

          program InitTypeDemo;

          type
            MyInteger = Integer value 42;

          var
            i: MyInteger;

          begin
            WriteLn (i)
          end.

     Here, all variables of type MyInteger are automatically initialized
     to 42 when created.

   * Arrays initializers look like this in BP:

          program BPArrayInitDemo;

          const
            MyStringsCount = 5;

          type
            Ident = String [20];

          const
            MyStrings: array [1 .. MyStringsCount] of Ident =
              ('export', 'implementation', 'import',
               'interface', 'module');

          begin
          end.

     And the following way in EP:

          program EPArrayInitDemo;

          const
            MyStringsCount = 5;

          type
            Ident = String (20);

          var
            MyStrings: array [1 .. MyStringsCount] of Ident value
              [1: 'export'; 2: 'implementation'; 3: 'import';
               4: 'interface'; 5: 'module'];

          begin
          end.

     There seem to be pros and cons to each style. GPC supports both as
     well as just about any thinkable mixture of them.

     Some folks don't like having to specify an index since it requires
     renumbering if you want to add a new item to the middle. However,
     if you index by an enumerated type, you might be able to avoid
     major renumbering by hand.


See also
--------

*Note Subroutine Parameter List Declaration::


File: gpc.info,  Node: Type Declaration,  Next: Variable Declaration,  Prev: Constant Declaration,  Up: Source Structures

6.1.4 Type Declaration
----------------------

A type declaration looks like this:

     type
       TYPE_IDENTIFIER = TYPE_DEFINITION;
       ...
       TYPE_IDENTIFIER = TYPE_DEFINITION;
   or, with preset content:
     type
       TYPE_IDENTIFIER = TYPE_DEFINITION value CONSTANT_EXPRESSION;
       ...
       TYPE_IDENTIFIER = TYPE_DEFINITION value CONSTANT_EXPRESSION;

   A type declaration part begins with the reserved word `type'.  It
declares a TYPE_IDENTIFIER which is defined by TYPE_DEFINITION.  A type
definition either can be an array, a record, a schema, a set, an
object, a subrange, an enumerated type, a pointer to another
type_identifier or simply another type_identifier which is to alias.
If a schema type is to be declared, TYPE_IDENTIFIER is followed by a
discriminant enclosed in parentheses:

     TYPE_IDENTIFIER (DISCRIMINANT) = SCHEMA_TYPE_DEFINITION;

   If `value' is specified, followed by a constant satisfying the type
definition, every variable of this type is initialized with
CONSTANT_EXPRESSION, unless it is initialized by `value' itself.  The
reserved word `value' can be replaced by `=', however `value' is not
allowed in ISO-Pascal and Borland Pascal, and the replacement by `=' is
not allowed in Extended Pascal.

Type declaration example
------------------------

     type
       { This side is the }     { That side is the }
       { type declaration }     { type definition  }

       Arrayfoo            = array [0 .. 9] of Integer;  { array definition }
       Recordfoo           = record                      { record definition }
                               Bar: Integer;
                             end;

            { schema def with discriminants ``x, y: Integer'' }
       SchemaFoo (x, y: Integer) = array [x .. y] of Integer;
       CharSetFoo          = set of Char;              { Def of a set }
       ObjectFoo           = object                    { Def of an object }
                               procedure DoAction;
                               constructor Init;
                               destructor Done;
                             end;
       SubrangeFoo         = -123..456;                { subrange def }

       EnumeratedFoo       = (Pope,John,the,Second);   { enum type def }
            { Def of a pointer to another type identifier }
       PInteger            = ^arrayfoo;
            { Def of an alias name for another type identifier }
       IdentityFoo         = Integer;
            { Def of an integer which was initialized by 123 }
       InitializedFoo      = Integer value 123;

See also
--------

*Note Type Definition::, *Note Data Types::, *Note Variable
Declaration::


File: gpc.info,  Node: Variable Declaration,  Next: Subroutine Declaration,  Prev: Type Declaration,  Up: Source Structures

6.1.5 Variable Declaration
--------------------------

A variable declaration looks like this:

     var
       VAR_IDENTIFIER: TYPE_IDENTIFIER;
       ...
       VAR_IDENTIFIER: TYPE_IDENTIFIER;
   or
     var
       VAR_IDENTIFIER: TYPE_DEFINITION;
       ...
       VAR_IDENTIFIER: TYPE_DEFINITION;
   and with initializing value:
     var
       VAR_IDENTIFIER: TYPE_IDENTIFIER value CONSTANT_EXPRESSION;
       ...
       VAR_IDENTIFIER: TYPE_IDENTIFIER value CONSTANT_EXPRESSION;
   or
     var
       VAR_IDENTIFIER: TYPE_DEFINITION value CONSTANT_EXPRESSION;
       ...
       VAR_IDENTIFIER: TYPE_DEFINITION value CONSTANT_EXPRESSION;

   A variable declaration part begins with the reserved word `var'.  It
declares a VAR_IDENTIFIER whose type either can be specified by a type
identifier, or by a type definion which either can be an array, a
record, a set, a subrange, an enumerated type or a pointer to an type
identifier.  If `value' is specified followed by a constant expression
satisfying the specified type, the variable declared is initialized with
CONSTANT_EXPRESSION.  The reserved word `value' can be replaced by `=',
however `value' is not allowed in ISO-Pascal and Borland Pascal, and the
replacement by `=' is not allowed in Extended Pascal.

See also
--------

*Note Type Definition::, *Note Type Declaration::, *Note Data Types::,
*Note The Declaring Statement::, *Note Subroutine Parameter List
Declaration::


File: gpc.info,  Node: Subroutine Declaration,  Next: Statements,  Prev: Variable Declaration,  Up: Source Structures

6.1.6 Subroutine Declaration
----------------------------

* Menu:

* The Procedure::
* The Function::
* The Operator::
* Subroutine Parameter List Declaration::


File: gpc.info,  Node: The Procedure,  Next: The Function,  Up: Subroutine Declaration

6.1.6.1 The Procedure
.....................

     procedure PROCEDURE_IDENTIFIER;
     DECLARATION_PART
     begin
       STATEMENT_PART
     end;
or with a parameter list:
     procedure PROCEDURE_IDENTIFIER (PARAMETER_LIST);
     DECLARATION_PART
     begin
       STATEMENT_PART
     end;

   A procedure is quite like a sub-program: The DECLARATION_PART
consists of label, constant, type, variable or subroutine declarations
in free order. The STATEMENT_PART consists of a sequence of statements.
If PARAMETER_LIST is specified, parameters can be passed to the
procedure and can be used in STATEMENT_PART. A recursive procedure call
is allowed.

See also
--------

*Note The Function::, *Note Subroutine Parameter List Declaration::


File: gpc.info,  Node: The Function,  Next: The Operator,  Prev: The Procedure,  Up: Subroutine Declaration

6.1.6.2 The Function
....................

     function FUNCTION_IDENTIFIER: FUNCTION_RESULT_TYPE;
     DECLARATION_PART
     begin
       STATEMENT_PART
     end;
or with a parameter list:
     function FUNCTION_IDENTIFIER (PARAMETER_LIST): RESULT_TYPE;
     DECLARATION_PART
     begin
       STATEMENT_PART
     end;

   A function is a subroutine which has a return value of type
FUNCTION_RESULT_TYPE. It is structured like the program: the
DECLARATION_PART consists of label, constant, type, variable or
subroutine declarations in free order. The STATEMENT_PART consists of a
sequence of statements. If PARAMETER_LIST is specified, parameters can
be passed to the function and can be used in STATEMENT_PART. The result
is set via an assignment:
     FUNCTION_IDENTIFIER := EXPRESSION
   Recursive function calls are allowed. Concerning the result type,
ISO 7185 Pascal and Borland Pascal only allow the intrinsic types,
subranges, enumerated types and pointer types to be returned. In
Extended Pascal, FUNCTION_RESULT_TYPE can be every assignable type.  Of
course, there are no type restrictions in GNU Pascal as well.  If
extended syntax is switched on, functions can be called like procedures
via procedure call statement.

See also
--------

*Note The Procedure::, *Note Subroutine Parameter List Declaration::,
*Note Data Types::


File: gpc.info,  Node: The Operator,  Next: Subroutine Parameter List Declaration,  Prev: The Function,  Up: Subroutine Declaration

6.1.6.3 The Operator
....................

GNU Pascal allows to define operators which can be used the infix style
in expressions. For a more detailed description, see *Note Operators::


File: gpc.info,  Node: Subroutine Parameter List Declaration,  Prev: The Operator,  Up: Subroutine Declaration

6.1.6.4 Subroutine Parameter List Declaration
.............................................

     PARAMETER; ...; PARAMETER

   Each parameter can start with a prefix (see below) describing how
the parameters are passed, followed by a comma seperated list of one or
more PARAMETER_IDENTIFIERS and an optional PARAMETER_TYPE.

     procedure DoIt (var x, y, z: OneType; a, b: AnotherType; var q);

   To understand parameter passing, first some definitions.

actual parameter
     the parameter passed in to the routine.

formal parameter
     the parameter as used inside the procedure.

by value
     the value of the actual parameter is copied on to the stack.

by reference
     the address of the actual parameter is copied on to the stack.

L-value
     (left hand of a `:=' statement) something that can be assigned
     to (not a constant, or const or protected variable or other
     immutable item).

R-value
     (right hand of a `:=' statement) anything you can get the   value
     of (could be a constant, an expression, a variable (whether
     const or protected or not) or just about anything.

addressable
     something you can get the address of (not a field of a packed
     structure or a variable with `attribute (register)' (GPC
     extension)).

aliasing
     accessing memory via two different names (e.g. a global variable
     passed by reference to a procedure can be accessed either as the
     global variable or the formal paramater). Generally this is very
     bad practice.

   Technical note: Parameters are not always passed on the stack, they
may also be passed in registers, especially on RISC machines.

   The prefix defines how a variable is passed on the stack and how you
can access the FORMAL_PARAMETER inside the procedure.  The prefix can
be one of:

nothing
          procedure DoIt (x: SOMETYPE);

     Technical: The actual parameter is passed by value or reference,
     but if passed by reference, it is then copied to a local copy on
     the stack. Aliasing has no effect on x.

     What it means: you can modify `x' inside the routine, but your
     changes will not affect the actual parameter (and vice versa). The
     actual parameter can be a constant or other immutable object, or a
     protected or const variable.

protected
          procedure DoIt (protected x: SOMETYPE);

     Technical: The actual parameter is passed by value or reference,
     but if passed by reference, it is then copied to a local copy on
     the stack. Aliasing has no effect on x. `protected' is a Extended
     Pascal extension.

     What it means: if you modify the actual parameter, this will not
     affect `x' inside the routine. The actual parameter can be a
     constant or other immutable object, or a protected or const
     variable. You are forbidden from modifying x inside the routine.

var
          procedure DoIt (var x: SOMETYPE);

     Technical: The actual parameter is passed by reference.  Aliasing
     will definitely change `x'.

     What it means: modifications to `x' inside the routine will change
     the actual parameter passed in. The actual parameter must be an
     addressable L-value (ie, it must be something you can take the
     address of and assign to).

     A parameter of this kind is called variable parameter and
     internally corresponds to an L-value pointer (to the specified
     type identifier if any). This declaration is necessary if the
     parameter is to be modified within the routine and to hold its
     value still after return.

const
          procedure DoIt (const x: SOMETYPE);

     Technical: The actual parameter is passed by value or reference.
     The compiler will make a copy of the actual parameter to have
     something it can address if the actual parameter is not
     addressable.  You are forbidden from modifying `x' inside the
     routine, and therefore you cannot modify the actual parameter.
     Aliasing may or may not change `x'. `const' is a Borland Pascal
     extension.

     What it means: You can pass any R-value. You cannot modify `x'
     inside the routine. If you change the actual parameter while inside
     the routine, `x' will have an undefined value.

protected var
          procedure DoIt (protected var x: SOMETYPE);

     Technical: The actual parameter is passed by reference. The
     compiler will never make a copy of the actual parameter. You are
     forbidden from modifying `x' inside the routine, and therefore you
     cannot modify the actual parameter. Aliasing will definitely change
     `x'.

     What it means: You can pass anything addressable. You cannot modify
     `x' inside the routine. If you change the actual parameter while
     inside the routine, `x' will change as well.

     In GPC, the `protected var' mode guarantees that the parameter is
     always passed by reference, making it the correct choice for
     calling C routines with `const' pointer parameters.


   If you omit the formal parameter type specification, then any type
may be passed to that parameter. Generally this is a bad idea, but
occasionally it can be useful, especially for low level code.

   As an Extended Pascal extension, you can also declare procedural
parameters directly:
     procedure PARAMETER_IDENTIFIER
   or:
     function PARAMETER_IDENTIFIER: PARAMETER_IDENTIFIER_RESULT_TYPE

   Example for parameter lists:
     program ParameterDemo;

     procedure Foo (var Bar; var Baz: Integer; const Fred: Integer);

       procedure Glork1 (function Foo: Integer; procedure Bar (Baz: Integer));
       begin
         Bar (Foo)
       end;

     begin
       Baz := Integer (Bar) + Fred
     end;

     var
       a, b, c: Integer;

     begin
       Foo (a, b, c)
     end.

See also
--------

*Note Data Types::, *Note var::, *Note const::, *Note protected::


File: gpc.info,  Node: Statements,  Next: Modules and Units,  Prev: Subroutine Declaration,  Up: Source Structures

6.1.7 Statements
----------------

* Menu:

* Assignment::
* begin end Compound Statement::
* if Statement::
* case Statement::
* for Statement::
* while Statement::
* repeat Statement::
* asm Inline::
* with Statement::
* goto Statement::
* Procedure Call::
* The Declaring Statement::
* Loop Control Statements::


File: gpc.info,  Node: Assignment,  Next: begin end Compound Statement,  Up: Statements

6.1.7.1 Assignment
..................

The way an assignment looks like:
     L-VALUE := EXPRESSION;

   This statement assigns any valid expression to L-VALUE. Make sure
that the result of EXPRESSION is compatible with L-VALUE, otherwise an
compilation error is reported. The `:=' is called assignment operator.
As long as L-VALUE and EXPRESSION are type compatible, they are
assignment compatible for _any definable type_ as well.


File: gpc.info,  Node: begin end Compound Statement,  Next: if Statement,  Prev: Assignment,  Up: Statements

6.1.7.2 begin end Compound Statement
....................................

It looks like that:
     begin
       STATEMENT;
       STATEMENT;
       ...
       STATEMENT
     end

   This statement joins several STATEMENTS together into one compound
statement which is treated as a single statement by the compiler. The
finishing semicolon before `end' can be left out.


File: gpc.info,  Node: if Statement,  Next: case Statement,  Prev: begin end Compound Statement,  Up: Statements

6.1.7.3 if Statement
....................

This statement has the following look:
     if BOOLEAN_EXPRESSION then
       STATEMENT
   or with an alternative statement:
     if BOOLEAN_EXPRESSION then
       STATEMENT1
     else
       STATEMENT2

   The `if' ... `then' statement consists of a boolean expression and a
STATEMENT, which is conditionally executed if the evaluation of
BOOLEAN_EXPRESSION yields true.

   If `if' ... `then' ... `else' is concerned, STATEMENT1 is executed
depending on BOOLEAN_EXPRESSION being true, otherwise STATEMENT2 is
executed alternatively. Note: the statement before else _must not_
finish with a semicolon.


File: gpc.info,  Node: case Statement,  Next: for Statement,  Prev: if Statement,  Up: Statements

6.1.7.4 case Statement
......................

     case EXPRESSION of
       SELECTOR: STATEMENT;
       ...
       SELECTOR: STATEMENT;
     end
or, with alternative statement sequence:
     case ORDINAL_EXPRESSION of
       SELECTOR: STATEMENT;
       ...
       SELECTOR: STATEMENT;
     otherwise                   { ``else'' instead of ``otherwise'' allowed }
       STATEMENT;
       ...
       STATEMENT;
     end
   or, as part of the invariant `record' type definition:
     type
       foo = record
         FIELD_DECLARATIONS
       case bar: VARIANT_TYPE of
         SELECTOR: (FIELD_DECLARATIONS);
         SELECTOR: (FIELD_DECLARATIONS);
         ...
       end;
   or, without a variant selector field,
     type
       foo = record
         FIELD_DECLARATIONS
       case VARIANT_TYPE of
         SELECTOR: (FIELD_DECLARATIONS);
         SELECTOR: (FIELD_DECLARATIONS);
         ...
       end;

   The `case' statement compares the value of ORDINAL_EXPRESSION to
each SELECTOR, which can be a constant, a subrange, or a list of them
separated by commas, being compatible with the result of
ORDINAL_EXPRESSION.  Note: duplicate selectors or range crossing is not
allowed unless {$borland-pascal} is specified. In case of equality the
corresponding statement is executed. If `otherwise' is specified and no
appropriate selector matched the expression, the series of statements
following `otherwise' is executed. As a synonym for `otherwise', `else'
can be used. The semicolon before `otherwise' is optional.

   @@ ????  The expression _must_ match one of the selectors in order
to continue, unless an alternative statement series is specified.

   For `case' in a variant record type definition, see *Note Record
Types::.

See also
--------

*Note if Statement::


File: gpc.info,  Node: for Statement,  Next: while Statement,  Prev: case Statement,  Up: Statements

6.1.7.5 for Statement
.....................

For ordinal index variables:
     for ORDINAL_VARIABLE := INITIAL_VALUE to FINAL_VALUE do
       STATEMENT
   or
     for ORDINAL_VARIABLE := INITIAL_VALUE downto FINAL_VALUE do
       STATEMENT

   For sets:
     for SET_ELEMENT_TYPE_VARIABLE in SOME_SET do
       STATEMENT

   For pointer index variables:
     for POINTER_VARIABLE := INITIAL_ADDRESS to FINAL_ADDRESS do
       STATEMENT
   or
     for POINTER_VARIABLE := INITIAL_ADDRESS downto FINAL_ADDRESS do
       STATEMENT

   The FOR statement is a control statement where an index variable
assumes every value of a certain range and for every value the index
variable assumes STATEMENT is executed. The range can be specified by
two bounds (which must be of the same type as the index variable, i.e.
ordinal or pointers) or by a set.

   For ordinal index variables:
   - If `to' is specified, the index counter is increased by one as
     long as INITIAL_VALUE is less or equal to FINAL VALUE,

   - if `downto' is specified, it is decreased by one as long as
     INITIAL_VALUE is greater or equal to FINAL_VALUE.

   For pointer index variables:
   - If `to' is specified, the index counter is increased by the size
     of the type the index variable points to (if it is a typed
     pointer, otherwise by one if it is typeless) as long as
     INITIAL_ADDRESS is less or equal to FINAL_ADDRESS,

   - if `downto' is specified, it is decreased by a corresponding value
     as long as INITIAL_ADDRESS is greater or equal to FINAL_ADDRESS.

   Since gpc provides a flat memory modell, all addresses are linear,
so they can be compared. Still, such loops should be used (if at all)
only for iterating through successive elements of an array.

   For sets:
   - STATEMENT is executed with the index variable (which must be
     ordinal and of the same type as the set elements) assuming every
     element in SOME_SET, however note that a set is a not-ordered
     structure.

   *Please note:* A modification of the index variable may result in
unpredictable action.

See also
--------

*Note Set Types::, *Note Pointer Arithmetics::, *Note repeat
Statement::, *Note for Statement::


File: gpc.info,  Node: while Statement,  Next: repeat Statement,  Prev: for Statement,  Up: Statements

6.1.7.6 while Statement
.......................

The while loop has the following form
     while BOOLEAN_EXPRESSION do
       STATEMENT

   The `while' statement declares a loop which is executed while
BOOLEAN_EXPRESSION is true. Since the terminating condition is checked
before execution of the loop body, STATEMENT may never be executed.

See also
--------

*Note repeat Statement::, *Note for Statement::


File: gpc.info,  Node: repeat Statement,  Next: asm Inline,  Prev: while Statement,  Up: Statements

6.1.7.7 repeat Statement
........................

     repeat
       STATEMENT;
       ...
       STATEMENT;
     until BOOLEAN_EXPRESSION

   The `repeat' ... `until' statement declares a loop which is repeated
until BOOLEAN_EXPRESSION is true. Since the terminating condition is
checked after execution of the loop body, the statement sequence is
executed at least once.

See also
--------

*Note while Statement::, *Note for Statement::


File: gpc.info,  Node: asm Inline,  Next: with Statement,  Prev: repeat Statement,  Up: Statements

6.1.7.8 asm Inline
..................

@@ ????
     asm (StatementList: String);

   The `asm' inline statement is a GNU Pascal extension. It requires
its parameter to be AT&T-noted assembler statements, and therefore it
is not compatible with that one of Borland Pascal.  STATEMENTLIST is a
string containing asm statements separated by semicolons.


File: gpc.info,  Node: with Statement,  Next: goto Statement,  Prev: asm Inline,  Up: Statements

6.1.7.9 with Statement
......................


File: gpc.info,  Node: goto Statement,  Next: Procedure Call,  Prev: with Statement,  Up: Statements

6.1.7.10 goto Statement
.......................

@@ ????  This statement looks like this:
     goto LABEL

   (Under construction.)


File: gpc.info,  Node: Procedure Call,  Next: The Declaring Statement,  Prev: goto Statement,  Up: Statements

6.1.7.11 Procedure Call
.......................

     SUBROUTINE_NAME;

   This statement calls the subroutine SUBROUTINE_NAME which can either
be a procedure or, if GNU extended syntax is turned on, a function. In
this case, the result is ignored.


File: gpc.info,  Node: The Declaring Statement,  Next: Loop Control Statements,  Prev: Procedure Call,  Up: Statements

6.1.7.12 The Declaring Statement
................................

This statement allows to declare a variable within a statement part. It
looks like this:
     var
       VAR_IDENTIFIER: TYPE_IDENTIFIER;
   or
     var
       VAR_IDENTIFIER: TYPE_DEFINITION;
   and with initializing value:
     var
       VAR_IDENTIFIER: TYPE_IDENTIFIER value EXPRESSION;
   or
     var
       VAR_IDENTIFIER: TYPE_DEFINITION value EXPRESSION;

   Unlike in declaration parts, the initializing EXPRESSION does not
have to be a constant expression. Note that every declaring statement
has to start with `var'. The name space of the variable extends from
its declaration to the end of the current matching statement sequence
(which can be a statement part (of the program, a function, a procedure
or an operator) or, within that part, a begin end compound statement, a
repeat loop, or the else branch of a case statement). This statement is
a GNU Pascal extension.

See also
--------

*Note Type Definition::, *Note Data Types::


File: gpc.info,  Node: Loop Control Statements,  Prev: The Declaring Statement,  Up: Statements

6.1.7.13 Loop Control Statements
................................

These are
     Continue;
   and
     Break;

   These simple statements _must not_ occur outside a loop, i.e. a
`for', `while' or `repeat' statement. `Continue' transfers control to
the beginning of the loop right by its call, `Break' exits the current
loop turn and continues loop execution.


File: gpc.info,  Node: Modules and Units,  Prev: Statements,  Up: Source Structures

6.1.8 Import Part and Module/Unit Concept
-----------------------------------------

* Menu:

* Modules::  The source structure of ISO 10206 Extended Pascal Modules.
* Units::    The source structure of UCSD/Borland Pascal Units.


File: gpc.info,  Node: Modules,  Next: Units,  Up: Modules and Units

6.1.8.1 The Source Structure of ISO 10206 Extended Pascal Modules
.................................................................

@@ Description missing here

   A module can have one or more `export' clauses and the name of an
`export' clause doesn't have to be equal to the name of the module.

   Sample module code with separate `interface' and `implementation'
parts:

     module DemoModule interface;  { interface part }

     export DemoModule = (FooType, SetFoo, GetFoo);

     type
       FooType = Integer;

     procedure SetFoo (f: FooType);
     function  GetFoo: FooType;

     end.

     module DemoModule implementation;  { implementation part }

     import
       StandardInput;
       StandardOutput;

     var
       Foo: FooType;

     { Note: the effect is the same as a `forward' directive would have:
       parameter lists and result types are not allowed in the
       declaration of exported routines, according to EP. In GPC, they
       are allowed, but not required. }
     procedure SetFoo;
     begin
       Foo := f
     end;

     function GetFoo;
     begin
       GetFoo := Foo
     end;

     to begin do
       begin
         Foo := 59;
         WriteLn ('Just an example of a module initializer. See comment below')
       end;

     to end do
       begin
         Foo := 0;
         WriteLn ('Goodbye')
       end;

     end.

   Alternatively the module interface and implementation may be
combined as follows:

     module DemoMod2;  { Alternative method }

     export Catch22 = (FooType, SetFoo, GetFoo);

     type
       FooType = Integer;

     procedure SetFoo (f: FooType);
     function  GetFoo: FooType;

     end; { note: this `end' is required here, even if the
            module-block below would be empty. }

     var
       Foo: FooType;

     procedure SetFoo;
     begin
       Foo := f
     end;

     function GetFoo;
     begin
       GetFoo := Foo
     end;

     end.

   Either one of the two methods may be used like this:

     program ModuleDemo (Output);

     import DemoModule;

     begin
       SetFoo (999);
       WriteLn (GetFoo);
     end.

     program ModDemo2 (Output);

     import Catch22 in 'demomod2.pas';

     begin
       SetFoo (999);
       WriteLn (GetFoo);
     end.

   Somewhat simpler GPC modules are also supported. *Please note:* This
is not supported in the Extended Pascal standard.

   This is a simpler module support that does not require exports,
imports, module headers etc.

   These non-standard simple GPC modules look like the following
example. They do not have an export part, do not have a separate
module-block, do not use import/export features.

   Instead, you have to emulate the exporting/importing yourself using
`attribute' and `external name'.

     module DemoMod3;

     type
       FooType = Integer;

     var
       Foo: FooType;

     procedure SetFoo (f: FooType); attribute (name = 'SetFoo');
     begin
       Foo := f
     end;

     function GetFoo: FooType; attribute (name = 'GetFoo');
     begin
       GetFoo := Foo;
     end;

     end.

     program ModDemo3 (Output);

     {$L demomod3.pas}  { explicitly link module }

     { Manually do the "import" from DemoMod3 }
     type
       FooType = Integer;

     procedure SetFoo (f: FooType); external name 'SetFoo';
     function  GetFoo: FooType;     external name 'GetFoo';

     begin
       SetFoo (999);
       WriteLn (GetFoo)
     end.

   Module initialization and finalization:

   The `to begin do' module initialization and `to end do' module
finalization constructs now work on _every_ target.

   By the way: The "GPC specific" module definition is almost identical
to the PXSC standard. With an additional keyword `global' which puts a
declaration into an export interface with the name of the module, it
will be the same. @@This is planned.


File: gpc.info,  Node: Units,  Prev: Modules,  Up: Modules and Units

6.1.8.2 The Source Structure of UCSD/Borland Pascal Units
.........................................................

A generic GNU Pascal unit looks like the following:

     unit NAME;

     interface

     IMPORT_PART

     INTERFACE_PART

     implementation

     IMPLEMENTATION_PART

     INITIALIZATION_PART

     end.

   The NAME of the unit should coincide with the name of the file with
the extension stripped. (If not, you can tell GPC the file name with
`uses foo in 'bar.pas'', see *Note uses::.)

   The IMPORT_PART is either empty or contains a `uses' clause to
import other units. It may also consist of an ISO-style `import'
specification. Note that the implementation part is not preceeded by a
second import part in GPC (see *Note import::).

   The INTERFACE_PART consists of constant, type, and variable
declarations, procedure and function headings which may be freely mixed.

   The IMPLEMENTATION_PART is like the declaration part of a program,
but the headers of procedures and functions may be abbreviated:
Parameter lists and function results may be omitted for procedures and
functions already declared in the interface part.

   The INITIALIZATION_PART may be missing, or it may be a `begin'
followed by one or more statements, such that the unit has a statement
part between this `begin' and the final `end'. Alternatively, a unit
may have ISO-style module initializers and finalizers, see *Note to
begin do::, *Note to end do::.

   Note that GPC does _not_ yet check whether all interface
declarations are resolved in the same unit. The implementation of
procedures and functions which are in fact not used may be omitted,
and/or procedures and functions may be implemented somewhere else, even
in a different language. However, relying on a GPC bug (that will
eventually be fixed) is not a good idea, so this is not recommended.
Instead, declare such routines as `external'.

   A unit exports everything declared in the interface section. The
exported interface has the name of the unit and is compatible with
Extended Pascal module interfaces since GPC uses the same code to
handle both.


File: gpc.info,  Node: Data Types,  Next: Operators,  Prev: Source Structures,  Up: Programming

6.2 Data Types
==============

* Menu:

* Type Definition::                The Declaration Part
* Ordinal Types::                  Built-in Ordinal Types
* Integer Types::                  Built-in Integer Types
* Real Types::                     Built-in Real Types
* String Types::                   Built-in Character and String Types
* Character Types::                Built-in Chararacter Types. See Ordinal Types
* Enumerated Types::               Enumerated Types. See also Ordinal Types
* File Types::                     Built-in Types for File Handling
* Boolean (Intrinsic)::            Built-in Type for Boolean values.
* Pointer (Intrinsic)::            The Intrinsic Pointer Type
* Type Definition Possibilities::  User-defined Types
* Machine-dependencies in Types::  Differences in Implementation


File: gpc.info,  Node: Type Definition,  Next: Ordinal Types,  Up: Data Types

6.2.1 Type Definition
---------------------

As described in *Note Type Declaration::, a type declaration part looks
like this:
     type
        TYPE_IDENTIFIER = TYPE_DEFINITION;
        ...
        TYPE_IDENTIFIER = TYPE_DEFINITION;
   where the left side is the type declaration and the right one the
type definition side. GNU Pascal offers various possibilities to
implement highly specialized and problem-specific data types.


File: gpc.info,  Node: Ordinal Types,  Next: Integer Types,  Prev: Type Definition,  Up: Data Types

6.2.2 Ordinal Types
-------------------

An ordinal type is one that can be mapped to a range of whole numbers.
It includes integer types, character types, enumerated types and
subrange types of them.

   A character type is represented by the intrinsic type `Char' which
can hold elements of the operating system's character set (usually
ASCII). Conversion between character types and integer types is
possible with the intrinsic functions `Ord' and `Chr'.

   An enumerated type defines a range of elements which are referred to
by identifiers. Conversion from enumerated types to integer types is
possible with the intrinsic function `Ord'. Conversion from integer to
ordinal types is only possible by type-casting or using the extended
form of `Succ'.

     var
       Foo: Char;       { foo can hold a character }
       Num: '0' .. '9'; { Can hold decimal digits, is a subrange type of Char }
       Day: (Monday, Tuesday, Wednesday, Thursday,
             Friday, Saturday, Sunday);  { Can hold weekdays }

See also
--------

*Note Ord::, *Note Chr::, *Note Type Casts::


File: gpc.info,  Node: Integer Types,  Next: Real Types,  Prev: Ordinal Types,  Up: Data Types

6.2.3 Integer Types
-------------------

Besides `Integer', GNU Pascal supports a large zoo of integer types.
Some of them you will find in other compilers, too, but most are GNU
Pascal extensions, introduced for particular needs. Many of these types
are synonyms for each other. In total, GPC provides 20 built-in integer
types, plus seven families you can play with. (Four of these "families"
are signed and unsigned, packed and unpacked subrange types; the others
are explained below.)

* Menu:

* Natural Integer Types::
* Main Branch Integer Types::
* Integer Types with Specified Size::
* Integer Types and Compatibility::
* Summary of Integer Types::

   See also: *Note Subrange Types::.


File: gpc.info,  Node: Natural Integer Types,  Next: Main Branch Integer Types,  Up: Integer Types

6.2.3.1 The CPU's Natural Integer Types
.......................................

For most purposes, you will always use `Integer', a signed integer type
which has the "natural" size of such types for the machine. On most
machines GPC runs on, this is a size of 32 bits, so `Integer' usually
has a range of `-2147483648..2147483647' (see *Note Integer::).

   If you need an unsigned integer type, the "natural" choice is
`Cardinal', also called `Word'. Like `Integer', it has 32 bits on most
machines and thus a range of `0..4294967295' (see *Note Cardinal::,
*Note Word::).

   These natural integer types should be your first choice for best
performance. For instance on an IA32 CPU operations with `Integer'
usually work faster than operations with shorter integer types like
`ShortInt' or `ByteInt' (see below).


File: gpc.info,  Node: Main Branch Integer Types,  Next: Integer Types with Specified Size,  Prev: Natural Integer Types,  Up: Integer Types

6.2.3.2 The Main Branch of Integer Types
........................................

`Integer', `Cardinal', and `Word' define the three "main branches" of
GPC's integer types. You won't always be able to deal with the natural
size; sometimes something smaller or longer will be needed. Especially
when interfacing with libraries written in other languages such as C,
you will need equivalents for their integer types.

   The following variants of integer types (plus one Boolean type) are
guaranteed to be compatible to the respective types of GNU C as listed
below (whereas `Integer', `Cardinal' and `Word' themselves are _not_
guaranteed to be compatible to any given C type). The sizes given,
however, are _not_ guaranteed. They are just typical values currently
used on some platforms, but they may be actually shorter or longer on
any given platform.

signed         unsigned     also unsigned    GNU C equivalent            size in bits
                                                                         (example)
ByteInt        ByteCard     Byte             [un]signed char             8
ShortInt       ShortCard    ShortWord        [unsigned] short int        16
CInteger       CCardinal    CWord            [unsigned] int              32
MedInt         MedCard      MedWord          [unsigned] long int         32
LongInt        LongCard     LongWord         [unsigned] long long int    64
--             SizeType     --               size_t                      32
PtrDiffType    --           --               ptrdiff_t                   32
PtrInt         PtrCard      PtrWord          --                          32
--             CBoolean     --               _Bool, bool                 8

   Since we don't know whether `LongInt' will always remain the
"longest" integer type available - maybe GNU C will get `long long long
int', one day, which we will support as `LongLongInt' - we have added
the synonym `LongestInt' for the longest available singed integer type,
and the same holds for `LongestCard' and `LongestWord'.


File: gpc.info,  Node: Integer Types with Specified Size,  Next: Integer Types and Compatibility,  Prev: Main Branch Integer Types,  Up: Integer Types

6.2.3.3 Integer Types with Specified Size
.........................................

In some situations you will need an integer type of a well-defined
size. For this purpose, GNU Pascal provides type attributes (*note
attribute::). The type

     Integer attribute (Size = 42)

is guaranteed to have a precision of 42 bits. In a realistic context,
you will most often give a power of two as the number of bits, and the
machine you will need it on will support variables of that size. If
this is the case, the specified precision will simultaneously be the
amount of storage needed for variables of this type.

   In short: If you want to be sure that you have a signed integer with
32 bits width, write `Integer attribute (Size = 32)', not just
`Integer' which might be bigger. The same works with unsigned integer
types such as `Cardinal' and `Word' and with Boolean types.

   This way, you _can't_ get a higher precision than that of
`LongestInt' or `LongestCard' (see *Note Main Branch Integer Types::).
If you need higher precision, you can look at the `GMP' unit (*note
GMP::) which provides integer types with arbitrary precision, but their
usage is different from normal integer types.


File: gpc.info,  Node: Integer Types and Compatibility,  Next: Summary of Integer Types,  Prev: Integer Types with Specified Size,  Up: Integer Types

6.2.3.4 Integer Types and Compatibility
.......................................

If you care about ISO compliance, _only_ use `Integer' and subranges of
`Integer'.

   Some of GPC's non-ISO integer types exist in Borland Pascal, too:
`Byte', `ShortInt', `Word', and `LongInt'. The sizes of these types,
however, are not the same as in Borland Pascal. Even for `Byte' this is
not guaranteed (while probable, though).

   When designing GNU Pascal, we thought about compatibility to Borland
Pascal. Since GNU Pascal is (at least) a 32-bit compiler, `Integer'
_must_ have (at least) 32 bits. But what to do with `Word'? Same size
as `Integer' (like in BP) or 16 bits (like in BP)? We decided to make
`Word' the "natural-sized" unsigned integer type, thus making it (at
least) 32 bits wide. Similarly, we decided to give `LongInt' twice the
size of `Integer' (like in BP) rather than making it 32 bits wide (like
in BP). So `LongInt' has 64 bits, and `ShortInt' has 16 bits on the
IA32 platform.

   On the other hand, to increase compatibility to Borland Pascal and
Delphi, GPC provides the alias name `Comp' for `LongInt' (64 bits on
IA32) and `SmallInt' for `ShortInt' (16 bits on IA32). Note that BP
treats `Comp' as a "real" type and allows assignments like `MyCompVar
:= 42.0'. Since we don't consider this a feature, GPC does not copy
this behaviour.


File: gpc.info,  Node: Summary of Integer Types,  Prev: Integer Types and Compatibility,  Up: Integer Types

6.2.3.5 Summary of Integer Types
................................

Here is a summary of all integer types defined in GPC. The sizes and
ranges are only _typical_ values, valid on some, but not all platforms.
Compatibility to GNU C however _is_ guaranteed.

*Note ByteInt::
     signed 8-bit integer type, `-128..128',
     compatible to `signed char' in GNU C.

*Note Byte: ByteCard.
     unsigned 8-bit integer type, `0..255',
     compatible to `unsigned char' in GNU C.

*Note ShortInt::
     signed 16-bit integer type, `-32768..32767',
     compatible to `short int' in GNU C.

*Note ShortWord: ShortCard.
     unsigned 16-bit integer type, `0..65535',
     compatible to `unsigned short int' in GNU C.

*Note Integer::
     signed 32-bit integer type, `-2147483648..2147483647',
     compatible to `int' in GNU C.

*Note Word: Cardinal.
     unsigned 32-bit integer type, `0..4294967295',
     compatible to `unsigned int' in GNU C.

*Note MedInt::
     signed 32-bit integer type, `-2147483648..2147483647',
     compatible to `long int' in GNU C.

*Note MedWord: MedCard.
     unsigned 32-bit integer type, `0..4294967295',
     compatible to `unsigned long int' in GNU C.

*Note LongInt::
     signed 64-bit integer type,
     `-9223372036854775808..9223372036854775807',
     compatible to `long long int' in GNU C.

*Note LongWord: LongCard.
     unsigned 64-bit integer type, `0..18446744073709551615',
     compatible to `unsigned long long int' in GNU C.

*Note LongestInt::
     signed 64-bit integer type,
     `-9223372036854775808..9223372036854775807'.

*Note LongestWord: LongestCard.
     unsigned 64-bit integer type, `0..18446744073709551615'.

*Note Comp::
     signed 64-bit integer type,
     `-9223372036854775808..9223372036854775807'.

*Note SmallInt::
     signed 16-bit integer type, `-32768..32767'.

*Note SizeType::
     integer type (usually unsigned) to represent the size of objects
     in memory

*Note PtrDiffType::
     signed integer type to represent the difference between two
     positions in memory

*Note PtrInt::
     signed integer type of the same size as a pointer

*Note PtrWord: PtrCard.
     unsigned integer type of the same size as a pointer

   To specify the number of bits definitely, use type attributes, *Note
attribute::.

     program IntegerTypesDemo (Output);

     var
       ByteVar: Byte;
       ShortIntVar: ShortInt;
       Foo: MedCard;
       Big: LongestInt;

     begin
       ShortIntVar := 1000;
       Big := MaxInt * ShortIntVar;
       ByteVar := 127;
       Foo := 16#deadbeef
     end.

   See also: *Note Subrange Types::.


File: gpc.info,  Node: Real Types,  Next: String Types,  Prev: Integer Types,  Up: Data Types

6.2.4 Built-in Real (Floating Point) Types
------------------------------------------

GPC has three built-in floating point types to represent real numbers.
Each of them is available under two names (for compatibility to other
compilers and languages).

   For most purposes, you will always use `Real' which is the only one
of them that is part of Standard and Extended Pascal. If memory
constraints apply, you might want to choose `ShortReal' for larger
arrays. On the other hand, if high precision is needed, you can use
`LongReal'. When interfacing with libraries written in other languages
such as C, you will need the equivalents for their real types.

   Note that not all machines support longer floating point types, so
`LongReal' is the same as `Real' on these machines. Also, some machines
may support a longer type, but not do all arithmetic operations (e.g.
the `Sin' function, *Note Sin::) in a precision higher than that of
`Real'. If you need higher precision, you can look at the `GMP' unit
(*note GMP::) which provides rational and real numbers with arbitrary
precision, but their usage is different from normal real types.

   The following real types are guaranteed to be compatible to the real
types of GNU C. The sizes given, however, are _not_ guaranteed.  They
are just typical values used on any IEEE compatible floating point
hardware, but they may be different on some machines.

type name    alternative name    GNU C equivalent    size in bits (typically)
ShortReal    Single              float               32
Real         Double              double              64
LongReal     Extended            long double         80


File: gpc.info,  Node: String Types,  Next: Character Types,  Prev: Real Types,  Up: Data Types

6.2.5 Strings Types
-------------------

There are several ways to use strings in GNU Pascal. One of them is the
use of the intrinsic string type `String' which is a predefined schema
type. The schema discriminant of this type holds the maximal length,
which is of type Integer, so values up to `MaxInt' can be specified.
For `String', an assignment is defined. There are many built-in
functions and procedures for comfortable strings handling.

   @@ ???? String procedures and functions.

   Another way to use strings is to use arrays of type `Char'. For
these, an intrinsic assignment is defined as well. Besides, `String'
and `Char' are assignment compatible. The preferred way, however, is
`String' because of the numerous possibilities for string handling.


File: gpc.info,  Node: Character Types,  Next: Enumerated Types,  Prev: String Types,  Up: Data Types

6.2.6 Character Types
---------------------

Character types are a special case of ordinal types.

See also
--------

*Note Ordinal Types::, *Note Chr::, *Note Ord::, *Note Pred::, *Note
Succ::.


File: gpc.info,  Node: Enumerated Types,  Next: File Types,  Prev: Character Types,  Up: Data Types

6.2.7 Enumerated Types
----------------------

     type
       ENUM_TYPE_IDENTIFIER = (IDENTIFIER, ..., IDENTIFIER);

   An enumerated type is a a special case of ordinal types and defines
a range of elements which are referred to by identifiers. Enumerated
types are ordered by occurence in the identifier list. So, they can be
used as index types in an array definition, and it is possible to
define subranges of them. Since they are ordered, they can be compared
to one another. The intrinsic function `Ord' applied to NAME_IDENTIFIER
returns the number of occurence in the identifier list (beginning with
zero), `Pred' and `Succ' return the predecessor and successor of
NAME_IDENTIFIER.  `Boolean' is a special case of an enumerated type.

See also
--------

*Note Ordinal Types::, *Note Array Types::, *Note Subrange Types::,
*Note Ord::, *Note Boolean::, *Note Char::, *Note Pred::, *Note Succ::.


File: gpc.info,  Node: File Types,  Next: Boolean (Intrinsic),  Prev: Enumerated Types,  Up: Data Types

6.2.8 File Types
----------------

Files are used to store data permanently, normally on hard drives or
floppies. There are tree types of files available: text files, typed
and untyped files.

   Text files are used to store text in them, where typed files are
used to store many entries of the same type in them, e.g.  addresses.
Text files and typed files are accessible by `Read' and `Write'
operations and do not need the parameter `BlockSize' in `Reset' or
`Rewrite'.  On the other hand, untyped files are used to store any type
of information in them but you need to use `BlockWrite' or `BlockRead'
to store or retrieve data out of this file.

     var
       F1: Text;   { a textfile }
       F2: file of Real;   { a typed filed used to store real values in it }
       F3: File;   { an untyped file }

See also
--------

*Note File Routines::, *Note Write::, *Note Read::, *Note BlockRead::,
*Note BlockWrite::, *Note Reset::, *Note Rewrite::


File: gpc.info,  Node: Boolean (Intrinsic),  Next: Pointer (Intrinsic),  Prev: File Types,  Up: Data Types

6.2.9 Boolean (Intrinsic)
-------------------------

The intrinsic Boolean represents boolean values, i.e. it can only assume
true and false (which are predefined constants). This type corresponds
to the enumerated type
     type
       Boolean = (False, True);
   Since it is declared this way, it follows:
     Ord (False) = 0
     Ord (True) = 1
     False < True
    There are four intrinsic logical operators. The logical `and',
`or' and `not'. In Borland Pascal and GNU Pascal, there is  a logical
"exclusive or" `xor'.

See also
--------

*Note Enumerated Types::, *Note and::, *Note or::, *Note not::, *Note
xor::


File: gpc.info,  Node: Pointer (Intrinsic),  Next: Type Definition Possibilities,  Prev: Boolean (Intrinsic),  Up: Data Types

6.2.10 Pointer (Intrinsic)
--------------------------

The intrinsic Pointer Type is a so-called unspecified or typeless
pointer (i.e. a pointer which does not point to any type but holds
simply a memory address).

See also
--------

*Note Pointer Types::, *Note nil::


File: gpc.info,  Node: Type Definition Possibilities,  Next: Machine-dependencies in Types,  Prev: Pointer (Intrinsic),  Up: Data Types

6.2.11 Type Definition Possibilities
------------------------------------

* Menu:

* Subrange Types::     Packed and non-packed Subranges
* Array Types::        Fields (Array Types)
* Record Types::       Structured Types (Record Types)
* Variant Records::    Record Types with Varying Fields
* Schema Types::       Schema Types
* Set Types::          Set Types
* Pointer Types::      Pointer Types
* Procedural Types::   Procedures Types
* Object Types::       Types for Object-Oriented Programming
* Type Initializers::  Types Carrying an Initial Value for Variables
* Restricted Types::   Hiding Internal Information about Types


File: gpc.info,  Node: Subrange Types,  Next: Array Types,  Up: Type Definition Possibilities

6.2.11.1 Subrange Types
.......................

GNU Pascal supports Standard Pascal's subrange types:

     program SubrangeDemo;
     type
       MonthInt = 1 .. 12;
       Capital = 'A' .. 'Z';
       ControlChar = ^A .. ^Z;  { `^A' = `Chr (1)' is a BP extension }
     begin
     end.
   Also possible: Subranges of enumerated types:
     program EnumSubrangeDemo;
     type
       { This is an enumerated type. }
       Days = (Mon, Tue, Wed, Thu, Fri, Sat, Sun);

       { This is a subrange of `Days'. }
       Working = Mon .. Fri;

     begin
     end.

   To increase performance, variables of such a type are aligned in a
way which makes them fastest to access by the CPU. As a result, `1 ..
12' occupies 4 bytes of storage on an IA32 CPU.

   For the case you want to save storage at the expense of speed, GPC
provides a `packed' variant of these as an extension:

     program PackedSubrangeDemo;
     type
       MonthInt = packed 1 .. 12;
     begin
     end.

   A variable of this type occupies the shortest possible (i.e.,
addressable) space in memory - one byte on an IA32 compatible CPU.

   See also: *Note packed::.


File: gpc.info,  Node: Array Types,  Next: Record Types,  Prev: Subrange Types,  Up: Type Definition Possibilities

6.2.11.2 Array Types
....................

     type
       ARRAY_TYPE_IDENTIFIER = array [INDEX_TYPE] of ELEMENT_TYPE
or
     type
       ARRAY_TYPE_IDENTIFIER = array [INDEX_TYPE, ..., INDEX_TYPE] of ELEMENT_TYPE

   The reserved word `array' defines an array type. INDEX_TYPE has to
be an ordinal type, subrange type or an enumerated type, where several
index types, separated by commas, are allowed. ELEMENT_TYPE is an
arbitrary type. An element of an array is accessed by
ARRAY_TYPE_VARIABLE [INDEX_NUMBER]. The upper and lower index bounds
can be determined by the intrinsic functions `High' and `Low'.

     type
       IntArray = array [1 .. 20] of Integer;
       Foo      = array [(Mo, Tu, We, Th, Fr, Sa, Su)] of Char;
       Bar      = array [0 .. 9, 'a' .. 'z', (Qux, Glork1, Fred)] of Real;
       Baz1     = array [1 .. 10] of IntArray;
       { equal (but declared differently): }
       Baz2     = array [1 .. 10, 1 .. 20] of Integer;

See also
--------

*Note High::, *Note Low::


File: gpc.info,  Node: Record Types,  Next: Variant Records,  Prev: Array Types,  Up: Type Definition Possibilities

6.2.11.3 Record Types
.....................

     type
       RECORD_TYPE_IDENTIFIER = record
         FIELD_IDENTIFIER: TYPE_DEFINITION;
         ...
         FIELD_IDENTIFIER: TYPE_DEFINITION;
       end;

   or, with a variant part,

     type
       RECORD_TYPE_IDENTIFIER = record
         FIELD_IDENTIFIER: TYPE_DEFINITION;
         ...
         FIELD_IDENTIFIER: TYPE_DEFINITION;
       case bar: VARIANT_TYPE of
         SELECTOR: (FIELD_DECLARATIONS);
         SELECTOR: (FIELD_DECLARATIONS);
         ...
       end;

   or, without a variant selector field,

     type
       RECORD_TYPE_IDENTIFIER = record
         FIELD_IDENTIFIER: TYPE_DEFINITION;
         ...
         FIELD_IDENTIFIER: TYPE_DEFINITION;
       case VARIANT_TYPE of
         SELECTOR: (FIELD_DECLARATIONS);
         SELECTOR: (FIELD_DECLARATIONS);
         ...
       end;

   The reserved word `record' defines a structure of fields.  Records
can be `packed' to save memory usage at the expense of speed.

   The reserved word `record' and record types are defined in ISO 7185
Pascal. According to ISO Pascal, the variant type must be an
identifier. GNU Pascal, like UCSD and Borland Pascal, also allows a
subrange here.

   A record field is accessed by RECORD_TYPE_VARIABLE . FIELD_IDENTIFIER

   See also: *Note packed::, *Note case Statement::.


File: gpc.info,  Node: Variant Records,  Next: Schema Types,  Prev: Record Types,  Up: Type Definition Possibilities

6.2.11.4 Variant Records
........................

GPC supports variant records like in EP and BP. The following
construction is not allowed in Extended Pascal, but in BP and GPC:

     program BPVariantRecordDemo;

     type
       PersonRec = record
         Age: Integer;
       case EyeColor: (Red, Green, Blue, Brown) of
         Red, Green : (WearsGlasses: Boolean);
         Blue, Brown: (LengthOfLashes: Integer);
       end;

     begin
     end.

   In EP, the variant field needs a type identifier, which, of course,
also works in GPC:

     program EPVariantRecordDemo;

     type
       EyeColorType = (Red, Green, Blue, Brown);

       PersonRec = record
         Age: Integer;
       case EyeColor: EyeColorType of
         Red, Green : (WearsGlasses: Boolean);
         Blue, Brown: (LengthOfLashes: Integer);
       end;

     begin
     end.


File: gpc.info,  Node: Schema Types,  Next: Set Types,  Prev: Variant Records,  Up: Type Definition Possibilities

6.2.11.5 EP's Schema Types including `String'
.............................................

Schemata are types that depend on one or more variables, called
"discriminants". They are an ISO 10206 Extended Pascal feature.

     type
       RealArray (n: Integer) = array [1 .. n] of Real;
       Matrix (n, m: PositiveInteger) = array [1 .. n, 1 .. m] of Integer;

   The type `RealArray' in this example is called a Schema with the
discriminant `n'.

   To declare a variable of such a type, write:

     var
       Foo: RealArray (42);

   The discriminants of every global or local schema variable are
initialized at the beginning of the procedure, function or program
where the schema variable is declared.

   Schema-typed variables "know" about their discriminants.
Discriminants can be accessed just like record fields:

     program Schema1Demo;
     type
       PositiveInteger = 1 .. MaxInt;
       RealArray (n: Integer) = array [1 .. n] of Real;
       Matrix (n, m: PositiveInteger) = array [1 .. n, 1 .. m] of Integer;

     var
       Foo: RealArray (42);

     begin
       WriteLn (Foo.n)  { yields 42 }
     end.

   Schemata may be passed as parameters. While types of schema
variables must always have specified discriminants (which may be other
variables), formal parameters (by reference or by value) may be of a
schema type without specified discriminant. In this, the actual
parameter may posses any discriminant. The discriminants of the
parameters get their values from the actual parameters.

   Also, _pointers_ to schema variables may be declared without a
discriminant:

     program Schema2Demo;
     type
       RealArray (n: Integer) = array [1 .. n] of Real;
       RealArrayPtr = ^RealArray;
     var
       Bar: RealArrayPtr;
     begin
     end.

   When applying `New' to such a pointer, you must specify the intended
value of the discriminant as a parameter:

     New (Bar, 137)

   As a GNU Pascal extension, the above can also be written as

     Bar := New (RealArrayPtr, 137)

   The allocated variable behaves like any other schema variable:

     program Schema3Demo;
     type
       RealArray (n: Integer) = array [1 .. n] of Real;
       RealArrayPtr = ^RealArray;
     var
       Bar: RealArrayPtr;
       i: Integer;
     begin
       Bar := New (RealArrayPtr, 137);
       for i := 1 to Bar^.n do
         Bar^[i] := 42
     end.

   Since the schema variable "knows" its size, pointers to schemata can
be disposed just like other pointers:

     Dispose (Bar)

   Schemata are not limited to arrays. They can be of any type that
normally requires constant values in its definition, for instance
subrange types, or records containing arrays etc. (Sets do not yet
work.)

   References to the schema discriminants are allowed, and the `with'
statement is also allowed, so one can say:

     program SchemaWithDemo;
     type
       RealArray (n: Integer) = array [1 .. n] of Real;
     var
       MyArray: RealArray (42);
     begin
       WriteLn (MyArray.n);  { writes 42 }
       with MyArray do
         WriteLn (n);        { writes 42 }
     end.

   Finally, here is a somewhat exotic example. Here, a `ColoredInteger'
behaves just like an ordinary integer, but it has an additional
property `Color' which can be accessed like a record field.

     program SchemaExoticDemo;

     type
       ColorType = (Red, Green, Blue);
       ColoredInteger (Color: ColorType) = Integer;

     var
       Foo: ColoredInteger (Green);

     begin
       Foo := 7;
       if Foo.Color = Red then
         Inc (Foo, 2)
       else
         Foo := Foo div 3
     end.

   An important schema is the predefined `String' schema (according to
Extended Pascal). It has one predefined discriminant identifier
`Capacity'. GPC implements the `String' schema as follows:

     type
       String (Capacity: Cardinal) = record
         Length: 0 .. Capacity;
         Chars: packed array [1 .. Capacity + 1] of Char
       end;

   The `Capacity' field may be directly referenced by the user, the
`Length' field is referenced by a predefined string function `Length
(Str)' and contains the current string length.  `Chars' contains the
chars in the string. The `Chars' and `Length' fields cannot be directly
referenced by a user program.

   If a formal value parameter is of type `String' (with or without
discriminant), the actual parameter may be either a `String' schema, a
fixed string (character array), a single character, a string literal or
a string expression. If the actual parameter is a `String' schema, it
is copied for the parameter in the usual way. If it is not a schema, a
`String' schema is created automatically, the actual parameter is
copied to the new variable and the `Capacity' field of the new variable
is set to the length of the actual parameter.

   Actual parameters to `var' parameters of type `String' must be
`String' schemata, not string literals or character arrays.

     program StringDemo (Output);

     type
       SType = String (10);
       SPtr  = ^String;

     var
       Str : SType;
       Str2: String (100000);
       Str3: String (20) value 'string expression';
       DStr: ^String;
       ZStr: SPtr;
       Len : Integer value 256;
       Ch  : Char value 'R';

     { `String' accepts any length of strings }
     procedure Foo (z: String);
     begin
       WriteLn ('Capacity: ', z.Capacity);
       WriteLn ('Length  : ', Length (z));
       WriteLn ('Contents: ', z);
     end;

     { Another way to use dynamic strings }
     procedure Bar (SLen: Integer);
     var
       LString: String (SLen);
       FooStr: type of LString;
     begin
       LString := 'Hello world!';
       Foo (LString);
       FooStr := 'How are you?';
       Foo (FooStr);
     end;

     begin
       Str  := 'KUKKUU';
       Str2 := 'A longer string variable';
       New (DStr, 1000);  { Select the string Capacity with `New' }
       DStr^ := 'The maximum length of this is 1000 chars';
       New (ZStr, Len);
       ZStr^ := 'This should fit here';
       Foo (Str);
       Foo (Str2);
       Foo ('This is a constant string');
       Foo ('This is a ' + Str3);
       Foo (Ch);  { A char parameter to string routine }
       Foo ('');  { An empty string }
       Foo (DStr^);
       Foo (ZStr^);
       Bar (10000);
     end.

   In the above example, the predefined procedure `New' was used to
select the capacity of the strings. Procedure `Bar' also has a string
whose size depends of the parameter passed to it and another string
whose type will be the same as the type of the first string, using the
`type of' construct.

   All string and character types are compatible as long as the
destination string is long enough to hold the source in assignments.
If the source string is shorter than the destination, the destination
is automatically blank padded if the destination string is not of
string schema type.


File: gpc.info,  Node: Set Types,  Next: Pointer Types,  Prev: Schema Types,  Up: Type Definition Possibilities

6.2.11.6 Set Types
..................

     SET_TYPE_IDENTIFIER = set of SET_ELEMENT_TYPE;

   SET_TYPE_IDENTIFIER is a set of elements from SET_ELEMENT_TYPE which
is either an ordinal type, an enumerated type or a subrange type.  Set
element representatives are joined together into a set by brackets:
     [SET_ELEMENT, ..., SET_ELEMENT]
   `[]' indicates the empty set, which is compatible with all set types.
Note: Borland Pascal restricts the maximal set size (i.e. the range of
the set element type) to 256, GNU Pascal has no such restriction.  The
number of elements a set variable is holding can be determined by the
intrinsic set function Card (which is a GNU Pascal extension, in
Extended Pascal and Borland Pascal you can use SizeOf instead but note
the element type size in bytes, then) to the set.  There are four
intrinsic binary set operations: the union `+', the intersection `*'
and the difference `-'. The symmetric difference `><' is an Extended
Pascal extension.

See also
--------

*Note Card::, *Note SizeOf::


File: gpc.info,  Node: Pointer Types,  Next: Procedural Types,  Prev: Set Types,  Up: Type Definition Possibilities

6.2.11.7 Pointer Types
......................

     POINTER_TYPE_IDENTIFIER = ^TYPE_IDENTIFIER;

   A pointer of the type POINTER_TYPE_IDENTIFIER holds the address at
which data of the type TYPE_IDENTIFIER is situated.  Unlike other
identifier declarations, where all identifiers in definition part have
to be declared before, in a pointer type declaration TYPE_IDENTIFIER
may be declared after POINTER_TYPE_IDENTIFIER. The data pointed to is
accessed by `POINTER_TYPE_VARIABLE^'. To mark an unassigned pointer,
the `nil' constant (which stands for "not in list") has to be assigned
to it, which is compatible with all pointer types.

     type
       ItselfFoo = ^ItselfFoo;  { possible but mostly senseless }

       PInt      = ^Integer;    { Pointer to an Integer }

       PNode     = ^TNode;      { Linked list }
       TNode     = record
         Key     : Integer;
         NextNode: PNode;
       end;

     var
       Foo, Bar: PInt;

     begin
       Foo := Bar;  { Modify address which foo is holding }
       Foo^ := 5;   { Access data foo is pointing to }
     end.

   GPC also suports pointers to procedures or function and calls
through them. This is a non-standard feature.

     program ProcPtrDemo (Output);

     type
       ProcPtr = ^procedure (i: Integer);

     var
       PVar: ProcPtr;

     procedure WriteInt (i: Integer);
     begin
       WriteLn ('Integer: ', i : 1)
     end;

     begin
       { Let PVar point to function WriteInt }
       PVar := @WriteInt;

       { Call the function by dereferencing the function pointer }
       PVar^ (12345)
     end.

   See also: *Note Pointer (Intrinsic)::.


File: gpc.info,  Node: Procedural Types,  Next: Object Types,  Prev: Pointer Types,  Up: Type Definition Possibilities

6.2.11.8 Procedural and Functional Types
........................................

For procedures without a parameter list:
     PROCEDURE_TYPE_IDENTIFIER = procedure NAME_IDENTIFIER;
   or functions:
     FUNCTION_TYPE_IDENTIFIER =
            function NAME_IDENTIFIER: FUNCTION_RESULT_TYPE;

   For procedures with a parameter list:
     PROCEDURE_TYPE_IDENTIFIER =
            procedure NAME_IDENTIFIER (PARAMETER_LIST);
   or functions:
     FUNCTION_TYPE_IDENTIFIER =
            function NAME_IDENTIFIER (PARAMETER_LIST): FUNCTION_RESULT_TYPE;

   Procedural types can be used as procedures or functions
respectively, but also a value can be assigned to them. Procedural
types are a Borland Pascal extension. In Borland Pascal,
FUNCTION_RESULT_TYPE can only be one of these types: ordinal types,
real types, pointer types, the intrinsic `String' type.  In GNU Pascal
every function result type for procedural types is allowed.

   BP has procedural and functional types:

     type
       CompareFunction = function (Key1, Key2: String): Integer;

     function Sort (Compare: CompareFunction);
     begin
       ...
     end;

   Standard Pascal has procedural and functional parameters:

     function Sort (function Compare (Key1, Key2: String): Integer);
     begin
       ...
     end;

   Both ways have pros and cons, e.g. in BP you can save, compare,
trade, etc. procedural values, or build arrays of them, while the SP
way does not require a type declaration and prevents problems with
uninitialized or invalid pointers (which in BP will usually crash the
program).

   GPC supports both ways. An important feature of Standard Pascal (but
not BP) that GPC also supports is the possibility to pass _local_
routines as procedural or functional parameters, even if the called
routine is declared far remote. The called routine can then call the
passed local routine and it will have access to the original caller's
local variables.

     program LocalProceduralParameterDemo;

     procedure CallProcedure (procedure Proc);
     begin
       Proc
     end;

     procedure MainProcedure;
     var LocalVariable: Integer;

       procedure LocalProcedure;
       begin
         WriteLn (LocalVariable)
       end;

     begin
       LocalVariable := 42;
       CallProcedure (LocalProcedure)
     end;

     begin
       MainProcedure
     end.

   See also: *Note The Procedure::, *Note The Function::, *Note
Subroutine Parameter List Declaration::, *Note Procedure Call::.


File: gpc.info,  Node: Object Types,  Next: Type Initializers,  Prev: Procedural Types,  Up: Type Definition Possibilities

6.2.11.9 Object Types
.....................

Object types are used to encapsulate data and methods.  Furthermore,
they implement a mechanism for inheritance.

See also
--------

*Note OOP::


File: gpc.info,  Node: Type Initializers,  Next: Restricted Types,  Prev: Object Types,  Up: Type Definition Possibilities

6.2.11.10 Initial values to type denoters
.........................................

A type may be initialized to a value of expression when it is declared,
like a variable, as in:

     program TypeVarInitDemo;
     type
       Int10   = Integer value 10;
       FooType = Real;
       MyType  = Char value Pred ('A');
       EType   = (a, b, c, d, e, f, g) value d;

     const
       Answer = 42;

     var
       ii : Int10;                    { Value of ii set to 10 }
       ch : MyType  value Pred ('z');
       aa : Integer value Answer + 10;
       foo: FooType value Sqr (Answer);
       e1 : EType;                    { value set to d }
       e2 : EType value g;            { value set to g }
     begin
     end.

   Extended Pascal requires the type initializers to be constant
expressions. GPC allows any valid expression.

   Note, however, that the expressions that affect the size of storage
allocated for objects (e.g. the length of arrays) may contain variables
only inside functions or procedures.

   GPC evaluates the initial values used for the type when an
identifier is declared for that type. If a variable is declared with a
type-denoter that uses a type-name which already has an initial value
the latter initialization has precedence.

   @@ GPC does not know how to calculate constant values for math
functions in the runtime library at compile time, e.g. `Exp (Sin
(2.4567))', so you should not use these kind of expressions in object
size expressions. (Extended Pascal allows this.)


File: gpc.info,  Node: Restricted Types,  Prev: Type Initializers,  Up: Type Definition Possibilities

6.2.11.11 Restricted Types
..........................

GPC supports `restricted' types, defined in Extended Pascal. A value of
a restricted type may be passed as a value parameter to a formal
parameter possessing its underlying type, or returned as the result of
a function. A variable of a restricted type may be passed as a variable
parameter to a formal parameter possessing the same type or its
underlying type. No other operations, such as accessing a component of
a restricted type value or performing arithmetic, are possible.

     program RestrictedDemo;

     type
       UnrestrictedRecord = record
         a: Integer;
       end;
       RestrictedRecord = restricted UnrestrictedRecord;

     var
       r1: UnrestrictedRecord;
       r2: RestrictedRecord;
       i: restricted Integer;
       k: Integer;

     function AccessRestricted (p: UnrestrictedRecord): RestrictedRecord;
     var URes: UnrestrictedRecord;
     begin
       { The parameter is treated as unrestricted, even though the actual
         parameter may be restricted }
       URes.a := p.a;
       { It is allowed to assign a function result }
       AccessRestricted := URes;
     end;

     begin
       r1.a := 354;

       { Assigning a restricted function result to a restricted variable }
       { @@ Verify if this should really be allowed????? }
       r2 := AccessRestricted (r1);

       { Passing a restricted value to unrestricted formal parameter is ok }
       r2 := AccessRestricted (r2);

       {$ifdef BUG}
       { *** The following statements are not allowed *** }
       k := r2.a;      { field access (reading) }
       r2.a := 100;    { field access (writing) }
       r1 := r2;       { assignment source is restricted }
       r2 := r1;       { assignment target is restricted }
       r1 := AccessRestricted (r2); { assigning a restricted function
                                      result to an unrestricted object }
       i  := 16#ffff;  { assignment target is restricted }
       k  := i + 2;    { arithmetic with restricted value }
       {$endif}
     end.


File: gpc.info,  Node: Machine-dependencies in Types,  Prev: Type Definition Possibilities,  Up: Data Types

6.2.12 Machine-dependencies in Types
------------------------------------

* Menu:

* Endianness::  How Integer Types are Stored on Different Machines
* Alignment::   How Variables are Placed in Memory


File: gpc.info,  Node: Endianness,  Next: Alignment,  Up: Machine-dependencies in Types

6.2.12.1 Endianness
...................

Endianness means the order in which the bytes of a value larger than
one byte are stored in memory. This affects, e.g., integer values and
pointers while, e.g., arrays of single-byte characters are not
affected. The GPC `String' schema, however, contains `Capacity' and
`Length' fields before the character array.  These fields are integer
values larger than one byte, so the `String' schema _is_ affected by
endianness.

   Endianness depends on the hardware, especially the CPU. The most
common forms are:

   * "Little-endian"

     Little-endian machines store the least significant byte on the
     lowest memory address (the word is stored "little-end-first").

     E.g., if the 32 bit value `$deadbeef' is stored on memory address
     `$1234' on a little-endian machine, the following bytes will
     occupy the memory positions:

     Address       Value
     $1234         $ef
     $1235         $be
     $1236         $ad
     $1237         $de

     Examples for little-endian machines are IA32 and compatible
     microprocessors and Alpha processors.

   * "Big-endian"

     Big-endian machines store the most significant byte on the lowest
     memory address (the word is stored "big-end-first").

     E.g., if the 32 bit value `$deadbeef' is stored on memory address
     `$1234' on a big-endian machine, the following bytes will occupy
     the memory positions:

     Address       Value
     $1234         $de
     $1235         $ad
     $1236         $be
     $1237         $ef

     Examples for big-endian machines are the Sparc and Motorola m68k
     CPU families and most RISC processors. Big-endian byte order is
     also used in the Internet protocols.


   _Note:_ There are processors which can run in both little-endian and
big-endian mode, e.g. the MIPS processors. A single program, however,
(unless it uses special machine code instructions) will always run in
one endianness.

   Under normal circumstances, programs do not need to worry about
endianness, the CPU handles it by itself. Endianness becomes important
when exchanging data between different machines, e.g.  via binary files
or over a network. To avoid problems, one has to choose the endianness
to use for the data exchange. E.g., the Internet uses big-endian data,
and most known data formats have a specified endianness (usually that
of the CPU on which the format was originally created). If you define
your own binary data format, you're free to choose the endianness to
use.

   To deal with endianness, GPC predefines the symbol
`__BYTES_LITTLE_ENDIAN__' on little-endian machines and
`__BYTES_BIG_ENDIAN__' on big-endian machines. Besides, the Run Time
System defines the constant `BytesBigEndian' as False on little-endian
machines and True on big-endian machines.

   There are also the symbols `__BITS_LITTLE_ENDIAN__',
`__BITS_BIG_ENDIAN__', `__WORDS_LITTLE_ENDIAN__',
`__WORDS_BIG_ENDIAN__' and the constants `BitsBigEndian' and
`WordsBigEndian' which concern the order of bits within a byte (e.g.,
in packed records) or of words within multiword-numbers, but these are
usually less important.

   The Run Time System also contains a number of routines to convert
endianness and to read or write data from/to binary files in a given
endianness, independent of the CPU's endianness. These routines are
described in the RTS reference (*note Run Time System::), under
`endianness'. The demo program `endiandemo.pas' contains an example on
how to use these routines.


File: gpc.info,  Node: Alignment,  Prev: Endianness,  Up: Machine-dependencies in Types

6.2.12.2 Alignment
..................

(Under construction.)  @@ ????


File: gpc.info,  Node: Operators,  Next: Parameters,  Prev: Data Types,  Up: Programming

6.3 Operators
=============

GNU Pascal supports all operators of ISO Pascal and Borland Pascal.  In
addition, you can define your own operators according to the Pascal-SC
(PXSC) syntax.

* Menu:

* Built-in Operators::
* User-defined Operators::


File: gpc.info,  Node: Built-in Operators,  Next: User-defined Operators,  Up: Operators

6.3.1 Built-in Operators
------------------------

The following table lists all built-in GNU Pascal operators, ordered by
precedence: `<' etc. have the lowest precedence, `not' etc. the
highest. As usual, the precedence of operators can be superseded with
parentheses.

   In an assignment statement, `:=' has lower precedence than all
operators. (This is rather obvious from the syntax of assignment
statements, and is merely noted for programmers familiar with C where
`=' is an operator.)

     <    =    >    in   <>   >=   <=
     +    -    or   +<   -<   +>   ->
     *    /    div  mod  and  shl  shr  xor  *<   /<   *>   />
     pow  **   ><
     not  @

   The Pascal-SC (PXSC) operators `+<', `-<', `+>', `->', `*<', `/<',
`*>', and `/>' are not yet implemented into GNU Pascal but may be
defined by the user (see below).


File: gpc.info,  Node: User-defined Operators,  Prev: Built-in Operators,  Up: Operators

6.3.2 User-defined Operators
----------------------------

GNU Pascal allows the (re-)definition of binary operators according to
the Pascal-SC (PXSC) syntax. The following vector addition example
illustrates how to do this:

     program OperatorDemo;

     type
       Vector3 = record
         x, y, z: Real;
       end;

     var
       a, b, c: Vector3 = (1, 2, 3);

     operator + (u, v: Vector3) w: Vector3;
     begin
       w.x := u.x + v.x;
       w.y := u.y + v.y;
       w.z := u.z + v.z;
     end;

     begin
       c := a + b
     end.

   Between the closing parenthesis of the argument list and the result
variable (`w' in the above example), GPC allows an optional equal sign.
This is not allowed in PXSC, but it is consistent with Extended
Pascal's function result variable definitions, where the equal sign is
obligatory (but also optional in GPC).

   The argument types needn't be equal, and the name of the operator
may be an identifier instead of a known symbol. You cannot define _new_
symbols in GPC.

   The PXSC operators `+>', `+<', etc. for exact numerical calculations
currently are not implemented in GPC, but you can define them. Also,
the other real-type operators do _not_ meet the requirements of PXSC; a
module which fixes that would be a welcome contribution.


File: gpc.info,  Node: Parameters,  Next: Pointer Arithmetics,  Prev: Operators,  Up: Programming

6.4 Procedure And Function Parameters
=====================================

* Menu:

* Protected Parameters::  Parameters declared `protected' or `const'
* Conformant Arrays::     The Standard way to pass arrays of variable size
* Open Arrays::           BP's alternative to Conformant Arrays


File: gpc.info,  Node: Protected Parameters,  Next: Conformant Arrays,  Up: Parameters

6.4.1 Parameters declared as `protected' or `const'
---------------------------------------------------

All the following works in GPC:

     procedure Foo (protected a, b, c: Integer);    { 3 arguments }
     procedure Foo (a, b, c, protected: Integer);   { 4 arguments }
     procedure Foo (a, b, protected, c: Integer);   { 4 arguments }
     procedure Foo (protected: Integer);            { 1 argument  }
     procedure Foo (var protected: Integer);        { 1 argument  }
     procedure Foo (protected protected: Integer);  { 1 argument  }

   Furthermore, GPC supports `const', according to BP, which is
equivalent to either `protected' or `protected var', up to the
compiler's discretion.


File: gpc.info,  Node: Conformant Arrays,  Next: Open Arrays,  Prev: Protected Parameters,  Up: Parameters

6.4.2 The Standard way to pass arrays of variable size
------------------------------------------------------

@@ (Under construction.)

   A feature of Standard Pascal level 1.


File: gpc.info,  Node: Open Arrays,  Prev: Conformant Arrays,  Up: Parameters

6.4.3 BP's alternative to Conformant Arrays
-------------------------------------------

Borland Pascal "open array" formal parameters are implemented into GPC.
Within the function body, they have integer type index with lower bound
0.

   In constrast to conformant arrays (which are not supported by BP),
open arrays allow any ordinal type as the index of the actual parameter
(which is useful, e.g., if you want to be able to pass values of any
enumeration type). However, they lose information about the lower bound
(which is a problem, e.g., if you want to return information to the
caller that relates to the actual array index, like the function
`IOSelect' in the Run Time System does).


File: gpc.info,  Node: String Slice Access,  Next: Type Casts,  Prev: Pointer Arithmetics,  Up: Programming

6.5 Accessing parts of strings (and other arrays)
=================================================

GPC allows the access of parts ("slices") of strings as defined in
Extended Pascal. For example:

     program StringSliceDemo;

     const
       HelloWorld = 'Hello, world!';

     begin
       WriteLn (HelloWorld[8 .. 12])  { yields `world' }
     end.

   As an extension, it also allows write access to a string slice:

     program SliceWriteDemo;

     var
       s: String (42) = 'Hello, world!';

     begin
       s[8 .. 12] := 'folks';
       WriteLn (s)  { yields `Hello, folks!' }
     end.

   As a further extension, GPC allows slice access also to non-string
arrays. However, the usefulness of this feature is rather limited
because of Pascal's strict type checking rules: If you have, e.g., an
`array [1 .. 10] of Integer' and take a slice `[1 .. 5]' of it, it will
not be compatible to another `array [1 .. 5] of Integer' because
distinct array types are not compatible in Pascal, even if they look
the same.

   However, array slice access can be used in connection with
conformant or open array parameters. See the program
`arrayslicedemo.pas' (in the `demos' directory) for an example.


File: gpc.info,  Node: Pointer Arithmetics,  Next: String Slice Access,  Prev: Parameters,  Up: Programming

6.6 Pointer Arithmetics
=======================

GPC allows to increment, decrement, compare, and subtract pointers or
to use them in `for' loops just like the C language.

   GPC implements the address operator `@' (a Borland Pascal extension).

     program PointerArithmeticDemo;
     var
       a: array [1 .. 7] of Char;
       p, q: ^Char;
       i: Integer;

     {$X+}  { We need extended syntax for pointer arithmetic }

     begin
       for p := @a[1] to @a[7] do
         p^ := 'x';

       p := @a[7];
       q := @a[3];
       while p > q do
         begin
           p^ := 'y';
           Dec (p)
         end;

       p := @a[7];
       q := @a[3];
       i := q - p;    { yields 4 }
     end.

   Incrementing a pointer by one means to increment the address it
contains by the size of the variable it is pointing to. For typeless
pointers (`Pointer'), the address is incremented by one instead.

   Similar things hold when decrementing a pointer.

   Subtracting two pointers yields the number of variables pointed to
between both pointers, i.e. the difference of the addresses divided by
the size of the variables pointed to. The pointers must be of the same
type.


File: gpc.info,  Node: Type Casts,  Next: OOP,  Prev: String Slice Access,  Up: Programming

6.7 Type Casts
==============

In some cases, especially in low-level situations, Pascal's strong
typing can be an obstacle. To temporarily circumvent this, GPC defines
explicit "type casts" in a Borland Pascal compatible way.

   There are two kinds of type casts, value type casts and variable type
casts.

   Value type casts

   To convert a value of one data type into another type, you can use
the target type like the name of a function that is called. The value
to be converted can be a variable or an expression. Both the value's
type and the destination type must be ordinal or pointer types. The
ordinal value (extended to pointers to mean the address) is preserved
in the cast.

   An example:

     program TypeCastDemo;

     var
       Ch: Char;
       i: Integer;

     begin
       i := Integer (Ch)
     end.

   Another, more complicated, example:

     program TypeCst2Demo;

     type
       CharPtr = ^Char;
       CharArray = array [0 .. 99] of Char;
       CharArrayPtr = ^CharArray;

     var
       Foo1, Foo2: CharPtr;
       Bar: CharArrayPtr;

     {$X+} { We need extended syntax in order to use ``Succ'' on a pointer }

     begin
       Foo1 := CharPtr (Bar);
       Foo2 := CharPtr (Succ (Bar))
     end.

   However, because of risks involved with type casts, explained below,
and because type-casts are non-standard, you should try to avoid type
casts whenever possible - and it should be possible in most cases. For
instance, the first example above could use the built-in function "Ord"
instead of the type cast:

     i := Ord (Ch);

   The assignments in the second example could be written in the
following way without any type casts:

     Foo1 := @Bar^[0];
     Foo2 := @Bar^[1];

   Note: In the case of pointers, a warning is issued if the
dereferenced target type requires a bigger alignment than the
dereferenced source type (see *Note Alignment::).

   Variable type casts

   It is also possible to temporarily change the type of a variable
(more generally, any "lvalue", i.e. something whose address can be
taken), without converting its contents in any way. This is called
variable type casting.

   The syntax is the same as for value type casting. The type-casted
variable is still the same variable (memory location) as the original
one, just with a different type. Outside of the type cast, the variable
keeps its original type.

   There are some important differences between value and variable type
casting:

   * Variable type casting only works on lvalues, not on expressions.

   * The result of a variable type casting is still an lvalue, so it can
     be used, e.g., on the left side of an assignment, or as the operand
     of an address operator, or passed by reference to a procedure.

   * No values are converted in variable type-casting. The contents of
     the variable, seen as a raw bit pattern, are just interpreted
     according to the new type.

   * Because bit patterns are just interpreted differently, the source
     and target type must have the same size. If this is not the case,
     GPC will give a warning.

   * Beware: Variable type casts might have unexpected effects on
     different platforms since you cannot rely on a specific way the
     data is stored (e.g. see *Note Endianness::).


   There are cases where a type-cast could be either a value or a
variable cast. This is when both types are ordinal or pointer, and of
the same size, and the value is an lvalue. Fortunately, in those cases,
the results of both forms are the same, since the same ordinal values
(or pointer addresses) are represented by the same bit patterns (when
of the same size). Therefore, it doesn't matter which form of
type-casting is actually used in these cases.

   When dealing with objects (see *Note OOP::), it is sometimes
necessary to cast a polymorphic pointer to an object into a pointer to
a more specialized (derived) object (after checking the actual type).
However, the `as' operator is a safer approach, so type-casts should be
used there only for backward-compatibility (e.g., to BP).

   See also: *Note absolute::, *Note Alignment::, *Note Endianness::,
*Note OOP::, *Note Ord::, *Note Chr::, *Note Round::, *Note Trunc::.


File: gpc.info,  Node: OOP,  Next: Compiler Directives,  Prev: Type Casts,  Up: Programming

6.8 Object-Oriented Programming
===============================

GNU Pascal allows multiple object models. The oldest one follows the
object model of Borland Pascal 7.0. The BP object extensions are almost
fully implemented into GPC. This includes inheritance, virtual and
non-virtual methods, constructors, destructors, pointer compatibility,
extended `New' syntax (with constructor call and/or as a Boolean
function), extended `Dispose' syntax (with destructor call).

   The Borland object model is different from the ISO draft, but now we
have also partial support of ISO draft (plus the Borland Delphi Object
Extensions which are quite similar to the ISO draft). Moreover most of
traditional Mac Pascal object model is covered.

   The syntax for an object type declaration is as follows:

     program ObjectDemo;

     type
       Str100 = String (100);

       FooParentPtr = ^FooParent;
       FooPtr = ^Foo;

       FooParent = object
         constructor Init;
         destructor Done; virtual;
         procedure Bar (c: Real); virtual;
         function Baz (b, a, z: Char) = s: Str100;  { not virtual }
       end;

       Foo = object (FooParent)
         x, y: Integer;
         constructor Init (a, b: Integer);
         destructor Done; virtual;
         procedure Bar (c: Real); virtual;  { overrides `FooParent.Bar' }
         z: Real;  { GPC extension: data fields after methods }
         function Baz: Boolean;  { new function }
       end;

     constructor FooParent.Init;
     begin
       WriteLn ('FooParent.Init')
     end;

     destructor FooParent.Done;
     begin
       WriteLn ('I''m also done.')
     end;

     procedure FooParent.Bar (c: Real);
     begin
       WriteLn ('FooParent.Bar (', c, ')')
     end;

     function FooParent.Baz (b, a, z: Char) = s: Str100;
     begin
       WriteStr (s, 'FooParent.Baz (', b, ', ', a, ', ', z, ')')
     end;

     constructor Foo.Init (a, b: Integer);
     begin
       inherited Init;
       x := a;
       y := b;
       z := 3.4;
       FooParent.Bar (1.7)
     end;

     destructor Foo.Done;
     begin
       WriteLn ('I''m done.');
       inherited Done
     end;

     procedure Foo.Bar (c: Real);
     begin
       WriteLn ('Foo.Bar (', c, ')')
     end;

     function Foo.Baz: Boolean;
     begin
       Baz := True
     end;

     var
       Ptr: FooParentPtr;

     begin
       Ptr := New (FooPtr, Init (2, 3));
       Ptr^.Bar (3);
       Dispose (Ptr, Done);
       New (Ptr, Init);
       with Ptr^ do
         WriteLn (Baz ('b', 'a', 'z'))
     end.

   Remarks:

   * The ordering of data fields and methods can be mixed.

   * GPC supports the `public' and `private' declarations like BP, and
     in addition also `protected' (scope limited to the current type
     and its descendants).

   * Constructors and destructors are ordinary functions, internally.
     When a constructor is called, GPC creates some inline code to
     initialize the object; destructors do nothing special.

   A pointer to `FooParent' may be assigned the address of a `Foo'
object. A `FooParent' formal `var' parameter may get a `Foo' object as
the actual parameter. In such cases, a call to a `virtual' method calls
the child's method, whereas a call to a non-`virtual' method selects
the parent's one:

     var
       MyFooParent: FooParentPtr;
       SomeFoo: Foo;

     [...]

       SomeFoo.Init (4, 2);
       MyFooParent := @SomeFoo;
       MyFooParent^.bar (3.14);  { calls `foo.bar' }
       MyFooParent^.baz ('b', 'a', 'z');  { calls `fooParent.baz' }
       if SomeFoo.baz then  { calls `foo.baz' }
         WriteLn ('Baz!');

   In a method, an overwritten method of a parent object can be called
either prefixing it with the parent type name, or using the keyword
`inherited':

     procedure Foo.Bar (c: Real);
     begin
       z := c;
       inherited bar (z)  { or: FooParent.Bar (z) }
     end;

   Use `FooParent.bar (z)' if you want to be sure that _this_ method is
called, even if somebody decides not to derive `foo' directly from
`fooParent' but to have some intermediate object.  If you want to call
the method `bar' of the immediate parent - whether it be `fooParent' or
whatever - use `inherited bar (z)'.

   To allocate an object on the heap, use `New' in one of the following
manners:

     var
       MyFoo: FooPtr;

       [...]

       New (MyFoo, Init (4, 2));

       MyFooParent := New (FooPtr, Init (4, 2))

   The second possibility has the advantage that `MyFoo' needn't be a
`FooPtr' but can also be a `FooParentPtr', i.e. a pointer to an
ancestor of `foo'.

   Destructors can and should be called within Dispose:

     Dispose (MyFooParent, Fini)


File: gpc.info,  Node: Compiler Directives,  Next: Library Routines,  Prev: OOP,  Up: Programming

6.9 Compiler Directives And The Preprocessor
============================================

GPC, like UCSD Pascal and BP, treats comments beginning with a `$'
immediately following the opening `{' or `(*' as a compiler directive.
As in Borland Pascal, `{$...}' and `(*$...*)' are equivalent. When a
single character plus a `+' or `-' follows, this is also called a
compiler switch.  All of these directives are case-insensitive (but
some of them have case-sensitive arguments). Directives are local and
can be changed during one compilation (except include files etc. where
this makes no sense).

   In general, compiler directives are compiler-dependent. (E.g., only
the include directive `{$I FileName}' is common to UCSD and BP.)
Because of BP's popularity, GPC supports all of BP's compiler
directives (and ignores those that are unnecessary on its platforms -
these are those not listed below), but it knows a lot more directives.

   Some BP directives are - of course not by chance - just an
alternative notation for C preprocessor directives. But there are
differences: BP's "conditional" definitions (`{$define Foo}') go into
another name space than the program's definitions. Therefore you can
define conditionals and check them via `{$ifdef Foo}', but the program
will not see them as an identifier `Foo', so macros do not exist in
Borland Pascal.

   GPC does support macros, but disables this feature when the
`--no-macros' option or the dialect option `--borland-pascal' or
`--delphi' is given, to mimic BP's behaviour. Therefore, the following
program will react differently when compiled with GPC either without
special options or with, e.g., the `--borland-pascal' option (and in
the latter case, it behaves the same as when compiled with BP).

     program MacroDemo;

     const Foo = 'Borland Pascal';

     {$define Foo 'Default'}

     begin
       WriteLn (Foo)
     end.

   Of course, you should not rely on such constructs in your programs.
To test if the program is compiled with GPC, you can test the `__GPC__'
conditional, and to test the dialect used in GPC, you can test the
dialect, e.g., with `{$ifopt borland-pascal}'.

   In general, almost every GPC specific command line option (*note GPC
Command Line Options::) can be turned into a compiler directive
(exceptions are those options that contain directory names, such as
`--unit-path', because they refer to the installation on a particular
system, and therefore should be set system-wide, rather than in a
source file):

     --foo       {$foo}
     --no-foo    {$no-foo}
     -Wbar       {$W bar}     { note the space after the `W' }
     -Wno-bar    {$W no-bar}

   The following table lists some such examples as well as all those
directives that do not correspond to command-line options or have
syntactical alternatives (for convenience and/or BP compatibility).

     --[no-]short-circuit   $B+ $B- like in Borland Pascal:
                                    $B- means short-circuit Boolean
                                    operators; $B+ complete evaluation

     --[no-]io-checking     $I+ $I- like in Borland Pascal:
                                    enable/disable I/O checking

     --[no-]range-checking  $R+ $R- like in Borland Pascal:
                                    enable/disable range checking

     --[no-]stack-checking  $S+ $S- like in Borland Pascal:
                                    enable/disable stack checking

     --[no-]typed-address   $T+ $T- like in Borland Pascal:
                                    make the result of the address
                                    operator and the Addr function a
                                    typed or untyped pointer

     -W[no-]warnings        $W+ $W- enable/disable warnings. Note: in
                                    `--borland-pascal' mode, the
                                    short version is disabled because
                                    $W+/$W- has a different meaning in
                                    Borland Pascal (which can safely be
                                    ignored in GPC), but the long version
                                    is still available.

     --[no-]extended-syntax $X+ $X- mostly like in Borland Pascal:
                                    enable/disable extended syntax
                                    (ignore function resuls, operator
                                    definitions, `PChar', pointer
                                    arithmetic, ...)

     --borland-pascal               disable or warn about GPC features
     --extended-pascal              not supported by the standard or
     --pascal-sc                    dialect given, do not warn about its
     etc.                           ``dangerous'' features (especially BP).
                                    The dialect can be changed during one
                                    compilation via directives like,
                                    e.g., `{$borland-pascal}'.

     {$M Hello!}                    write message `Hello!' to
                                    standard error during compilation. In
                                    `--borland-pascal' mode, it is
                                    ignored it if only numbers follow
                                    (for compatibility to Borland
                                    Pascal's memory directive)

     {$define FOO}                  like in Borland Pascal:
     or                             define FOO (for conditional compilation)
     {$CIDefine FOO}                (case-insensitively)

     --cidefine=FOO                 the same on the command line

     {$CSDefine FOO}                define FOO case-sensitively

     -D FOO                         the same on the command line
     or                             Note: `--define' on the command
     --csdefine=FOO                 line is case-sensitive like in GCC,
     or                             but `{$define}' in the source code
     --define=FOO                   is case-insensitive like in BP

     {$define loop while True do}   define `loop' to be `while True do'
     or                             as a macro like in C. The name of the
     {$CIDefine loop ...}           macro is case-insensitive. Note:
                                    Macros are disabled in
                                    `--borland-pascal' mode because BP
                                    doesn't support macros.

     --cidefine="loop=..."          the same on the command line

     {$CSDefine loop ...}           define a case-sensitive macro

     --csdefine="loop=..."          the same on the command line
     or
     --define="loop=..."

     {$I FileName}                  like in Borland Pascal:
                                    include `filename.pas'
                                    (the name is converted to lower case)

     {$undef FOO}                   like in Borland Pascal: undefine FOO

     {$ifdef FOO}                   conditional compilation
       ...                          (like in Borland Pascal).
     {$else}                        Note: GPC predefines the symbol
       ...                          `__GPC__' (with two leading
     {$endif}                       and trailing underscores).

     {$include "filename.pas"}      include (case-sensitive)

     {$include <filename.pas>}      the same, but don't search in the
                                    current directory
   ...and all the other C preprocessor directives.

   You also can use the preprocessor directives in C style, e.g.
`#include', but this is deprecated because of possible confusion with
Borland Pascal style `#42' character constants.  Besides, in the Pascal
style, e.g. `{$include "foo.bar"}', there may be more than one
directive in the same line.


File: gpc.info,  Node: Library Routines,  Next: Other Languages,  Prev: Compiler Directives,  Up: Programming

6.10 Routines Built-in or in the Run Time System
================================================

In this section we describe the routines and other declarations that
are built into the compiler or part of the Run Time System, sorted by
topics.

* Menu:

* File Routines::
* String Operations::
* Accessing Command Line Arguments::
* Memory Management Routines::
* Operations for Integer and Ordinal Types::
* Complex Number Operations::
* Set Operations::
* Date And Time Routines::


File: gpc.info,  Node: File Routines,  Next: String Operations,  Up: Library Routines

6.10.1 File Routines
--------------------

Extended Pascal treats files quite differently from Borland Pascal.
GPC supports both forms, even in mixed ways, and provides many
extensions.

   @@ A lot missing here

   * An example of getting the size of a file (though a `FileSize'
     function is already built-in).

          function FileSize (FileName : String) : LongInt;
          var
            f: bindable file [0 .. MaxInt] of Char;
            b: BindingType;
          begin
            Unbind (f);
            b := Binding (f);
            b.Name := FileName;
            Bind(f, b);
            b := Binding(f);
            SeekRead (f, 0);
            if Empty (f) then
              FileSize := 0
            else
              FileSize := LastPosition (f) + 1;
            Unbind(f);
          end;

     Prospero's Extended Pascal has a bug in this case. Replace the
     MaxInt in the type definition of f by a sufficiently large
     integer. GNU Pascal works correct in this case.

   * GPC implements "lazy" text file I/O, i.e. does a `Put' as soon as
     possible and a `Get' as late as possible. This should avoid most
     of the problems sometimes considered to be the most stupid feature
     of Pascal. When passing a file buffer as parameter the buffer is
     validated when the parameter is passed.

   * GPC supports direct access files. E.g., declaring a type for a
     file that contains 100 integers.

          program DirectAccessFileDemo;
          type
            DFile = file [1 .. 100] of Integer;
          var
            F: DFile;
            P, N: 1 .. 100;
          begin
            Rewrite (F);
            P := 42;
            N := 17;
            SeekWrite (F, P);
            Write (F, N)
          end.

     The following direct access routines may be applied to a direct
     access file:

    `SeekRead   (F, N);      { Open file in inspection mode, seek to record N }'

    `SeekWrite  (F, N);      { Open file in generation mode, seek to record N }'

    `SeekUpdate (F, N);      { Open file in update mode, seek to record N }'

    `Update (F);             { Writes F^, position not changed. F^ kept. }'

    `p := Position (F);      { Yield the current record number }'

    `p := LastPosition (F);  { Yield the last record number in file }'

     If the file is open for inspection or update, `Get' may be applied.
     If the file is open for generation or update, `Put' may be applied.

   * In BP, you can associate file variables with files using the
     `Assign' procedure which GPC supports.

          program AssignTextDemo;
          var
            t: Text;
            Line: String (4096);
          begin
            Assign (t, 'mytext.txt');
            Reset (t);
            while not EOF (t) do
              begin
                ReadLn (t, Line);
                WriteLn (Line)
              end
          end.

   * In Extended Pascal, files are considered entities external to your
     program. External entities, which don't need to be files, need to
     be bound to a variable your program. Any variable to which external
     entities can be bound needs to be declared `bindable'. Extended
     Pascal has the `Bind' function that binds a variable to an
     external entity as well as `Unbind' to undo a binding and the
     function `Binding' to get the current binding of a variable.

     GPC supports these routines when applied to files. The compiler
     will reject binding of other object types.

     Only the fields `Bound' and `Name' of the predefined record type
     `BindingType' are required by Extended Pascal.  Additionally, GPC
     implements some extensions. For the full definition of
     `BindingType', see *Note BindingType::.

     The following is an example of binding:

          program BindingDemo (Input, Output, f);

          var
            f: bindable Text;
            b: BindingType;

          procedure BindFile (var f: Text);
          var
            b: BindingType;
          begin
            Unbind (f);
            b := Binding (f);
            repeat
              Write ('Enter a file name: ');
              ReadLn (b.Name);
              Bind (f, b);
              b := Binding (f);
              if not b.Bound then
                WriteLn ('File not bound -- try again.')
            until b.Bound
          end;

          begin
            BindFile (f);
            { Now the file f is bound to an external file. We can use the
              implementation defined fields of BindingType to check if the
              file exists and is readable, writable or executable. }
            b := Binding (f);
            Write ('The file ');
            if b.Existing then
              WriteLn ('exists.')
            else
              WriteLn ('does not exist.');
            Write ('It is ');
            if not b.Readable then Write ('not ');
            Write ('readable, ');
            if not b.Writable then Write ('not ');
            Write ('writable and ');
            if not b.Executable then Write ('not ');
            WriteLn ('executable.')
          end.


   Note that Prospero's Pascal defaults to creating the file if it does
not exists! You need to use Prospero's local addition of setting
`b.Existing' to `True' to work-around this. GPC does not behave like
this.


File: gpc.info,  Node: String Operations,  Next: Accessing Command Line Arguments,  Prev: File Routines,  Up: Library Routines

6.10.2 String Operations
------------------------

In the following description, `s1' and `s2' may be arbitrary string
expressions, `s' is a variable of string type.

`WriteStr (s, write-parameter-list)'

`ReadStr (s1, read-parameter-list)'
     Write to a string and read from a string.  The parameter lists are
     identical to `Write'/`Read' from `Text' files. The semantics is
     closely modeled after file I/O.

`Index (s1, s2)'
     If `s2' is empty, return 1 else if `s1' is empty return 0 else
     returns the position of `s2' in `s1' (an integer).

`Length (s1)'
     Return the length of `s1' (an integer from `0 .. s1.Capacity').

`Trim (s1)'
     Returns a new string with spaces stripped of the end of `s'.

`SubStr (s1, i)'

`SubStr (s1, i, j)'
     Return a new substring of `s1' that contains `j' characters
     starting from `i'. If `j' is missing, return all the characters
     starting from `i'.

`EQ (s1, s2)'

`NE (s1, s2)'

`LT (s1, s2)'

`LE (s1, s2)'

`GT (s1, s2)'

`GE (s1, s2)'
     Lexicographic comparisons of `s1' and `s2'. Returns a boolean
     result. Strings are not padded with spaces.

`s1 =  s2'

`s1 <> s2'

`s1 <  s2'

`s1 <= s2'

`s1 >  s2'

`s1 >= s2'
     Lexicographic comparisons of `s1' and `s2'. Returns a boolean
     result. The shorter string is blank padded to length of the longer
     one, but only in `--extended-pascal' mode.

   GPC supports string catenation with the `+' operator or the `Concat'
function. All string-types are compatible, so you may catenate any
chars, fixed length strings and variable length strings.

     program ConcatDemo (Input, Output);

     var
       Ch  : Char;
       Str : String (100);
       Str2: String (50);
       FStr: packed array [1 .. 20] of Char;

     begin
        Ch := '$';
        FStr := 'demo';  { padded with blanks }
        Write ('Give me some chars to play with: ');
        ReadLn (Str);
        Str := '^' + 'prefix:' + Str + ':suffix:' + FStr + Ch;
        WriteLn (Concat ('Le', 'ng', 'th'), ' = ', Length (Str));
        WriteLn (Str)
     end.

   Note: The length of strings in GPC is limited only by the range of
`Integer' (at least 32 bits, i.e., 2 GB, on most platforms), or the
available memory, whichever is smaller).

   When trying to write programs portable to other EP compilers, it is
however safe to assume a limit of about 32 KB. At least Prospero's
Extended Pascal compiler limits strings to 32760 bytes. DEC Pascal
limits strings to 65535 bytes.


File: gpc.info,  Node: Accessing Command Line Arguments,  Next: Memory Management Routines,  Prev: String Operations,  Up: Library Routines

6.10.3 Accessing Command Line Arguments
---------------------------------------

GPC supports access to the command line arguments with the BP
compatible `ParamStr' and `ParamCount' functions.

   * `ParamStr[0]' is the program name,

   * `ParamStr[1] .. ParamStr[ParamCount]' are the arguments.

   The program below accesses the command line arguments.

     program CommandLineArgumentsDemo (Output);

     var
       Counter: Integer;

     begin
       WriteLn ('This program displays command line arguments one per line.');
       for Counter := 0 to ParamCount do
         WriteLn ('Command line argument #', Counter, ' is `',
                  ParamStr (Counter), '''')
     end.


File: gpc.info,  Node: Memory Management Routines,  Next: Operations for Integer and Ordinal Types,  Prev: Accessing Command Line Arguments,  Up: Library Routines

6.10.4 Memory Management Routines
---------------------------------

Besides the standard `New' and `Dispose' routines, GPC also allows BP
style dynamic memory management with `GetMem' and `FreeMem':

     GetMem (MyPtr, 1024);
     FreeMem (MyPtr, 1024);

   One somehow strange feature of Borland is *not* supported: You
cannot free parts of a variable with `FreeMem', while the rest is still
used and can be freed later by another `FreeMem' call:

     program PartialFreeMemDemo;

     type
       Vector = array [0 .. 1023] of Integer;
       VecPtr = ^Vector;

     var
       p, q: VecPtr;

     begin
       GetMem (p, 1024 * SizeOf (Integer));
       q := VecPtr (@p^[512]);

       { ... }

       FreeMem (p, 512 * SizeOf (Integer));

       { ... }

       FreeMem (q, 512 * SizeOf (Integer));
     end.


File: gpc.info,  Node: Operations for Integer and Ordinal Types,  Next: Complex Number Operations,  Prev: Memory Management Routines,  Up: Library Routines

6.10.5 Operations for Integer and Ordinal Types
-----------------------------------------------

   * Bit manipulations: The BP style bit shift operators `shl' and
     `shr' exist in GPC as well as bitwise `and', `or', `xor' and `not'
     for integer values.

          2#100101 and (1 shl 5) = 2#100000

     GPC also supports `and', `or', `xor' and `not' as procedures:

          program BitOperatorProcedureDemo;
          var x: Integer;
          begin
            x := 7;
            and (x, 14);  { sets x to 6 }
            xor (x, 3);   { sets x to 5 }
          end.

   * Succ, Pred: The standard functions `Succ' and `Pred' exist in GPC
     and accept a second parameter.

   * Increment, decrement: The BP built-in Procedures `Inc' and `Dec'
     exist in GPC.

          program IncDecDemo;
          var
            i: Integer;
            c: Char;
          begin
            Inc (i);     { i := i + 1; }
            Dec (i, 7);  { i := i - 7; }
            Inc (c, 3);  { c := Succ (c, 3); }
          end.

   * `Min', `Max': These are a GNU Pascal extension and work for reals
     as well as for ordinal types. Mixing reals and integers is okay,
     the result is real then.



File: gpc.info,  Node: Complex Number Operations,  Next: Set Operations,  Prev: Operations for Integer and Ordinal Types,  Up: Library Routines

6.10.6 Complex Number Operations
--------------------------------

@@ A lot of details missing here

   * binary operators `+', `-', `*', `/' and unary `-', `+'

   * exponentiation operators (`pow' and `**')

   * functions (`Sqr', `SqRt', `Exp', `Ln', `Sin', `Cos', `ArcSin',
     `ArcCos', `ArcTan')

   * number info with `Re', `Im' and `Arg' functions

   * numbers constructed by `Cmplx' or `Polar'

   The following sample programs illustrates most of the `Complex' type
operations.

     program ComplexOperationsDemo (Output);

     var
       z1, z2: Complex;
       Len, Angle: Real;

     begin
       z1 := Cmplx (2, 1);
       WriteLn;
       WriteLn ('Complex number z1 is: (', Re (z1) : 1, ',', Im (z1) : 1, ')');
       WriteLn;
       z2 := Conjugate(z1); { GPC extension }
       WriteLn ('Conjugate of z1 is: (', Re (z2) : 1, ',', Im (z2) : 1, ')');
       WriteLn;
       Len   := Abs (z1);
       Angle := Arg (z1);
       WriteLn ('The polar representation of z1 is: Length=', Len : 1,
                ', Angle=', Angle : 1);
       WriteLn;
       z2 := Polar (Len, Angle);
       WriteLn ('Converting (Length, Angle) back to (x, y) gives: (',
                Re (z2) : 1, ',', Im (z2) : 1, ')');
       WriteLn;
       WriteLn ('The following operations operate on the complex number z1');
       WriteLn;
       z2 := ArcTan (z1);
       WriteLn ('ArcTan (z1) = (', Re (z2), ', ', Im (z2), ')');
       WriteLn;
       z2 := z1 ** 3.141;
       WriteLn ('z1 ** 3.141 =', Re (z2), ', ', Im (z2), ')');
       WriteLn;
       z2 := Sin (z1);
       WriteLn ('Sin (z1) = (', Re (z2), ', ', Im (z2), ')');
       WriteLn ('(Cos, Ln, Exp, SqRt and Sqr exist also.)');
       WriteLn;
       z2 := z1 pow 8;
       WriteLn ('z1 pow 8 = (', Re (z2), ', ', Im (z2), ')');
       WriteLn;
       z2 := z1 pow (-8);
       WriteLn ('z1 pow (-8) = (', Re (z2), ', ', Im (z2), ')');
     end.


File: gpc.info,  Node: Set Operations,  Next: Date And Time Routines,  Prev: Complex Number Operations,  Up: Library Routines

6.10.7 Set Operations
---------------------

GPC supports Standard Pascal set operations. In addition it supports
the Extended Pascal set operation symmetric difference (`set1 >< set2')
operation whose result consists of those elements which are in exactly
one of the operannds.

   It also has a function that counts the elements in the set: `a :=
Card (set1)'.

   In the following description, S1 and S2 are variables of set type, s
is of the base type of the set.

`S1 := S2'
     Assign a set to a set variable.

`S1 + S2'
     Union of sets.

`S1 - S2'
     Difference between two sets.

`S1 * S2'
     Intersection of two sets.

`S1 >< S2'
     Symmetric difference

`S1 = S2'
     Comparison between two sets. Returns boolean result. `True' if
     `S1' has the same elements as `S2'.

`S1 <> S2'
     Comparison between two sets. Returns boolean result. `True' if
     `S1' does not have the same elements as `S2'.

`S1 < S2'

`S2 > S1'
     Comparison between two sets. Returns boolean result. `True' if
     `S1' is a strict subset of `S2'.

`S1 <= S2'

`S2 >= S1'
     Comparison between two sets. Returns boolean result. `True' if
     `S1' is a subset of (or equal to) `S2'.

`s in S1'
     Set membership test between an element `s' and a set. Returns
     boolean result. `True' if `s' is an element of `S1'.

   The following example demonstrates some `set' operations. The results
of the operations are given in the comments.

     program SetOpDemo;

     type
       TCharSet = set of Char;

     var
       S1, S2, S3: TCharSet;
       Result: Boolean;

     begin
       S1 := ['a', 'b', 'c'];
       S2 := ['c', 'd', 'e'];
       S3 := S1 + S2;       { S3 = ['a', 'b', 'c', 'd', 'e'] }
       S3 := S1 * S2;       { S3 = ['c'] }
       S3 := S1 - S2;       { S3 = ['a', 'b'] }
       S3 := S1 >< S2;      { S3 = ['a', 'b', 'd', 'e'] }

       S1 := ['c', 'd', 'e'];
       Result := S1 = S2;   { False }
       Result := S1 < S2;   { False }
       Result := S1 <= S2;  { True }

       S1 := ['c', 'd'];
       Result := S1 <> S2;  { True }
       Result := S2 > S1;   { True }
       Result := S2 >= S1   { True }
     end.


File: gpc.info,  Node: Date And Time Routines,  Prev: Set Operations,  Up: Library Routines

6.10.8 Date And Time Routines
-----------------------------

`procedure GetTimeStamp (var t: TimeStamp);'

`function Date (t: TimeStamp): packed array [1 .. DateLength] of Char;'

`function Time (t: TimeStamp): packed array [1 .. TimeLength] of Char;'

   `DateLength' and `TimeLength' are implementation dependent constants.

   `GetTimeStamp (t)' fills the record `t' with values. If they are
valid, the Boolean flags are set to True.

   `TimeStamp' is a predefined type in the Extended Pascal standard. It
may be extended in an implementation, and is indeed extended in GPC.
For the full definition of `TimeStamp', see *Note TimeStamp::.


File: gpc.info,  Node: Other Languages,  Next: Notes for Debugging,  Prev: Library Routines,  Up: Programming

6.11 Interfacing with Other Languages
=====================================

The standardized GNU compiler back-end makes it relatively easy to
share libraries between GNU Pascal and other GNU compilers. On
Unix-like platforms (_not_ on Dos-like platforms), the GNU compiler
back-end usually complies to the standards defined for that system, so
communication with other compilers should be easy, too.

   In this chapter we discuss how to import libraries written in other
languages, and how to import libraries written in GNU Pascal from other
languages. While the examples will specialize to compatibility to GNU
C, generalization is straightforward if you are familiar with the other
language in question.

* Menu:

* Importing Libraries from Other Languages::
* Exporting GPC Libraries to Other Languages::


File: gpc.info,  Node: Importing Libraries from Other Languages,  Next: Exporting GPC Libraries to Other Languages,  Up: Other Languages

6.11.1 Importing Libraries from Other Languages
-----------------------------------------------

To use a function written in another language, you need to provide an
external declaration for it - either in the program, or in the
interface part of a unit, or a module.

   Let's say you want to use the following C library from Pascal:

     File `callc.c':

     #include <unistd.h>
     #include "callc.h"

     int foo = 1;

     void bar (void)
     {
       sleep (foo);
     }

     File `callc.h':

     /* Actually, we wouldn't need this header file, and could instead
        put these prototypes into callc.c, unless we want to use callc.c
        also from other C source files. */

     extern int foo;
     extern void bar (void);

   Then your program can look like this:

     program CallCDemo;

     {$L callc.c}  { Or: `callc.o' if you don't have the source }

     var
       MyFoo: CInteger; external name 'foo';

     procedure Bar; external name 'bar';

     begin
       MyFoo := 42;
       Bar
     end.

   Or, if you want to provide a `CallCUnit' unit:

     unit CallCUnit;

     interface

     var
       MyFoo: CInteger; external name 'foo';

     procedure Bar; external name 'bar';

     implementation

     {$L callc.c}  { Or: `callc.o' if you don't have the source }

     end.

     program CallCUDemo;

     uses CallCUnit;

     begin
       MyFoo := 42;
       Bar
     end.

   You can either link your program manually with `callc.o' or put a
compiler directive `{$L callc.o}' into your program or unit, and then
GPC takes care of correct linking. If you have the source of the C
library (you always have it if it is Free Software), you can even write
`{$L callc.c}' in the program (like above). Then GPC will also link
with `callc.o', but in addition GPC will run the C compiler whenever
`callc.c' has changed if `--automake' is given, too.

   While it is often convenient, there is no must to give the C
function `bar' the name `Bar' in Pascal; you can name it as you like
(e.g., the variable `MyFoo' has a C name of `foo' in the example above).

   If you omit the `name', the default is the Pascal identifier,
converted to lower-case. So, in this example, the `name' could be
omitted for `Bar', but not for `MyFoo'.

   It is important that data types of both languages are mapped
correctly onto each other. C's `int', for instance, translates to GPC's
`CInteger', and C's `unsigned long' to `MedCard'. For a complete list
of integer types with their C counterparts, see *Note Integer Types::.

   In some cases it can be reasonable to translate a C pointer
parameter to a Pascal `var' parameter.  Since const parameters in GPC
can be passed by value _or_ by reference internally, possibly depending
on the system, `const foo *' parameters to C functions _cannot_
reliably be declared as `const' in Pascal. However, Extended Pascal's
`protected var' can be used since this guarantees passing by reference.

   Some libraries provide a `main' function and require your program's
"main" to be named differently. To achive this with GPC, invoke it with
an option `--gpc-main="GPCmain"' (where `GPCmain' is an example how you
might want to name the program). You can also write it into your source
as a directive `{$gpc-main="GPCmain"}'.


File: gpc.info,  Node: Exporting GPC Libraries to Other Languages,  Prev: Importing Libraries from Other Languages,  Up: Other Languages

6.11.2 Exporting GPC Libraries to Other Languages
-------------------------------------------------

The `.o' files produced by GPC are in the same format as those of all
other GNU compilers, so there is no problem in writing libraries for
other languages in Pascal. To use them, you will need to write kind of
interface - a header file in C. However there are some things to take
into account, especially if your Pascal unit exports objects:

   * By default, GPC capitalizes the first letter (only) of each
     identifier, so `procedure FooBAR' must be imported as `extern void
     Foobar()' from C.

   * If you want to specify the external name explicitly, use
     `attribute':

          procedure FooBAR; attribute (name = 'FooBAR');
          begin
            WriteLn ('FooBAR')
          end;

     This one can be imported from C with `extern void FooBar()'.

   * Objects are "records" internally.  They have an implicit `vmt'
     field which contains a pointer to the "virtual method table".
     This table is another record of the following structure:

          type
            VMT = record
              ObjectSize: PtrInt;     { Size of object in bytes }
              NegObjectSize: PtrInt;  { Negated size }
              Methods: array [1 .. n] of procedure;
                { Pointers to the virtual methods. The entries are of the
                   repective procedure or function types. }
            end;

     You can call a virtual method of an object from C if you explicitly
     declare this `struct' and explicitly dereference the `Fun' array.
     The VMT of an object `FooBAR' is an external (in C sense) variable
     `vmt_Foobar' internally.

   * Methods of objects are named `Myobject_Mymethod' (with exactly two
     capital letters) internally.

   * If you want to put a program in a library for some reason, and you
     want to give the `main' program an internal name different from
     `main', call GPC with the command-line option
     `--gpc-main="GPCmain"' (see the previous subsection).



File: gpc.info,  Node: Notes for Debugging,  Next: I18N,  Prev: Other Languages,  Up: Programming

6.12 Notes for Debugging
========================

   * The GNU debugger, `gdb', does not yet understand Pascal sets,
     files or subranges. Now `gdb' allows you to debug these things,
     even though it does not yet understand some stabs.

   * Forward referencing pointers generate debug info that appears as
     generic pointers.

   * No information of `with' statements is currently given to the
     debugger.

   * When debugging, please note that the Initial Letter In Each
     Identifier Is In Upper Case And The Rest Are In Lower Case, unless
     explicitly overriden with `name' (*note name::). This is to reduce
     name clashes with libc and other possible libraries.

   * All visible GPC Run Time System routines have linker names starting
     with `_p_'.

   * The linker name of the main program is `pascal_main_program'.
     This is done because ISO Standard wants to have the program name in
     a separate name space.


File: gpc.info,  Node: I18N,  Next: Run Time System,  Prev: Notes for Debugging,  Up: Programming

6.13 How to use I18N in own programs
====================================

This chapter discusses shortly how to use the Internationalization
(I18N) features of GNU Pascal.

Prerequisite
------------

You need to have gettext installed. Try to compile
`demos/gettextdemo.pas'. Furthermore, you should download a tool named
`pas2po' from `http://www.gnu-pascal.org/contrib/eike/'.

The source
----------

We would like to translate the messages provided with this simple
example different languages (here: German) without touching the source
for each language:

     program Hello1;

     begin
       WriteLn ('Hello, World!');
       WriteLn ('The answer of the questions is: ', 42)
     end.

Preparing the source
--------------------

To do so, we must prepare the source to use gettext:

     program Hello2;

     uses GPC, Intl;

     var s: TString;

     begin
       Discard (BindTextDomain ('hello2', '/usr/share/locale/'));
       Discard (TextDomain ('hello2'));
       WriteLn (GetText ('Hello, World!'));
       s := FormatString (GetText ('The answer of the questions is %s'), 42);
       WriteLn (s)
     end.

   `BindTextDomain' sets the path to find our message catalogs in the
system. This path is system dependent. `TextDomain' tells the program
to use this catalog. `GetText' looks up the given string in the catalog
and returns a translated string within the current locale settings.
`FormatString' replaces some format specifiers with the following
argument. `%s' is the first following argument. After this step is
done, we do not need to touch the sourcefile any longer. The output of
this program is as follows:

     Hello, World!
     The answer of the questions is 42

Getting the translatable strings
--------------------------------

There are lots of strings in the above example, but only those
surrounded with `GetText' should be translated. We use `pas2po
hello2.pas -o hello2.po' to extract the messages. The output is:

     # This file was created by pas2po with 'hello2.pas'.
     # Please change this file manually.
     # SOME DESCRIPTIVE TITLE.
     # Copyright (C) YEAR Free Software Foundation, Inc.
     # FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
     #
     #, fuzzy
     msgid ""
     msgstr ""
     "Project-Id-Version: PACKAGE VERSION\n"
     "POT-Creation-Date: 2003-04-27 20:48+0200\n"
     "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
     "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
     "Language-Team: LANGUAGE <LL@li.org>\n"
     "MIME-Version: 1.0\n"
     "Content-Type: text/plain; charset=CHARSET\n"
     "Content-Transfer-Encoding: 8bit\n"

     #hello2.pas:10
     msgid "Hello, World!"
     msgstr ""

     #hello2.pas:11
     msgid "The answer of the questions is %s"
     msgstr ""

   Now we translate the message ids into German language, and set some
needful informations at their appropriate places. The following steps
must be repeated for each language we would like to support:

     # This file was created by pas2po with 'hello2.pas'.
     # Copyright (C) 2003 Free Software Foundation, Inc.
     # Eike Lange  <eike@g-n-u.de>, 2003.
     msgid ""
     msgstr ""
     "Project-Id-Version: Hello2 1.0\n"
     "POT-Creation-Date: 2003-04-27 12:00+0200\n"
     "PO-Revision-Date: 2003-04-27 12:06+0200\n"
     "Last-Translator: Eike Lange <eike@g-n-u.de>\n"
     "Language-Team: de <de@li.org>\n"
     "MIME-Version: 1.0\n"
     "Content-Type: text/plain; charset=ISO-8859-1\n"
     "Content-Transfer-Encoding: 8bit\n"

     #hello2.pas:10
     msgid "Hello, World!"
     msgstr "Hallo, Welt!"

     #hello2.pas:11
     msgid "The answer of the questions is %s"
     msgstr "'%s' lautet die Antwort auf die Frage."

   Please note that we swapped text and numeric arguments and added
some single quotes arround the first argument. We compile the message
catalog with `msgfmt -vv hello2.po -o hello2.mo' and install the file
`hello2.mo' at `/usr/share/locale/de/LC_MESSAGES/' With a german locale
setting, the output should be as follows:

     Hallo, Welt!
     '42' lautet die Antwort auf die Frage.

System dependent notes:
-----------------------

The topmost path where message catalogs reside is system dependent:

for DJGPP:
     `GetEnv ('$DJDIR') + '/share/locale''

for Mac OS X:
     `/usr/share/locale' or `/sw/share/locale'

for Linux, *BSD:
     `/usr/share/locale' or `/usr/local/share/locale'

See also
--------

*Note Gettext: (gettext)Gettext, *Note FormatString::, *Note Intl::.


File: gpc.info,  Node: Run Time System,  Next: GPC Units,  Prev: I18N,  Up: Programming

6.14 Pascal declarations for GPC's Run Time System
==================================================

Below is a Pascal source of the declarations in GPC's Run Time System
(RTS). A file `gpc.pas' with the same contents is included in the GPC
distribution in a `units' subdirectory of the directory containing
`libgcc.a'. (To find out the correct directory for your installation,
type `gpc --print-file-name=units' on the command line.)

     { This file was generated automatically by make-gpc-pas.
       DO NOT CHANGE THIS FILE MANUALLY! }

     { Pascal declarations of the GPC Run Time System that are visible to
       each program.

       This unit contains Pascal declarations of many RTS routines which
       are not built into the compiler and can be called from programs.
       Don't copy the declarations from this unit into your programs, but
       rather include this unit with a `uses' statement. The reason is
       that the internal declarations, e.g. the linker names, may change,
       and this unit will be changed accordingly. @@In the future, this
       unit might be included into every program automatically, so there
       will be no need for a `uses' statement to make the declarations
       here available.

       Note about `protected var' parameters:
       Since `const' parameters in GPC may be passed by value *or* by
       reference internally, possibly depending on the system,
       `const foo *' parameters to C functions *cannot* reliably be
       declared as `const' in Pascal. However, Extended Pascal's
       `protected var' can be used since this guarantees passing by
       reference.

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Authors: Jukka Virtanen <jtv@hut.fi>
                Peter Gerwinski <peter@gerwinski.de>
                Frank Heckenbach <frank@pascal.gnu.de>
                J.J. v.der Heijden <j.j.vanderheijden@student.utwente.nl>
                Nicola Girardi <nicola@g-n-u.de>
                Prof. Abimbola A. Olowofoyeku <African_Chief@bigfoot.com>
                Emil Jerabek <jerabek@math.cas.cz>
                Maurice Lombardi <Maurice.Lombardi@ujf-grenoble.fr>
                Toby Ewing <ewing@iastate.edu>
                Mirsad Todorovac <mtodorov_69@yahoo.com>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ <> 20060325}
     {$error
     Trying to compile gpc.pas with a non-matching GPC version is likely
     to cause problems.

     In case you are building the RTS separately from GPC, make sure you
     install a current GPC version previously. If you are building GPC
     now and this message appears, something is wrong -- if you are
     overriding the GCC_FOR_TARGET or GPC_FOR_TARGET make variables, this
     might be the problem. If you are cross-building GPC, build and
     install a current GPC cross-compiler first, sorry. If that's not the
     case, please report it as a bug.

     If you are not building GPC or the RTS currently, you might have
     installed things in the wrong place, so the compiler and RTS
     versions do not match.}
     {$endif}

     { Command-line options must not change the layout of RTS types
       declared here. }
     {$no-pack-struct, maximum-field-alignment 0}

     module GPC;

     export
       GPC = all;
       GPC_CP = (ERead { @@ not really, but an empty export doesn't work
       } );
       GPC_EP = (ERead { @@ not really, but an empty export doesn't work
       } );
       GPC_BP = (MaxLongInt, ExitCode, ErrorAddr, FileMode, Pos);
       GPC_Delphi = (MaxLongInt, Int64, InitProc, EConvertError,
                     ExitCode, ErrorAddr, FileMode, Pos, SetString,
       StringOfChar,
                     TextFile, AssignFile, CloseFile);

     type
       GPC_FDR = AnyFile;

     { Pascal declarations of the GPC Run Time System routines that are
       implemented in C, from rtsc.pas }

     const
       { Maximum size of a variable }
       MaxVarSize = MaxInt div 8;

     { If set, characters >= #$80 are assumed to be letters even if the
       locale routines don't say so. This is a kludge because some
       systems don't have correct non-English locale tables. }
     var
       FakeHighLetters: Boolean; attribute (name = '_p_FakeHighLetters');
       external;

     type
       PCStrings = ^TCStrings;
       TCStrings = array [0 .. MaxVarSize div SizeOf (CString) - 1] of
       CString;

       Int64 = Integer attribute (Size = 64);
       UnixTimeType = LongInt;  { This is hard-coded in the compiler. Do
       not change here. }
       MicroSecondTimeType = LongInt;
       FileSizeType = LongInt;
       SignedSizeType = Integer attribute (Size = BitSizeOf (SizeType));
       TSignalHandler = procedure (Signal: CInteger);

       StatFSBuffer = record
         BlockSize, BlocksTotal, BlocksFree: LongInt;
         FilesTotal, FilesFree: CInteger
       end;

       InternalSelectType = record
         Handle: CInteger;
         Read, Write, Exception: Boolean
       end;

       PString = ^String;

       { `Max' so the range of the array does not become invalid for
         Count = 0 }
       PPStrings = ^TPStrings;
       TPStrings (Count: Cardinal) = array [1 .. Max (Count, 1)] of
       PString;

       GlobBuffer = record
         Result: PPStrings;
         Internal1: Pointer;
         Internal2: PCStrings;
         Internal3: CInteger
       end;

     { Mathematical routines }

     function  SinH (x: Real): Real; attribute (const); external
       name '_p_SinH';
     function  CosH (x: Real): Real; attribute (const); external
       name '_p_CosH';
     function  ArcTan2 (y: Real; x: Real): Real; attribute (const);
       external name '_p_ArcTan2';
     function  IsInfinity (x: LongReal): Boolean; attribute (const);
       external name '_p_IsInfinity';
     function  IsNotANumber (x: LongReal): Boolean; attribute (const);
       external name '_p_IsNotANumber';
     procedure SplitReal (x: LongReal; var Exponent: CInteger; var
       Mantissa: LongReal); external name '_p_SplitReal';

     { Character routines }

     { Convert a character to lower case, according to the current
       locale. }
     function  LoCase (ch: Char): Char; attribute (const); external
       name '_p_LoCase';
     function  IsUpCase (ch: Char): Boolean; attribute (const); external
       name '_p_IsUpCase';
     function  IsLoCase (ch: Char): Boolean; attribute (const); external
       name '_p_IsLoCase';
     function  IsAlpha (ch: Char): Boolean; attribute (const); external
       name '_p_IsAlpha';
     function  IsAlphaNum (ch: Char): Boolean; attribute (const);
       external name '_p_IsAlphaNum';
     function  IsAlphaNumUnderscore (ch: Char): Boolean; attribute
       (const); external name '_p_IsAlphaNumUnderscore';
     function  IsSpace (ch: Char): Boolean; attribute (const); external
       name '_p_IsSpace';
     function  IsPrintable (ch: Char): Boolean; attribute (const);
       external name '_p_IsPrintable';

     { Time routines }

     { Sleep for a given number of seconds. }
     procedure Sleep (Seconds: CInteger); external name '_p_Sleep';

     { Sleep for a given number of microseconds. }
     procedure SleepMicroSeconds (MicroSeconds: CInteger); external
       name '_p_SleepMicroSeconds';

     { Set an alarm timer. }
     function  Alarm (Seconds: CInteger): CInteger; external
       name '_p_Alarm';

     { Convert a Unix time value to broken-down local time.
       All parameters except Time may be Null. }
     procedure UnixTimeToTime (Time: UnixTimeType; var Year: CInteger;
       var Month: CInteger; var Day: CInteger; var Hour: CInteger; var
       Minute: CInteger; var Second: CInteger;
                                     var TimeZone: CInteger; var DST:
       Boolean; var TZName1: CString; var TZName2: CString); external
       name '_p_UnixTimeToTime';

     { Convert broken-down local time to a Unix time value. }
     function  TimeToUnixTime (Year: CInteger; Month: CInteger; Day:
       CInteger; Hour: CInteger; Minute: CInteger; Second: CInteger):
       UnixTimeType; external name '_p_TimeToUnixTime';

     { Get the real time. MicroSecond can be Null and is ignored then. }
     function  GetUnixTime (var MicroSecond: CInteger): UnixTimeType;
       external name '_p_GetUnixTime';

     { Get the CPU time used. MicroSecond can be Null and is ignored
       then. }
     function  GetCPUTime (var MicroSecond: CInteger): CInteger; external
       name '_p_GetCPUTime';

     { Signal and process routines }

     { Extract information from the status returned by PWait }
     function  StatusExited (Status: CInteger): Boolean; attribute
       (const); external name '_p_StatusExited';
     function  StatusExitCode (Status: CInteger): CInteger; attribute
       (const); external name '_p_StatusExitCode';
     function  StatusSignaled (Status: CInteger): Boolean; attribute
       (const); external name '_p_StatusSignaled';
     function  StatusTermSignal (Status: CInteger): CInteger; attribute
       (const); external name '_p_StatusTermSignal';
     function  StatusStopped (Status: CInteger): Boolean; attribute
       (const); external name '_p_StatusStopped';
     function  StatusStopSignal (Status: CInteger): CInteger; attribute
       (const); external name '_p_StatusStopSignal';

     { Install a signal handler and optionally return the previous
       handler. OldHandler and OldRestart may be Null. }
     function  InstallSignalHandler (Signal: CInteger; Handler:
       TSignalHandler; Restart: Boolean; UnlessIgnored: Boolean;
       var OldHandler: TSignalHandler; var OldRestart: Boolean): Boolean;
       external name '_p_InstallSignalHandler';

     { Block or unblock a signal. }
     procedure BlockSignal (Signal: CInteger; Block: Boolean); external
       name '_p_BlockSignal';

     { Test whether a signal is blocked. }
     function  SignalBlocked (Signal: CInteger): Boolean; external
       name '_p_SignalBlocked';

     { Sends a signal to a process. Returns True if successful. If Signal
       is 0, it doesn't send a signal, but still checks whether it would
       be possible to send a signal to the given process. }
     function  Kill (PID: CInteger; Signal: CInteger): Boolean; external
       name '_p_Kill';

     { Constant for WaitPID }
     const
       AnyChild = -1;

     { Waits for a child process with the given PID (or any child process
       if PID = AnyChild) to terminate or be stopped. Returns the PID of
       the process. WStatus will contain the status and can be evaluated
       with StatusExited etc.. If nothing happened, and Block is False,
       the function will return 0, and WStatus will be 0. If an error
       occurred (especially on single tasking systems where WaitPID is
       not possible), the function will return a negative value, and
       WStatus will be 0. }
     function  WaitPID (PID: CInteger; var WStatus: CInteger; Block:
       Boolean): CInteger; external name '_p_WaitPID';

     { Returns the process ID. }
     function  ProcessID: CInteger; external name '_p_ProcessID';

     { Returns the process group. }
     function  ProcessGroup: CInteger; external name '_p_ProcessGroup';

     { Returns the real or effective user ID of the process. }
     function  UserID (Effective: Boolean): CInteger; external
       name '_p_UserID';

     { Tries to change the real and/or effective user ID. }
     function  SetUserID (Real: CInteger; Effective: CInteger): Boolean;
       external name '_p_SetUserID';

     { Returns the real or effective group ID of the process. }
     function  GroupID (Effective: Boolean): CInteger; external
       name '_p_GroupID';

     { Tries to change the real and/or effective group ID. }
     function  SetGroupID (Real: CInteger; Effective: CInteger): Boolean;
       external name '_p_SetGroupID';

     { Low-level file routines. Mostly for internal use. }

     { Get information about a file system. }
     function  StatFS (Path: CString; var Buf: StatFSBuffer): Boolean;
       external name '_p_StatFS';
     function  CStringOpenDir (DirName: CString): Pointer; external
       name '_p_CStringOpenDir';
     function  CStringReadDir (Dir: Pointer): CString; external
       name '_p_CStringReadDir';
     procedure CStringCloseDir (Dir: Pointer); external
       name '_p_CStringCloseDir';

     { Returns the value of the symlink FileName in a CString allocated
       from the heap. Returns nil if it is no symlink or the function
       is not supported. }
     function  ReadLink (FileName: CString): CString; external
       name '_p_ReadLink';

     { Returns a pointer to a *static* buffer! }
     function  CStringRealPath (Path: CString): CString; external
       name '_p_CStringRealPath';

     { File mode constants that are ORed for BindingType.Mode, ChMod,
       CStringChMod and Stat. The values below are valid for all OSs
       (as far as supported). If the OS uses different values, they're
       converted internally. }
     const
       fm_SetUID           = 8#4000;
       fm_SetGID           = 8#2000;
       fm_Sticky           = 8#1000;
       fm_UserReadable     = 8#400;
       fm_UserWritable     = 8#200;
       fm_UserExecutable   = 8#100;
       fm_GroupReadable    = 8#40;
       fm_GroupWritable    = 8#20;
       fm_GroupExecutable  = 8#10;
       fm_OthersReadable   = 8#4;
       fm_OthersWritable   = 8#2;
       fm_OthersExecutable = 8#1;

     { Constants for Access and OpenHandle }
     const
       MODE_EXEC     = 1 shl 0;
       MODE_WRITE    = 1 shl 1;
       MODE_READ     = 1 shl 2;
       MODE_FILE     = 1 shl 3;
       MODE_CREATE   = 1 shl 4;
       MODE_EXCL     = 1 shl 5;
       MODE_TRUNCATE = 1 shl 6;
       MODE_APPEND   = 1 shl 7;
       MODE_BINARY   = 1 shl 8;

     { Check if a file name is accessible. }
     function  Access (FileName: CString; Request: CInteger): CInteger;
       external name '_p_Access';

     { Get information about a file. Any argument except FileName can
       be Null. }
     function  Stat (FileName: CString; var Size: FileSizeType;
       var ATime: UnixTimeType; var MTime: UnixTimeType; var CTime:
       UnixTimeType;
       var User: CInteger; var Group: CInteger; var Mode: CInteger; var
       Device: CInteger; var INode: CInteger; var Links: CInteger;
       var SymLink: Boolean; var Dir: Boolean; var Special: Boolean):
       CInteger; external name '_p_Stat';
     function  OpenHandle (FileName: CString; Mode: CInteger): CInteger;
       external name '_p_OpenHandle';
     function  ReadHandle (Handle: CInteger; Buffer: Pointer; Size:
       SizeType): SignedSizeType; external name '_p_ReadHandle';
     function  WriteHandle (Handle: CInteger; Buffer: Pointer; Size:
       SizeType): SignedSizeType; external name '_p_WriteHandle';
     function  CloseHandle (Handle: CInteger): CInteger; external
       name '_p_CloseHandle';
     procedure FlushHandle (Handle: CInteger); external
       name '_p_FlushHandle';
     function  DupHandle (Src: CInteger; Dest: CInteger): CInteger;
       external name '_p_DupHandle';
     function  SetFileMode (Handle: CInteger; Mode: CInteger; On:
       Boolean): CInteger; attribute (ignorable); external
       name '_p_SetFileMode';
     function  CStringRename (OldName: CString; NewName: CString):
       CInteger; external name '_p_CStringRename';
     function  CStringUnlink (FileName: CString): CInteger; external
       name '_p_CStringUnlink';
     function  CStringChDir (FileName: CString): CInteger; external
       name '_p_CStringChDir';
     function  CStringMkDir (FileName: CString): CInteger; external
       name '_p_CStringMkDir';
     function  CStringRmDir (FileName: CString): CInteger; external
       name '_p_CStringRmDir';
     function  UMask (Mask: CInteger): CInteger; attribute (ignorable);
       external name '_p_UMask';
     function  CStringChMod (FileName: CString; Mode: CInteger):
       CInteger; external name '_p_CStringChMod';
     function  CStringChOwn (FileName: CString; Owner: CInteger; Group:
       CInteger): CInteger; external name '_p_CStringChOwn';
     function  CStringUTime (FileName: CString; AccessTime: UnixTimeType;
       ModificationTime: UnixTimeType): CInteger; external
       name '_p_CStringUTime';

     { Constants for SeekHandle }
     const
       SeekAbsolute = 0;
       SeekRelative = 1;
       SeekFileEnd  = 2;

     { Seek to a position on a file handle. }
     function  SeekHandle (Handle: CInteger; Offset: FileSizeType;
       Whence: CInteger): FileSizeType; external name '_p_SeekHandle';
     function  TruncateHandle (Handle: CInteger; Size: FileSizeType):
       CInteger; external name '_p_TruncateHandle';
     function  LockHandle (Handle: CInteger; WriteLock: Boolean; Block:
       Boolean): Boolean; external name '_p_LockHandle';
     function  UnlockHandle (Handle: CInteger): Boolean; external
       name '_p_UnlockHandle';
     function  SelectHandle (Count: CInteger; var Events:
       InternalSelectType; MicroSeconds: MicroSecondTimeType): CInteger;
       external name '_p_SelectHandle';

     { Constants for MMapHandle and MemoryMap }
     const
       mm_Readable   = 1;
       mm_Writable   = 2;
       mm_Executable = 4;

     { Try to map (a part of) a file to memory. }
     function  MMapHandle (Start: Pointer; Length: SizeType; Access:
       CInteger; Shared: Boolean; Handle: CInteger; Offset:
       FileSizeType): Pointer; external name '_p_MMapHandle';

     { Unmap a previous memory mapping. }
     function  MUnMapHandle (Start: Pointer; Length: SizeType): CInteger;
       external name '_p_MUnMapHandle';

     { Returns the file name of the terminal device that is open on
       Handle. Returns nil if (and only if) Handle is not open or not
       connected to a terminal. If NeedName is False, it doesn't bother
       to search for the real name and just returns DefaultName if it
       is a terminal and nil otherwise. DefaultName is also returned if
       NeedName is True, Handle is connected to a terminal, but the
       system does not provide information about the real file name. }
     function  GetTerminalNameHandle (Handle: CInteger; NeedName:
       Boolean; DefaultName: CString): CString; external
       name '_p_GetTerminalNameHandle';

     { System routines }

     { Sets the process group of Process (or the current one if Process
       is 0) to ProcessGroup (or its PID if ProcessGroup is 0). Returns
       True if successful. }
     function  SetProcessGroup (Process: CInteger; ProcessGroup:
       CInteger): Boolean; external name '_p_SetProcessGroup';

     { Sets the process group of a terminal given by Terminal (as a file
       handle) to ProcessGroup. ProcessGroup must be the ID of a process
       group in the same session. Returns True if successful. }
     function  SetTerminalProcessGroup (Handle: CInteger; ProcessGroup:
       CInteger): Boolean; external name '_p_SetTerminalProcessGroup';

     { Returns the process group of a terminal given by Terminal (as a
       file handle), or -1 on error. }
     function  GetTerminalProcessGroup (Handle: CInteger): CInteger;
       external name '_p_GetTerminalProcessGroup';

     { Set the standard input's signal generation, if it is a terminal. }
     procedure SetInputSignals (Signals: Boolean); external
       name '_p_SetInputSignals';

     { Get the standard input's signal generation, if it is a terminal. }
     function  GetInputSignals: Boolean; external
       name '_p_GetInputSignals';

     { Internal routines }

     { Returns system information if available. Fields not available will
       be set to nil. }
     procedure CStringSystemInfo (var SysName: CString; var NodeName:
       CString; var Release: CString; var Version: CString; var Machine:
       CString; var DomainName: CString); external
       name '_p_CStringSystemInfo';

     { Returns the path of the running executable *if possible*. }
     function  CStringExecutablePath (Buffer: CString): CString; external
       name '_p_CStringExecutablePath';

     { Sets ErrNo to the value of `errno' and returns the description
       for this error. May return nil if not supported! ErrNo may be
       Null (then only the description is returned). }
     function  CStringStrError (var ErrNo: CInteger): CString; external
       name '_p_CStringStrError';

     { Mathematical routines, from math.pas }

     function Ln1Plus  (x: Real) = y: Real; attribute (const, name
       = '_p_Ln1Plus'); external;

     { String handling routines (lower level), from string1.pas }

     { TString is a string type that is used for function results and
       local variables, as long as undiscriminated strings are not
       allowed there. The default size of 2048 characters should be
       enough for file names on any system, but can be changed when
       necessary. It should be at least as big as MAXPATHLEN. }

     const
       MaxLongInt = High (LongInt);

       TStringSize = 2048;
       SpaceCharacters = [' ', #9];
       NewLine = "\n";  { the separator of lines within a string }
       LineBreak = {$if defined (__OS_DOS__) and not defined (__CYGWIN__)
       and not defined (__MSYS__)}
                   "\r\n"
                   {$else}
                   "\n"
                   {$endif};  { the separator of lines within a file }

     type
       TString    = String (TStringSize);
       TStringBuf = packed array [0 .. TStringSize] of Char;
       CharSet    = set of Char;
       Str64      = String (64);
       TInteger2StringBase = Cardinal(2) .. Cardinal(36);
       TInteger2StringWidth = 0 .. High (TString);

     var
       NumericBaseDigits: array [0 .. 35] of Char; attribute (const, name
       = '_p_NumericBaseDigits'); external;
       NumericBaseDigitsUpper: array [0 .. 35] of Char; attribute (const,
       name = '_p_NumericBaseDigitsUpper'); external;

       CParamCount: Integer; attribute (name = '_p_CParamCount');
       external;
       CParameters: PCStrings; attribute (name = '_p_CParameters');
       external;

     function  MemCmp      (const s1, s2; Size: SizeType): CInteger;
       external name 'memcmp';
     function  MemComp     (const s1, s2; Size: SizeType): CInteger;
       external name 'memcmp';
     function  MemCompCase (const s1, s2; Size: SizeType): Boolean;
       attribute (name = '_p_MemCompCase'); external;

     procedure UpCaseString    (var s: String); attribute (name
       = '_p_UpCaseString'); external;
     procedure LoCaseString    (var s: String); attribute (name
       = '_p_LoCaseString'); external;
     function  UpCaseStr       (const s: String) = Result: TString;
       attribute (name = '_p_UpCaseStr'); external;
     function  LoCaseStr       (const s: String) = Result: TString;
       attribute (name = '_p_LoCaseStr'); external;

     function  StrEqualCase    (const s1, s2: String): Boolean; attribute
       (name = '_p_StrEqualCase'); external;

     function  Pos             (const SubString, s: String): Integer;
       attribute (name = '_p_Pos'); external;
     function  PosChar         (const ch: Char; const s: String):
       Integer; attribute (name = '_p_PosChar'); external;
     function  LastPos         (const SubString, s: String): Integer;
       attribute (name = '_p_LastPos'); external;
     function  PosCase         (const SubString, s: String): Integer;
       attribute (name = '_p_PosCase'); external;
     function  LastPosCase     (const SubString, s: String): Integer;
       attribute (name = '_p_LastPosCase'); external;
     function  CharPos         (const Chars: CharSet; const s: String):
       Integer; attribute (name = '_p_CharPos'); external;
     function  LastCharPos     (const Chars: CharSet; const s: String):
       Integer; attribute (name = '_p_LastCharPos'); external;

     function  PosFrom         (const SubString, s: String; From:
       Integer): Integer; attribute (name = '_p_PosFrom'); external;
     function  LastPosTill     (const SubString, s: String; Till:
       Integer): Integer; attribute (name = '_p_LastPosTill'); external;
     function  PosFromCase     (const SubString, s: String; From:
       Integer): Integer; attribute (name = '_p_PosFromCase'); external;
     function  LastPosTillCase (const SubString, s: String; Till:
       Integer): Integer; attribute (name = '_p_LastPosTillCase');
       external;
     function  CharPosFrom     (const Chars: CharSet; const s: String;
       From: Integer): Integer; attribute (name = '_p_CharPosFrom');
       external;
     function  LastCharPosTill (const Chars: CharSet; const s: String;
       Till: Integer): Integer; attribute (name = '_p_LastCharPosTill');
       external;

     function  IsPrefix        (const Prefix, s: String): Boolean;
       attribute (name = '_p_IsPrefix'); external;
     function  IsSuffix        (const Suffix, s: String): Boolean;
       attribute (name = '_p_IsSuffix'); external;
     function  IsPrefixCase    (const Prefix, s: String): Boolean;
       attribute (name = '_p_IsPrefixCase'); external;
     function  IsSuffixCase    (const Suffix, s: String): Boolean;
       attribute (name = '_p_IsSuffixCase'); external;

     function  CStringLength      (Src: CString): SizeType; attribute
       (inline, name = '_p_CStringLength'); external;
     function  CStringEnd         (Src: CString): CString; attribute
       (inline, name = '_p_CStringEnd'); external;
     function  CStringNew         (Src: CString): CString; attribute
       (name = '_p_CStringNew'); external;
     function  CStringComp        (s1, s2: CString): Integer; attribute
       (name = '_p_CStringComp'); external;
     function  CStringCaseComp    (s1, s2: CString): Integer; attribute
       (name = '_p_CStringCaseComp'); external;
     function  CStringLComp       (s1, s2: CString; MaxLen: SizeType):
       Integer; attribute (name = '_p_CStringLComp'); external;
     function  CStringLCaseComp   (s1, s2: CString; MaxLen: SizeType):
       Integer; attribute (name = '_p_CStringLCaseComp'); external;
     function  CStringCopy        (Dest, Source: CString): CString;
       attribute (ignorable, name = '_p_CStringCopy'); external;
     function  CStringCopyEnd     (Dest, Source: CString): CString;
       attribute (ignorable, name = '_p_CStringCopyEnd'); external;
     function  CStringLCopy       (Dest, Source: CString; MaxLen:
       SizeType): CString; attribute (ignorable, name
       = '_p_CStringLCopy'); external;
     function  CStringMove        (Dest, Source: CString; Count:
       SizeType): CString; attribute (ignorable, name
       = '_p_CStringMove'); external;
     function  CStringCat         (Dest, Source: CString): CString;
       attribute (ignorable, name = '_p_CStringCat'); external;
     function  CStringLCat        (Dest, Source: CString; MaxLen:
       SizeType): CString; attribute (ignorable, name
       = '_p_CStringLCat'); external;
     function  CStringChPos       (Src: CString; ch: Char): CString;
       attribute (inline, name = '_p_CStringChPos'); external;
     function  CStringLastChPos   (Src: CString; ch: Char): CString;
       attribute (inline, name = '_p_CStringLastChPos'); external;
     function  CStringPos         (s, SubString: CString): CString;
       attribute (name = '_p_CStringPos'); external;
     function  CStringLastPos     (s, SubString: CString): CString;
       attribute (name = '_p_CStringLastPos'); external;
     function  CStringCasePos     (s, SubString: CString): CString;
       attribute (name = '_p_CStringCasePos'); external;
     function  CStringLastCasePos (s, SubString: CString): CString;
       attribute (name = '_p_CStringLastCasePos'); external;
     function  CStringUpCase      (s: CString): CString; attribute (name
       = '_p_CStringUpCase'); external;
     function  CStringLoCase      (s: CString): CString; attribute (name
       = '_p_CStringLoCase'); external;
     function  CStringIsEmpty     (s: CString): Boolean; attribute (name
       = '_p_CStringIsEmpty'); external;
     function  NewCString         (const Source: String): CString;
       attribute (name = '_p_NewCString'); external;
     function  CStringCopyString  (Dest: CString; const Source: String):
       CString; attribute (name = '_p_CStringCopyString'); external;
     procedure CopyCString        (Source: CString; var Dest: String);
       attribute (name = '_p_CopyCString'); external;

     function  NewString       (const s: String) = Result: PString;
       attribute (name = '_p_NewString'); external;
     procedure DisposeString   (p: PString); external name '_p_Dispose';

     procedure SetString       (var s: String; Buffer: PChar; Count:
       Integer); attribute (name = '_p_SetString'); external;
     function  StringOfChar    (ch: Char; Count: Integer) = s: TString;
       attribute (name = '_p_StringOfChar'); external;

     procedure TrimLeft        (var s: String); attribute (name
       = '_p_TrimLeft'); external;
     procedure TrimRight       (var s: String); attribute (name
       = '_p_TrimRight'); external;
     procedure TrimBoth        (var s: String); attribute (name
       = '_p_TrimBoth'); external;
     function  TrimLeftStr     (const s: String) = Result: TString;
       attribute (name = '_p_TrimLeftStr'); external;
     function  TrimRightStr    (const s: String) = Result: TString;
       attribute (name = '_p_TrimRightStr'); external;
     function  TrimBothStr     (const s: String) = Result: TString;
       attribute (name = '_p_TrimBothStr'); external;
     function  LTrim           (const s: String) = Result: TString;
       external name '_p_TrimLeftStr';

     function  GetStringCapacity (const s: String): Integer; attribute
       (name = '_p_GetStringCapacity'); external;

     { A shortcut for a common use of WriteStr as a function }
     function  Integer2String (i: Integer) = s: Str64; attribute (name
       = '_p_Integer2String'); external;

     { Convert integer n to string in base Base. }
     function  Integer2StringBase (n: LongestInt; Base:
       TInteger2StringBase): TString; attribute (name
       = '_p_Integer2StringBase'); external;

     { Convert integer n to string in base Base, with sign, optionally in
       uppercase representation and with printed base, padded with
       leading zeroes between `[<Sign>]<Base>#' and the actual digits to
       specified Width. }
     function  Integer2StringBaseExt (n: LongestInt; Base:
       TInteger2StringBase; Width: TInteger2StringWidth; Upper: Boolean;
       PrintBase: Boolean): TString; attribute (name
       = '_p_Integer2StringBaseExt'); external;

     { String handling routines (higher level), from string2.pas }

     type
       PChars0 = ^TChars0;
       TChars0 = array [0 .. MaxVarSize div SizeOf (Char) - 1] of Char;

       PPChars0 = ^TPChars0;
       TPChars0 = array [0 .. MaxVarSize div SizeOf (PChars0) - 1] of
       PChars0;

       PChars = ^TChars;
       TChars = packed array [1 .. MaxVarSize div SizeOf (Char)] of Char;

       { Under development. Interface subject to change.
         Use with caution. }
       { When a const or var AnyString parameter is passed, internally
         these records are passed as const parameters. Value AnyString
         parameters are passed like value string parameters. }
       ConstAnyString = record
         Length: Integer;
         Chars: PChars
       end;

       { Capacity is the allocated space (used internally). Count is the
         actual number of environment strings. The CStrings array
         contains the environment strings, terminated by a nil pointer,
         which is not counted in Count. @CStrings can be passed to libc
         routines like execve which expect an environment (see
         GetCEnvironment). }
       PEnvironment = ^TEnvironment;
       TEnvironment (Capacity: Integer) = record
         Count: Integer;
         CStrings: array [1 .. Capacity + 1] of CString
       end;

     var
       Environment: PEnvironment; attribute (name = '_p_Environment');
       external;

     { Get an environment variable. If it does not exist, GetEnv returns
       the empty string, which can't be distinguished from a variable
       with an empty value, while CStringGetEnv returns nil then. Note,
       Dos doesn't know empty environment variables, but treats them as
       non-existing, and does not distinguish case in the names of
       environment variables. However, even under Dos, empty environment
       variables and variable names with different case can now be set
       and used within GPC programs. }
     function  GetEnv (const EnvVar: String): TString; attribute (name
       = '_p_GetEnv'); external;
     function  CStringGetEnv (EnvVar: CString): CString; attribute (name
       = '_p_CStringGetEnv'); external;

     { Sets an environment variable with the name given in VarName to the
       value Value. A previous value, if any, is overwritten. }
     procedure SetEnv (const VarName, Value: String); attribute (name
       = '_p_SetEnv'); external;

     { Un-sets an environment variable with the name given in VarName. }
     procedure UnSetEnv (const VarName: String); attribute (name
       = '_p_UnSetEnv'); external;

     { Returns @Environment^.CStrings, converted to PCStrings, to be
       passed to libc routines like execve which expect an environment. }
     function  GetCEnvironment: PCStrings; attribute (name
       = '_p_GetCEnvironment'); external;

     type
       FormatStringTransformType = ^function (const Format: String):
       TString;

     var
       FormatStringTransformPtr: FormatStringTransformType; attribute
       (name = '_p_FormatStringTransformPtr'); external;

     { Runtime error and signal handling routines, from error.pas }

     const
       EAssert = 306;
       EAssertString = 307;
       EOpen = 405;
       EMMap = 408;
       ERead = 413;
       EWrite = 414;
       EWriteReadOnly = 422;
       ENonExistentFile = 436;
       EOpenRead = 442;
       EOpenWrite = 443;
       EOpenUpdate = 444;
       EReading = 464;
       EWriting = 466;
       ECannotWriteAll = 467;
       ECannotFork = 600;
       ECannotSpawn = 601;
       EProgramNotFound = 602;
       EProgramNotExecutable = 603;
       EPipe = 604;
       EPrinterRead = 610;
       EIOCtl = 630;
       EConvertError = 875;
       ELibraryFunction = 952;
       EExitReturned = 953;

       RuntimeErrorExitValue = 42;

     var
       { Error number (after runtime error) or exit status (after Halt)
         or 0 (during program run and after succesful termination). }
       ExitCode: Integer; attribute (name = '_p_ExitCode'); external;

       { Contains the address of the code where a runtime occurred, nil
         if no runtime error occurred. }
       ErrorAddr: Pointer; attribute (name = '_p_ErrorAddr'); external;

       { Error message }
       ErrorMessageString: TString; attribute (name
       = '_p_ErrorMessageString'); external;

       { String parameter to some error messages, *not* the text of the
         error message (the latter can be obtained with
         GetErrorMessage). }
       InOutResString: PString; attribute (name = '_p_InOutResString');
       external;

       { Optional libc error string to some error messages. }
       InOutResCErrorString: PString; attribute (name
       = '_p_InOutResCErrorString'); external;

       RTSErrorFD: Integer; attribute (name = '_p_ErrorFD'); external;
       RTSErrorFileName: PString; attribute (name = '_p_ErrorFileName');
       external;

     function  GetErrorMessage                 (n: Integer): CString;
       attribute (name = '_p_GetErrorMessage'); external;
     procedure RuntimeError                    (n: Integer); attribute
       (noreturn, name = '_p_RuntimeError'); external;
     procedure RuntimeErrorErrNo               (n: Integer); attribute
       (noreturn, name = '_p_RuntimeErrorErrNo'); external;
     procedure RuntimeErrorInteger             (n: Integer; i: MedInt);
       attribute (noreturn, name = '_p_RuntimeErrorInteger'); external;
     procedure RuntimeErrorCString             (n: Integer; s: CString);
       attribute (noreturn, name = '_p_RuntimeErrorCString'); external;
     procedure InternalError                   (n: Integer); attribute
       (noreturn, name = '_p_InternalError'); external;
     procedure InternalErrorInteger            (n: Integer; i: MedInt);
       attribute (noreturn, name = '_p_InternalErrorInteger'); external;
     procedure InternalErrorCString            (n: Integer; s: CString);
       attribute (noreturn, name = '_p_InternalErrorCString'); external;
     procedure RuntimeWarning                  (Message: CString);
       attribute (name = '_p_RuntimeWarning'); external;
     procedure RuntimeWarningInteger           (Message: CString; i:
       MedInt); attribute (name = '_p_RuntimeWarningInteger'); external;
     procedure RuntimeWarningCString           (Message: CString; s:
       CString); attribute (name = '_p_RuntimeWarningCString'); external;

     procedure IOError                         (n: Integer; ErrNoFlag:
       Boolean); attribute (iocritical, name = '_p_IOError'); external;
     procedure IOErrorInteger                  (n: Integer; i: MedInt;
       ErrNoFlag: Boolean); attribute (iocritical, name
       = '_p_IOErrorInteger'); external;
     procedure IOErrorCString                  (n: Integer; s: CString;
       ErrNoFlag: Boolean); attribute (iocritical, name
       = '_p_IOErrorCString'); external;

     function  GetIOErrorMessage = Res: TString; attribute (name
       = '_p_GetIOErrorMessage'); external;
     procedure CheckInOutRes; attribute (name = '_p_CheckInOutRes');
       external;

     { Registers a procedure to be called to restore the terminal for
       another process that accesses the terminal, or back for the
       program itself. Used e.g. by the CRT unit. The procedures must
       allow for being called multiple times in any order, even at the
       end of the program (see the comment for RestoreTerminal). }
     procedure RegisterRestoreTerminal (ForAnotherProcess: Boolean;
       procedure Proc); attribute (name = '_p_RegisterRestoreTerminal');
       external;

     { Unregisters a procedure registered with RegisterRestoreTerminal.
       Returns False if the procedure had not been registered, and True
       if it had been registered and was unregistered successfully. }
     function  UnregisterRestoreTerminal (ForAnotherProcess: Boolean;
       procedure Proc): Boolean; attribute (name
       = '_p_UnregisterRestoreTerminal'); external;

     { Calls the procedures registered by RegisterRestoreTerminal. When
       restoring the terminal for another process, the procedures are
       called in the opposite order of registration. When restoring back
       for the program, they are called in the order of registration.

       `RestoreTerminal (True)' will also be called at the end of the
       program, before outputting any runtime error message. It can also
       be used if you want to write an error message and exit the program
       (especially when using e.g. the CRT unit). For this purpose, to
       avoid side effects, call RestoreTerminal immediately before
       writing the error message (to StdErr, not to Output!), and then
       exit the program (e.g. with Halt). }
     procedure RestoreTerminal (ForAnotherProcess: Boolean); attribute
       (name = '_p_RestoreTerminal'); external;

     procedure AtExit (procedure Proc); attribute (name = '_p_AtExit');
       external;

     function  ReturnAddr2Hex (p: Pointer) = s: TString; attribute (name
       = '_p_ReturnAddr2Hex'); external;

     { This function is used to write error messages etc. It does not use
       the Pascal I/O system here because it is usually called at the
       very end of a program after the Pascal I/O system has been shut
       down. }
     function  WriteErrorMessage (const s: String; StdErrFlag: Boolean):
       Boolean; attribute (name = '_p_WriteErrorMessage'); external;

     procedure SetReturnAddress (Address: Pointer); attribute (name
       = '_p_SetReturnAddress'); external;
     procedure RestoreReturnAddress; attribute (name
       = '_p_RestoreReturnAddress'); external;

     { Returns a description for a signal }
     function  StrSignal (Signal: Integer) = Res: TString; attribute
       (name = '_p_StrSignal'); external;

     { Installs some signal handlers that cause runtime errors on certain
       signals. This procedure runs only once, and returns immediately
       when called again (so you can't use it to set the signals again if
       you changed them meanwhile). @@Does not work on all systems (since
       the handler might have too little stack space). }
     procedure InstallDefaultSignalHandlers; attribute (name
       = '_p_InstallDefaultSignalHandlers'); external;

     var
       { Signal actions }
       SignalDefault: TSignalHandler; attribute (const); external
       name '_p_SIG_DFL';
       SignalIgnore : TSignalHandler; attribute (const); external
       name '_p_SIG_IGN';
       SignalError  : TSignalHandler; attribute (const); external
       name '_p_SIG_ERR';

       { Signals. The constants are set to the signal numbers, and
         are 0 for signals not defined. }
       { POSIX signals }
       SigHUp   : Integer; attribute (const); external name '_p_SIGHUP';
       SigInt   : Integer; attribute (const); external name '_p_SIGINT';
       SigQuit  : Integer; attribute (const); external name '_p_SIGQUIT';
       SigIll   : Integer; attribute (const); external name '_p_SIGILL';
       SigAbrt  : Integer; attribute (const); external name '_p_SIGABRT';
       SigFPE   : Integer; attribute (const); external name '_p_SIGFPE';
       SigKill  : Integer; attribute (const); external name '_p_SIGKILL';
       SigSegV  : Integer; attribute (const); external name '_p_SIGSEGV';
       SigPipe  : Integer; attribute (const); external name '_p_SIGPIPE';
       SigAlrm  : Integer; attribute (const); external name '_p_SIGALRM';
       SigTerm  : Integer; attribute (const); external name '_p_SIGTERM';
       SigUsr1  : Integer; attribute (const); external name '_p_SIGUSR1';
       SigUsr2  : Integer; attribute (const); external name '_p_SIGUSR2';
       SigChld  : Integer; attribute (const); external name '_p_SIGCHLD';
       SigCont  : Integer; attribute (const); external name '_p_SIGCONT';
       SigStop  : Integer; attribute (const); external name '_p_SIGSTOP';
       SigTStp  : Integer; attribute (const); external name '_p_SIGTSTP';
       SigTTIn  : Integer; attribute (const); external name '_p_SIGTTIN';
       SigTTOu  : Integer; attribute (const); external name '_p_SIGTTOU';

       { Non-POSIX signals }
       SigTrap  : Integer; attribute (const); external name '_p_SIGTRAP';
       SigIOT   : Integer; attribute (const); external name '_p_SIGIOT';
       SigEMT   : Integer; attribute (const); external name '_p_SIGEMT';
       SigBus   : Integer; attribute (const); external name '_p_SIGBUS';
       SigSys   : Integer; attribute (const); external name '_p_SIGSYS';
       SigStkFlt: Integer; attribute (const); external
       name '_p_SIGSTKFLT';
       SigUrg   : Integer; attribute (const); external name '_p_SIGURG';
       SigIO    : Integer; attribute (const); external name '_p_SIGIO';
       SigPoll  : Integer; attribute (const); external name '_p_SIGPOLL';
       SigXCPU  : Integer; attribute (const); external name '_p_SIGXCPU';
       SigXFSz  : Integer; attribute (const); external name '_p_SIGXFSZ';
       SigVTAlrm: Integer; attribute (const); external
       name '_p_SIGVTALRM';
       SigProf  : Integer; attribute (const); external name '_p_SIGPROF';
       SigPwr   : Integer; attribute (const); external name '_p_SIGPWR';
       SigInfo  : Integer; attribute (const); external name '_p_SIGINFO';
       SigLost  : Integer; attribute (const); external name '_p_SIGLOST';
       SigWinCh : Integer; attribute (const); external
       name '_p_SIGWINCH';

       { Signal subcodes (only used on some systems, -1 if not used) }
       FPEIntegerOverflow      : Integer; attribute (const); external
       name '_p_FPE_INTOVF_TRAP';
       FPEIntegerDivisionByZero: Integer; attribute (const); external
       name '_p_FPE_INTDIV_TRAP';
       FPESubscriptRange       : Integer; attribute (const); external
       name '_p_FPE_SUBRNG_TRAP';
       FPERealOverflow         : Integer; attribute (const); external
       name '_p_FPE_FLTOVF_TRAP';
       FPERealDivisionByZero   : Integer; attribute (const); external
       name '_p_FPE_FLTDIV_TRAP';
       FPERealUnderflow        : Integer; attribute (const); external
       name '_p_FPE_FLTUND_TRAP';
       FPEDecimalOverflow      : Integer; attribute (const); external
       name '_p_FPE_DECOVF_TRAP';

     { Routines called implicitly by the compiler. }
     procedure GPC_Assert (Condition: Boolean; const Message: String);
       attribute (name = '_p_Assert'); external;
     function  ObjectTypeIs (Left, Right: PObjectType): Boolean;
       attribute (const, name = '_p_ObjectTypeIs'); external;
     procedure ObjectTypeAsError; attribute (noreturn, name
       = '_p_ObjectTypeAsError'); external;
     procedure DisposeNilError; attribute (noreturn, name
       = '_p_DisposeNilError'); external;
     procedure CaseNoMatchError; attribute (noreturn, name
       = '_p_CaseNoMatchError'); external;
     procedure DiscriminantsMismatchError; attribute (noreturn, name
       = '_p_DiscriminantsMismatchError'); external;
     procedure NilPointerError; attribute (noreturn, name
       = '_p_NilPointerError'); external;
     procedure InvalidPointerError (p: Pointer); attribute (noreturn,
       name = '_p_InvalidPointerError'); external;
     procedure InvalidObjectError; attribute (noreturn, name
       = '_p_InvalidObjectError'); external;
     procedure RangeCheckError; attribute (noreturn, name
       = '_p_RangeCheckError'); external;
     procedure IORangeCheckError; attribute (name
       = '_p_IORangeCheckError'); external;
     procedure SubrangeError; attribute (noreturn, name
       = '_p_SubrangeError'); external;
     procedure ModRangeError; attribute (noreturn, name
       = '_p_ModRangeError'); external;

     { Pointer checking with `--pointer-checking-user-defined' }

     procedure DefaultValidatePointer (p: Pointer); attribute (name
       = '_p_DefaultValidatePointer'); external;

     type
       ValidatePointerType = ^procedure (p: Pointer);

     var
       ValidatePointerPtr: ValidatePointerType; attribute (name
       = '_p_ValidatePointerPtr'); external;

     { Time and date routines, from time.pas }

     const
       InvalidYear = -MaxInt;

     var
       { DayOfWeekName is a constant and therefore does not respect the
         locale. Therefore, it's recommended to use FormatTime instead. }
       DayOfWeekName: array [0 .. 6] of String [9]; attribute (const,
       name = '_p_DayOfWeekName'); external;

       { MonthName is a constant and therefore does not respect the
         locale. Therefore, it's recommended to use FormatTime instead. }
       MonthName: array [1 .. 12] of String [9]; attribute (const, name
       = '_p_MonthName'); external;

     function  GetDayOfWeek (Day, Month, Year: Integer): Integer;
       attribute (name = '_p_GetDayOfWeek'); external;
     function  GetDayOfYear (Day, Month, Year: Integer): Integer;
       attribute (name = '_p_GetDayOfYear'); external;
     function  GetSundayWeekOfYear (Day, Month, Year: Integer): Integer;
       attribute (name = '_p_GetSundayWeekOfYear'); external;
     function  GetMondayWeekOfYear (Day, Month, Year: Integer): Integer;
       attribute (name = '_p_GetMondayWeekOfYear'); external;
     procedure GetISOWeekOfYear (Day, Month, Year: Integer; var ISOWeek,
       ISOWeekYear: Integer); attribute (name = '_p_GetISOWeekOfYear');
       external;
     procedure UnixTimeToTimeStamp (UnixTime: UnixTimeType; var
       aTimeStamp: TimeStamp); attribute (name
       = '_p_UnixTimeToTimeStamp'); external;
     function  TimeStampToUnixTime (protected var aTimeStamp: TimeStamp):
       UnixTimeType; attribute (name = '_p_TimeStampToUnixTime');
       external;
     function  GetMicroSecondTime: MicroSecondTimeType; attribute (name
       = '_p_GetMicroSecondTime'); external;

     { Is the year a leap year? }
     function  IsLeapYear (Year: Integer): Boolean; attribute (name
       = '_p_IsLeapYear'); external;

     { Returns the length of the month, taking leap years into account. }
     function  MonthLength (Month, Year: Integer): Integer; attribute
       (name = '_p_MonthLength'); external;

     { Formats a TimeStamp value according to a Format string. The format
       string can contain date/time items consisting of `%', followed by
       the specifiers listed below. All characters outside of these items
       are copied to the result unmodified. The specifiers correspond to
       those of the C function strftime(), including POSIX.2 and glibc
       extensions and some more extensions. The extensions are also
       available on systems whose strftime() doesn't support them.

       The following modifiers may appear after the `%':

       `_'  The item is left padded with spaces to the given or default
            width.

       `-'  The item is not padded at all.

       `0'  The item is left padded with zeros to the given or default
            width.

       `/'  The item is right trimmed if it is longer than the given
            width.

       `^'  The item is converted to upper case.

       `~'  The item is converted to lower case.

       After zero or more of these flags, an optional width may be
       specified for padding and trimming. It must be given as a decimal
       number (not starting with `0' since `0' has a meaning of its own,
       see above).

       Afterwards, the following optional modifiers may follow. Their
       meaning is locale-dependent, and many systems and locales just
       ignore them.

       `E'  Use the locale's alternate representation for date and time.
            In a Japanese locale, for example, `%Ex' might yield a date
            format based on the Japanese Emperors' reigns.

       `O'  Use the locale's alternate numeric symbols for numbers. This
            modifier applies only to numeric format specifiers.

       Finally, exactly one of the following specifiers must appear. The
       padding rules listed here are the defaults that can be overriden
       with the modifiers listed above.

       `a'  The abbreviated weekday name according to the current locale.

       `A'  The full weekday name according to the current locale.

       `b'  The abbreviated month name according to the current locale.

       `B'  The full month name according to the current locale.

       `c'  The preferred date and time representation for the current
            locale.

       `C'  The century of the year. This is equivalent to the greatest
            integer not greater than the year divided by 100.

       `d'  The day of the month as a decimal number (`01' .. `31').

       `D'  The date using the format `%m/%d/%y'. NOTE: Don't use this
            format if it can be avoided. Things like this caused Y2K
            bugs!

       `e'  The day of the month like with `%d', but padded with blanks
            (` 1' .. `31').

       `F'  The date using the format `%Y-%m-%d'. This is the form
            specified in the ISO 8601 standard and is the preferred form
            for all uses.

       `g'  The year corresponding to the ISO week number, but without
            the century (`00' .. `99'). This has the same format and
            value as `y', except that if the ISO week number (see `V')
            belongs to the previous or next year, that year is used
            instead. NOTE: Don't use this format if it can be avoided.
            Things like this caused Y2K bugs!

       `G'  The year corresponding to the ISO week number. This has the
            same format and value as `Y', except that if the ISO week
            number (see `V') belongs to the previous or next year, that
            year is used instead.

       `h'  The abbreviated month name according to the current locale.
            This is the same as `b'.

       `H'  The hour as a decimal number, using a 24-hour clock
            (`00' .. `23').

       `I'  The hour as a decimal number, using a 12-hour clock
            (`01' .. `12').

       `j'  The day of the year as a decimal number (`001' .. `366').

       `k'  The hour as a decimal number, using a 24-hour clock like `H',
            but padded with blanks (` 0' .. `23').

       `l'  The hour as a decimal number, using a 12-hour clock like `I',
            but padded with blanks (` 1' .. `12').

       `m'  The month as a decimal number (`01' .. `12').

       `M'  The minute as a decimal number (`00' .. `59').

       `n'  A single newline character.

       `p'  Either `AM' or `PM', according to the given time value; or
            the corresponding strings for the current locale. Noon is
            treated as `PM' and midnight as `AM'.

       `P'  Either `am' or `pm', according to the given time value; or
            the corresponding strings for the current locale, printed in
            lowercase characters. Noon is treated as `pm' and midnight as
            `am'.

       `Q'  The fractional part of the second. This format has special
            effects on the modifiers. The width, if given, determines the
            number of digits to output. Therefore, no actual clipping or
            trimming is done. However, if padding with spaces is
            specified, any trailing (i.e., right!) zeros are converted to
            spaces, and if "no padding" is specified, they are removed.
            The default is "padding with zeros", i.e. trailing zeros are
            left unchanged. The digits are cut when necessary without
            rounding (otherwise, the value would not be consistent with
            the seconds given by `S' and `s'). Note that GPC's TimeStamp
            currently provides for microsecond resolution, so there are
            at most 6 valid digits (which is also the default width), any
            further digits will be 0 (but if TimeStamp will ever change,
            this format will be adjusted). However, the actual resolution
            provided by the operating system via GetTimeStamp etc. may be
            far lower (e.g., ~1/18s under Dos).

       `r'  The complete time using the AM/PM format of the current
            locale.

       `R'  The hour and minute in decimal numbers using the format
            `%H:%M'.

       `s'  Unix time, i.e. the number of seconds since the epoch, i.e.,
            since 1970-01-01 00:00:00 UTC. Leap seconds are not counted
            unless leap second support is available.

       `S'  The seconds as a decimal number (`00' .. `60').

       `t'  A single tab character.

       `T'  The time using decimal numbers using the format `%H:%M:%S'.

       `u'  The day of the week as a decimal number (`1' .. `7'), Monday
            being `1'.

       `U'  The week number of the current year as a decimal number
            (`00' .. `53'), starting with the first Sunday as the first
            day of the first week. Days preceding the first Sunday in the
            year are considered to be in week `00'.

       `V'  The ISO 8601:1988 week number as a decimal number
            (`01' .. `53'). ISO weeks start with Monday and end with
            Sunday. Week `01' of a year is the first week which has the
            majority of its days in that year; this is equivalent to the
            week containing the year's first Thursday, and it is also
            equivalent to the week containing January 4. Week `01' of a
            year can contain days from the previous year. The week before
            week `01' of a year is the last week (`52' or `53') of the
            previous year even if it contains days from the new year.

       `w'  The day of the week as a decimal number (`0' .. `6'), Sunday
            being `0'.

       `W'  The week number of the current year as a decimal number
            (`00' .. `53'), starting with the first Monday as the first
            day of the first week. All days preceding the first Monday in
            the year are considered to be in week `00'.

       `x'  The preferred date representation for the current locale, but
            without the time.

       `X'  The preferred time representation for the current locale, but
            with no date.

       `y'  The year without a century as a decimal number
            (`00' .. `99'). This is equivalent to the year modulo 100.
            NOTE: Don't use this format if it can be avoided. Things like
            this caused Y2K bugs!

       `Y'  The year as a decimal number, using the Gregorian calendar.
            Years before the year `1' are numbered `0', `-1', and so on.

       `z'  RFC 822/ISO 8601:1988 style numeric time zone (e.g., `-0600'
            or `+0100'), or nothing if no time zone is determinable.

       `Z'  The time zone abbreviation (empty if the time zone can't be
            determined).

       `%'  (i.e., an item `%%') A literal `%' character. }
     function  FormatTime (const Time: TimeStamp; const Format: String) =
       Res: TString; attribute (name = '_p_FormatTime'); external;

     { Pseudo random number generator, from random.pas }

     type
       RandomSeedType = Cardinal attribute (Size = 32);
       RandomizeType  = ^procedure;
       SeedRandomType = ^procedure (Seed: RandomSeedType);
       RandRealType   = ^function: LongestReal;
       RandIntType    = ^function (MaxValue: LongestCard): LongestCard;

     procedure SeedRandom (Seed: RandomSeedType); attribute (name
       = '_p_SeedRandom'); external;

     var
       RandomizePtr : RandomizeType; attribute (name
       = '_p_RandomizePtr'); external;
       SeedRandomPtr: SeedRandomType; attribute (name
       = '_p_SeedRandomPtr'); external;
       RandRealPtr  : RandRealType; attribute (name = '_p_RandRealPtr');
       external;
       RandIntPtr   : RandIntType; attribute (name = '_p_RandIntPtr');
       external;

     { File name routines, from fname.pas }

     { Define constants for different systems:

       OSDosFlag:         flag to indicate whether the target system is
                          Dos

       QuotingCharacter:  the character used to quote wild cards and
                          other special characters (#0 if not available)

       PathSeparator:     the separator of multiple paths, e.g. in the
                          PATH environment variable

       DirSeparator:      the separator of the directories within a full
                          file name

       DirSeparators:     a set of all possible directory and drive name
                          separators

       ExtSeparator:      the separator of a file name extension

       DirRoot:           the name of the root directory

       DirSelf:           the name of a directory in itself

       DirParent:         the name of the parent directory

       MaskNoStdDir:      a file name mask that matches all names except
                          the standard directories DirSelf and DirParent

       NullDeviceName:    the full file name of the null device

       TtyDeviceName:     the full file name of the current Tty

       ConsoleDeviceName: the full file name of the system console. On
                          Dos systems, this is the same as the Tty, but
                          on systems that allow remote login, this is a
                          different thing and may reach a completely
                          different user than the one running the
                          program, so use it with care.

       EnvVarCharsFirst:  the characters accepted at the beginning of the
                          name of an environment variable without quoting

       EnvVarChars:       the characters accepted in the name of an
                          environment variable without quoting

       PathEnvVar:        the name of the environment variable which
                          (usually) contains the executable search path

       ShellEnvVar:       the name of the environment variable which
                          (usually) contains the path of the shell
                          executable (see GetShellPath)

       ShellExecCommand:  the option to the (default) shell to execute
                          the command specified in the following argument
                          (see GetShellPath)

       ConfigFileMask:    a mask for the option file name as returned by
                          ConfigFileName

       FileNamesCaseSensitive:
                          flag to indicate whether file names are case
                          sensitive }

     const
       UnixShellEnvVar        = 'SHELL';
       UnixShellExecCommand   = '-c';

     {$ifdef __OS_DOS__}

     {$if defined (__CYGWIN__) or defined(__MSYS__)}
       {$define __POSIX_WIN32__}
     {$endif}

     const
       OSDosFlag              = True;
       QuotingCharacter       = #0;
       PathSeparator          = {$ifdef __POSIX_WIN32__} ':' {$else} ';'
       {$endif};
       DirSeparator           = '\';
       DirSeparators          = [':', '\', '/'];
       ExtSeparator           = '.';
       DirRoot                = '\';
       DirSelf                = '.';
       DirParent              = '..';
       MaskNoStdDir           = '{*,.[^.]*,..?*}';
       NullDeviceName         = 'nul';
       TtyDeviceName          = 'con';
       ConsoleDeviceName      = 'con';
       EnvVarCharsFirst       = ['A' .. 'Z', 'a' .. 'z', '_'];
       EnvVarChars            = EnvVarCharsFirst + ['0' .. '9'];
       PathEnvVar             = 'PATH';
       ShellEnvVar            = 'COMSPEC';
       ShellExecCommand       = '/c';
       ConfigFileMask         = '*.cfg';
       FileNamesCaseSensitive = False;

     {$else}

     const
       OSDosFlag              = False;
       QuotingCharacter       = '\';
       PathSeparator          = ':';
       DirSeparator           = '/';
       DirSeparators          = ['/'];
       ExtSeparator           = '.';
       DirRoot                = '/';
       DirSelf                = '.';
       DirParent              = '..';
       MaskNoStdDir           = '{*,.[^.]*,..?*}';
       NullDeviceName         = '/dev/null';
       TtyDeviceName          = '/dev/tty';
       ConsoleDeviceName      = '/dev/console';
       EnvVarCharsFirst       = ['A' .. 'Z', 'a' .. 'z', '_'];
       EnvVarChars            = EnvVarCharsFirst + ['0' .. '9'];
       PathEnvVar             = 'PATH';
       ShellEnvVar            = UnixShellEnvVar;
       ShellExecCommand       = UnixShellExecCommand;
       ConfigFileMask         = '.*';
       FileNamesCaseSensitive = True;

     {$endif}

     const
       WildCardChars = ['*', '?', '[', ']'];
       FileNameSpecialChars = (WildCardChars + SpaceCharacters +
       ['{', '}', '$', QuotingCharacter]) - DirSeparators;

     type
       DirPtr = Pointer;

     { Convert ch to lower case if FileNamesCaseSensitive is False, leave
       it unchanged otherwise. }
     function  FileNameLoCase (ch: Char): Char; attribute (name
       = '_p_FileNameLoCase'); external;

     { Change a file name to use the OS dependent directory separator }
     function  Slash2OSDirSeparator (const s: String) = Result: TString;
       attribute (name = '_p_Slash2OSDirSeparator'); external;

     { Change a file name to use '/' as directory separator }
     function  OSDirSeparator2Slash (const s: String) = Result: TString;
       attribute (name = '_p_OSDirSeparator2Slash'); external;

     { Like Slash2OSDirSeparator for CStrings. *Note*: overwrites the
       CString }
     function  Slash2OSDirSeparator_CString (s: CString): CString;
       attribute (ignorable, name = '_p_Slash2OSDirSeparator_CString');
       external;

     { Like OSDirSeparator2Slash for CStrings. *Note*: overwrites the
       CString }
     function  OSDirSeparator2Slash_CString (s: CString): CString;
       attribute (ignorable, name = '_p_OSDirSeparator2Slash_CString');
       external;

     { Add a DirSeparator to the end of s, if there is not already one
       and s denotes an existing directory }
     function  AddDirSeparator (const s: String) = Result: TString;
       attribute (name = '_p_AddDirSeparator'); external;

     { Like AddDirSeparator, but also if the directory does not exist }
     function  ForceAddDirSeparator (const s: String) = Result: TString;
       attribute (name = '_p_ForceAddDirSeparator'); external;

     { Remove all trailing DirSeparators from s, if there are any, as
       long as removing them doesn't change the meaning (i.e., they don't
       denote the root directory. }
     function  RemoveDirSeparator (const s: String) = Result: TString;
       attribute (name = '_p_RemoveDirSeparator'); external;

     { Returns the current directory using OS dependent directory
       separators }
     function  GetCurrentDirectory: TString; attribute (name
       = '_p_GetCurrentDirectory'); external;

     { Returns a directory suitable for storing temporary files using OS
       dependent directory separators. If found, the result always ends
       in DirSeparator. If no suitable directory is found, an empty
       string is returned. }
     function  GetTempDirectory: TString; attribute (name
       = '_p_GetTempDirectory'); external;

     { Returns a non-existing file name in the directory given. If the
       directory doesn't exist or the Directory name is empty, an I/O
       error is raised, and GetTempFileNameInDirectory returns the empty
       string. }
     function  GetTempFileNameInDirectory (const Directory: String) =
       Result: TString; attribute (iocritical, name
       = '_p_GetTempFileNameInDirectory'); external;

     { Returns a non-existing file name in GetTempDirectory. If no temp
       directory is found, i.e. GetTempDirectory returns the empty
       string, an I/O error is raised, and GetTempFileName returns the
       empty string as well. }
     function  GetTempFileName: TString; attribute (iocritical, name
       = '_p_GetTempFileName'); external;

     { The same as GetTempFileName, but returns a CString allocated from
       the heap. }
     function  GetTempFileName_CString: CString; attribute (iocritical,
       name = '_p_GetTempFileName_CString'); external;

     { Returns True if the given file name is an existing plain file }
     function  FileExists      (const aFileName: String): Boolean;
       attribute (name = '_p_FileExists'); external;

     { Returns True if the given file name is an existing directory }
     function  DirectoryExists (const aFileName: String): Boolean;
       attribute (name = '_p_DirectoryExists'); external;

     { Returns True if the given file name is an existing file, directory
       or special file (device, pipe, socket, etc.) }
     function  PathExists      (const aFileName: String): Boolean;
       attribute (name = '_p_PathExists'); external;

     { If a file of the given name exists in one of the directories given
       in DirList (separated by PathSeparator), returns the full path,
       otherwise returns an empty string. If aFileName already contains
       an element of DirSeparators, returns Slash2OSDirSeparator
       (aFileName) if it exists. }
     function  FSearch (const aFileName, DirList: String): TString;
       attribute (name = '_p_FSearch'); external;

     { Like FSearch, but only find executable files. Under Dos, if not
       found, the function tries appending '.com', '.exe', '.bat' and
       `.cmd' (the last one only if $COMSPEC points to a `cmd.exe'), so
       you don't have to specify these extensions in aFileName (and with
       respect to portability, it might be preferable not to do so). }
     function  FSearchExecutable (const aFileName, DirList: String) =
       Result: TString; attribute (name = '_p_FSearchExecutable');
       external;

     { Replaces all occurrences of `$FOO' and `~' in s by the value of
       the environment variables FOO or HOME, respectively. If a variable
       is not defined, the function returns False, and s contains the
       name of the undefined variable (or the empty string if the
       variable name is invalid, i.e., doesn't start with a character
       from EnvVarCharsFirst). Otherwise, if all variables are found, s
       contains the replaced string, and True is returned. }
     function  ExpandEnvironment (var s: String): Boolean; attribute
       (name = '_p_ExpandEnvironment'); external;

     { Expands the given path name to a full path name. Relative paths
       are expanded using the current directory, and occurrences of
       DirSelf and DirParent are resolved. Under Dos, the result is
       converted to lower case and a trailing ExtSeparator (except in a
       trailing DirSelf or DirParent) is removed, like Dos does. If the
       directory, i.e. the path without the file name, is invalid, the
       empty string is returned. }
     function  FExpand       (const Path: String): TString; attribute
       (name = '_p_FExpand'); external;

     { Like FExpand, but unquotes the directory before expanding it, and
       quotes WildCardChars again afterwards. Does not check if the
       directory is valid (because it may contain wild card characters).
       Symlinks are expanded only in the directory part, not the file
       name. }
     function  FExpandQuoted (const Path: String): TString; attribute
       (name = '_p_FExpandQuoted'); external;

     { FExpands Path, and then removes the current directory from it, if
       it is a prefix of it. If OnlyCurDir is set, the current directory
       will be removed only if Path denotes a file in, not below, it. }
     function  RelativePath (const Path: String; OnlyCurDir, Quoted:
       Boolean) = Result: TString; attribute (name = '_p_RelativePath');
       external;

     { Is aFileName a UNC filename? (Always returns False on non-Dos
       systems.) }
     function  IsUNC (const aFileName: String): Boolean; attribute (name
       = '_p_IsUNC'); external;

     { Splits a file name into directory, name and extension. Each of
       Dir, BaseName and Ext may be Null. }
     procedure FSplit (const Path: String; var Dir, BaseName, Ext:
       String); attribute (name = '_p_FSplit'); external;

     { Functions that extract one or two of the parts from FSplit.
       DirFromPath returns DirSelf + DirSeparator if the path contains no
       directory. }
     function  DirFromPath     (const Path: String) = Dir: TString;
       attribute (name = '_p_DirFromPath'); external;
     function  NameFromPath    (const Path: String) = BaseName: TString;
       attribute (name = '_p_NameFromPath'); external;
     function  ExtFromPath     (const Path: String) = Ext: TString;
       attribute (name = '_p_ExtFromPath'); external;
     function  NameExtFromPath (const Path: String): TString; attribute
       (name = '_p_NameExtFromPath'); external;

     { Start reading a directory. If successful, a pointer is returned
       that can be used for subsequent calls to ReadDir and finally
       CloseDir. On failure, an I/O error is raised and (in case it is
       ignored) nil is returned. }
     function  OpenDir  (const DirName: String) = Res: DirPtr; attribute
       (iocritical, name = '_p_OpenDir'); external;

     { Reads one entry from the directory Dir, and returns the file name.
       On errors or end of directory, the empty string is returned. }
     function  ReadDir  (Dir: DirPtr): TString; attribute (name
       = '_p_ReadDir'); external;

     { Closes a directory opened with OpenDir. }
     procedure CloseDir (Dir: DirPtr); attribute (name = '_p_CloseDir');
       external;

     { Returns the first position of a non-quoted character of CharSet in
       s, or 0 if no such character exists. }
     function  FindNonQuotedChar (Chars: CharSet; const s: String; From:
       Integer): Integer; attribute (name = '_p_FindNonQuotedChar');
       external;

     { Returns the first occurence of SubString in s that is not quoted
       at the beginning, or 0 if no such occurence exists. }
     function  FindNonQuotedStr (const SubString, s: String; From:
       Integer): Integer; attribute (name = '_p_FindNonQuotedStr');
       external;

     { Does a string contain non-quoted wildcard characters? }
     function  HasWildCards (const s: String): Boolean; attribute (name
       = '_p_HasWildCards'); external;

     { Does a string contain non-quoted wildcard characters, braces or
       spaces? }
     function  HasWildCardsOrBraces (const s: String): Boolean; attribute
       (name = '_p_HasWildCardsOrBraces'); external;

     { Insert QuotingCharacter into s before any special characters }
     function  QuoteFileName (const s: String; const SpecialCharacters:
       CharSet) = Result: TString; attribute (name = '_p_QuoteFileName');
       external;

     { Remove QuotingCharacter from s }
     function  UnQuoteFileName (const s: String) = Result: TString;
       attribute (name = '_p_UnQuoteFileName'); external;

     { Splits s at non-quoted spaces and expands non-quoted braces like
       bash does. The result and its entries should be disposed after
       usage, e.g. with DisposePPStrings. }
     function  BraceExpand (const s: String) = Result: PPStrings;
       attribute (name = '_p_BraceExpand'); external;

     { Dispose of a PPStrings array as well as the strings it contains.
       If you want to keep the strings (by assigning them to other string
       pointers), you should instead free the PPStrings array with
       `Dispose'. }
     procedure DisposePPStrings (Strings: PPStrings); attribute (name
       = '_p_DisposePPStrings'); external;

     { Tests if a file name matches a shell wildcard pattern (?, *, []) }
     function  FileNameMatch (const Pattern, FileName: String): Boolean;
       attribute (name = '_p_FileNameMatch'); external;

     { FileNameMatch with BraceExpand }
     function  MultiFileNameMatch (const Pattern, FileName: String):
       Boolean; attribute (name = '_p_MultiFileNameMatch'); external;

     { File name globbing }
     { GlobInit is implied by Glob and MultiGlob, not by GlobOn and
       MultiGlobOn. GlobOn and MultiGlobOn must be called after GlobInit,
       Glob or MultiGlob. MultiGlob and MultiGlobOn do brace expansion,
       Glob and GlobOn do not. GlobFree frees the memory allocated by the
       globbing functions and invalidates the results in Buf. It should
       be called after globbing. }
     procedure GlobInit    (var Buf: GlobBuffer); attribute (name
       = '_p_GlobInit'); external;
     procedure Glob        (var Buf: GlobBuffer; const Pattern: String);
       attribute (name = '_p_Glob'); external;
     procedure GlobOn      (var Buf: GlobBuffer; const Pattern: String);
       attribute (name = '_p_GlobOn'); external;
     procedure MultiGlob   (var Buf: GlobBuffer; const Pattern: String);
       attribute (name = '_p_MultiGlob'); external;
     procedure MultiGlobOn (var Buf: GlobBuffer; const Pattern: String);
       attribute (name = '_p_MultiGlobOn'); external;
     procedure GlobFree    (var Buf: GlobBuffer); attribute (name
       = '_p_GlobFree'); external;

     type
       TPasswordEntry = record
         UserName, RealName, Password, HomeDirectory, Shell: PString;
         UID, GID: Integer
       end;

       PPasswordEntries = ^TPasswordEntries;
       TPasswordEntries (Count: Integer) = array [1 .. Max (1, Count)] of
       TPasswordEntry;

     { Finds a password entry by user name. Returns True if found, False
       otherwise. }
     function  GetPasswordEntryByName (const UserName: String; var Entry:
       TPasswordEntry) = Res: Boolean; attribute (name
       = '_p_GetPasswordEntryByName'); external;

     { Finds a password entry by UID. Returns True if found, False
       otherwise. }
     function  GetPasswordEntryByUID (UID: Integer; var Entry:
       TPasswordEntry) = Res: Boolean; attribute (name
       = '_p_GetPasswordEntryByUID'); external;

     { Returns all password entries, or nil if none found. }
     function  GetPasswordEntries = Res: PPasswordEntries; attribute
       (name = '_p_GetPasswordEntries'); external;

     { Dispose of a TPasswordEntry. }
     procedure DisposePasswordEntry (Entry: TPasswordEntry); attribute
       (name = '_p_DisposePasswordEntry'); external;

     { Dispose of a PPasswordEntries. }
     procedure DisposePasswordEntries (Entries: PPasswordEntries);
       attribute (name = '_p_DisposePasswordEntries'); external;

     { Returns the mount point (Unix) or drive (Dos) which is part of the
       given path. If the path does not contain any (i.e., is a relative
       path), an empty string is returned. Therefore, if you want to get
       the mount point or drive in any case, apply `FExpand' or
       `RealPath' to the argument. }
     function  GetMountPoint (const Path: String) = Result: TString;
       attribute (name = '_p_GetMountPoint'); external;

     type
       TSystemInfo = record
         OSName,
         OSRelease,
         OSVersion,
         MachineType,
         HostName,
         DomainName: TString
       end;

     { Returns system information if available. Fields not available will
       be empty. }
     function  SystemInfo = Res: TSystemInfo; attribute (name
       = '_p_SystemInfo'); external;

     { Returns the path to the shell (as the result) and the option that
       makes it execute the command specified in the following argument
       (in `Option'). Usually these are the environment value of
       ShellEnvVar, and ShellExecCommand, but on Dos systems, the
       function will first try UnixShellEnvVar, and UnixShellExecCommand
       because ShellEnvVar will usually point to command.com, but
       UnixShellEnvVar can point to bash which is usually a better choice
       when present. If UnixShellEnvVar is not set, or the shell given
       does not exist, it will use ShellEnvVar, and ShellExecCommand.
       Option may be Null (in case you want to invoke the shell
       interactively). }
     function  GetShellPath (var Option: String) = Res: TString;
       attribute (name = '_p_GetShellPath'); external;

     { Returns the path of the running executable. *Note*: On most
       systems, this is *not* guaranteed to be the full path, but often
       just the same as `ParamStr (0)' which usually is the name given on
       the command line. Only on some systems with special support, it
       returns the full path when `ParamStr (0)' doesn't. }
     function  ExecutablePath: TString; attribute (name
       = '_p_ExecutablePath'); external;

     { Returns a file name suitable for a global (system-wide) or local
       (user-specific) configuration file, depending on the Global
       parameter. The function does not guarantee that the file name
       returned exists or is readable or writable.

       In the following table, the base name `<base>' is given with the
       BaseName parameter. If it is empty, the base name is the name of
       the running program (as returned by ExecutablePath, without
       directory and extension. `<prefix>' (Unix only) stands for the
       value of the Prefix parameter (usual values include '', '/usr' and
       '/usr/local'). `<dir>' (Dos only) stands for the directory where
       the running program resides. `$foo' stands for the value of the
       environment variable `foo'.

               Global                    Local
       Unix:   <prefix>/etc/<base>.conf  $HOME/.<base>

       DJGPP:  $DJDIR\etc\<base>.ini     $HOME\<base>.cfg
               <dir>\<base>.ini          <dir>\<base>.cfg

       Other   $HOME\<base>.ini          $HOME\<base>.cfg
         Dos:  <dir>\<base>.ini          <dir>\<base>.cfg

       As you see, there are two possibilities under Dos. If the first
       file exists, it is returned. Otherwise, if the second file exists,
       that is returned. If none of them exists (but the program might
       want to create a file), if the environment variable (DJDIR or
       HOME, respectively) is set, the first file name is returned,
       otherwise the second one. This rather complicated scheme should
       give the most reasonable results for systems with or without DJGPP
       installed, and with or without already existing config files. Note
       that DJDIR is always set on systems with DJGPP installed, while
       HOME is not. However, it is easy for users to set it if they want
       their config files in a certain directory rather than with the
       executables. }
     function  ConfigFileName (const Prefix, BaseName: String; Global:
       Boolean): TString; attribute (name = '_p_ConfigFileName');
       external;

     { Returns a directory name suitable for global, machine-independent
       data. The function garantees that the name returned ends with a
       DirSeparator, but does not guarantee that it exists or is
       readable or writable.

       Note: If the prefix is empty, it is assumed to be '/usr'. (If you
       really want /share, you could pass '/' as the prefix, but that's
       very uncommon.)

       Unix:   <prefix>/share/<base>/

       DJGPP:  $DJDIR\share\<base>\
               <dir>\

       Other   $HOME\<base>\
         Dos:  <dir>\

       About the symbols used above, and the two possibilities under Dos,
       see the comments for ConfigFileName. }
     function  DataDirectoryName (const Prefix, BaseName: String):
       TString; attribute (name = '_p_DataDirectoryName'); external;

     { Executes a command line. Reports execution errors via the IOResult
       mechanism and returns the exit status of the executed program.
       Execute calls RestoreTerminal with the argument True before and
       False after executing the process, ExecuteNoTerminal does not. }
     function  Execute (const CmdLine: String): Integer; attribute
       (iocritical, name = '_p_Execute'); external;
     function  ExecuteNoTerminal (const CmdLine: String): Integer;
       attribute (iocritical, name = '_p_ExecuteNoTerminal'); external;

     { File handling routines, from files.pas }

     type
       TextFile = Text;
       TOpenMode = (fo_None, fo_Reset, fo_Rewrite, fo_Append,
       fo_SeekRead, fo_SeekWrite, fo_SeekUpdate);
       PAnyFile = ^AnyFile;

       TOpenProc   = procedure (var PrivateData; Mode: TOpenMode);
       TSelectFunc = function  (var PrivateData; Writing: Boolean):
       Integer;  { called before SelectHandle, must return a file handle
       }
       TSelectProc = procedure (var PrivateData; var ReadSelect,
       WriteSelect, ExceptSelect: Boolean);  { called before and after
       SelectHandle }
       TReadFunc   = function  (var PrivateData; var   Buffer; Size:
       SizeType): SizeType;
       TWriteFunc  = function  (var PrivateData; const Buffer; Size:
       SizeType): SizeType;
       TFileProc   = procedure (var PrivateData);
       TFlushProc  = TFileProc;
       TCloseProc  = TFileProc;
       TDoneProc   = TFileProc;

     { Flags that can be `or'ed into FileMode. The default value of
       FileMode is FileMode_Reset_ReadWrite. The somewhat confusing
       numeric values are meant to be compatible to BP (as far as
       BP supports them). }
     const
       { Allow writing to binary files opened with Reset }
       FileMode_Reset_ReadWrite      = 2;

       { Do not allow reading from files opened with Rewrite }
       FileMode_Rewrite_WriteOnly    = 4;

       { Do not allow reading from files opened with Extend }
       FileMode_Extend_WriteOnly     = 8;

       { Allow writing to text files opened with Reset }
       FileMode_Text_Reset_ReadWrite = $100;

     var
       FileMode: Integer; attribute (name = '_p_FileMode'); external;

     { Get the external name of a file }
     function  FileName (protected var f: GPC_FDR): TString; attribute
       (name = '_p_FileName'); external;

     procedure IOErrorFile (n: Integer; protected var f: GPC_FDR;
       ErrNoFlag: Boolean); attribute (iocritical, name
       = '_p_IOErrorFile'); external;

     procedure GetBinding (protected var f: GPC_FDR; var b: BindingType);
       attribute (name = '_p_GetBinding'); external;
     procedure ClearBinding (var b: BindingType); attribute (name
       = '_p_ClearBinding'); external;

     { TFDD interface @@ Subject to change! Use with caution! }
     procedure AssignTFDD (var f: GPC_FDR;
                           aOpenProc:    TOpenProc;
                           aSelectFunc:  TSelectFunc;
                           aSelectProc:  TSelectProc;
                           aReadFunc:    TReadFunc;
                           aWriteFunc:   TWriteFunc;
                           aFlushProc:   TFlushProc;
                           aCloseProc:   TCloseProc;
                           aDoneProc:    TDoneProc;
                           aPrivateData: Pointer); attribute (name
       = '_p_AssignTFDD'); external;

     procedure SetTFDD    (var f: GPC_FDR;
                           aOpenProc:    TOpenProc;
                           aSelectFunc:  TSelectFunc;
                           aSelectProc:  TSelectProc;
                           aReadFunc:    TReadFunc;
                           aWriteFunc:   TWriteFunc;
                           aFlushProc:   TFlushProc;
                           aCloseProc:   TCloseProc;
                           aDoneProc:    TDoneProc;
                           aPrivateData: Pointer); attribute (name
       = '_p_SetTFDD'); external;

     { Any parameter except f may be Null }
     procedure GetTFDD    (var f: GPC_FDR;
                           var aOpenProc:    TOpenProc;
                           var aSelectFunc:  TSelectFunc;
                           var aSelectProc:  TSelectProc;
                           var aReadFunc:    TReadFunc;
                           var aWriteFunc:   TWriteFunc;
                           var aFlushProc:   TFlushProc;
                           var aCloseProc:   TCloseProc;
                           var aDoneProc:    TDoneProc;
                           var aPrivateData: Pointer); attribute (name
       = '_p_GetTFDD'); external;

     procedure FileMove (var f: GPC_FDR; NewName: CString; Overwrite:
       Boolean); attribute (iocritical, name = '_p_FileMove'); external;

     const
       NoChange = -1;  { can be passed to ChOwn for Owner and/or Group to
       not change that value }

     procedure CloseFile (var f: GPC_FDR); attribute (name
       = '_p_CloseFile'); external;
     procedure ChMod (var f: GPC_FDR; Mode: Integer); attribute
       (iocritical, name = '_p_ChMod'); external;
     procedure ChOwn (var f: GPC_FDR; Owner, Group: Integer); attribute
       (iocritical, name = '_p_ChOwn'); external;

     { Checks if data are available to be read from f. This is
       similar to `not EOF (f)', but does not block on "files" that
       can grow, like Ttys or pipes. }
     function  CanRead (var f: GPC_FDR): Boolean; attribute (name
       = '_p_CanRead'); external;

     { Checks if data can be written to f. }
     function  CanWrite (var f: GPC_FDR): Boolean; attribute (name
       = '_p_CanWrite'); external;

     { Get the file handle. }
     function  FileHandle (protected var f: GPC_FDR): Integer; attribute
       (name = '_p_FileHandle'); external;

     { Lock/unlock a file. }
     function  FileLock (var f: GPC_FDR; WriteLock, Block: Boolean):
       Boolean; attribute (name = '_p_FileLock'); external;
     function  FileUnlock (var f: GPC_FDR): Boolean; attribute (name
       = '_p_FileUnlock'); external;

     { Try to map (a part of) a file to memory. }
     function  MemoryMap (Start: Pointer; Length: SizeType; Access:
       Integer; Shared: Boolean;
                          var f: GPC_FDR; Offset: FileSizeType): Pointer;
       attribute (name = '_p_MemoryMap'); external;

     { Unmap a previous memory mapping. }
     procedure MemoryUnMap (Start: Pointer; Length: SizeType); attribute
       (name = '_p_MemoryUnMap'); external;

     type
       Natural = 1 .. MaxInt;
       IOSelectEvents = (SelectReadOrEOF, SelectRead, SelectEOF,
       SelectWrite, SelectException, SelectAlways);

     type
       IOSelectType = record
         f: PAnyFile;
         Wanted: set of IOSelectEvents;
         Occurred: set of Low (IOSelectEvents) .. Pred (SelectAlways)
       end;

     { Waits for one of several events to happen. Returns when one or
       more of the wanted events for one of the files occur. If they have
       already occurred before calling the function, it returns
       immediately. MicroSeconds can specify a timeout. If it is 0, the
       function will return immediately, whether or not an event has
       occurred. If it is negative, the function will wait forever until
       an event occurs. The Events parameter can be Null, in which case
       the function only waits for the timeout. If any of the file
       pointers (f) in Events are nil or the files pointed to are closed,
       they are simply ignored for convenience.

       It returns the index of one of the files for which any event has
       occurred. If events have occurred for several files, is it
       undefined which of these file's index is returned. If no event
       occurs until the timeout, 0 is returned. If an error occurs or the
       target system does not have a `select' system call and Events is
       not Null, a negative value is returned. In the Occurred field of
       the elements of Events, events that have occurred are set. The
       state of events not wanted is undefined.

       The possible events are:
       SelectReadOrEOF: the file is at EOF or data can be read now.
       SelectRead:      data can be read now.
       SelectEOF:       the file is at EOF.
       SelectWrite:     data can be written now.
       SelectException: an exception occurred on the file.
       SelectAlways:    if this is set, *all* requested events will be
                        checked for this file in any case. Otherwise,
                        checks may be skipped if already another event
                        for this or another file was found.

       Notes:
       Checking for EOF requires some reading ahead internally (just like
       the EOF function) which can be avoided by setting SelectReadOrEOF
       instead of SelectRead and SelectEOF. If this is followed by, e.g.,
       a BlockRead with 4 parameters, the last parameter will be 0 if and
       only the file is at EOF, and otherwise, data will be read directly
       from the file without reading ahead and buffering.

       SelectAlways should be set for files whose events are considered
       to be of higher priority than others. Otherwise, if one is
       interested in just any event, not setting SelectAlways may be a
       little faster. }
     function  IOSelect (var Events: array [m .. n: Natural] of
       IOSelectType; MicroSeconds: MicroSecondTimeType): Integer;
       attribute (name = '_p_IOSelect'); external;

     { A simpler interface to SelectIO for the most common use. Waits for
       SelectReadOrEOF on all files and returns an index. }
     function  IOSelectRead (const Files: array [m .. n: Natural] of
       PAnyFile; MicroSeconds: MicroSecondTimeType): Integer; attribute
       (name = '_p_IOSelectRead'); external;

     { Bind a filename to an external file }
     procedure AssignFile   (var t: AnyFile; const FileName: String);
       attribute (name = '_p_AssignFile'); external;
     procedure AssignBinary (var t: Text; const FileName: String);
       attribute (name = '_p_AssignBinary'); external;
     procedure AssignHandle (var t: AnyFile; Handle: Integer; CloseFlag:
       Boolean); attribute (name = '_p_AssignHandle'); external;

     { Under development }
     procedure AnyStringTFDD_Reset (var f: GPC_FDR; var Buf:
       ConstAnyString); attribute (name = '_p_AnyStringTFDD_Reset');
       external;
     { @@ procedure AnyStringTFDD_Rewrite (var f: GPC_FDR; var Buf:
       VarAnyString); attribute (name = '_p_AnyStringTFDD_Rewrite'); }
     procedure StringTFDD_Reset (var f: GPC_FDR; var Buf: ConstAnyString;
       var s: array [m .. n: Integer] of Char); attribute (name
       = '_p_StringTFDD_Reset'); external;
     { @@ procedure StringTFDD_Rewrite (var f: GPC_FDR; var Buf:
       VarAnyString; var s: String); attribute (name
       = '_p_StringTFDD_Rewrite'); }

     { Returns True is a terminal device is open on the file f, False if
       f is not open or not connected to a terminal. }
     function  IsTerminal (protected var f: GPC_FDR): Boolean; attribute
       (name = '_p_IsTerminal'); external;

     { Returns the file name of the terminal device that is open on the
       file f. Returns the empty string if (and only if) f is not open or
       not connected to a terminal. }
     function  GetTerminalName (protected var f: GPC_FDR): TString;
       attribute (name = '_p_GetTerminalName'); external;

     { Command line option parsing, from getopt.pas }

     const
       EndOfOptions      = #255;
       NoOption          = #1;
       UnknownOption     = '?';
       LongOption        = #0;
       UnknownLongOption = '?';

     var
       FirstNonOption        : Integer; attribute (name
       = '_p_FirstNonOption'); external;
       HasOptionArgument     : Boolean; attribute (name
       = '_p_HasOptionArgument'); external;
       OptionArgument        : TString; attribute (name
       = '_p_OptionArgument'); external;
       UnknownOptionCharacter: Char; attribute (name
       = '_p_UnknownOptionCharacter'); external;
       GetOptErrorFlag       : Boolean; attribute (name
       = '_p_GetOptErrorFlag'); external;

     { Parses command line arguments for options and returns the next
       one.

       If a command line argument starts with `-', and is not exactly `-'
       or `--', then it is an option element. The characters of this
       element (aside from the initial `-') are option characters. If
       `GetOpt' is called repeatedly, it returns successively each of the
       option characters from each of the option elements.

       If `GetOpt' finds another option character, it returns that
       character, updating `FirstNonOption' and internal variables so
       that the next call to `GetOpt' can resume the scan with the
       following option character or command line argument.

       If there are no more option characters, `GetOpt' returns
       EndOfOptions. Then `FirstNonOption' is the index of the first
       command line argument that is not an option. (The command line
       arguments have been permuted so that those that are not options
       now come last.)

       OptString must be of the form `[+|-]abcd:e:f:g::h::i::'.

       a, b, c are options without arguments
       d, e, f are options with required arguments
       g, h, i are options with optional arguments

       Arguments are text following the option character in the same
       command line argument, or the text of the following command line
       argument. They are returned in OptionArgument. If an option has no
       argument, OptionArgument is empty. The variable HasOptionArgument
       tells whether an option has an argument. This is mostly useful for
       options with optional arguments, if one wants to distinguish an
       empty argument from no argument.

       If the first character of OptString is `+', GetOpt stops at the
       first non-option argument.

       If it is `-', GetOpt treats non-option arguments as options and
       return NoOption for them.

       Otherwise, GetOpt permutes arguments and handles all options,
       leaving all non-options at the end. However, if the environment
       variable POSIXLY_CORRECT is set, the default behaviour is to stop
       at the first non-option argument, as with `+'.

       The special argument `--' forces an end of option-scanning
       regardless of the first character of OptString. In the case of
       `-', only `--' can cause GetOpt to return EndOfOptions with
       FirstNonOption <= ParamCount.

       If an option character is seen that is not listed in OptString,
       UnknownOption is returned. The unrecognized option character is
       stored in UnknownOptionCharacter. Unless GetOptErrorFlag is set to
       False, an error message is printed to StdErr automatically. }
     function  GetOpt (const OptString: String): Char; attribute (name
       = '_p_GetOpt'); external;

     type
       OptArgType = (NoArgument, RequiredArgument, OptionalArgument);

       OptionType = record
         OptionName: CString;
         Argument  : OptArgType;
         Flag      : ^Char;  { if nil, v is returned. Otherwise, Flag^ is
       ... }
         v         : Char    { ... set to v, and LongOption is returned }
       end;

     { Recognize short options, described by OptString as above, and long
       options, described by LongOptions.

       Long-named options begin with `--' instead of `-'. Their names may
       be abbreviated as long as the abbreviation is unique or is an
       exact match for some defined option. If they have an argument, it
       follows the option name in the same argument, separated from the
       option name by a `=', or else the in next argument. When GetOpt
       finds a long-named option, it returns LongOption if that option's
       `Flag' field is non-nil, and the value of the option's `v' field
       if the `Flag' field is nil.

       LongIndex, if not Null, returns the index in LongOptions of the
       long-named option found. It is only valid when a long-named option
       has been found by the most recent call.

       If LongOnly is set, `-' as well as `--' can indicate a long
       option. If an option that starts with `-' (not `--') doesn't match
       a long option, but does match a short option, it is parsed as a
       short option instead. If an argument has the form `-f', where f is
       a valid short option, don't consider it an abbreviated form of a
       long option that starts with `f'. Otherwise there would be no way
       to give the `-f' short option. On the other hand, if there's a
       long option `fubar' and the argument is `-fu', do consider that an
       abbreviation of the long option, just like `--fu', and not `-f'
       with argument `u'. This distinction seems to be the most useful
       approach.

       As an additional feature (not present in the C counterpart), if
       the last character of OptString is `-' (after a possible starting
       `+' or `-' character), or OptString is empty, all long options
       with a nil `Flag' field will automatically be recognized as short
       options with the character given by the `v' field. This means, in
       the common (and recommended) case that all short options have long
       equivalents, you can simply pass an empty OptString (or pass `+-'
       or `--' as OptString if you want this behaviour, see the comment
       for GetOpt), and you will only have to maintain the LongOptions
       array when you add or change options. }
     function  GetOptLong (const OptString: String; const LongOptions:
       array [m .. n: Integer] of OptionType { can be Null };
                           var LongIndex: Integer { can be Null };
       LongOnly: Boolean): Char; attribute (name = '_p_GetOptLong');
       external;

     { Reset GetOpt's state and make the next GetOpt or GetOptLong start
       (again) with the StartArgument'th argument (may be 1). This is
       useful for special purposes only. It is *necessary* to do this
       after altering the contents of CParamCount/CParameters (which is
       not usually done, either). }
     procedure ResetGetOpt (StartArgument: Integer); attribute (name
       = '_p_ResetGetOpt'); external;

     { Set operations, from sets.pas }

     { All set operations are built-in identifiers and not declared in
       gpc.pas. }

     { Heap management routines, from heap.pas }

     { GPC implements both Mark/Release and Dispose. Both can be mixed
       freely in the same program. Dispose should be preferred, since
       it's faster. }

     { C heap management routines. NOTE: if Release is used anywhere in
       the program, CFreeMem and CReAllocMem may not be used for pointers
       that were not allocated with CGetMem. }
     function  CGetMem     (Size: SizeType): Pointer; external
       name 'malloc';
     procedure CFreeMem    (aPointer: Pointer); external name 'free';
     function  CReAllocMem (aPointer: Pointer; NewSize: SizeType):
       Pointer; external name 'realloc';

     type
       GetMemType     = ^function (Size: SizeType): Pointer;
       FreeMemType    = ^procedure (aPointer: Pointer);
       ReAllocMemType = ^function (aPointer: Pointer; NewSize: SizeType):
       Pointer;

     { These variables can be set to user-defined routines for memory
       allocation/deallocation. GetMemPtr may return nil when
       insufficient memory is available. GetMem/New will produce a
       runtime error then. }
     var
       GetMemPtr    : GetMemType; attribute (name = '_p_GetMemPtr');
       external;
       FreeMemPtr   : FreeMemType; attribute (name = '_p_FreeMemPtr');
       external;
       ReAllocMemPtr: ReAllocMemType; attribute (name
       = '_p_ReAllocMemPtr'); external;

       { Address of the lowest byte of heap used }
       HeapLow: PtrCard; attribute (name = '_p_HeapLow'); external;

       { Address of the highest byte of heap used }
       HeapHigh: PtrCard; attribute (name = '_p_HeapHigh'); external;

       { If set to true, `Dispose' etc. will raise a runtime error if
         given an invalid pointer. }
       HeapChecking: Boolean; attribute (name = '_p_HeapChecking');
       external;

     const
       UndocumentedReturnNil = Pointer (-1);

     function  SuspendMark: Pointer; attribute (name = '_p_SuspendMark');
       external;
     procedure ResumeMark (p: Pointer); attribute (name
       = '_p_ResumeMark'); external;

     { Calls the procedure Proc for each block that would be released
       with `Release (aMark)'. aMark must have been marked with Mark. For
       an example of its usage, see the HeapMon unit. }
     procedure ForEachMarkedBlock (aMark: Pointer; procedure Proc
       (aPointer: Pointer; aSize: SizeType; aCaller: Pointer)); attribute
       (name = '_p_ForEachMarkedBlock'); external;

     procedure ReAllocMem (var aPointer: Pointer; NewSize: SizeType);
       attribute (name = '_p_ReAllocMem'); external;

     { Memory transfer procedures, from move.pas }

     { The move operations are built-in identifiers and not declared in
       gpc.pas. }

     { Routines to handle endianness, from endian.pas }

     { Boolean constants about endianness and alignment }

     const
       BitsBigEndian  = {$ifdef __BITS_LITTLE_ENDIAN__}
                        False
                        {$elif defined (__BITS_BIG_ENDIAN__)}
                        True
                        {$else}
                        {$error Bit endianness is not defined!}
                        {$endif};

       BytesBigEndian = {$ifdef __BYTES_LITTLE_ENDIAN__}
                        False
                        {$elif defined (__BYTES_BIG_ENDIAN__)}
                        True
                        {$else}
                        {$error Byte endianness is not defined!}
                        {$endif};

       WordsBigEndian = {$ifdef __WORDS_LITTLE_ENDIAN__}
                        False
                        {$elif defined (__WORDS_BIG_ENDIAN__)}
                        True
                        {$else}
                        {$error Word endianness is not defined!}
                        {$endif};

       NeedAlignment  = {$ifdef __NEED_ALIGNMENT__}
                        True
                        {$elif defined (__NEED_NO_ALIGNMENT__)}
                        False
                        {$else}
                        {$error Alignment is not defined!}
                        {$endif};

     { Convert single variables from or to little or big endian format.
       This only works for a single variable or a plain array of a simple
       type. For more complicated structures, this has to be done for
       each component separately! Currently, ConvertFromFooEndian and
       ConvertToFooEndian are the same, but this might not be the case on
       middle-endian machines. Therefore, we provide different names. }
     procedure ReverseBytes            (var Buf; ElementSize, Count:
       SizeType); attribute (name = '_p_ReverseBytes'); external;
     procedure ConvertFromLittleEndian (var Buf; ElementSize, Count:
       SizeType); attribute (name = '_p_ConvertLittleEndian'); external;
     procedure ConvertFromBigEndian    (var Buf; ElementSize, Count:
       SizeType); attribute (name = '_p_ConvertBigEndian'); external;
     procedure ConvertToLittleEndian   (var Buf; ElementSize, Count:
       SizeType); external name '_p_ConvertLittleEndian';
     procedure ConvertToBigEndian      (var Buf; ElementSize, Count:
       SizeType); external name '_p_ConvertBigEndian';

     { Read a block from a file and convert it from little or
       big endian format. This only works for a single variable or a
       plain array of a simple type, note the comment for
       `ConvertFromLittleEndian' and `ConvertFromBigEndian'. }
     procedure BlockReadLittleEndian   (var aFile: File; var   Buf;
       ElementSize, Count: SizeType); attribute (iocritical, name
       = '_p_BlockRead_LittleEndian'); external;
     procedure BlockReadBigEndian      (var aFile: File; var   Buf;
       ElementSize, Count: SizeType); attribute (iocritical, name
       = '_p_BlockRead_BigEndian'); external;

     { Write a block variable to a file and convert it to little or big
       endian format before. This only works for a single variable or a
       plain array of a simple type. Apart from this, note the comment
       for `ConvertToLittleEndian' and `ConvertToBigEndian'. }
     procedure BlockWriteLittleEndian  (var aFile: File; const Buf;
       ElementSize, Count: SizeType); attribute (iocritical, name
       = '_p_BlockWrite_LittleEndian'); external;
     procedure BlockWriteBigEndian     (var aFile: File; const Buf;
       ElementSize, Count: SizeType); attribute (iocritical, name
       = '_p_BlockWrite_BigEndian'); external;

     { Read and write strings from/to binary files, where the length is
       stored in the given endianness and with a fixed size (64 bits),
       and therefore is independent of the system. }
     procedure ReadStringLittleEndian  (var f: File; var s: String);
       attribute (iocritical, name = '_p_ReadStringLittleEndian');
       external;
     procedure ReadStringBigEndian     (var f: File; var s: String);
       attribute (iocritical, name = '_p_ReadStringBigEndian'); external;
     procedure WriteStringLittleEndian (var f: File; const s: String);
       attribute (iocritical, name = '_p_WriteStringLittleEndian');
       external;
     procedure WriteStringBigEndian    (var f: File; const s: String);
       attribute (iocritical, name = '_p_WriteStringBigEndian');
       external;

     { Initialization, from init.pas }

     var
       InitProc: ^procedure; attribute (name = '_p_InitProc'); external;


File: gpc.info,  Node: GPC Units,  Prev: Run Time System,  Up: Programming

6.15 Units included with GPC
============================

GPC distributions now include a number of useful Pascal units and a
complete set of BP compatibility units - except for the `Graph' unit
(which is currently distributed separately due to its license) and the
OOP stuff. The main use of these units is to provide a way to port BP
programs to GPC as easily as possible. Some of the units also implement
functionaliy not available otherwise.

   Most of the BP compatibility units - except `CRT' and `Printer' -
are merely meant to let programs written for BP compile with GPC as
easily as possible. They should not be used in newly written code, and
for code ported from BP to GPC, it is suggested to replace them
successively with the more powerful - and often easier to use -
alternatives that GPC's Run Time System (*note Run Time System::)
offers.

   The following sections describe all units included with GPC (besides
the `GPC' module which describes the interface to the Run Time System,
*Note Run Time System::).

* Menu:

* CRT::          BP compatibility: CRT & WinCRT, portable, with many extensions
* Dos::          BP compatibility: Dos
* DosUnix::      Overcome some differences between Dos and Unix
* FileUtils::    Higher level file and directory handling
* GMP::          Arithmetic with unlimited size and precision
* GPCUtil::      Turbo Power compatibility, etc.
* HeapMon::      Primitive heap checking
* Intl::         Internationalization
* MD5::          `MD5' Message Digests
* Overlay::      BP compatibility: Overlay
* Pipes::        Start a child process, connected with pipes, also on Dos
* Ports::        BP compatibility (partly): `Port', `PortW' arrays
* Printer::      BP compatibility: Printer, portable
* RegEx::        Regular Expression matching and substituting
* Strings::      BP compatibility: Strings
* StringUtils::  Higher level string handling
* System::       BP compatibility: System
* TFDD::         Some text file tricks
* Trap::         Trap runtime errors
* Turbo3::       BP compatibility: Turbo3
* WinDos::       BP compatibility: WinDos


File: gpc.info,  Node: CRT,  Next: Dos,  Up: GPC Units

6.15.1 BP compatibility: CRT & WinCRT, portable, with many extensions
---------------------------------------------------------------------

The following listing contains the interface of the CRT unit.

   `CRT' is a `curses' based unit for text screen handling.  It is
compatible to BP's `CRT' unit, even in a lot of minor details like the
values of function key codes and includes some routines for
compatibility with TP5's `Win' unit as well as BP's `WinCRT' and Turbo
Power's `TPCrt' units, and some extensions.

   The unit has been extended by many functions that were lacking in
BP's unit and required assembler code or direct memory/port access to
be implemented under BP. The GPC version is now fully suited for
portable, real-world programming without any dirty tricks.

   The unit is also available as `WinCRT', completely identical to
`CRT'. The only purpose of this "feature" is to let programs written
for TPW or BP, with a `uses WinCRT' directive, compile without changes.
Unlike TPW/BP's `WinCRT' unit, GPC's unit is not crippled, compared to
`CRT'.

   To use this unit, you will need the `ncurses' (version 5.0 or newer)
or `PDCurses' library which can be found in
`http://www.gnu-pascal.de/libs/'.

     { CRT (Crt Replacement Tool)
       Portable BP compatible CRT unit for GPC with many extensions

       This unit is aware of terminal types. This means programs using
       this unit will work whether run locally or while being logged in
       remotely from a system with a completely different terminal type
       (as long as the appropriate terminfo entry is present on the
       system where the program is run).

       NOTES:

       - The CRT unit needs the ncurses and panel libraries which should
         be available for almost any system. For Dos systems, where
         ncurses is not available, it is configured to use the PDCurses
         and its panel library instead. On Unix systems with X11, it can
         also use PDCurses (xcurses) and xpanel to produce X11 programs.
         The advantage is that the program won't need an xterm with a
         valid terminfo entry, the output may look a little nicer and
         function keys work better than in an xterm, but the disadvantage
         is that it will only run under X. The ncurses and PDCurses
         libraries (including panel and xpanel, resp.) can be found in
         http://www.gnu-pascal.de/libs/
         (Note that ncurses is already installed on many Unix systems.)
         For ncurses, version 5.0 or newer is required.

         When an X11 version under Unix is wanted, give `-DX11' when
         compiling crt.pas and crtc.c (or when compiling crt.pas or a
         program that uses CRT with `--automake'). On pre-X11R6 systems,
         give `-DNOX11R6' additionally. You might also have to give the
         path to the X11 libraries with `-L', e.g. `-L /usr/X11/lib'.

       - A few features cannot be implemented in a portable way and are
         only available on some systems:

           Sound, NoSound 1)                  -----------------------.
           GetShiftState                      ------------------.    |
           TextMode etc. 2)                   -------------.    |    |
           CRTSavePreviousScreen              --------.    |    |    |
           Interrupt signal (Ctrl-C) handling ---.    |    |    |    |
                                                 |    |    |    |    |
         Linux/IA32 3) (terminal)                X    X 4) X 5) X 6) X 6)
         Other Unix (terminal)                   X    X 7) X 5) -    -
         Unix (X11 version)                      X    X    -    X    -
         Dos (DJGPP)                             X    X    X    X    X
         MS-Windows (Cygwin, mingw, MSYS)        X    -    X 8) X    -

         Notes:

         1) If you define NO_CRT_DUMMY_SOUND while compiling CRT, you
            will get linking errors when your program tries to use
            Sound/NoSound on a platform where it's not supported (which
            is useful to detect at compile time if playing sound is a
            major task of your program). Otherwise, Sound/NoSound will
            simply do nothing (which is usually acceptable if the program
            uses these routines just for an occasional beep).

         2) Changing to monochrome modes works on all platforms. Changing
            the screen size only works on those indicated. However, even
            on the platforms not supported, the program will react to
            screen size changes by external means (e.g. changing the
            window size with the mouse if running in a GUI window or
            resizing a console or virtual terminal).

         3) Probably also on other processors, but I've had no chance to
            test this yet.

         4) Only on a local console with access permissions to the
            corresponding virtual console memory device or using the
            `crtscreen' utility (see crtscreen.c in the demos directory).

         5) Only if supported by an external command (e.g., in xterms and
            on local Linux consoles). The command to be called can be
            defined in the environment variable `RESIZETERM' (where the
            variables `columns' and `lines' in the command are set to the
            size wanted). If not set, the code will try `resize -s' in an
            xterm and otherwise `SVGATextMode' and `setfont'. For this to
            work, these utilities need to be present in the PATH or
            `/usr/sbin' or `/usr/local/sbin'. Furthermore, SVGATextMode
            and setfont require root permissions, either to the
            executable of the program compiled with CRT or to resizecons
            (called by setfont) or SVGATextMode. To allow the latter, do
            "chmod u+s `which resizecons`" and/or
            "chmod u+s `which SVGATextMode`", as root once, but only if
            you really want each user to be allowed to change the text
            mode.

         6) Only on local consoles.

         7) Some terminals only. Most xterms etc. support it as well as
            other terminals that support an "alternate screen" in the
            smcup/rmcup terminal capabilities.

         8) Only with PDCurses, not with ncurses. Changing the number of
            screen *columns* doesn't work in a full-screen session.

       - When CRT is initialized (automatically or explicitly; see the
         comments for CRTInit), the screen is cleared, and at the end of
         the program, the cursor is placed at the bottom of the screen
         (curses behaviour).

       - All the other things (including most details like color and
         function key constants) are compatible with BP's CRT unit, and
         there are many extensions that BP's unit does not have.

       - When the screen size is changed by an external event (e.g.,
         resizing an xterm or changing the screen size from another VC
         under Linux), the virtual "function key" kbScreenSizeChanged is
         returned. Applications can use the virtual key to resize their
         windows. kbScreenSizeChanged will not be returned if the screen
         size change was initiated by the program itself (by using
         TextMode or SetScreenSize). Note that TextMode sets the current
         panel to the full screen size, sets the text attribute to the
         default and clears the window (BP compatibility), while
         SetScreenSize does not.

       - After the screen size has been changed, whether by using
         TextMode, SetScreenSize or by an external event, ScreenSize will
         return the new screen size. The current window and all panels
         will have been adjusted to the new screen size. This means, if
         their right or lower ends are outside the new screen size, the
         windows are moved to the left and/or top as far as necessary. If
         this is not enough, i.e., if they are wider/higher than the new
         screen size, they are shrinked to the total screen width/height.
         When the screen size is enlarged, window sizes are not changed,
         with one exception: Windows that extend through the whole screen
         width/height are enlarged to the whole new screen width/height
         (in particular, full-screen windows remain full-screen). This
         behaviour might not be optimal for all purposes, but you can
         always resize your windows in your application after the screen
         size change.

       - (ncurses only) The environment variable `ESCDELAY' specifies the
         number of milliseconds allowed between an `Esc' character and
         the rest of an escape sequence (default 1000). Setting it to a
         value too small can cause problems with programs not recognizing
         escape sequences such as function keys, especially over slow
         network connections. Setting it to a value too large can delay
         the recognition of an `ESC' key press notably. On local Linux
         consoles, e.g., 10 seems to be a good value.

       - When trying to write portable programs, don't rely on exactly
         the same look of your output and the availability of all the key
         combinations. Some kinds of terminals support only some of the
         display attributes and special characters, and usually not all
         of the keys declared are really available. Therefore, it's safer
         to provide the same function on different key combinations and
         to not use the more exotic ones.

       - CRT supports an additional modifier key (if present), called
         `Extra'. On DJGPP, it's the <Scroll Lock> key, under X11 it's
         the modifier #4, and on a local Linux console, it's the `CtrlL'
         modifier (value 64) which is unused on many keytabs and can be
         mapped to any key(s), e.g. to those keys on new keyboards with
         these ugly symbols waiting to be replaced by penguins (keycodes
         125 and 127) by inserting the following two lines into your
         /etc/default.keytab and reloading the keytab with `loadkeys'
         (you usually have to do this as root):

         keycode 125 = CtrlL
         keycode 127 = CtrlL

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License.

       Please also note the license of the curses library used. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030722}
     {$error This unit requires GPC release 20030722 or newer.}
     {$endif}

     unit {$ifdef THIS_IS_WINCRT} WinCRT {$else} CRT {$endif};

     interface

     uses GPC;

     const
       { CRT modes }
       BW40          = 0;            { 40x25 Black/White }
       CO40          = 1;            { 40x25 Color }
       BW80          = 2;            { 80x25 Black/White }
       CO80          = 3;            { 80x25 Color }
       Mono          = 7;            { 80x25 Black/White }
       Font8x8       = 256;          { Add-in for 80x43 or 80x50 mode }

       { Mode constants for Turbo Pascal 3.0 compatibility }
       C40           = CO40;
       C80           = CO80;

       { Foreground and background color constants }
       Black         = 0;
       Blue          = 1;
       Green         = 2;
       Cyan          = 3;
       Red           = 4;
       Magenta       = 5;
       Brown         = 6;
       LightGray     = 7;

       { Foreground color constants }
       DarkGray      = 8;
       LightBlue     = 9;
       LightGreen    = 10;
       LightCyan     = 11;
       LightRed      = 12;
       LightMagenta  = 13;
       Yellow        = 14;
       White         = 15;

       { Add-in for blinking }
       Blink         = 128;

     type
       TTextAttr = Byte;

     var
       { If False (default: True), catch interrupt signals (SIGINT;
         Ctrl-C), and other flow control characters as well as SIGTERM,
         SIGHUP and perhaps other signals }
       CheckBreak: Boolean = True; attribute (name = 'crt_CheckBreak');

       { If True (default : False), replace Ctrl-Z by #0 in input }
       CheckEOF: Boolean = False; attribute (name = 'crt_CheckEOF');

       { Ignored -- meaningless here }
       DirectVideo: Boolean = True;

       { Ignored -- curses or the terminal driver will take care of that
         when necessary }
       CheckSnow: Boolean = False;

       { Current (sic!) text mode }
       LastMode: CCardinal = 3; attribute (name = 'crt_LastMode');

       { Current text attribute }
       TextAttr: TTextAttr = 7; attribute (name = 'crt_TextAttr');

       { Window upper left coordinates. *Obsolete*! Please see WindowMin
         below. }
       WindMin: CCardinal = High (CCardinal); attribute (name
       = 'crt_WindMin');

       { Window lower right coordinates. *Obsolete*! Please see WindowMax
         below. }
       WindMax: CCardinal = High (CCardinal); attribute (name
       = 'crt_WindMax');

     procedure AssignCRT (var f: Text);
     function  KeyPressed: Boolean; external name 'crt_KeyPressed';
     function  ReadKey: Char; external name 'crt_ReadKey';

     { Not effective on all platforms, see above. See also SetScreenSize
       and SetMonochrome. }
     procedure TextMode (Mode: Integer);

     procedure Window (x1, y1, x2, y2: CInteger); external
       name 'crt_Window';
     procedure GotoXY (x, y: CInteger); external name 'crt_GotoXY';
     function  WhereX: CInteger; external name 'crt_WhereX';
     function  WhereY: CInteger; external name 'crt_WhereY';
     procedure ClrScr; external name 'crt_ClrScr';
     procedure ClrEOL; external name 'crt_ClrEOL';
     procedure InsLine; external name 'crt_InsLine';
     procedure DelLine; external name 'crt_DelLine';
     procedure TextColor (Color: TTextAttr);
     procedure TextBackground (Color: TTextAttr);
     procedure LowVideo;
     procedure HighVideo;
     procedure NormVideo;
     procedure Delay (MS: CCardinal); external name 'crt_Delay';

     { Not available on all platforms, see above }
     procedure Sound (Hz: CCardinal); external name 'crt_Sound';
     procedure NoSound; external name 'crt_NoSound';

     { =================== Extensions over BP's CRT =================== }

     { Initializes the CRT unit. Should be called before using any of
       CRT's routines.

       Note: For BP compatibility, CRT is initizalized automatically when
       (almost) any of its routines are used for the first time. In this
       case, some defaults are set to match BP more closely. In
       particular, the PC charset (see SetPCCharSet) is enabled then
       (disabled otherwise), and the update level (see SetCRTUpdate) is
       set to UpdateRegularly (UpdateWaitInput otherwise). This feature
       is meant for BP compatibility *only*. Don't rely on it when
       writing a new program. Use CRTInit then, and set the defaults to
       the values you want explicitly.

       SetCRTUpdate is one of those few routines which will not cause CRT
       to be initialized immediately, and a value set with it will
       survive both automatic and explicit initialization, so you can use
       it to set the update level without caring which way CRT will be
       initialized. (This does not apply to SetPCCharSet. Since it works
       on a per-panel basis, it has to initialize CRT first, so there is
       a panel to start with.)

       If you terminate the program before calling CRTInit or any routine
       that causes automatic initialization, curses will never be
       initialized, so e.g., the screen won't be cleared. This can be
       useful, e.g., to check the command line arguments (or anything
       else) and if there's a problem, write an error and abort. Just be
       sure to write the error to StdErr, not Output (because Output will
       be assigned to CRT, and therefore writing to Output will cause CRT
       to be initialized, and because errors belong to StdErr, anyway),
       and to call `RestoreTerminal (True)' before (just to be sure, in
       case some code -- perhaps added later, or hidden in the
       initialization of some unit -- does initialize CRT). }
     procedure CRTInit; external name 'crt_Init';

     { Changes the input and output file and the terminal description CRT
       uses. Only effective with ncurses, and only if called before CRT
       is initialized (automatically or explicitly; see the comments for
       CRTInit). If TerminalType is nil, the default will be used. If
       InputFile and/or OutputFile are Null, they remain unchanged. }
     procedure CRTSetTerminal (TerminalType: CString; var InputFile,
       OutputFile: AnyFile); attribute (name = 'crt_SetTerminal');

     { If called with an argument True, it causes CRT to save the
       previous screen contents if possible (see the comments at the
       beginning of the unit), and restore them when calling
       RestoreTerminal (True). After RestoreTerminal (False), they're
       saved again, and at the end of the program, they're restored. If
       called with an argument False, it will prohibit this behaviour.
       The default, if this procedure is not called, depends on the
       terminal (generally it is active on most xterms and similar and
       not active on most other terminals).

       This procedure should be called before initializing CRT (using
       CRTInit or automatically), otherwise the previous screen contents
       may already have been overwritten. It has no effect under XCurses,
       because the program uses its own window, anyway. }
     procedure CRTSavePreviousScreen (On: Boolean); external
       name 'crt_SavePreviousScreen';

     { Returns True if CRTSavePreviousScreen was called with argument
       True and the functionality is really available. Note that the
       result is not reliable until CRT is initialized, while
       CRTSavePreviousScreen should be called before CRT is initialized.
       That's why they are two separate routines. }
     function  CRTSavePreviousScreenWorks: Boolean; external
       name 'crt_SavePreviousScreenWorks';

     { If CRT is initialized automatically, not via CRTInit, and
       CRTAutoInitProc is not nil, it will be called before actually
       initializing CRT. }
     var
       CRTAutoInitProc: procedure = nil; attribute (name
       = 'crt_AutoInitProc');

     { Aborts with a runtime error saying that CRT was not initialized.
       If you set CRTAutoInitProc to this procedure, you can effectively
       disable CRT's automatic initialization. }
     procedure CRTNotInitialized; attribute (name
       = 'crt_NotInitialized');

     { Set terminal to shell or curses mode. An internal procedure
       registered by CRT via RegisterRestoreTerminal does this as well,
       so CRTSetCursesMode has to be called only in unusual situations,
       e.g. after executing a process that changes terminal modes, but
       does not restore them (e.g. because it crashed or was killed), and
       the process was not executed with the Execute routine, and
       RestoreTerminal was not called otherwise. If you set it to False
       temporarily, be sure to set it back to True before doing any
       further CRT operations, otherwise the result may be strange. }
     procedure CRTSetCursesMode (On: Boolean); external
       name 'crt_SetCursesMode';

     { Do the same as `RestoreTerminal (True)', but also clear the screen
       after restoring the terminal (except for XCurses, because the
       program uses its own window, anyway). Does not restore and save
       again the previous screen contents if CRTSavePreviousScreen was
       called. }
     procedure RestoreTerminalClearCRT; attribute (name
       = 'crt_RestoreTerminalClearCRT');

     { Keyboard and character graphics constants -- BP compatible! =:-}
     {$i crt.inc}

     var
       { Tells whether the XCurses version of CRT is used }
       XCRT: Boolean = {$ifdef XCURSES} True {$else} False {$endif};
       attribute (name = 'crt_XCRT');

       { If True (default: False), the Beep procedure and writing #7 do a
         Flash instead }
       VisualBell: Boolean = False; attribute (name = 'crt_VisualBell');

       { Cursor shape codes. Only to be used in very special cases. }
       CursorShapeHidden: CInteger = 0; attribute (name
       = 'crt_CursorShapeHidden');
       CursorShapeNormal: CInteger = 1; attribute (name
       = 'crt_CursorShapeNormal');
       CursorShapeFull:   CInteger = 2; attribute (name
       = 'crt_CursorShapeFull');

     type
       TKey = CCardinal;

       TCursorShape = (CursorIgnored, CursorHidden, CursorNormal,
       CursorFat, CursorBlock);

       TCRTUpdate = (UpdateNever, UpdateWaitInput, UpdateInput,
                     UpdateRegularly, UpdateAlways);

       TPoint = record
         x, y: CInteger
       end;

       PCharAttr = ^TCharAttr;
       TCharAttr = record
         ch       : Char;
         Attr     : TTextAttr;
         PCCharSet: Boolean
       end;

       PCharAttrs = ^TCharAttrs;
       TCharAttrs = array [1 .. MaxVarSize div SizeOf (TCharAttr)] of
       TCharAttr;

       TWindowXYInternalCard8 = Cardinal attribute (Size = 8);
       TWindowXYInternalFill = Integer attribute (Size = BitSizeOf
       (CCardinal) - 16);
       TWindowXY = packed record
         {$ifdef __BYTES_BIG_ENDIAN__}
         Fill: TWindowXYInternalFill;
         y, x: TWindowXYInternalCard8
         {$elif defined (__BYTES_LITTLE_ENDIAN__)}
         x, y: TWindowXYInternalCard8;
         Fill: TWindowXYInternalFill
         {$else}
         {$error Endianness is not defined!}
         {$endif}
       end;

     { Make sure TWindowXY really has the same size as WindMin and
       WindMax. The value of the constant will always be True, and is of
       no further interest. }
     const
       AssertTWindowXYSize = CompilerAssert ((SizeOf (TWindowXY) = SizeOf
       (WindMin)) and
                                             (SizeOf (TWindowXY) = SizeOf
       (WindMax)));

     var
       { Window upper and left coordinates. More comfortable to access
         than WindMin, but also *obsolete*. WindMin and WindowMin still
         work, but have the problem that they implicitly limit the window
         size to 255x255 characters. Though that's not really small for a
         text window, it's easily possible to create bigger ones (e.g. in
         an xterm with a small font, on a high resolution screen and/or
         extending over several virutal desktops). When using coordinates
         greater than 254, the corresponding bytes in WindowMin/WindowMax
         will be set to 254, so, e.g., programs which do
         `Inc (WindowMin.x)' will not fail quite as badly (but probably
         still fail). The routines Window and GetWindow use Integer
         coordinates, and don't suffer from any of these problems, so
         they should be used instead. }
       WindowMin: TWindowXY absolute WindMin;

       { Window lower right coordinates. More comfortable to access than
         WindMax, but also *obsolete* (see the comments for WindowMin).
         Use Window and GetWindow instead. }
       WindowMax: TWindowXY absolute WindMax;

       { The attribute set by NormVideo }
       NormAttr: TTextAttr = 7; attribute (name = 'crt_NormAttr');

       { Tells whether the current mode is monochrome }
       IsMonochrome: Boolean = False; attribute (name
       = 'crt_IsMonochrome');

       { This value can be set to a combination of the shFoo constants
         and will be ORed to the actual shift state returned by
         GetShiftState. This can be used to easily simulate shift keys on
         systems where they can't be accessed. }
       VirtualShiftState: CInteger = 0; attribute (name
       = 'crt_VirtualShiftState');

     { Returns the size of the screen. Note: In BP's WinCRT unit,
       ScreenSize is a variable. But since writing to it from a program
       is pointless, anyway, providing a function here should not cause
       any incompatibility. }
     function  ScreenSize: TPoint; attribute (name
       = 'crt_GetScreenSize');

     { Change the screen size if possible. }
     procedure SetScreenSize (x, y: CInteger); external
       name 'crt_SetScreenSize';

     { Turns colors off or on. }
     procedure SetMonochrome (Monochrome: Boolean); external
       name 'crt_SetMonochrome';

     { Tell which modifier keys are currently pressed. The result is a
       combination of the shFoo constants defined in crt.inc, or 0 on
       systems where this function is not supported -- but note
       VirtualShiftState. If supported, ReadKey automatically converts
       kbIns and kbDel keys to kbShIns and kbShDel, resp., if shift is
       pressed. }
     function  GetShiftState: CInteger; external
       name 'crt_GetShiftState';

     { Get the extent of the current window. Use this procedure rather
       than reading WindMin and WindMax or WindowMin and WindowMax, since
       this routine allows for window sizes larger than 255. The
       resulting coordinates are 1-based (like in Window, unlike WindMin,
       WindMax, WindowMin and WindowMax). Any of the parameters may be
       Null in case you're interested in only some of the coordinates. }
     procedure GetWindow (var x1, y1, x2, y2: Integer); attribute (name
       = 'crt_GetWindow');

     { Determine when to update the screen. The possible values are the
       following. The given conditions *guarantee* updates. However,
       updates may occur more frequently (even if the update level is set
       to UpdateNever). About the default value, see the comments for
       CRTInit.

       UpdateNever    : never (unless explicitly requested with
                        CRTUpdate)
       UpdateWaitInput: before Delay and CRT input, unless typeahead is
                        detected
       UpdateInput    : before Delay and CRT input
       UpdateRegularly: before Delay and CRT input and otherwise in
                        regular intervals without causing too much
                        refresh. This uses a timer on some systems
                        (currently, Unix with ncurses). This was created
                        for BP compatibility, but for many applications,
                        a lower value causes less flickering in the
                        output, and additionally, timer signals won't
                        disturb other operations. Under DJGPP, this
                        always updates immediately, but this fact should
                        not mislead DJGPP users into thinking this is
                        always so.
       UpdateAlways   : after each output. This can be very slow. (Not so
                        under DJGPP, but this fact should not mislead
                        DJGPP users ...) }
     procedure SetCRTUpdate (UpdateLevel: TCRTUpdate); external
       name 'crt_SetUpdateLevel';

     { Do an update now, independently of the update level }
     procedure CRTUpdate; external name 'crt_Update';

     { Do an update now and completely redraw the screen }
     procedure CRTRedraw; external name 'crt_Redraw';

     { Return Ord (key) for normal keys and $100 * Ord (fkey) for
       function keys }
     function  ReadKeyWord: TKey; external name 'crt_ReadKeyWord';

     { Extract the character and scan code from a TKey value }
     function  Key2Char (k: TKey): Char;
     function  Key2Scan (k: TKey): Char;

     { Convert a key to upper/lower case if it is a letter, leave it
       unchanged otherwise }
     function  UpCaseKey (k: TKey): TKey;
     function  LoCaseKey (k: TKey): TKey;

     { Return key codes for the combination of the given key with Ctrl,
       Alt, AltGr or Extra, resp. Returns 0 if the combination is
       unknown. }
     function  CtrlKey  (ch: Char): TKey; attribute (name
       = 'crt_CtrlKey');
     function  AltKey   (ch: Char): TKey; external name 'crt_AltKey';
     function  AltGrKey (ch: Char): TKey; external name 'crt_AltGrKey';
     function  ExtraKey (ch: Char): TKey; external name 'crt_ExtraKey';

     { Check if k is a pseudo key generated by a deadly signal trapped }
     function  IsDeadlySignal (k: TKey): Boolean;

     { Produce a beep or a screen flash }
     procedure Beep; external name 'crt_Beep';
     procedure Flash; external name 'crt_Flash';

     { Get size of current window (calculated using GetWindow) }
     function  GetXMax: Integer;
     function  GetYMax: Integer;

     { Get/goto an absolute position }
     function  WhereXAbs: Integer;
     function  WhereYAbs: Integer;
     procedure GotoXYAbs (x, y: Integer);

     { Turn scrolling on or off }
     procedure SetScroll (State: Boolean); external name 'crt_SetScroll';

     { Read back whether scrolling is enabled }
     function  GetScroll: Boolean; external name 'crt_GetScroll';

     { Determine whether to interpret non-ASCII characters as PC ROM
       characters (True), or in a system dependent way (False). About the
       default, see the comments for CRTInit. }
     procedure SetPCCharSet (PCCharSet: Boolean); external
       name 'crt_SetPCCharSet';

     { Read back the value set by SetPCCharSet }
     function  GetPCCharSet: Boolean; external name 'crt_GetPCCharSet';

     { Determine whether to interpret #7, #8, #10, #13 as control
       characters (True, default), or as graphics characters (False) }
     procedure SetControlChars (UseControlChars: Boolean); external
       name 'crt_SetControlChars';

     { Read back the value set by SetControlChars }
     function  GetControlChars: Boolean; external
       name 'crt_GetControlChars';

     procedure SetCursorShape (Shape: TCursorShape); external
       name 'crt_SetCursorShape';
     function  GetCursorShape: TCursorShape; external
       name 'crt_GetCursorShape';

     procedure HideCursor;
     procedure HiddenCursor;
     procedure NormalCursor;
     procedure FatCursor;
     procedure BlockCursor;
     procedure IgnoreCursor;

     { Simulates a block cursor by writing a block character onto the
       cursor position. The procedure automatically finds the topmost
       visible panel whose shape is not CursorIgnored and places the
       simulated cursor there (just like the hardware cursor), with
       matching attributes, if the cursor shape is CursorFat or
       CursorBlock (otherwise, no simulated cursor is shown).

       Calling this procedure again makes the simulated cursor disappear.
       In particular, to get the effect of a blinking cursor, you have to
       call the procedure repeatedly (say, 8 times a second). CRT will
       not do this for you, since it does not intend to be your main
       event loop. }
     procedure SimulateBlockCursor; external
       name 'crt_SimulateBlockCursor';

     { Makes the cursor simulated by SimulateBlockCursor disappear if it
       is active. Does nothing otherwise. You should call this procedure
       after using SimulateBlockCursor before doing any further CRT
       output (though failing to do so should not hurt except for
       possibly leaving the simulated cursor in its old position longer
       than it should). }
     procedure SimulateBlockCursorOff; external
       name 'crt_SimulateBlockCursorOff';

     function  GetTextColor: Integer;
     function  GetTextBackground: Integer;

     { Write string at the given position without moving the cursor.
       Truncated at the right margin. }
     procedure WriteStrAt (x, y: Integer; const s: String; Attr:
       TTextAttr);

     { Write (several copies of) a char at then given position without
       moving the cursor. Truncated at the right margin. }
     procedure WriteCharAt (x, y, Count: Integer; ch: Char; Attr:
       TTextAttr);

     { Write characters with specified attributes at the given position
       without moving the cursor. Truncated at the right margin. }
     procedure WriteCharAttrAt (x, y, Count: CInteger; CharAttr:
       PCharAttrs); external name 'crt_WriteCharAttrAt';

     { Write a char while moving the cursor }
     procedure WriteChar (ch: Char);

     { Read a character from a screen position }
     procedure ReadChar (x, y: CInteger; var ch: Char; var Attr:
       TTextAttr); external name 'crt_ReadChar';

     { Change only text attributes, leave characters. Truncated at the
       right margin. }
     procedure ChangeTextAttr (x, y, Count: Integer; NewAttr: TTextAttr);

     { Fill current window }
     procedure FillWin (ch: Char; Attr: TTextAttr); external
       name 'crt_FillWin';

     { Calculate size of memory required for ReadWin in current window. }
     function  WinSize: SizeType; external name 'crt_WinSize';

     { Save window contents. Buf must be WinSize bytes large. }
     procedure ReadWin (var Buf); external name 'crt_ReadWin';

     { Restore window contents saved by ReadWin. The size of the current
       window must match the size of the window from which ReadWin was
       used, but the position may be different. }
     procedure WriteWin (const Buf); external name 'crt_WriteWin';

     type
       WinState = record
         x1, y1, x2, y2, WhereX, WhereY, NewX1, NewY1, NewX2, NewY2:
       Integer;
         TextAttr: TTextAttr;
         CursorShape: TCursorShape;
         ScreenSize: TPoint;
         Buffer: ^Byte
       end;

     { Save window position and size, cursor position, text attribute and
       cursor shape -- *not* the window contents. }
     procedure SaveWin (var State: WinState);

     { Make a new window (like Window), and save the contents of the
       screen below the window as well as the position and size, cursor
       position, text attribute and cursor shape of the old window. }
     procedure MakeWin (var State: WinState; x1, y1, x2, y2: Integer);

     { Create window in full size, save previous text mode and all values
       that MakeWin does. }
     procedure SaveScreen (var State: WinState);

     { Restore the data saved by SaveWin, MakeWin or SaveScreen. }
     procedure RestoreWin (var State: WinState);

     { Panels }

     type
       TPanel = Pointer;

     function  GetActivePanel: TPanel; external
       name 'crt_GetActivePanel';
     procedure PanelNew                 (x1, y1, x2, y2: CInteger;
       BindToBackground: Boolean); external name 'crt_PanelNew';
     procedure PanelDelete              (Panel: TPanel); external
       name 'crt_PanelDelete';
     procedure PanelBindToBackground    (Panel: TPanel; BindToBackground:
       Boolean); external name 'crt_PanelBindToBackground';
     function  PanelIsBoundToBackground (Panel: TPanel): Boolean;
       external name 'crt_PanelIsBoundToBackground';
     procedure PanelActivate            (Panel: TPanel); external
       name 'crt_PanelActivate';
     procedure PanelHide                (Panel: TPanel); external
       name 'crt_PanelHide';
     procedure PanelShow                (Panel: TPanel); external
       name 'crt_PanelShow';
     function  PanelHidden              (Panel: TPanel): Boolean;
       external name 'crt_PanelHidden';
     procedure PanelTop                 (Panel: TPanel); external
       name 'crt_PanelTop';
     procedure PanelBottom              (Panel: TPanel); external
       name 'crt_PanelBottom';
     procedure PanelMoveAbove           (Panel, Above: TPanel); external
       name 'crt_PanelMoveAbove';
     procedure PanelMoveBelow           (Panel, Below: TPanel); external
       name 'crt_PanelMoveBelow';
     function  PanelAbove               (Panel: TPanel): TPanel; external
       name 'crt_PanelAbove';
     function  PanelBelow               (Panel: TPanel): TPanel; external
       name 'crt_PanelBelow';

     { TPCRT compatibility }

     { Write a string at the given position without moving the cursor.
       Truncated at the right margin. }
     procedure WriteString (const s: String; y, x: Integer);

     { Write a string at the given position with the given attribute
       without moving the cursor. Truncated at the right margin. }
     procedure FastWriteWindow (const s: String; y, x: Integer; Attr:
       TTextAttr);

     { Write a string at the given absolute position with the given
      attribute without moving the cursor. Truncated at the right
       margin. }
     procedure FastWrite       (const s: String; y, x: Integer; Attr:
       TTextAttr);

     { WinCRT compatibility }

     const
       cw_UseDefault = Integer ($8000);

     var
       { Ignored }
       WindowOrg : TPoint = (cw_UseDefault, cw_UseDefault);
       WindowSize: TPoint = (cw_UseDefault, cw_UseDefault);
       Origin    : TPoint = (0, 0);
       InactiveTitle: PChar = '(Inactive %s)';
       AutoTracking: Boolean = True;
       WindowTitle: {$ifdef __BP_TYPE_SIZES__}
                    array [0 .. 79] of Char
                    {$else}
                    TStringBuf
                    {$endif};

       { Cursor location, 0-based }
       Cursor    : TPoint = (0, 0); attribute (name = 'crt_Cursor');

     procedure InitWinCRT; attribute (name = 'crt_InitWinCRT');

     { Halts the program }
     procedure DoneWinCRT; attribute (noreturn, name = 'crt_DoneWinCRT');

     procedure WriteBuf (Buffer: PChar; Count: SizeType); attribute (name
       = 'crt_WriteBuf');

     function  ReadBuf (Buffer: PChar; Count: SizeType): SizeType;
       attribute (name = 'crt_ReadBuf');

     { 0-based coordinates! }
     procedure CursorTo (x, y: Integer); attribute (name
       = 'crt_CursorTo');

     { Dummy }
     procedure ScrollTo (x, y: Integer); attribute (name
       = 'crt_ScrollTo');

     { Dummy }
     procedure TrackCursor; attribute (name = 'crt_TrackCursor');


File: gpc.info,  Node: Dos,  Next: DosUnix,  Prev: CRT,  Up: GPC Units

6.15.2 BP compatibility: Dos
----------------------------

The following listing contains the interface of the Dos unit.

   This is a portable implementation of most routines from BP's `Dos'
unit. A few routines that are Dos - or even IA32 real mode - specific,
are only available if `__BP_UNPORTABLE_ROUTINES__' is defined, *Note BP
Incompatibilities::.

   The same functionality and much more is available in the Run Time
System, *Note Run Time System::. In some cases, the RTS routines have
the same interface as the routines in this unit (e.g.  `GetEnv',
`FSplit', `FExpand', `FSearch'), in other cases, they have different
names and/or easier and less limiting interfaces (e.g. `ReadDir' etc.
vs. `FindFirst' etc.), and are often more efficient.

   Therefore, using this unit is not recommended in newly written
programs.

     { Portable BP compatible Dos unit

       This unit supports most of the routines and declarations of BP's
       Dos unit.

       Notes:

       - The procedures Keep, GetIntVec, SetIntVec are not supported
         since they make only sense for Dos real-mode programs (and GPC
         compiled programs do not run in real-mode, even on IA32 under
         Dos). The procedures Intr and MsDos are only supported under
         DJGPP if `__BP_UNPORTABLE_ROUTINES__' is defined (with the
         `-D__BP_UNPORTABLE_ROUTINES__' option). A few other routines are
         also only supported with this define, but on all platforms (but
         they are crude hacks, that's why they are not supported without
         this define).

       - The internal structure of file variables (FileRec and TextRec)
         is different in GPC. However, as far as TFDDs are concerned,
         there are other ways to achieve the same in GPC, see the GPC
         unit.

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Authors: Frank Heckenbach <frank@pascal.gnu.de>
                Prof. Abimbola A. Olowofoyeku <African_Chief@bigfoot.com>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-,maximum-field-alignment 0}
     {$if __GPC_RELEASE__ < 20030412}
     {$error This unit requires GPC release 20030412 or newer.}
     {$endif}

     module Dos;

     { GPC and this unit use `AnyFile' for different meanings. Export
       renaming helps us to avoid a conflict here. If you use both units,
       the meaning of the latter one will be effective, but you always
       get the built-in meaning by using `GPC_AnyFile'. }
     export Dos = all (DosAnyFile => AnyFile, FSearch, FExpand, FSplit,
       GetEnv);

     import GPC (MaxLongInt => GPC_Orig_MaxLongInt); System;

     type
       GPC_AnyFile = AnyFile;
       Byte8 = Cardinal attribute (Size = 8);
       Word16 = Cardinal attribute (Size = 16);
       Word32 = Cardinal attribute (Size = 32);
       TDosAttr = Word;

     const
       { File attribute constants }
       ReadOnly   = $01;
       Hidden     = $02;  { set for dot files except '.' and '..' }
       SysFile    = $04;  { not supported }
       VolumeID   = $08;  { not supported }
       Directory  = $10;
       Archive    = $20;  { means: not executable }
       DosAnyFile = $3f;

       { Flag bit masks -- only used by the unportable Dos routines }
       FCarry     = 1;
       FParity    = 4;
       FAuxiliary = $10;
       FZero      = $40;
       FSign      = $80;
       FOverflow  = $800;

       { DosError codes }
       DosError_FileNotFound = 2;
       DosError_PathNotFound = 3;
       DosError_AccessDenied = 5;
       DosError_InvalidMem   = 9;
       DosErorr_InvalidEnv   = 10;
       DosError_NoMoreFiles  = 18;
       DosError_IOError      = 29;
       DosError_ReadFault    = 30;

     type
       { String types. Not used in this unit, but declared for
         compatibility. }
       ComStr  = String [127];  { Command line string }
       PathStr = String [79];   { File pathname string }
       DirStr  = String [67];   { Drive and directory string }
       NameStr = String [8];    { File name string }
       ExtStr  = String [4];    { File extension string }

       TextBuf = array [0 .. 127] of Char;

       { Search record used by FindFirst and FindNext }
       SearchRecFill = packed array [1 .. 21] of Byte8;
       SearchRec = record
         Fill: SearchRecFill;
         Attr: Byte8;
         Time,
         Size: LongInt;
         Name: {$ifdef __BP_TYPE_SIZES__}
               String [12]
               {$else}
               TString
               {$endif}
       end;

       { Date and time record used by PackTime and UnpackTime }
       DateTime = record
         Year, Month, Day, Hour, Min, Sec: Word
       end;

       { 8086 CPU registers -- only used by the unportable Dos routines }
       Registers = record
       case Boolean of
         False: (ax, bx, cx, dx, bp, si, di, ds, es, Flags: Word16);
         True : (al, ah, bl, bh, cl, ch, dl, dh: Byte8)
       end;

     var
       { Error status variable }
       DosError: Integer = 0;

     procedure GetDate (var Year, Month, Day, DayOfWeek: Word);
     procedure GetTime (var Hour, Minute, Second, Sec100: Word);
     procedure GetCBreak (var BreakOn: Boolean);
     procedure SetCBreak (BreakOn: Boolean);
     { GetVerify and SetVerify are dummies except for DJGPP (in the
       assumption that any real OS knows by itself when and how to verify
       its disks). }
     procedure GetVerify (var VerifyOn: Boolean);
     procedure SetVerify (VerifyOn: Boolean);
     function  DiskFree (Drive: Byte): LongInt;
     function  DiskSize (Drive: Byte): LongInt;
     procedure GetFAttr (var f: GPC_AnyFile; var Attr: TDosAttr);
     procedure SetFAttr (var f: GPC_AnyFile; Attr: TDosAttr);
     procedure GetFTime (var f: GPC_AnyFile; var MTime: LongInt);
     procedure SetFTime (var f: GPC_AnyFile; MTime: LongInt);

     { FindFirst and FindNext are quite inefficient since they emulate
       all the brain-dead Dos stuff. If at all possible, the standard
       routines OpenDir, ReadDir and CloseDir (in the GPC unit) should be
       used instead. }
     procedure FindFirst (const Path: String; Attr: TDosAttr; var SR:
       SearchRec);
     procedure FindNext  (var SR: SearchRec);

     procedure FindClose (var SR: SearchRec);
     procedure UnpackTime (p: LongInt; var t: DateTime);
     procedure PackTime (const t: DateTime; var p: LongInt);
     function  EnvCount: Integer;
     function  EnvStr (EnvIndex: Integer): TString;
     procedure SwapVectors;
     { Exec executes a process via Execute, so RestoreTerminal is called
       with the argument True before and False after executing the
       process. }
     procedure Exec (const Path, Params: String);
     function  DosExitCode: Word;

     { Unportable Dos-only routines and declarations }

     {$ifdef __BP_UNPORTABLE_ROUTINES__}
     {$ifdef __GO32__}
     { These are unportable Dos-only declarations and routines, since
       interrupts are Dos and CPU specific (and have no place in a
       high-level program, anyway). }
     procedure Intr (IntNo: Byte; var Regs: Registers);
     procedure MsDos (var Regs: Registers);
     {$endif}

     { Though probably all non-Dos systems have versions numbers as well,
       returning them here would usually not do what is expected, e.g.
       testing if certain Dos features are present by comparing the
       version number. Therefore, this routine always returns 7 (i.e.,
       version 7.0) on non-Dos systems, in the assumption that any real
       OS has at least the features of Dos 7. }
     function  DosVersion: Word;

     { Changing the system date and time is a system administration task,
       not allowed to a normal process. On non-Dos systems, these
       routines emulate the changed date/time, but only for GetTime and
       GetDate (not the RTS date/time routines), and only for this
       process, not for child processes or even the parent process or
       system-wide. }
     procedure SetDate (Year, Month, Day: Word);
     procedure SetTime (Hour, Minute, Second, Sec100: Word);
     {$endif}


File: gpc.info,  Node: DosUnix,  Next: FileUtils,  Prev: Dos,  Up: GPC Units

6.15.3 Overcome some differences between Dos and Unix
-----------------------------------------------------

The following listing contains the interface of the DosUnix unit.

   This unit is there to overcome some of those differences between Dos
and Unix systems that are not automatically hidden by GPC and the Run
Time System. Currently features translation of bash style input/output
redirections (`foo 2>&1') into `redir' calls for DJGPP (`redir -eo
foo') and a way to read files with Dos CR/LF pairs on any system.

   When necessary, new features will be added to the unit in future
releases.

     { Some routines to support writing programs portable between Dos and
       Unix. Perhaps it would be a good idea not to put features to make
       Dos programs Unix-compatible (shell redirections) and vice versa
       (reading Dos files from Unix) together into one unit, but rather
       into two units, DosCompat and UnixCompat or so -- let's wait and
       see, perhaps when more routines suited for this/these unit(s) will
       be found, the design will become clearer ...

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030412}
     {$error This unit requires GPC release 20030412 or newer.}
     {$endif}

     unit DosUnix;

     interface

     uses GPC;

     { This function is meant to be used when you want to invoke a system
       shell command (e.g. via Execute or Exec from the Dos unit) and
       want to specify input/output redirections for the command invoked.
       It caters for the different syntax between DJGPP (with the `redir'
       utility) and other systems.

       To use it, code your redirections in bash style (see the table
       below) in your command line string, pass this string to this
       function, and the function's result to Execute or the other
       routines.

       The function translates the following bash style redirections
       (characters in brackets are optional) into a redir call under Dos
       systems except EMX, and leave them unchanged under other systems.
       Note: `redir' comes with DJGPP, but it should be possible to
       install it on other Dos systems as well. OS/2's shell, however,
       supports bash style redirections, I was told, so we don't
       translate on EMX.

       [0]<     file      redirect standard input from file
       [1]>[|]  file      redirect standard output to file
       [1]>>    file      append standard output to file
       [1]>&2             redirect standard output to standard error
       2>[|]    file      redirect standard error to file
       2>>      file      append standard error to file
       2>&1               redirect standard error to standard output
       &> file            redirect both standard output and standard
                          error to file }
     function  TranslateRedirections (const Command: String) = s:
       TString;

     { Under Unix, translates CR/LF pairs to single LF characters when
       reading from f, and back when writing to f. Under Dos, does
       nothing because the run time system alrady does this job. In the
       result, you can read both Dos and Unix files, and files written
       will be Dos. }
     procedure AssignDos (var f: AnyFile; const FileName: String);

     { Translates a character from the "OEM" charset used under Dos to
       the ISO-8859-1 (Latin1) character set. }
     function  OEM2Latin1 (ch: Char): Char;
     function  OEM2Latin1Str (const s: String) = r: TString;

     { Translates a character from the ISO-8859-1 (Latin1) character set
       to the "OEM" charset used under Dos. }
     function  Latin12OEM (ch: Char): Char;
     function  Latin12OEMStr (const s: String) = r: TString;


File: gpc.info,  Node: FileUtils,  Next: GMP,  Prev: DosUnix,  Up: GPC Units

6.15.4 Higher level file and directory handling
-----------------------------------------------

The following listing contains the interface of the FileUtils unit.

   This unit provides some routines for file and directory handling on
a higher level than those provided by the RTS.

     { Some routines for file and directory handling on a higher level
       than those provided by the RTS.

       Copyright (C) 2000-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030412}
     {$error This unit requires GPC release 20030412 or newer.}
     {$endif}

     unit FileUtils;

     interface

     uses GPC;

     type
       TStringProc = procedure (const s: String);

     { Finds all files matching the given Mask in the given Directory and
       all subdirectories of it. The matching is done using all wildcards
       and brace expansion, like MultiFileNameMatch does. For each file
       found, FileAction is executed. For each directory found (including
       `.' and `..' if they match the Mask!), DirAction is executed. If
       MainDirFirst is True, this happens before processing the files in
       the directory and below, otherwise afterwards. (The former is
       useful, e.g., if this is used to copy a directory tree and
       DirAction does a MkDir, while the latter behaviour is required
       when removing a directory tree and DirAction does a RmDir.) Both
       FileAction and DirAction can be nil in which case nothing is done
       for files or directories found, respectively. (If DirAction is
       nil, the value of DirsFirst does not matter.) Of course,
       FileAction and DirAction may also be identical. The procedure
       leaves InOutRes set in case of any error. If FileAction or
       DirAction return with InOutRes set, FindFiles recognizes this and
       returns immediately. }
     procedure FindFiles (const Directory, Mask: String; MainDirFirst:
       Boolean;
                          FileAction, DirAction: TStringProc); attribute
       (iocritical);

     { Creates the directory given by Path and all directories in between
       that are necessary. Does not report an error if the directory
       already exists, but, of course, if it cannot be created because of
       missing permissions or because Path already exists as a file. }
     procedure MkDirs (const Path: String); attribute (iocritical);

     { Removes Path if empty as well as any empty parent directories.
       Does not report an error if the directory is not empty. }
     procedure RmDirs (const Path: String); attribute (iocritical);

     { Copies the file Source to Dest, overwriting Dest if it exists and
       can be written to. Returns any errors in IOResult. If Mode >= 0,
       it will change the permissions of Dest to Mode immediately after
       creating it and before writing any data to it. That's useful,
       e.g., if Dest is not meant to be world-readable, because if you'd
       do a ChMod after FileCopy, you might leave the data readable
       (depending on the umask) during the copying. If Mode < 0, Dest
       will be set to the same permissions Source has. In any case, Dest
       will be set to the modification time of Source after copying. On
       any error, the destination file is erased. This is to avoid
       leaving partial files in case of full file systems (one of the
       most common reasons for errors). }
     procedure FileCopy (const Source, Dest: String; Mode: Integer);
       attribute (iocritical);

     { Creates a backup of FileName in the directory BackupDirectory or,
       if BackupDirectory is empty, in the directory of FileName. Errors
       are returned in IOResult (and on any error, no partial backup file
       is left), but if FileName does not exist, this does *not* count as
       an error (i.e., BackupFile will just return without setting
       IOResult then). If OnlyUserReadable is True, the backup file will
       be given only user-read permissions, nothing else.

       The name chosen for the backup depends on the Simple and Short
       parameters. The short names will fit into 8+3 characters (whenever
       possible), while the long ones conform to the conventions used by
       most GNU tools. If Simple is True, a simple backup file name will
       be used, and previous backups under the same name will be
       overwritten (if possible). Otherwise, backups will be numbered,
       where the number is chosen to be larger than all existing backups,
       so it will be unique and increasing in chronological order. In
       particular:

       Simple  Short  Backup name
       True    True   Base name of FileName plus '.bak'
       False   True   Base name of FileName plus '.b' plus a number
       True    False  Base name plus extension of FileName plus '~'
       False   False  Base name plus extension of FileName plus '.~', a
                      number and '~' }
     procedure BackupFile (const FileName, BackupDirectory: String;
       Simple, Short, OnlyUserReadable: Boolean); attribute (iocritical);


File: gpc.info,  Node: GMP,  Next: GPCUtil,  Prev: FileUtils,  Up: GPC Units

6.15.5 Arithmetic with unlimited size and precision
---------------------------------------------------

The following listing contains the interface of the GMP unit.

   This unit provides an interface to the GNU Multiprecision Library to
perform arithmetic on integer, rational and real numbers of unlimited
size and precision.

   To use this unit, you will need the `gmp' library which can be found
in `http://www.gnu-pascal.de/libs/'.

     { Definitions for GNU multiple precision functions: arithmetic with
       integer, rational and real numbers of arbitrary size and
       precision.

       Translation of the C header (gmp.h) of the GMP library. Tested
       with GMP 3.x and 4.x.

       To use the GMP unit, you will need the GMP library which can be
       found in http://www.gnu-pascal.de/libs/

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License.

       Please also note the license of the GMP library. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}
     {$nested-comments}

     { If HAVE_GMP4 is set (the default unless HAVE_GMP3 is set, some
       interface changes made in GMP 4 are taken into account.
       I.e., if this is set wrong, programs might fail. However, this
       only affects a few routines related to random numbers. }
     {$if not defined (HAVE_GMP3)}
     {$define HAVE_GMP4}
     {$endif}

     {$undef GMP}  { in case it's set by the user }
     unit GMP;

     interface

     uses GPC;

     {$if defined (__mips) and defined (_ABIN32) and defined (HAVE_GMP3)}
     { Force the use of 64-bit limbs for all 64-bit MIPS CPUs if ABI
       permits. }
     {$define _LONG_LONG_LIMB}
     {$endif}

     type
       {$ifdef _SHORT_LIMB}
       mp_limb_t        = CCardinal;
       mp_limb_signed_t = CInteger;
       {$elif defined (_LONG_LONG_LIMB)}
       mp_limb_t        = LongCard;
       mp_limb_signed_t = LongInt;
       {$else}
       mp_limb_t        = MedCard;
       mp_limb_signed_t = MedInt;
       {$endif}

       mp_ptr           = ^mp_limb_t;

       {$if defined (_CRAY) and not defined (_CRAYMPP)}
       mp_size_t        = CInteger;
       mp_exp_t         = CInteger;
       {$else}
       mp_size_t        = MedInt;
       mp_exp_t         = MedInt;
       {$endif}

       mpz_t = record
         mp_alloc,
         mp_size: CInteger;
         mp_d:    mp_ptr
       end;

       mpz_array_ptr = ^mpz_array;
       mpz_array = array [0 .. MaxVarSize div SizeOf (mpz_t) - 1] of
       mpz_t;

       mpq_t = record
         mp_num,
         mp_den: mpz_t
       end;

       mpf_t = record
         mp_prec,
         mp_size: CInteger;
         mp_exp:  mp_exp_t;
         mp_d:    mp_ptr
       end;

       TAllocFunction    = function (Size: SizeType): Pointer;
       TReAllocFunction  = function (var Dest: Pointer; OldSize, NewSize:
       SizeType): Pointer;
       TDeAllocProcedure = procedure (Src: Pointer; Size: SizeType);

     var
       mp_bits_per_limb: CInteger; attribute (const); external
       name '__gmp_bits_per_limb';

     procedure mp_set_memory_functions (AllocFunction: TAllocFunction;
                                        ReAllocFunction:
       TReAllocFunction;
                                        DeAllocProcedure:
       TDeAllocProcedure); external name '__gmp_set_memory_functions';

     { Integer (i.e. Z) routines }

     procedure mpz_init             (var Dest: mpz_t); external
       name '__gmpz_init';
     procedure mpz_clear            (var Dest: mpz_t); external
       name '__gmpz_clear';
     function  mpz_realloc          (var Dest: mpz_t; NewAlloc:
       mp_size_t): Pointer; external name '__gmpz_realloc';
     procedure mpz_array_init       (Dest: mpz_array_ptr; ArraySize,
       FixedNumBits: mp_size_t); external name '__gmpz_array_init';

     procedure mpz_set              (var Dest: mpz_t; protected var Src:
       mpz_t); external name '__gmpz_set';
     procedure mpz_set_ui           (var Dest: mpz_t; Src: MedCard);
       external name '__gmpz_set_ui';
     procedure mpz_set_si           (var Dest: mpz_t; Src: MedInt);
       external name '__gmpz_set_si';
     procedure mpz_set_d            (var Dest: mpz_t; Src: Real);
       external name '__gmpz_set_d';
     procedure mpz_set_q            (var Dest: mpz_t; Src: mpq_t);
       external name '__gmpz_set_q';
     procedure mpz_set_f            (var Dest: mpz_t; Src: mpf_t);
       external name '__gmpz_set_f';
     function  mpz_set_str          (var Dest: mpz_t; Src: CString; Base:
       CInteger): CInteger; external name '__gmpz_set_str';

     procedure mpz_init_set         (var Dest: mpz_t; protected var Src:
       mpz_t); external name '__gmpz_init_set';
     procedure mpz_init_set_ui      (var Dest: mpz_t; Src: MedCard);
       external name '__gmpz_init_set_ui';
     procedure mpz_init_set_si      (var Dest: mpz_t; Src: MedInt);
       external name '__gmpz_init_set_si';
     procedure mpz_init_set_d       (var Dest: mpz_t; Src: Real);
       external name '__gmpz_init_set_d';
     function  mpz_init_set_str     (var Dest: mpz_t; Src: CString; Base:
       CInteger): CInteger; external name '__gmpz_init_set_str';

     function  mpz_get_ui           (protected var Src: mpz_t): MedCard;
       external name '__gmpz_get_ui';
     function  mpz_get_si           (protected var Src: mpz_t): MedInt;
       external name '__gmpz_get_si';
     function  mpz_get_d            (protected var Src: mpz_t): Real;
       external name '__gmpz_get_d';
     { Pass nil for Dest to let the function allocate memory for it }
     function  mpz_get_str          (Dest: CString; Base: CInteger;
       protected var Src: mpz_t): CString; external
       name '__gmpz_get_str';

     procedure mpz_add              (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_add';
     procedure mpz_add_ui           (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_add_ui';
     procedure mpz_sub              (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_sub';
     procedure mpz_sub_ui           (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_sub_ui';
     procedure mpz_mul              (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_mul';
     procedure mpz_mul_ui           (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_mul_ui';
     procedure mpz_mul_2exp         (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_mul_2exp';
     procedure mpz_neg              (var Dest: mpz_t; protected var Src:
       mpz_t); external name '__gmpz_neg';
     procedure mpz_abs              (var Dest: mpz_t; protected var Src:
       mpz_t); external name '__gmpz_abs';
     procedure mpz_fac_ui           (var Dest: mpz_t; Src: MedCard);
       external name '__gmpz_fac_ui';

     procedure mpz_tdiv_q           (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_tdiv_q';
     procedure mpz_tdiv_q_ui        (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_tdiv_q_ui';
     procedure mpz_tdiv_r           (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_tdiv_r';
     procedure mpz_tdiv_r_ui        (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_tdiv_r_ui';
     procedure mpz_tdiv_qr          (var DestQ, DestR: mpz_t; protected
       var Src1, Src2: mpz_t); external name '__gmpz_tdiv_qr';
     procedure mpz_tdiv_qr_ui       (var DestQ, DestR: mpz_t; protected
       var Src1: mpz_t; Src2: MedCard); external
       name '__gmpz_tdiv_qr_ui';

     procedure mpz_fdiv_q           (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_fdiv_q';
     function  mpz_fdiv_q_ui        (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard): MedCard; external name '__gmpz_fdiv_q_ui';
     procedure mpz_fdiv_r           (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_fdiv_r';
     function  mpz_fdiv_r_ui        (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard): MedCard; external name '__gmpz_fdiv_r_ui';
     procedure mpz_fdiv_qr          (var DestQ, DestR: mpz_t; protected
       var Src1, Src2: mpz_t); external name '__gmpz_fdiv_qr';
     function  mpz_fdiv_qr_ui       (var DestQ, DestR: mpz_t; protected
       var Src1: mpz_t; Src2: MedCard): MedCard; external
       name '__gmpz_fdiv_qr_ui';
     function  mpz_fdiv_ui          (protected var Src1: mpz_t; Src2:
       MedCard): MedCard; external name '__gmpz_fdiv_ui';

     procedure mpz_cdiv_q           (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_cdiv_q';
     function  mpz_cdiv_q_ui        (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard): MedCard; external name '__gmpz_cdiv_q_ui';
     procedure mpz_cdiv_r           (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_cdiv_r';
     function  mpz_cdiv_r_ui        (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard): MedCard; external name '__gmpz_cdiv_r_ui';
     procedure mpz_cdiv_qr          (var DestQ, DestR: mpz_t; protected
       var Src1,Src2: mpz_t); external name '__gmpz_cdiv_qr';
     function  mpz_cdiv_qr_ui       (var DestQ, DestR: mpz_t; protected
       var Src1: mpz_t; Src2: MedCard): MedCard; external
       name '__gmpz_cdiv_qr_ui';
     function  mpz_cdiv_ui          (protected var Src1: mpz_t;
       Src2:MedCard): MedCard; external name '__gmpz_cdiv_ui';

     procedure mpz_mod              (var Dest: mpz_t; protected var
       Src1,Src2: mpz_t); external name '__gmpz_mod';
     procedure mpz_divexact         (var Dest: mpz_t; protected var
       Src1,Src2: mpz_t); external name '__gmpz_divexact';

     procedure mpz_tdiv_q_2exp      (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_tdiv_q_2exp';
     procedure mpz_tdiv_r_2exp      (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_tdiv_r_2exp';
     procedure mpz_fdiv_q_2exp      (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_fdiv_q_2exp';
     procedure mpz_fdiv_r_2exp      (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_fdiv_r_2exp';

     procedure mpz_powm             (var Dest: mpz_t; protected var Base,
       Exponent, Modulus: mpz_t); external name '__gmpz_powm';
     procedure mpz_powm_ui          (var Dest: mpz_t; protected var Base:
       mpz_t; Exponent: MedCard; protected var Modulus: mpz_t); external
       name '__gmpz_powm_ui';
     procedure mpz_pow_ui           (var Dest: mpz_t; protected var Base:
       mpz_t; Exponent: MedCard); external name '__gmpz_pow_ui';
     procedure mpz_ui_pow_ui        (var Dest: mpz_t; Base, Exponent:
       MedCard); external name '__gmpz_ui_pow_ui';

     procedure mpz_sqrt             (var Dest: mpz_t; protected var Src:
       mpz_t); external name '__gmpz_sqrt';
     procedure mpz_sqrtrem          (var Dest, DestR: mpz_t; protected
       var Src: mpz_t); external name '__gmpz_sqrtrem';
     function  mpz_perfect_square_p (protected var Src: mpz_t): CInteger;
       external name '__gmpz_perfect_square_p';

     function  mpz_probab_prime_p   (protected var Src: mpz_t;
       Repetitions: CInteger): CInteger; external
       name '__gmpz_probab_prime_p';
     procedure mpz_gcd              (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_gcd';
     function  mpz_gcd_ui           (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard): MedCard; external name '__gmpz_gcd_ui';
     procedure mpz_gcdext           (var Dest, DestA, DestB: mpz_t;
       protected var SrcA, SrcB: mpz_t); external name '__gmpz_gcdext';
     function  mpz_invert           (var Dest: mpz_t; protected var Src,
       Modulus: mpz_t): CInteger; external name '__gmpz_invert';
     function  mpz_jacobi           (protected var Src1, Src2: mpz_t):
       CInteger; external name '__gmpz_jacobi';

     function  mpz_cmp              (protected var Src1, Src2: mpz_t):
       CInteger; external name '__gmpz_cmp';
     function  mpz_cmp_ui           (protected var Src1: mpz_t; Src2:
       MedCard): CInteger; external name '__gmpz_cmp_ui';
     function  mpz_cmp_si           (protected var Src1: mpz_t; Src2:
       MedInt): CInteger; external name '__gmpz_cmp_si';
     function  mpz_sgn              (protected var Src: mpz_t): CInteger;
       attribute (inline);

     procedure mpz_and              (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_and';
     procedure mpz_ior              (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_ior';
     procedure mpz_com              (var Dest: mpz_t; protected var Src:
       mpz_t); external name '__gmpz_com';
     function  mpz_popcount         (protected var Src: mpz_t): MedCard;
       external name '__gmpz_popcount';
     function  mpz_hamdist          (protected var Src1, Src2: mpz_t):
       MedCard; external name '__gmpz_hamdist';
     function  mpz_scan0            (protected var Src: mpz_t;
       StartingBit: MedCard): MedCard; external name '__gmpz_scan0';
     function  mpz_scan1            (protected var Src: mpz_t;
       StartingBit: MedCard): MedCard; external name '__gmpz_scan1';
     procedure mpz_setbit           (var Dest: mpz_t; BitIndex: MedCard);
       external name '__gmpz_setbit';
     procedure mpz_clrbit           (var Dest: mpz_t; BitIndex: MedCard);
       external name '__gmpz_clrbit';

     procedure mpz_random           (var Dest: mpz_t; MaxSize:
       mp_size_t); external name '__gmpz_random';
     procedure mpz_random2          (var Dest: mpz_t; MaxSize:
       mp_size_t); external name '__gmpz_random2';
     function  mpz_sizeinbase       (protected var Src: mpz_t; Base:
       CInteger): SizeType; external name '__gmpz_sizeinbase';

     { Rational (i.e. Q) routines }

     procedure mpq_canonicalize     (var Dest: mpq_t); external
       name '__gmpq_canonicalize';

     procedure mpq_init             (var Dest: mpq_t); external
       name '__gmpq_init';
     procedure mpq_clear            (var Dest: mpq_t); external
       name '__gmpq_clear';
     procedure mpq_set              (var Dest: mpq_t; protected var Src:
       mpq_t); external name '__gmpq_set';
     procedure mpq_set_z            (var Dest: mpq_t; protected var Src:
       mpz_t); external name '__gmpq_set_z';
     procedure mpq_set_ui           (var Dest: mpq_t; Nom, Den: MedCard);
       external name '__gmpq_set_ui';
     procedure mpq_set_si           (var Dest: mpq_t; Nom: MedInt; Den:
       MedCard); external name '__gmpq_set_si';

     procedure mpq_add              (var Dest: mpq_t; protected var Src1,
       Src2: mpq_t); external name '__gmpq_add';
     procedure mpq_sub              (var Dest: mpq_t; protected var Src1,
       Src2: mpq_t); external name '__gmpq_sub';
     procedure mpq_mul              (var Dest: mpq_t; protected var Src1,
       Src2: mpq_t); external name '__gmpq_mul';
     procedure mpq_div              (var Dest: mpq_t; protected var Src1,
       Src2: mpq_t); external name '__gmpq_div';
     procedure mpq_neg              (var Dest: mpq_t; protected var Src:
       mpq_t); external name '__gmpq_neg';
     procedure mpq_inv              (var Dest: mpq_t; protected var Src:
       mpq_t); external name '__gmpq_inv';

     function  mpq_cmp              (protected var Src1, Src2: mpq_t):
       CInteger; external name '__gmpq_cmp';
     function  mpq_cmp_ui           (protected var Src1: mpq_t; Nom2,
       Den2: MedCard): CInteger; external name '__gmpq_cmp_ui';
     function  mpq_sgn              (protected var Src: mpq_t): CInteger;
       attribute (inline);
     function  mpq_equal            (protected var Src1, Src2: mpq_t):
       CInteger; external name '__gmpq_equal';

     function  mpq_get_d            (protected var Src: mpq_t): Real;
       external name '__gmpq_get_d';
     procedure mpq_set_num          (var Dest: mpq_t; protected var Src:
       mpz_t); external name '__gmpq_set_num';
     procedure mpq_set_den          (var Dest: mpq_t; protected var Src:
       mpz_t); external name '__gmpq_set_den';
     procedure mpq_get_num          (var Dest: mpz_t; protected var Src:
       mpq_t); external name '__gmpq_get_num';
     procedure mpq_get_den          (var Dest: mpz_t; protected var Src:
       mpq_t); external name '__gmpq_get_den';

     { Floating point (i.e. R) routines }

     procedure mpf_set_default_prec (Precision: MedCard); external
       name '__gmpf_set_default_prec';
     procedure mpf_init             (var Dest: mpf_t); external
       name '__gmpf_init';
     procedure mpf_init2            (var Dest: mpf_t; Precision:
       MedCard); external name '__gmpf_init2';
     procedure mpf_clear            (var Dest: mpf_t); external
       name '__gmpf_clear';
     procedure mpf_set_prec         (var Dest: mpf_t; Precision:
       MedCard); external name '__gmpf_set_prec';
     function  mpf_get_prec         (protected var Src: mpf_t): MedCard;
       external name '__gmpf_get_prec';
     procedure mpf_set_prec_raw     (var Dest: mpf_t; Precision:
       MedCard); external name '__gmpf_set_prec_raw';

     procedure mpf_set              (var Dest: mpf_t; protected var Src:
       mpf_t); external name '__gmpf_set';
     procedure mpf_set_ui           (var Dest: mpf_t; Src: MedCard);
       external name '__gmpf_set_ui';
     procedure mpf_set_si           (var Dest: mpf_t; Src: MedInt);
       external name '__gmpf_set_si';
     procedure mpf_set_d            (var Dest: mpf_t; Src: Real);
       external name '__gmpf_set_d';
     procedure mpf_set_z            (var Dest: mpf_t; protected var Src:
       mpz_t); external name '__gmpf_set_z';
     procedure mpf_set_q            (var Dest: mpf_t; protected var Src:
       mpq_t); external name '__gmpf_set_q';
     function  mpf_set_str          (var Dest: mpf_t; Src: CString; Base:
       CInteger): CInteger; external name '__gmpf_set_str';

     procedure mpf_init_set         (var Dest: mpf_t; protected var Src:
       mpf_t); external name '__gmpf_init_set';
     procedure mpf_init_set_ui      (var Dest: mpf_t; Src: MedCard);
       external name '__gmpf_init_set_ui';
     procedure mpf_init_set_si      (var Dest: mpf_t; Src: MedInt);
       external name '__gmpf_init_set_si';
     procedure mpf_init_set_d       (var Dest: mpf_t; Src: Real);
       external name '__gmpf_init_set_d';
     function  mpf_init_set_str     (var Dest: mpf_t; Src: CString; Base:
       CInteger): CInteger; external name '__gmpf_init_set_str';

     function  mpf_get_d            (protected var Src: mpf_t): Real;
       external name '__gmpf_get_d';
     { Pass nil for Dest to let the function allocate memory for it }
     function  mpf_get_str          (Dest: CString; var Exponent:
       mp_exp_t; Base: CInteger;
                                     NumberOfDigits: SizeType; protected
       var Src: mpf_t): CString; external name '__gmpf_get_str';

     procedure mpf_add              (var Dest: mpf_t; protected var Src1,
       Src2: mpf_t); external name '__gmpf_add';
     procedure mpf_add_ui           (var Dest: mpf_t; protected var Src1:
       mpf_t; Src2: MedCard); external name '__gmpf_add_ui';
     procedure mpf_sub              (var Dest: mpf_t; protected var Src1,
       Src2: mpf_t); external name '__gmpf_sub';
     procedure mpf_ui_sub           (var Dest: mpf_t; Src1: MedCard;
       protected var Src2: mpf_t); external name '__gmpf_ui_sub';
     procedure mpf_sub_ui           (var Dest: mpf_t; protected var Src1:
       mpf_t; Src2: MedCard); external name '__gmpf_sub_ui';
     procedure mpf_mul              (var Dest: mpf_t; protected var Src1,
       Src2: mpf_t); external name '__gmpf_mul';
     procedure mpf_mul_ui           (var Dest: mpf_t; protected var Src1:
       mpf_t; Src2: MedCard); external name '__gmpf_mul_ui';
     procedure mpf_div              (var Dest: mpf_t; protected var Src1,
       Src2: mpf_t); external name '__gmpf_div';
     procedure mpf_ui_div           (var Dest: mpf_t; Src1: MedCard;
       protected var Src2: mpf_t); external name '__gmpf_ui_div';
     procedure mpf_div_ui           (var Dest: mpf_t; protected var Src1:
       mpf_t; Src2: MedCard); external name '__gmpf_div_ui';
     procedure mpf_sqrt             (var Dest: mpf_t; protected var Src:
       mpf_t); external name '__gmpf_sqrt';
     procedure mpf_sqrt_ui          (var Dest: mpf_t; Src: MedCard);
       external name '__gmpf_sqrt_ui';
     procedure mpf_neg              (var Dest: mpf_t; protected var Src:
       mpf_t); external name '__gmpf_neg';
     procedure mpf_abs              (var Dest: mpf_t; protected var Src:
       mpf_t); external name '__gmpf_abs';
     procedure mpf_mul_2exp         (var Dest: mpf_t; protected var Src1:
       mpf_t; Src2: MedCard); external name '__gmpf_mul_2exp';
     procedure mpf_div_2exp         (var Dest: mpf_t; protected var Src1:
       mpf_t; Src2: MedCard); external name '__gmpf_div_2exp';

     function  mpf_cmp              (protected var Src1, Src2: mpf_t):
       CInteger; external name '__gmpf_cmp';
     function  mpf_cmp_si           (protected var Src1: mpf_t; Src2:
       MedInt): CInteger; external name '__gmpf_cmp_si';
     function  mpf_cmp_ui           (protected var Src1: mpf_t; Src2:
       MedCard): CInteger; external name '__gmpf_cmp_ui';
     function  mpf_eq               (protected var Src1, Src2: mpf_t;
       NumberOfBits: MedCard): CInteger; external name '__gmpf_eq';
     procedure mpf_reldiff          (var Dest: mpf_t; protected var Src1,
       Src2: mpf_t); external name '__gmpf_reldiff';
     function  mpf_sgn              (protected var Src: mpf_t): CInteger;
       attribute (inline);

     procedure mpf_random2          (var Dest: mpf_t; MaxSize: mp_size_t;
       MaxExp: mp_exp_t); external name '__gmpf_random2';

     {$if False}  { @@ commented out because they use C file pointers }
     function  mpz_inp_str          (var Dest: mpz_t; Src: CFilePtr;
       Base: CInteger): SizeType; external name '__gmpz_inp_str';
     function  mpz_inp_raw          (var Dest: mpz_t; Src: CFilePtr):
       SizeType; external name '__gmpz_inp_raw';
     function  mpz_out_str          (Dest: CFilePtr; Base: CInteger;
       protected var Src: mpz_t): SizeType; external
       name '__gmpz_out_str';
     function  mpz_out_raw          (Dest: CFilePtr; protected var Src:
       mpz_t): SizeType ; external name '__gmpz_out_raw';
     { @@ mpf_out_str has a bug in GMP 2.0.2: it writes a spurious #0
       before the exponent for negative numbers }
     function  mpf_out_str          (Dest: CFilePtr; Base: CInteger;
       NumberOfDigits: SizeType; protected var Src: mpf_t): SizeType;
       external name '__gmpf_out_str';
     function  mpf_inp_str          (var Dest: mpf_t; Src: CFilePtr;
       Base: CInteger): SizeType; external name '__gmpf_inp_str';
     {$endif}

     { Available random number generation algorithms. }
     type
       gmp_randalg_t = (GMPRandAlgLC { Linear congruential. });

     const
       GMPRandAlgDefault = GMPRandAlgLC;

     { Linear congruential data struct. }
     type
       gmp_randata_lc = record
         a: mpz_t;  { Multiplier. }
         c: MedCard;  { Adder. }
         m: mpz_t;  { Modulus (valid only if M2Exp = 0). }
         M2Exp: MedCard;  { If <> 0, modulus is 2 ^ M2Exp. }
       end;

     type
       gmp_randstate_t = record
         Seed: mpz_t;  { Current seed. }
         Alg: gmp_randalg_t;  { Algorithm used. }
         AlgData: record  { Algorithm specific data. }
         case gmp_randalg_t of
           GMPRandAlgLC: (lc: ^gmp_randata_lc)  { Linear congruential. }
         end
       end;

     procedure gmp_randinit         (var State: gmp_randstate_t; Alg:
       gmp_randalg_t; ...); external name '__gmp_randinit';
     procedure gmp_randinit_lc      (var State: gmp_randstate_t; {$ifdef
       HAVE_GMP4} protected var {$endif} a: mpz_t; c: MedCard; {$ifdef
       HAVE_GMP4} protected var {$endif} m: mpz_t); external
       name '__gmp_randinit_lc';
     procedure gmp_randinit_lc_2exp (var State: gmp_randstate_t; {$ifdef
       HAVE_GMP4} protected var {$endif} a: mpz_t; c: MedCard; M2Exp:
       MedCard); external name '__gmp_randinit_lc_2exp';
     procedure gmp_randseed         (var State: gmp_randstate_t; Seed:
       mpz_t); external name '__gmp_randseed';
     procedure gmp_randseed_ui      (var State: gmp_randstate_t; Seed:
       MedCard); external name '__gmp_randseed_ui';
     procedure gmp_randclear        (var State: gmp_randstate_t);
       external name '__gmp_randclear';

     procedure mpz_addmul_ui        (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_addmul_ui';
     procedure mpz_bin_ui           (var Dest: mpz_t; protected var Src1:
       mpz_t; Src2: MedCard); external name '__gmpz_bin_ui';
     procedure mpz_bin_uiui         (var Dest: mpz_t; Src1, Src2:
       MedCard); external name '__gmpz_bin_uiui';
     function  mpz_cmpabs           (protected var Src1, Src2: mpz_t):
       CInteger; external name '__gmpz_cmpabs';
     function  mpz_cmpabs_ui        (protected var Src1: mpz_t; Src2:
       MedCard): CInteger; external name '__gmpz_cmpabs_ui';
     procedure mpz_dump             (protected var Src: mpz_t); external
       name '__gmpz_dump';
     procedure mpz_fib_ui           (var Dest: mpz_t; Src: MedCard);
       external name '__gmpz_fib_ui';
     function  mpz_fits_sint_p      (protected var Src: mpz_t): CInteger;
       external name '__gmpz_fits_sint_p';
     function  mpz_fits_slong_p     (protected var Src: mpz_t): CInteger;
       external name '__gmpz_fits_slong_p';
     function  mpz_fits_sshort_p    (protected var Src: mpz_t): CInteger;
       external name '__gmpz_fits_sshort_p';
     function  mpz_fits_uint_p      (protected var Src: mpz_t): CInteger;
       external name '__gmpz_fits_uint_p';
     function  mpz_fits_ulong_p     (protected var Src: mpz_t): CInteger;
       external name '__gmpz_fits_ulong_p';
     function  mpz_fits_ushort_p    (protected var Src: mpz_t): CInteger;
       external name '__gmpz_fits_ushort_p';
     procedure mpz_lcm              (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_lcm';
     procedure mpz_nextprime        (var Dest: mpz_t; protected var Src:
       mpz_t); external name '__gmpz_nextprime';
     function  mpz_perfect_power_p  (protected var Src: mpz_t): CInteger;
       external name '__gmpz_perfect_power_p';
     function  mpz_remove           (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t): MedCard; external name '__gmpz_remove';
     function  mpz_root             (var Dest: mpz_t; protected var Src:
       mpz_t; n: MedCard): CInteger; external name '__gmpz_root';
     procedure mpz_rrandomb         (var ROP: mpz_t; var State:
       gmp_randstate_t; n: MedCard); external name '__gmpz_rrandomb';
     procedure mpz_swap             (var v1, v2: mpz_t); external
       name '__gmpz_swap';
     function  mpz_tdiv_ui          (protected var Src1: mpz_t; Src2:
       MedCard): MedCard; external name '__gmpz_tdiv_ui';
     function  mpz_tstbit           (protected var Src1: mpz_t; Src2:
       MedCard): CInteger; external name '__gmpz_tstbit';
     procedure mpz_urandomb         ({$ifdef HAVE_GMP4} var {$endif} ROP:
       mpz_t; var State: gmp_randstate_t; n: MedCard); external
       name '__gmpz_urandomb';
     procedure mpz_urandomm         ({$ifdef HAVE_GMP4} var {$endif} ROP:
       mpz_t; var State: gmp_randstate_t; {$ifdef HAVE_GMP4} protected
       var {$endif} n: mpz_t); external name '__gmpz_urandomm';
     procedure mpz_xor              (var Dest: mpz_t; protected var Src1,
       Src2: mpz_t); external name '__gmpz_xor';

     procedure mpq_set_d            (var Dest: mpq_t; Src: Real);
       external name '__gmpq_set_d';

     procedure mpf_ceil             (var Dest: mpf_t; protected var Src:
       mpf_t); external name '__gmpf_ceil';
     procedure mpf_floor            (var Dest: mpf_t; protected var Src:
       mpf_t); external name '__gmpf_floor';
     {$ifdef HAVE_GMP4}
     function  mpf_get_si           (protected var Src: mpf_t): MedInt;
       external name '__gmpf_get_si';
     function  mpf_get_ui           (protected var Src: mpf_t): MedCard;
       external name '__gmpf_get_ui';
     function  mpf_get_d_2exp       (var Exp: MedInt; protected var Src:
       mpf_t): Real; external name '__gmpf_get_d_2exp';
     {$endif}
     procedure mpf_pow_ui           (var Dest: mpf_t; protected var Src1:
       mpf_t; Src2: MedCard); external name '__gmpf_pow_ui';
     procedure mpf_trunc            (var Dest: mpf_t; protected var Src:
       mpf_t); external name '__gmpf_trunc';
     procedure mpf_urandomb         (ROP: mpf_t; var State:
       gmp_randstate_t; n: MedCard); external name '__gmpf_urandomb';

     const
       GMPErrorNone = 0;
       GMPErrorUnsupportedArgument = 1;
       GMPErrorDivisionByZero = 2;
       GMPErrorSqrtOfNegative = 4;
       GMPErrorInvalidArgument = 8;
       GMPErrorAllocate = 16;

     var
       gmp_errno: CInteger; external name '__gmp_errno';

     { Extensions to the GMP library, implemented in this unit }

     procedure mpf_exp    (var Dest: mpf_t; protected var Src: mpf_t);
     procedure mpf_ln     (var Dest: mpf_t; protected var Src: mpf_t);
     procedure mpf_pow    (var Dest: mpf_t; protected var Src1, Src2:
       mpf_t);
     procedure mpf_sin    (var Dest: mpf_t; protected var Src: mpf_t);
     procedure mpf_cos    (var Dest: mpf_t; protected var Src: mpf_t);
     procedure mpf_arctan (var Dest: mpf_t; protected var Src: mpf_t);
     procedure mpf_pi     (var Dest: mpf_t);


File: gpc.info,  Node: GPCUtil,  Next: HeapMon,  Prev: GMP,  Up: GPC Units

6.15.6 Turbo Power compatibility, etc.
--------------------------------------

The following listing contains the interface of the GPCUtil unit.

   This unit provides some utility routines for compatibility to some
units available for BP, like some `Turbo Power' units.

     { Some utility routines for compatibility to some units available
       for BP, like some `Turbo Power' units.

       @@NOTE - SOME OF THE ROUTINES IN THIS UNIT MAY NOT WORK CORRECTLY.
       TEST CAREFULLY AND USE WITH CARE!

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Authors: Prof. Abimbola A. Olowofoyeku <African_Chief@bigfoot.com>
                Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030412}
     {$error This unit requires GPC release 20030412 or newer.}
     {$endif}

     module GPCUtil;

     export GPCUtil = all
            (
             { Return the current working directory }
             GetCurrentDirectory => ThisDirectory,

             { Does a directory exist? }
             DirectoryExists => IsDirectory,

             { Does file name s exist? }
             FileExists => ExistFile,

             { Return just the directory path of Path. Returns
               DirSelf + DirSeparator if Path contains no directory. }
             DirFromPath => JustPathName,

             { Return just the file name part without extension of Path.
               Empty if Path contains no file name. }
             NameFromPath => JustFileName,

             { Return just the extension of Path. Empty if Path contains
               no extension. }
             ExtFromPath => JustExtension,

             { Return the full pathname of Path }
             FExpand => FullPathName,

             { Add a DirSeparator to the end of s if there is not
               already one. }
             ForceAddDirSeparator => AddBackSlash,

             { Return a string stripped of leading spaces }
             TrimLeftStr => TrimLead,

             { Return a string stripped of trailing spaces }
             TrimRightStr => TrimTrail,

             { Return a string stripped of leading and trailing spaces }
             TrimBothStr => Trim,

             { Convert a string to lowercase }
             LoCaseStr => StLoCase,

             { Convert a string to uppercase }
             UpCaseStr => StUpCase
            );

     import GPC;

     { Replace all occurences of OldC with NewC in s and return the
       result }
     function  ReplaceChar (const s: String; OldC, NewC: Char) = Res:
       TString;

     { Break a string into 2 parts, using Ch as a marker }
     function  BreakStr (const Src: String; var Dest1, Dest2: String; ch:
       Char): Boolean; attribute (ignorable);

     { Convert a CString to an Integer }
     function  PChar2Int (s: CString) = i: Integer;

     { Convert a CString to a LongInt }
     function  PChar2Long (s: CString) = i: LongInt;

     { Convert a CString to a Double }
     function  PChar2Double (s: CString) = x: Double;

     { Search for s as an executable in the path and return its location
       (full pathname) }
     function  PathLocate (const s: String): TString;

     { Copy file Src to Dest and return the number of bytes written }
     function  CopyFile (const Src, Dest: String; BufSize: Integer):
       LongInt; attribute (ignorable);

     { Copy file Src to Dest and return the number of bytes written;
       report the number of bytes written versus total size of the source
       file }
     function  CopyFileEx (const Src, Dest: String; BufSize: Integer;
       function Report (Reached, Total: LongInt): LongInt) = BytesCopied:
       LongInt; attribute (ignorable);

     { Turbo Power compatibility }

     { Execute the program prog. Dummy1 and Dummy2 are for compatibility
       only; they are ignored. }
     function  ExecDos (const Prog: String; Dummy1: Boolean; Dummy2:
       Pointer): Integer; attribute (ignorable);

     { Return whether Src exists in the path as an executable -- if so
       return its full location in Dest }
     function  ExistOnPath (const Src: String; var Dest: String) =
       Existing: Boolean;

     { Change the extension of s to Ext (do not include the dot!) }
     function  ForceExtension (const s, Ext: String) = Res: TString;

     { Convert Integer to PChar; uses NewCString to allocate memory for
       the result, so you must call StrDispose to free the memory later }
     function  Int2PChar (i: Integer): PChar;

     { Convert Integer to string }
     function  Int2Str (i: Integer) = s: TString;

     { Convert string to Integer }
     function  Str2Int (const s: String; var i: Integer): Boolean;
       attribute (ignorable);

     { Convert string to LongInt }
     function  Str2Long (const s: String; var i: LongInt): Boolean;
       attribute (ignorable);

     { Convert string to Double }
     function  Str2Real (const s: String; var i: Double): Boolean;
       attribute (ignorable);

     { Return a string right-padded to length Len with ch }
     function  PadCh (const s: String; ch: Char; Len: Integer) = Padded:
       TString;

     { Return a string right-padded to length Len with spaces }
     function  Pad (const s: String; Len: Integer): TString;

     { Return a string left-padded to length Len with ch }
     function  LeftPadCh (const s: String; ch: Char; Len: Byte) = Padded:
       TString;

     { Return a string left-padded to length Len with blanks }
     function  LeftPad (const s: String; Len: Integer): TString;

     { Uniform access to big memory blocks for GPC and BP. Of course, for
       programs that are meant only for GPC, you can use the usual
       New/Dispose routines. But for programs that should compile with
       GPC and BP, you can use the following routines for GPC. In the GPC
       unit for BP (gpc-bp.pas), you can find emulations for BP that try
       to provide access to as much memory as possible, despite the
       limitations of BP. The drawback is that this memory cannot be used
       freely, but only with the following moving routines. }

     type
       PBigMem = ^TBigMem;
       TBigMem (MaxNumber: SizeType) = record
         { Public fields }
         Number, BlockSize: SizeType;
         Mappable: Boolean;
         { Private fields }
         Pointers: array [1 .. Max (1, MaxNumber)] of ^Byte
       end;

     { Note: the number of blocks actually allocated may be smaller than
       WantedNumber. Check the Number field of the result. }
     function  AllocateBigMem (WantedNumber, aBlockSize: SizeType;
       WantMappable: Boolean) = p: PBigMem;
     procedure DisposeBigMem (p: PBigMem);
     procedure MoveToBigMem (var Source; p: PBigMem; BlockNumber:
       SizeType);
     procedure MoveFromBigMem (p: PBigMem; BlockNumber: SizeType; var
       Dest);
     { Maps a big memory block into normal addressable memory and returns
       its address. The memory must have been allocated with
       WantMappable = True. The mapping is only valid until the next
       MapBigMem call. }
     function  MapBigMem (p: PBigMem; BlockNumber: SizeType): Pointer;


File: gpc.info,  Node: HeapMon,  Next: Intl,  Prev: GPCUtil,  Up: GPC Units

6.15.7 Primitive heap checking
------------------------------

The following listing contains the interface of the HeapMon unit.

   This unit provide a rather primitive means to watch the heap, i.e.
check if all pointers that were allocated are released again. This is
meant as a debugging help for avoiding memory leaks.

   More extensive heap checking is provided by libraries like `efence'
which can be used in GPC programs without special provisions.

     { A unit to watch the heap, i.e. check if all pointers that were
       allocated are released again. It is meant as a debugging help to
       detect memory leaks.

       Use it in the main program before all other units. When, at the
       end of the program, some pointers that were allocated, have not
       been released, the unit writes a report to StdErr or another file
       (see below). Only pointers allocated via the Pascal mechanisms
       (New, GetMem) are tracked, not pointers allocated with direct libc
       calls or from C code. After a runtime error, pointers are not
       checked.

       Note that many units and libraries allocate memory for their own
       purposes and don't always release it at the end. Therefore, the
       usefulness of this unit is rather limited.

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     unit HeapMon;

     interface

     uses GPC;

     { This unit is automatically activated when used. The following
       declarations are only needed for special purposes. }

     { The report generated at the end can be redirected to a certain
       file by pointing HeapMonOutput to it. If not set, the report will
       be printed to the error messages file given with `--gpc-rts'
       options if given, and StdErr otherwise. }
     var
       HeapMonOutput: ^Text = nil;

     { HeapMonReport can be used to print a report on non-released memory
       blocks at an arbitrary point during a program run to the file f.
       It is invoked automatically at the end, so usually you don't have
       to call it. Returns True if any non-released blocks were found,
       False otherwise. }
     function HeapMonReport (var f: Text; DoRestoreTerminal: Boolean) =
       Res: Boolean; attribute (ignorable);


File: gpc.info,  Node: Intl,  Next: MD5,  Prev: HeapMon,  Up: GPC Units

6.15.8 Internationalization
---------------------------

The following listing contains the interface of the Intl unit.

   This unit provides national language support via locales and `.mo'
files.

     { Welcome to the wonderful world of
       INTERNATIONALIZATION (i18n).

       This unit provides the powerful mechanism of national language
       support by accessing `.mo' files and locale information.

       It includes:
         locales (not xlocales) and libintl.

       See documentation for gettext (`info gettext') for details.

       Because GPC can deal with both CStrings and Pascal Strings, there
       is an interface for both types of arguments and function results
       with slightly different names.

       E.g. for Pascal strings:

         function GetText (const MsgId: String): TString;

       And the same as above, but with a C interface:

         function GetTextC (MsgId: CString): CString;

       `PLConv' in Pascal is very different from `struct lconv *' in C.
       Element names do not have underscores and have sometimes different
       sizes. The conversion is done automatically and has correct
       results.

       Furthermore, we have a tool similar to `xgettext' to extract all
       strings out of a Pascal source. It extracts the strings and writes
       a complete `.po' file to a file. See
       http://www.gnu-pascal.de/contrib/eike/
       The filename is pas2po-VERSION.tar.gz.

       Copyright (C) 2001-2006 Free Software Foundation, Inc.

       Author: Eike Lange <eike.lange@uni-essen.de>

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU Library General Public License as
       published by the Free Software Foundation, version 2.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       Library General Public License for more details.

       You should have received a copy of the GNU Library General Public
       License along with this library; see the file COPYING.LIB. If not,
       write to the Free Software Foundation, Inc., 59 Temple Place -
       Suite 330, Boston, MA 02111-1307, USA. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     unit Intl;

     interface

     uses GPC;

     type
       IntlString = String (16);

       { Pascal translation from OrigLConv in intlc.c }
       PLConv = ^TLConv;
       TLConv = record
         { Numeric (non-monetary) information. }

         { Decimal point character. }
         DecimalPoint: IntlString;

         { Thousands separator. }
         ThousandsSep: IntlString;

         { Each element is the number of digits in each group;
           elements with higher indices are farther left.
           An element with value CharMax means that no further grouping
           is done.
           An element with value Chr (0) means that the previous element
           is used for all groups farther left. }
         Grouping: IntlString;

         { Monetary information. }

         { First three chars are a currency symbol from ISO 4217.
           Fourth char is the separator.  Fifth char is Chr (0). }
         IntCurrSymbol: IntlString;

         { Local currency symbol. }
         CurrencySymbol: IntlString;

         { Decimal point character. }
         MonDecimalPoint: IntlString;

         { Thousands separator. }
         MonThousandsSep: IntlString;

         { Like `Grouping' element (above). }
         MonGrouping: IntlString;

         { Sign for positive values. }
         PositiveSign: IntlString;

         { Sign for negative values. }
         NegativeSign: IntlString;

         { Int'l fractional digits. }
         IntFracDigits: ByteInt;

         { Local fractional digits. }
         FracDigits: ByteInt;

         { 1 if CurrencySymbol precedes a positive value, 0 if it
           succeeds. }
         PCSPrecedes: ByteInt;

         { 1 iff a space separates CurrencySymbol from a positive
           value. }
         PSepBySpace: ByteInt;

         { 1 if CurrencySymbol precedes a negative value, 0 if it
           succeeds. }
         NCSPrecedes: ByteInt;

         { 1 iff a space separates CurrencySymbol from a negative
           value. }
         NSepBySpace: ByteInt;

         { Positive and negative sign positions:
           0 Parentheses surround the quantity and CurrencySymbol.
           1 The sign string precedes the quantity and CurrencySymbol.
           2 The sign string follows the quantity and CurrencySymbol.
           3 The sign string immediately precedes the CurrencySymbol.
           4 The sign string immediately follows the CurrencySymbol. }
         PSignPosn,
         NSignPosn: ByteInt;
       end;

     { Please do not assign anything to these identifiers! }
     var
       LC_CTYPE:    CInteger; external name '_p_LC_CTYPE';
       LC_NUMERIC:  CInteger; external name '_p_LC_NUMERIC';
       LC_TIME:     CInteger; external name '_p_LC_TIME';
       LC_COLLATE:  CInteger; external name '_p_LC_COLLATE';
       LC_MONETARY: CInteger; external name '_p_LC_MONETARY';
       LC_MESSAGES: CInteger; external name '_p_LC_MESSAGES';
       LC_ALL:      CInteger; external name '_p_LC_ALL';
       CharMax:     Char; external name '_p_CHAR_MAX';

     {@section Locales }

     { Set and/or return the current locale. }
     function SetLocale (Category: Integer; const Locale: String):
       TString; attribute (ignorable);

     { Set and/or return the current locale. Same as above, but returns
       a CString. }
     function SetLocaleC (Category: Integer; const Locale: String):
       CString; attribute (ignorable);

     { Return the numeric/monetary information for the current locale.
       The result is allocated from the heap. You can Dispose it when
       you don't need it anymore. }
     function LocaleConv: PLConv;

     {@section GetText }

     { Look up MsgId in the current default message catalog for the
       current LC_MESSAGES locale.  If not found, returns MsgId itself
       (the default text). }
     function GetText (const MsgId: String): TString;

     { Same as above, but with a C interface }
     function GetTextC (MsgId: CString): CString;

     { Look up MsgId in the DomainName message catalog for the current
       LC_MESSAGES locale. }
     function DGetText (const DomainName, MsgId: String): TString;

     { Same as above, but with a C interface }
     function DGetTextC (DomainName, MsgId: CString): CString;

     { Look up MsgId in the DomainName message catalog for the current
       Category locale. }
     function DCGetText (const DomainName, MsgId: String; Category:
       Integer): TString;

     { Same as above, but with a C interface }
     function DCGetTextC (DomainName, MsgId: CString; Category: Integer):
       CString;

     { Set the current default message catalog to DomainName.
       If DomainName is empty, reset to the default of `messages'. }
     function TextDomain (const DomainName: String): TString; attribute
       (ignorable);

     { Same as above, but with a C interface.
       If DomainName is nil, return the current default. }
     function TextDomainC (DomainName: CString): CString; attribute
       (ignorable);

     { Specify that the DomainName message catalog will be found
       in DirName rather than in the system locale data base. }
     function BindTextDomain (const DomainName, DirName: String):
       TString; attribute (ignorable);

     { Same as above, but with a C interface }
     function BindTextDomainC (DomainName, DirName: CString): CString;
       attribute (ignorable);


File: gpc.info,  Node: MD5,  Next: Overlay,  Prev: Intl,  Up: GPC Units

6.15.9 `MD5' Message Digests
----------------------------

The following listing contains the interface of the MD5 unit.

   This unit provides functions to compute `MD5' message digest of
files or memory blocks, according to the definition of `MD5' in `RFC
1321' from April 1992.

     { Functions to compute MD5 message digest of files or memory blocks,
       according to the definition of MD5 in RFC 1321 from April 1992.

       Copyright (C) 1995, 1996, 2000-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       Based on the C code written by Ulrich Drepper
       <drepper@gnu.ai.mit.edu>, 1995 as part of glibc.

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU Library General Public License as
       published by the Free Software Foundation, version 2.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       Library General Public License for more details.

       You should have received a copy of the GNU Library General Public
       License along with this library; see the file COPYING.LIB. If not,
       write to the Free Software Foundation, Inc., 59 Temple Place -
       Suite 330, Boston, MA 02111-1307, USA. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     unit MD5;

     interface

     uses GPC;

     { Representation of a MD5 value. It is always in little endian byte
       order and therefore portable. }
     type
       Card8 = Cardinal attribute (Size = 8);
       TMD5 = array [1 .. 16] of Card8;

     const
       MD5StrLength = 2 * High (TMD5);

     type
       MD5String = String (MD5StrLength);

     { Computes MD5 message digest for Length bytes in Buffer. }
     procedure MD5Buffer (const Buffer; Length: SizeType; var MD5: TMD5);

     { Computes MD5 message digest for the contents of the file f. }
     procedure MD5File (var f: File; var MD5: TMD5); attribute
       (iocritical);

     { Initializes a MD5 value with zeros. }
     procedure MD5Clear (var MD5: TMD5);

     { Compares two MD5 values for equality. }
     function MD5Compare (const Value1, Value2: TMD5): Boolean;

     { Converts an MD5 value to a string. }
     function MD5Str (const MD5: TMD5) = s: MD5String;

     { Converts a string to an MD5 value. Returns True if successful. }
     function MD5Val (const s: String; var MD5: TMD5): Boolean;

     { Composes two MD5 values to a single one. }
     function MD5Compose (const Value1, Value2: TMD5) = Dest: TMD5;


File: gpc.info,  Node: Overlay,  Next: Pipes,  Prev: MD5,  Up: GPC Units

6.15.10 BP compatibility: Overlay
---------------------------------

The following listing contains the interface of the Overlay unit.

   This is just a dummy replacement for BP's `Overlay' unit, since GPC
doesn't need overlays.

     { Dummy BP compatible overlay unit for GPC

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030412}
     {$error This unit requires GPC release 20030412 or newer.}
     {$endif}

     unit Overlay;

     interface

     const
       OvrOK = 0;
       OvrError = -1;
       OvrNotFound = -2;
       OvrNoMemory = -3;
       OvrIOError = -4;
       OvrNoEMSDriver = -5;
       OvrNoEMSMemory = -6;

     const
       OvrEmsPages: Word = 0;
       OvrTrapCount: Word = 0;
       OvrLoadCount: Word = 0;
       OvrFileMode: Byte = 0;

     type
       OvrReadFunc = function (OvrSeg: Word): Integer;

     var
       OvrReadBuf: OvrReadFunc;
       OvrResult: Integer = 0;

     procedure OvrInit (aFileName: String);
     procedure OvrInitEMS;
     procedure OvrSetBuf (Size: LongInt);
     function  OvrGetBuf: LongInt;
     procedure OvrSetRetry (Size: LongInt);
     function  OvrGetRetry: LongInt;
     procedure OvrClearBuf;


File: gpc.info,  Node: Pipes,  Next: Ports,  Prev: Overlay,  Up: GPC Units

6.15.11 Start a child process, connected with pipes, also on Dos
----------------------------------------------------------------

The following listing contains the interface of the Pipes unit.

   This unit provides routines to start a child process and write
to/read from its Input/Output/StdErr via pipes. All of this is emulated
transparently under Dos as far as possible.

     { Piping data from and to processes

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     { Keep this consistent with the one in pipesc.c }
     {$if defined (MSDOS) or defined (__MINGW32__)}
     {$define NOFORK}
     {$endif}

     unit Pipes;

     interface

     uses GPC;

     const
       PipeForking = {$ifdef NOFORK} False {$else} True {$endif};

     type
       TProcedure = procedure;

       PWaitPIDResult = ^TWaitPIDResult;
       TWaitPIDResult = (PIDNothing, PIDExited, PIDSignaled, PIDStopped,
       PIDUnknown);

       PPipeProcess = ^TPipeProcess;
       TPipeProcess = record
         PID      : Integer;         { Process ID of process forked }
         SignalPID: Integer;         { Process ID to send the signal to.
                                       Equals PID by default }
         OpenPipes: Integer;         { Number of pipes to/from the
                                       process, for internal use }
         Signal   : Integer;         { Send this signal (if not 0) to the
                                       process after all pipes have been
                                       closed after some time }
         Seconds  : Integer;         { Wait so many seconds before
                                       sending the signal if the process
                                       has not terminated by itself }
         Wait     : Boolean;         { Wait for the process, even longer
                                       than Seconds seconds, after
                                       sending the signal (if any) }
         Result   : PWaitPIDResult;  { Default nil. If a pointer to a
                                       variable is stored here, its
                                       destination will contain the
                                       information whether the process
                                       terminated by itself, or was
                                       terminated or stopped by a signal,
                                       when waiting after closing the
                                       pipes }
         Status   : ^Integer;        { Default nil. If a pointer to a
                                       variable is stored here, its
                                       destination will contain the exit
                                       status if the process terminated
                                       by itself, or the number of the
                                       signal otherwise, when waiting
                                       after closing the pipes }
       end;

     var
       { Default values for TPipeProcess records created by Pipe }
       DefaultPipeSignal : Integer = 0;
       DefaultPipeSeconds: Integer = 0;
       DefaultPipeWait   : Boolean = True;

     { The procedure Pipe starts a process whose name is given by
       ProcessName, with the given parameters (can be Null if no
       parameters) and environment, and create pipes from and/or to the
       process' standard input/output/error. ProcessName is searched for
       in the PATH with FSearchExecutable. Any of ToInputFile,
       FromOutputFile and FromStdErrFile can be Null if the corresponding
       pipe is not wanted. FromOutputFile and FromStdErrFile may be
       identical, in which case standard output and standard error are
       redirected to the same pipe. The behaviour of other pairs of files
       being identical is undefined, and useless, anyway. The files are
       Assigned and Reset or Rewritten as appropriate. Errors are
       returned in IOResult. If Process is not Null, a pointer to a
       record is stored there, from which the PID of the process created
       can be read, and by writing to which the action after all pipes
       have been closed can be changed. (The record is automatically
       Dispose'd of after all pipes have been closed.) If automatic
       waiting is turned off, the caller should get the PID from the
       record before it's Dispose'd of, and wait for the process sometime
       in order to avoid zombies. If no redirections are performed (i.e.,
       all 3 files are Null), the caller should wait for the process with
       WaitPipeProcess. When an error occurs, Process is not assigned to,
       and the state of the files is undefined, so be sure to check
       IOResult before going on.

       ChildProc, if not nil, is called in the child process after
       forking and redirecting I/O, but before executing the new process.
       It can even be called instead of executing a new process
       (ProcessName can be empty then).

       The procedure even works under Dos, but, of course, in a limited
       sense: if ToInputFile is used, the process will not actually be
       started until ToInputFile is closed. Signal, Seconds and Wait of
       TPipeProcess are ignored, and PID and SignalPID do not contain a
       Process ID, but an internal value without any meaning to the
       caller. Result will always be PIDExited. So, Status is the only
       interesting field (but Result should also be checked). Since there
       is no forking under Dos, ChildProc, if not nil, is called in the
       main process before spawning the program. So, to be portable, it
       should not do any things that would influence the process after
       the return of the Pipe function.

       The only portable way to use "pipes" in both directions is to call
       `Pipe', write all the Input data to ToInputFile, close
       ToInputFile, and then read the Output and StdErr data from
       FromOutputFile and FromStdErrFile. However, since the capacity of
       pipes is limited, one should also check for Data from
       FromOutputFile and FromStdErrFile (using CanRead, IOSelect or
       IOSelectRead) while writing the Input data (under Dos, there
       simply won't be any data then, but checking for data doesn't do
       any harm). Please see pipedemo.pas for an example. }
     procedure Pipe (var ToInputFile, FromOutputFile, FromStdErrFile:
       AnyFile; const ProcessName: String; protected var Parameters:
       TPStrings; ProcessEnvironment: PCStrings; var Process:
       PPipeProcess; ChildProc: TProcedure); attribute (iocritical);

     { Waits for a process created by Pipe as determined in the Process
       record. (Process is Dispose'd of afterwards.) Returns True if
       successful. }
     function WaitPipeProcess (Process: PPipeProcess): Boolean; attribute
       (ignorable);

     { Alternative interface from PExecute }

     const
       PExecute_First   = 1;
       PExecute_Last    = 2;
       PExecute_One     = PExecute_First or PExecute_Last;
       PExecute_Search  = 4;
       PExecute_Verbose = 8;

     { PExecute: execute a chain of processes.

       Program and Arguments are the arguments to execv/execvp.

       Flags and PExecute_Search is non-zero if $PATH should be searched.
       Flags and PExecute_First is nonzero for the first process in
       chain. Flags and PExecute_Last is nonzero for the last process in
       chain.

       The result is the pid on systems like Unix where we fork/exec and
       on systems like MS-Windows and OS2 where we use spawn. It is up to
       the caller to wait for the child.

       The result is the exit code on systems like MSDOS where we spawn
       and wait for the child here.

       Upon failure, ErrMsg is set to the text of the error message,
       and -1 is returned. `errno' is available to the caller to use.

       PWait: cover function for wait.

       PID is the process id of the task to wait for. Status is the
       `status' argument to wait. Flags is currently unused (allows
       future enhancement without breaking upward compatibility). Pass 0
       for now.

       The result is the process ID of the child reaped, or -1 for
       failure.

       On systems that don't support waiting for a particular child, PID
       is ignored. On systems like MSDOS that don't really multitask
       PWait is just a mechanism to provide a consistent interface for
       the caller. }
     function  PExecute (ProgramName: CString; Arguments: PCStrings; var
       ErrMsg: String; Flags: Integer): Integer; attribute (ignorable);
     function  PWait (PID: Integer; var Status: Integer; Flags: Integer):
       Integer; attribute (ignorable);


File: gpc.info,  Node: Ports,  Next: Printer,  Prev: Pipes,  Up: GPC Units

6.15.12 BP compatibility (partly): `Port', `PortW' arrays
---------------------------------------------------------

The following listing contains the interface of the Ports unit.

   This unit provides access routines for the hardware ports on the
IA32, as a partial replacement for BP's `Port' and `PortW' pseudo
arrays.

   Since port access is platform-specific, this unit cannot be used in
code intended to be portable. Even on the IA32, its use can often be
avoided - e.g. Linux provides a number of `ioctl' functions, and DJGPP
provides some routines to achieve things that would require port access
under BP. Therefore, it is recommended to avoid using this unit
whenever possible.

     { Access functions for I/O ports for GPC on an IA32 platform. This
       unit is *not* portable. It works only on IA32 platforms (tested
       under Linux and DJGPP). It is provided here only to serve as a
       replacement for BP's Port and PortW pseudo arrays.

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}
     {$ifndef __i386__}
     {$error The Ports unit is only for the IA32 platform}
     {$endif}

     unit Ports;

     interface

     { Port access functions }
     function  InPortB  (PortNumber: ShortWord): Byte;
     function  InPortW  (PortNumber: ShortWord): ShortWord;
     procedure OutPortB (PortNumber: ShortWord; aValue: Byte);
     procedure OutPortW (PortNumber, aValue: ShortWord);

     { libc functions for getting access to the ports -- only for root
       processes, of course -- and to give up root privileges after
       getting access to the ports for setuid root programs. Dummies
       under DJGPP. }
     {$ifdef MSDOS}
     function  IOPerm (From, Num: MedCard; On: Integer): Integer;
       attribute (name = 'ioperm');
     function  IOPL (Level: Integer): Integer; attribute (name = 'iopl');
     function  SetEUID (EUID: Integer): Integer; attribute (name
       = 'seteuid');
     {$else}
     function  IOPerm (From, Num: MedCard; On: Integer): Integer;
       external name 'ioperm';
     function  IOPL (Level: Integer): Integer; external name 'iopl';
     function  SetEUID (EUID: Integer): Integer; external name 'seteuid';
     {$endif}


File: gpc.info,  Node: Printer,  Next: RegEx,  Prev: Ports,  Up: GPC Units

6.15.13 BP compatibility: Printer, portable
-------------------------------------------

The following listing contains the interface of the Printer unit.

   This unit provides printer access, compatible to BP's `Printer'
unit, for Dos (using printer devices) and Unix systems (using printer
utilities).

   For BP compatibility, the variable `Lst' is provided, but for newly
written programs, it is recommended to use the `AssignPrinter'
procedure on a text file, and close the file when done (thereby
committing the printer job). This method allows for sending multiple
printer jobs in the same program.

     { BP compatible printer unit with extensions

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     unit Printer;

     interface

     uses GPC {$ifndef __OS_DOS__}, Pipes {$endif};

     var
       { Dos-like systems: writing to a printer device }

       { The file name to write printer output into }
       PrinterDeviceName: PString = @'prn';

       { Unix-like systems: printing via a printer program }

       { The file name of the printer program. If it contains a '/', it
         will be taken as a complete path, otherwise the file name will
         be searched for in the PATH with FSearchExecutable. }
       PrinterCommand: PString = @'lpr';

       { Optional command line parameters for the printer program.
         Ignored when nil. }
       PrinterArguments: PPStrings = nil;

       { How to deal with the printer spooler after the printer pipe is
         closed, cf. the Pipes unit. }
       PrinterPipeSignal : Integer = 0;
       PrinterPipeSeconds: Integer = 0;
       PrinterPipeWait   : Boolean = True;

     { Text file opened to default printer }
     var
       Lst: Text;

     { Assign a file to the printer. Lst will be assigned to the default
       printer at program start, but other files can be assigned to the
       same or other printers (possibly after changing the variables
       above). SpoolerOutput, if not Null, will be redirected from the
       printer spooler's standard output and error. If you use this, note
       that a deadlock might arise when trying to write data to the
       spooler while its output is not being read, though this seems
       quite unlikely, since most printer spoolers don't write so much
       output that could fill a pipe. Under Dos, where no spooler is
       involved, SpoolerOutput, if not Null, will be reset to an empty
       file for compatibility. }
     procedure AssignPrinter (var f: AnyFile; var SpoolerOutput:
       AnyFile);


File: gpc.info,  Node: RegEx,  Next: Strings,  Prev: Printer,  Up: GPC Units

6.15.14 Regular Expression matching and substituting
----------------------------------------------------

The following listing contains the interface of the RegEx unit.

   This unit provides routines to match strings against regular
expressions and perform substitutions using matched subexpressions.
Regular expressions are strings with some characters having special
meanings. They describe (match) a class of strings. They are similar to
wild cards used in file name matching, but much more powerful.

   To use this unit, you will need the `rx' library which can be found
in `http://www.gnu-pascal.de/libs/'.

     {$nested-comments}

     { Regular expression matching and replacement

       The RegEx unit provides routines to match strings against regular
       expressions and perform substitutions using matched
       subexpressions.

       To use the RegEx unit, you will need the rx library which can be
       found in http://www.gnu-pascal.de/libs/

       Regular expressions are strings with some characters having
       special meanings. They describe (match) a class of strings. They
       are similar to wild cards used in file name matching, but much
       more powerful.

       There are two kinds of regular expressions supported by this unit,
       basic and extended regular expressions. The difference between
       them is not functionality, but only syntax. The following is a
       short overview of regular expressions. For a more thorough
       explanation see the literature, or the documentation of the rx
       library, or man pages of programs like grep(1) and sed(1).

       Basic           Extended        Meaning
       `.'             `.'             matches any single character
       `[aei-z]'       `[aei-z]'       matches either `a', `e', or any
                                       character from `i' to `z'
       `[^aei-z]'      `[^aei-z]'      matches any character but `a',
                                       `e', or `i' .. `z'
                                       To include in such a list the the
                                       characters `]', `^', or `-', put
                                       them first, anywhere but first, or
                                       first or last, resp.
       `[[:alnum:]]'   `[[:alnum:]]'   matches any alphanumeric character
       `[^[:digit:]]'  `[^[:digit:]]'  matches anything but a digit
       `[a[:space:]]'  `[a[:space:]]'  matches the letter `a' or a space
                                       character (space, tab)
       ...                             (there are more classes available)
       `\w'            `\w'            = [[:alnum:]]
       `\W'            `\W'            = [^[:alnum:]]
       `^'             `^'             matches the empty string at the
                                       beginning of a line
       `$'             `$'             matches the empty string at the
                                       end of a line
       `*'             `*'             matches zero or more occurences of
                                       the preceding expression
       `\+'            `+'             matches one or more occurences of
                                       the preceding expression
       `\?'            `?'             matches zero or one occurence of
                                       the preceding expression
       `\{N\}'         `{N}'           matches exactly N occurences of
                                       the preceding expression (N is an
                                       integer number)
       `\{M,N\}'       `{M,N}'         matches M to N occurences of the
                                       preceding expression (M and N are
                                       integer numbers, M <= N)
       `AB'            `AB'            matches A followed by B (A and B
                                       are regular expressions)
       `A\|B'          `A|B'           matches A or B (A and B are
                                       regular expressions)
       `\( \)'         `( )'           forms a subexpression, to override
                                       precedence, and for subexpression
                                       references
       `\7'            `\7'            matches the 7'th parenthesized
                                       subexpression (counted by their
                                       start in the regex), where 7 is a
                                       number from 1 to 9 ;-).
                                       *Please note:* using this feature
                                       can be *very* slow or take very
                                       much memory (exponential time and
                                       space in the worst case, if you
                                       know what that means ...).
       `\'             `\'             quotes the following character if
                                       it's special (i.e. listed above)
       rest            rest            any other character matches itself

       Precedence, from highest to lowest:
       * parentheses (`()')
       * repetition (`*', `+', `?', `{}')
       * concatenation
       * alternation (`|')

       When performing substitutions using matched subexpressions of a
       regular expression (see `ReplaceSubExpressionReferences'), the
       replacement string can reference the whole matched expression with
       `&' or `\0', the 7th subexpression with `\7' (just like in the
       regex itself, but using it in replacements is not slow), and the
       7th subexpression converted to upper/lower case with `\u7' or
       `\l7', resp. (which also works for the whole matched expression
       with `\u0' or `\l0'). A verbatim `&' or `\' can be specified with
       `\&' or `\\', resp.

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License.

       Please also note the license of the rx library. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     unit RegEx;

     interface

     uses GPC;

     const
       { `BasicRegExSpecialChars' contains all characters that have
         special meanings in basic regular expressions.
         `ExtRegExSpecialChars' contains those that have special meanings
         in extended regular expressions. }
       BasicRegExSpecialChars = ['.', '[', ']', '^', '$', '*', '\'];
       ExtRegExSpecialChars   =
       ['.', '[', ']', '^', '$', '*', '+', '?', '{', '}', '|', '(', ')', '\'];

     type
       { The type used by the routines of the `RegEx' unit to store
         regular expressions in an internal format. The fields RegEx,
         RegMatch, ErrorInternal, From and Length are only used
         internally. SubExpressions can be read after `NewRegEx' and will
         contain the number of parenthesized subexpressions. Error should
         be checked after `NewRegEx'. It will be `nil' when it succeeded,
         and contain an error message otherwise. }
       RegExType = record
         RegEx, RegMatch: Pointer;  { Internal }
         ErrorInternal: CString;    { Internal }
         From, Length: CInteger;    { Internal }
         SubExpressions: CInteger;
         Error: PString
       end;

     { Simple interface to regular expression matching. Matches a regular
       expression against a string starting from a specified position.
       Returns the position of the first match, or 0 if it does not
       match, or the regular expression is invalid. }
     function  RegExPosFrom (const Expression: String; ExtendedRegEx,
       CaseInsensitive: Boolean; const s: String; From: Integer) =
       MatchPosition: Integer;

     { Creates the internal format of a regular expression. If
       ExtendedRegEx is True, Expression is assumed to denote an extended
       regular expression, otherwise a basic regular expression.
       CaseInsensitive determines if the case of letters will be ignored
       when matching the expression. If NewLines is True, `NewLine'
       characters in a string matched against the expression will be
       treated as dividing the string in multiple lines, so that `$' can
       match before the NewLine and `^' can match after. Also, `.' and
       `[^...]' will not match a NewLine then. }
     procedure NewRegEx (var RegEx: RegExType; const Expression: String;
       ExtendedRegEx, CaseInsensitive, NewLines: Boolean);

     { Disposes of a regular expression created with `NewRegEx'. *Must*
       be used after `NewRegEx' before the RegEx variable becomes invalid
       (i.e., goes out of scope or a pointer pointing to it is Dispose'd
       of). }
     procedure DisposeRegEx (var RegEx: RegExType); external
       name '_p_DisposeRegEx';

     { Matches a regular expression created with `NewRegEx' against a
       string. }
     function  MatchRegEx (var RegEx: RegExType; const s: String;
       NotBeginningOfLine, NotEndOfLine: Boolean): Boolean;

     { Matches a regular expression created with `NewRegEx' against a
       string, starting from a specified position. }
     function  MatchRegExFrom (var RegEx: RegExType; const s: String;
       NotBeginningOfLine, NotEndOfLine: Boolean; From: Integer):
       Boolean;

     { Finds out where the regular expression matched, if `MatchRegEx' or
       `MatchRegExFrom' were successful. If n = 0, it returns the
       position of the whole match, otherwise the position of the n'th
       parenthesized subexpression. MatchPosition and MatchLength will
       contain the position (counted from 1) and length of the match, or
       0 if it didn't match. (Note: MatchLength can also be 0 for a
       successful empty match, so check whether MatchPosition is 0 to
       find out if it matched at all.) MatchPosition or MatchLength may
       be Null and is ignored then. }
     procedure GetMatchRegEx (var RegEx: RegExType; n: Integer; var
       MatchPosition, MatchLength: Integer);

     { Checks if the string s contains any quoted characters or
       (sub)expression references to the regular expression RegEx created
       with `NewRegEx'. These are `&' or `\0' for the whole matched
       expression (if OnlySub is not set) and `\1' .. `\9' for the n'th
       parenthesized subexpression. Returns 0 if it does not contain any,
       and the number of references and quoted characters if it does. If
       an invalid reference (i.e. a number bigger than the number of
       subexpressions in RegEx) is found, it returns the negative value
       of the (first) invalid reference. }
     function  FindSubExpressionReferences (var RegEx: RegExType; const
       s: String; OnlySub: Boolean): Integer;

     { Replaces (sub)expression references in ReplaceStr by the actual
       (sub)expressions and unquotes quoted characters. To be used after
       the regular expression RegEx created with `NewRegEx' was matched
       against s successfully with `MatchRegEx' or `MatchRegExFrom'. }
     function  ReplaceSubExpressionReferences (var RegEx: RegExType;
       const s, ReplaceStr: String) = Res: TString;

     { Returns the string for a regular expression that matches exactly
       one character out of the given set. It can be combined with the
       usual operators to form more complex expressions. }
     function  CharSet2RegEx (const Characters: CharSet) = s: TString;


File: gpc.info,  Node: Strings,  Next: StringUtils,  Prev: RegEx,  Up: GPC Units

6.15.15 BP compatibility: Strings
---------------------------------

The following listing contains the interface of the Strings unit.

   This is a compatibility unit to BP's `Strings' unit to handle C
style `#0'-terminated strings.

   The same functionality and much more is available in the Run Time
System, *Note Run Time System::, under clearer names (starting with a
`CString' prefix),

   Moreover, the use of `#0'-terminated C-style strings (`PChar' or
`CString') is generally not recommended in GPC, since GPC provides ways
to deal with Pascal-style strings of arbitrary and dynamic size in a
comfortable way, as well as automatic conversion to C-style strings in
order to call external C functions.

   Therefore, using this unit is not recommended in newly written
programs.

     { BP compatible Strings unit

       Copyright (C) 1999-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     module Strings;

     export Strings = all (CStringLength => StrLen, CStringEnd => StrEnd,
                           CStringMove => StrMove, CStringCopy =>
       StrCopy,
                           CStringCopyEnd => StrECopy, CStringLCopy =>
       StrLCopy,
                           CStringCopyString => StrPCopy, CStringCat =>
       StrCat,
                           CStringLCat => StrLCat, CStringComp =>
       StrComp,
                           CStringCaseComp => StrIComp, CStringLComp =>
       StrLComp,
                           CStringLCaseComp => StrLIComp, CStringChPos =>
       StrScan,
                           CStringLastChPos => StrRScan, CStringPos =>
       StrPos,
                           CStringLastPos => StrRPos, CStringUpCase =>
       StrUpper,
                           CStringLoCase => StrLower, CStringIsEmpty =>
       StrEmpty,
                           CStringNew => StrNew);

     import GPC;

     function StrPas (aString: CString): TString;
     procedure StrDispose (s: CString); external name '_p_Dispose';


File: gpc.info,  Node: StringUtils,  Next: System,  Prev: Strings,  Up: GPC Units

6.15.16 Higher level string handling
------------------------------------

The following listing contains the interface of the StringUtils unit.

   This unit provides some routines for string handling on a higher
level than those provided by the RTS.

     { Some routines for string handling on a higher level than those
       provided by the RTS.

       Copyright (C) 1999-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     unit StringUtils;

     interface

     uses GPC;

     { Various routines }

     { Appends Source to s, truncating the result if necessary. }
     procedure AppendStr (var s: String; const Source: String);

     { Cuts s to MaxLength characters. If s is already MaxLength
       characters or shorter, it doesn't change anything. }
     procedure StrCut (var s: String; MaxLength: Integer);

     { Returns the number of disjoint occurences of SubStr in s. Returns
       0 if SubStr is empty. }
     function  StrCount (const SubStr: String; s: String): Integer;

     { Returns s, with all disjoint occurences of Source replaced by
       Dest. }
     function  StrReplace (const s, Source, Dest: String) = Result:
       TString;

     { Sets of characters accepted for `True' and `False' by
       Char2Boolean and StrReadBoolean. }
     var
       CharactersTrue : CharSet = ['Y', 'y'];
       CharactersFalse: CharSet = ['N', 'n'];

     { If ch is an element of CharactersTrue, Dest is set to True,
       otherwise if it is an element of CharactersFalse, Dest is set to
       False. In both cases True is returned. If ch is not an element of
       either set, Dest is set to False and False is returned. }
     function  Char2Boolean (ch: Char; var Dest: Boolean): Boolean;
       attribute (ignorable);

     { Converts a digit character to its numeric value. Handles every
       base up to 36 (0 .. 9, a .. z, upper and lower case recognized).
       Returns -1 if the character is not a digit at all. If you want to
       use it for a base < 36, you have to check if the result is smaller
       than the base and not equal to -1. }
     function  Char2Digit (ch: Char): Integer;

     { Encode a string in a printable format (quoted printable). All
       occurences of EscapeChar within the string are encoded. If
       QuoteHigh is True, all characters above the ASCII range are
       encoded as well (required in "7 bit" environments, as per several
       RFCs). `=' is always encoded, as required for proper decoding, as
       are all characters below space (control characters), so if you
       don't need an escape char yourself, you can pass #0 for
       EscapeChar. }
     function  QuoteStringEscape (const s: String; EscapeChar: Char;
       QuoteHigh: Boolean): TString;

     { Encode a string in a printable format (quoted printable and
       surrounded with `"'). All occurences of `"' within the string are
       encoded, so the result string contains exactly two `"' characters
       (at the beginning and ending). This is useful to store arbitrary
       strings in text files while keeping them as readable as possible
       (which is the goal of the quoted printable encoding in general,
       see RFC 1521, section 5.1) and being able to read them back
       losslessly (with UnQuoteString). }
     function  QuoteString (const s: String): TString;

     { Encode a string in a printable format suitable for StrReadEnum.
       All occurences of `,' within the string are encoded. }
     function  QuoteEnum (const s: String): TString;

     { Decode a string encoded by QuoteString (removing the `"' and
       expanding quoted printable encoded characters). Returns True if
       successful and False if the string has an invalid form. A string
       returned by QuoteString is always valid. }
     function  UnQuoteString (var s: String): Boolean; attribute
       (ignorable);

     { Decode a quoted-printable string (not enclosed in `"', unlike for
       UnQuoteString). Returns True if successful and False if the string
       has an invalid form. In the latter case, it still decodes as much
       as is valid, even after the error position. }
     function  UnQPString (var s: String): Boolean; attribute
       (ignorable);

     { Quotes a string as done in shells, i.e. all special characters are
       enclosed in either `"' or `'', where `"', `$' and ``' are always
       enclosed in `'' and `'' is always enclosed in `"'. }
     function  ShellQuoteString (const s: String) = Res: TString;

     { Replaces all tab characters in s with the appropriate amount of
       spaces, assuming tab stops at every TabSize columns. Returns True
       if successful and False if the expanded string would exceed the
       capacity of s. In the latter case, some, but not all of the tabs
       in s may have been expanded. }
     function  ExpandTabs (var s: String; TabSize: Integer): Boolean;
       attribute (ignorable);

     { Returns s, with all occurences of C style escape sequences (e.g.
       `\n') replaced by the characters they mean. If AllowOctal is True,
       also octal character specifications (e.g. `\007') are replaced. If
       RemoveQuoteChars is True, any other backslashes are removed (e.g.
       `\*' -> `*' and `\\' -> `\'), otherwise they are kept, and also
       `\\' is left as two backslashes then. }
     function  ExpandCEscapeSequences (const s: String; RemoveQuoteChars,
       AllowOctal: Boolean) = r: TString;

     { Routines for TPStrings }

     { Initialise a TPStrings variable, allocate Size characters for each
       element. This procedure does not dispose of any previously
       allocated storage, so if you use it on a previously used variable
       without freeing the storage yourself, this might cause memory
       leaks. }
     procedure AllocateTPStrings (var Strings: TPStrings; Size: Integer);

     { Clear all elements (set them to empty strings), does not free any
       storage. }
     procedure ClearTPStrings (var Strings: TPStrings);

     { Divide a string into substrings, using Separators as separator. A
       single trailing separator is ignored. Further trailing separators
       as well as any leading separators and multiple separators in a row
       produce empty substrings. }
     function TokenizeString (const Source: String; Separators: CharSet)
       = Res: PPStrings;

     { Divide a string into substrings, using SpaceCharacters as
       separators. The splitting is done according the usual rules of
       shells, using (and removing) single and double quotes and
       QuotingCharacter. Multiple, leading, and trailing separators are
       ignored. If there is an error, a message is stored in ErrMsg (if
       not Null), and nil is returned. nil is also returned (without an
       error message) if s is empty. }
     function ShellTokenizeString (const s: String; var ErrMsg: String) =
       Tokens: PPStrings;

     { String parsing routines }

     { All the following StrReadFoo functions behave similarly. They read
       items from a string s, starting at index i, to a variable Dest.
       They skip any space characters (spaces and tabs) by incrementing i
       first. They return True if successful, False otherwise. i is
       incremented accordingly if successful, otherwise i is left
       unchanged, apart from the skipping of space characters, and Dest
       is undefined. This behaviour makes it easy to use the functions in
       a row like this:

         i := 1;
         if StrReadInt    (s, i, Size)  and StrReadComma (s, i) and
            StrReadQuoted (s, i, Name)  and StrReadComma (s, i) and
            ...
            StrReadReal   (s, i, Angle) and (i > Length (s)) then ...

       (The check `i > Length (s)' is in case you don't want to accept
       trailing "garbage".) }

     { Just skip any space characters as described above. }
     procedure StrSkipSpaces (const s: String; var i: Integer);

     { Read a quoted string (as produced by QuoteString) from a string
       and unquote the result using UnQuoteString. It is considered
       failure if the result (unquoted) would be longer than the capacity
       of Dest. }
     function  StrReadQuoted (const s: String; var i: Integer; var Dest:
       String): Boolean; attribute (ignorable);

     { Read a string delimited with Delimiter from a string and return
       the result with the delimiters removed. It is considered failure
       if the result (without delimiters) would be longer than the
       capacity of Dest. }
     function  StrReadDelimited (const s: String; var i: Integer; var
       Dest: String; Delimiter: Char): Boolean; attribute (ignorable);

     { Read a word (consisting of anything but space characters and
       commas) from a string. It is considered failure if the result
       would be longer than the capacity of Dest. }
     function  StrReadWord (const s: String; var i: Integer; var Dest:
       String): Boolean; attribute (ignorable);

     { Check that a certain string is contained in s (after possible
       space characters). }
     function  StrReadConst (const s: String; var i: Integer; const
       Expected: String) = Res: Boolean; attribute (ignorable);

     { A simpler to use version of StrReadConst that expects a `,'. }
     function  StrReadComma (const s: String; var i: Integer) = Res:
       Boolean; attribute (ignorable);

     { Read an integer number from a string. }
     function  StrReadInt (const s: String; var i: Integer; var Dest:
       Integer): Boolean; attribute (ignorable);

     { Read a real number from a string. }
     function  StrReadReal (const s: String; var i: Integer; var Dest:
       Real): Boolean; attribute (ignorable);

     { Read a Boolean value, represented by a single character
       from CharactersTrue or CharactersFalse (cf. Char2Boolean), from a
       string. }
     function  StrReadBoolean (const s: String; var i: Integer; var Dest:
       Boolean): Boolean; attribute (ignorable);

     { Read an enumerated value, i.e., one of the entries of IDs, from a
       string, and stores the ordinal value, i.e., the index in IDs
       (always zero-based) in Dest. }
     function  StrReadEnum (const s: String; var i: Integer; var Dest:
       Integer; const IDs: array of PString): Boolean; attribute
       (ignorable);

     { String hash table }

     const
       DefaultHashSize = 1403;

     type
       THash = Cardinal;

       PStrHashList = ^TStrHashList;
       TStrHashList = record
         Next: PStrHashList;
         s: PString;
         i: Integer;
         p: Pointer
       end;

       PStrHashTable = ^TStrHashTable;
       TStrHashTable (Size: Cardinal) = record
         CaseSensitive: Boolean;
         Table: array [0 .. Size - 1] of PStrHashList
       end;

     function  HashString          (const s: String): THash;
     function  NewStrHashTable     (Size: Cardinal; CaseSensitive:
       Boolean) = HashTable: PStrHashTable;
     procedure AddStrHashTable     (HashTable: PStrHashTable; s: String;
       i: Integer; p: Pointer);
     procedure DeleteStrHashTable  (HashTable: PStrHashTable; s: String);
     function  SearchStrHashTable  (HashTable: PStrHashTable; const s:
       String; var p: Pointer): Integer;  { p may be Null }
     procedure StrHashTableUsage   (HashTable: PStrHashTable; var
       Entries, Slots: Integer);
     procedure DisposeStrHashTable (HashTable: PStrHashTable);


File: gpc.info,  Node: System,  Next: TFDD,  Prev: StringUtils,  Up: GPC Units

6.15.17 BP compatibility: System
--------------------------------

The following listing contains the interface of the System unit.

   This unit contains only BP's more exotic routines which are not
recommended to be used in new programs. Most of their functionality can
be achieved by more standard means already.

   _Note:_ `MemAvail' and `MaxAvail', provided in this unit, cannot
easily be achieved by other means. However, it is not recommended to
use them on any multi-tasking system at all, where memory is a shared
resource. The notes in the unit give some hints about how to avoid
using them.

   On special request, i.e., by defining the conditionals
`__BP_TYPE_SIZES__', `__BP_RANDOM__' and/or `__BP_PARAMSTR_0__', the
unit also provides BP compatible integer type sizes, a 100% BP
compatible pseudo random number generator and/or BP compatible
`ParamStr (0)' behaviour (the latter, however, only on some systems).

     { BP and partly Delphi compatible System unit for GPC

       This unit is released as part of the GNU Pascal project. It
       implements some rather exotic BP and Delphi compatibility
       features. Even many BP and Delphi programs don't need them, but
       they're here for maximum compatibility. Most of BP's and Delphi's
       System units' features are built into the compiler or the RTS.

       Note: The things in this unit are really exotic. If you haven't
       used BP or Delphi before, you don't want to look at this unit. :-)

       This unit depends on the conditional defines `__BP_TYPE_SIZES__',
       `__BP_RANDOM__', `__BP_PARAMSTR_0__' and `__BP_NO_ALLOCMEM__'.

       If `__BP_TYPE_SIZES__' is defined (with the `-D__BP_TYPE_SIZES__'
       option), the integer data types will be redefined to the sizes
       they have in BP or Delphi. Note that this might cause problems,
       e.g. when passing var parameters of integer types between units
       that do and don't use System. However, of the BP compatibility
       units, only Dos and WinDos use such parameters, and they have been
       taken care of so they work.

       If `__BP_RANDOM__' is defined (`-D__BP_RANDOM__'), this unit will
       provide an exactly BP compatible pseudo random number generator.
       In particular, the range for integer randoms will be truncated to
       16 bits like in BP. The RandSeed variable is provided, and if it's
       set to the same value as BP's RandSeed, it produces exactly the
       same sequence of pseudo random numbers that BP's pseudo random
       number generator does (whoever might need this ... ;-). Even the
       Randomize function will behave exactly like in BP. However, this
       will not be noted unless one explicitly tests for it.

       If `__BP_PARAMSTR_0__' is defined (`-D__BP_PARAMSTR_0__'), this
       unit will change the value of `ParamStr (0)' to that of
       `ExecutablePath', overwriting the value actually passed by the
       caller, to imitate BP's/Dos's behaviour. However *note*: On most
       systems, `ExecutablePath' is *not* guaranteed to return the full
       path, so defining this symbol doesn't change anything. In general,
       you *cannot* expect to find the full executable path, so better
       don't even try it, or your program will (at best) run on some
       systems. For most cases where BP programs access their own
       executable, there are cleaner alternatives available.

       If `__BP_NO_ALLOCMEM__' is defined (`-D__BP_NO_ALLOCMEM__'), the
       two Delphi compatible functions `AllocMemCount' and `AllocMemSize'
       will not be provided. The advantage is that this unit will not
       have to `Mark' the heap which makes memory de-/allocations much
       faster if the program doesn't use `Mark' otherwise.

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Authors: Peter Gerwinski <peter@gerwinski.de>
                Prof. Abimbola A. Olowofoyeku <African_Chief@bigfoot.com>
                Frank Heckenbach <frank@pascal.gnu.de>
                Dominik Freche <dominik.freche@gmx.net>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     module System;

     export System = all (FileMode {$ifdef __BP_TYPE_SIZES__},
       SystemInteger => Integer, SystemWord => Word {$endif});

     import GPC (MaxLongInt => GPC_MaxLongInt);

     var
       { Chain of procedures to be executed at the end of the program }
       ExitProc: ^procedure = nil;

       { Contains all the command line arguments passed to the program,
         concatenated, with spaces between them }
       CmdLine: CString;

       {$ifdef __BP_RANDOM__}
       { Random seed, initialized by Randomize, but can also be set
         explicitly }
       RandSeed: Integer attribute (Size = 32) = 0;
       {$endif}

     type
       OrigInt = Integer;
       OrigWord = Word;

       { Delphi }
       SmallInt = Integer attribute (Size = 16);
       DWord    = Cardinal attribute (Size = 32);

       { Short BP compatible type sizes if wanted }
       {$ifdef __BP_TYPE_SIZES__}
       ByteBool      = Boolean attribute (Size = 8);
       WordBool      = Boolean attribute (Size = 16);
       LongBool      = Boolean attribute (Size = 32);
       ShortInt      = Integer attribute (Size = 8);
       SystemInteger = Integer attribute (Size = 16);
       LongInt       = Integer attribute (Size = 32);
       Comp          = Integer attribute (Size = 64);
       Byte          = Cardinal attribute (Size = 8);
       SystemWord    = Cardinal attribute (Size = 16);
       LongWord      = Cardinal attribute (Size = 32);  { Delphi }
       {$else}
       SystemInteger = Integer;
       SystemWord    = Word;
       {$endif}

       {$if False}  { @@ doesn't work well (dialec3.pas) -- when GPC gets
       short
                         strings, it will be unnecessary }
       {$ifopt borland-pascal}
       String = String [255];
       {$endif}
       {$endif}

     const
       MaxInt     = High (SystemInteger);
       MaxLongInt = High (LongInt);

     { Return the lowest-order byte of x }
     function  Lo (x: LongestInt): Byte;

     { Return the second-lowest-order byte of x }
     function  Hi (x: LongestInt): Byte;

     { Swap the lowest-order and second-lowest-order bytes, mask out the
       higher-order ones }
     function  Swap (x: LongestInt): SystemWord;

     { Store the current directory name (on the given drive number if
       drive <> 0) in s }
     procedure GetDir (Drive: Byte; var s: String);

     { Dummy routine for compatibility. @@Use two overloaded versions
       rather than varargs when possible. }
     procedure SetTextBuf (var f: Text; var Buf; ...);

     { Mostly useless BP compatible variables }
     var
       SelectorInc: SystemWord = $1000;
       Seg0040: SystemWord = $40;
       SegA000: SystemWord = $a000;
       SegB000: SystemWord = $b000;
       SegB800: SystemWord = $b800;
       Test8086: Byte = 2;
       Test8087: Byte = 3;  { floating-point arithmetic is emulated
                              transparently by the OS if not present
                              in hardware }
       OvrCodeList: SystemWord = 0;
       OvrHeapSize: SystemWord = 0;
       OvrDebugPtr: Pointer = nil;
       OvrHeapOrg: SystemWord = 0;
       OvrHeapPtr: SystemWord = 0;
       OvrHeapEnd: SystemWord = 0;
       OvrLoadList: SystemWord = 0;
       OvrDosHandle: SystemWord = 0;
       OvrEmsHandle: SystemWord = $ffff;
       HeapOrg: Pointer absolute HeapLow;
       HeapPtr: Pointer absolute HeapHigh;
       HeapEnd: Pointer = Pointer (High (PtrCard));
       FreeList: Pointer = nil;
       FreeZero: Pointer = nil;
       StackLimit: SystemWord = 0;
       HeapList: SystemWord = 0;
       HeapLimit: SystemWord = 1024;
       HeapBlock: SystemWord = 8192;
       HeapAllocFlags: SystemWord = 2;
       CmdShow: SystemInteger = 0;
       SaveInt00: Pointer = nil;
       SaveInt02: Pointer = nil;
       SaveInt0C: Pointer = nil;
       SaveInt0D: Pointer = nil;
       SaveInt1B: Pointer = nil;
       SaveInt21: Pointer = nil;
       SaveInt23: Pointer = nil;
       SaveInt24: Pointer = nil;
       SaveInt34: Pointer = nil;
       SaveInt35: Pointer = nil;
       SaveInt36: Pointer = nil;
       SaveInt37: Pointer = nil;
       SaveInt38: Pointer = nil;
       SaveInt39: Pointer = nil;
       SaveInt3A: Pointer = nil;
       SaveInt3B: Pointer = nil;
       SaveInt3C: Pointer = nil;
       SaveInt3D: Pointer = nil;
       SaveInt3E: Pointer = nil;
       SaveInt3F: Pointer = nil;
       SaveInt75: Pointer = nil;
       RealModeRegs: array [0 .. 49] of Byte =
         (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
          0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
          0, 0, 0, 0, 0, 0, 0, 0);

     { Mostly useless BP compatible pointer functions }
     function  Ofs (const x): PtrWord;
     function  Seg (const x): PtrWord;
     function  Ptr (Seg, Ofs: PtrWord): Pointer;
     function  CSeg: PtrWord;
     function  DSeg: PtrWord;
     function  SSeg: PtrWord;
     function  SPtr: PtrWord;

     { Routines to handle BP's 6 byte `Real' type which is formatted like
       this:

       47                                                   0
       -|------- -------- -------- -------- --------|--------
        |                                           |
        +----------+                   +------------+
       47 Sign Bit |  8..46 Mantissa   | 0..7 Biased Exponent

       This format does not support infinities, NaNs and denormalized
       numbers. The first digit after the binary point is not stored and
       assumed to be 1. (This is called the normalized representation of
       a binary floating point number.)

       In GPC, this type is represented by the type `BPReal' which is
       binary compatible to BP's type, and can therefore be used in
       connection with binary files used by BP programs.

       The functions `RealToBPReal' and `BPRealToReal' convert between
       this type and GPC's `Real' type. Apart from that, `BPReal' should
       be treated as opaque.

       The variables `BPRealIgnoreOverflow' and `BPRealIgnoreUnderflow'
       determine what to do in the case of overflows and underflows. The
       default values are BP compatible. }

     var
       { Ignore overflows, and use the highest possible value instead. }
       BPRealIgnoreOverflow: Boolean = False;

       { Ignore underflows, and use 0 instead. This is BP's behaviour,
         but has the disadvantage of diminishing computation precision. }
       BPRealIgnoreUnderflow: Boolean = True;

     type
       BPRealInteral = Cardinal attribute (Size = 8);
       BPReal = packed record
         Format: packed array [1 .. 6] of BPRealInteral
       end;

     function RealToBPReal (r: Real) = BR: BPReal;
     function BPRealToReal (const BR: BPReal) = RealValue: Real;

     { Heap management stuff }

     const
       { Possible results for HeapError }
       HeapErrorRunError = 0;
       HeapErrorNil      = 1;
       HeapErrorRetry    = 2;

     var
       { If assigned to a function, it will be called when memory
         allocations do not find enough free memory. Its result
         determines if a run time error should be raised (the default),
         or nil should be returned, or the allocation should be retried
         (causing the routine to be called again if the allocation still
         doesn't succeed).

         Notes:

         - Returning nil can cause some routines of the RTS and units
           (shipped with GPC or third-party) to crash when they don't
           expect nil, so better don't use this mechanism, but rather
           CGetMem where needed.

         - Letting the allocation be retried, of course, only makes sense
           if the routine freed some memory before -- otherwise it will
           cause an infinite loop! So, a meaningful HeapError routine
           should dispose of some temporary objects, if available, and
           return HeapErrorRetry, and return HeapErrorRunError when no
           (more) of them are available. }
       HeapError: ^function (Size: SystemWord): SystemInteger = nil;

     { Just returns HeapErrorNil. When this function is assigned to
       HeapError, GetMem and New will return a nil pointer instead of
       causing a runtime error when the allocation fails. See the comment
       for HeapError above. }
     function  HeapErrorNilReturn (Size: SystemWord): SystemInteger;

     { Return the total free memory/biggest free memory block. Except
       under Win32 and DJGPP, these are expensive routines -- try to
       avoid them. Under Win32, MaxAvail returns the same as MemAvail, so
       don't rely on being able to allocate a block of memory as big as
       MaxAvail indicates. Generally it's preferable to not use these
       functions at all in order to do a safe allocation, but just try to
       allocate the memory needed using CGetMem, and check for a nil
       result. What makes these routines unrealiable is, e.g., that on
       multi-tasking systems, another process may allocate memory after
       you've called MemAvail/MaxAvail and before you get to do the next
       allocation. Also, please note that some systems over-commit
       virtual memory which may cause MemAvail to return a value larger
       than the actual (physical plus swap) memory available. Therefore,
       if you want to be "sure" (modulo the above restrictions) that the
       memory is actually available, use MaxAvail. }
     function  MemAvail: Cardinal;
     function  MaxAvail: Cardinal;

     { Delphi compatibility }

     function  CompToDouble (x: Comp): Double;
     function  DoubleToComp (x: Double): Comp;
     {$ifndef __BP_NO_ALLOCMEM__}
     function  AllocMemCount = Count: SystemInteger;
     function  AllocMemSize = Size: SizeType;
     {$endif}
     procedure Assert (Condition: Boolean);
     procedure DefaultAssertErrorProc (const Message, FileName: String;
       LineNumber: SystemInteger; ErrorAddr: Pointer);

     var
       AssertErrorProc: ^procedure (const Message, FileName: String;
       LineNumber: SystemInteger; ErrorAddr: Pointer) =
       @DefaultAssertErrorProc;
       NoErrMsg: Boolean = False;


File: gpc.info,  Node: TFDD,  Next: Trap,  Prev: System,  Up: GPC Units

6.15.18 Some text file tricks
-----------------------------

The following listing contains the interface of the TFDD unit.

   This unit provides some tricks with text files, e.g. a "tee" file
which causes everything written to it to be written to two other files.

     { Some text file tricks.

       Copyright (C) 2002-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030412}
     {$error This unit requires GPC release 20030412 or newer.}
     {$endif}

     unit TFDD;

     interface

     uses GPC;

     { Write to multiple files. Everything written to Dest after calling
       this procedure will be written to both File1 and File2. Can be
       chained. }
     procedure MultiFileWrite (var Dest, File1, File2: AnyFile);


File: gpc.info,  Node: Trap,  Next: Turbo3,  Prev: TFDD,  Up: GPC Units

6.15.19 Trap runtime errors
---------------------------

The following listing contains the interface of the Trap unit.

   This unit allows you to trap runtime errors, so a runtime error will
not abort the program, but pass the control back to a point within the
program. Use with care, and read the notes in the interface, please.

     { Trapping runtime errors

       The Trap unit allows you to trap runtime errors, so a runtime
       error will not abort the program, but pass the control back to a
       point within the program.

       The usage is simple. The TrapExec procedure can be called with a
       function (p) as an argument. p must take a Boolean argument. p
       will immediately be called with False given as its argument. When
       a runtime error would otherwise be caused while p is active, p
       will instead be called again with True as its argument. After p
       returns, runtime error trapping ends.

       When the program terminates (e.g. by reaching its end or by a Halt
       statement) and a runtime error was trapped during the run, Trap
       will set the ExitCode and ErrorAddr variables to indicate the
       trapped error.

       Notes:

       - After trapping a runtime error, your program might not be in a
         stable state. If the runtime error was a "minor" one (such as a
         range checking or arithmetic error), it should not be a problem.
         But if you, e.g., write a larger application and use Trap to
         prevent a sudden abort caused by an unexpected runtime error,
         you should make the program terminate regularly as soon as
         possible after a trapped error (perhaps by telling the user to
         save the data, then terminate the program and report the bug to
         you).

       - Since the trapping mechanism *jumps* back, it has all the
         negative effects that a (non-local!) `goto' can have! You should
         be aware of the consequences of all active procedures being
         terminated at an arbitrary point!

       - Nested traps are supported, i.e. you can call TrapExec again
         within a routine called by another TrapExec instance. Runtime
         errors trapped within the inner TrapExec invocation will be
         trapped by the inner TrapExec, while runtime errors trapped
         after its termination will be trapped by the outer TrapExec
         again.

       Copyright (C) 1996-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030303}
     {$error This unit requires GPC release 20030303 or newer.}
     {$endif}

     unit Trap;

     interface

     uses GPC;

     var
       TrappedExitCode: Integer = 0;
       TrappedErrorAddr: Pointer = nil;
       TrappedErrorMessageString: TString = '';

     { Trap runtime errors. See the comment at the top. }
     procedure TrapExec (procedure p (Trapped: Boolean));

     { Forget about saved errors from the innermost TrapExec instance. }
     procedure TrapReset;


File: gpc.info,  Node: Turbo3,  Next: WinDos,  Prev: Trap,  Up: GPC Units

6.15.20 BP compatibility: Turbo3
--------------------------------

The following listing contains the interface of the Turbo3 unit.

   This is a compatibility unit to BP's `Turbo3' compatibility unit to
TP3. ;-) It is not meant to be used in any newly written code.

     { Turbo Pascal 3.0 compatibility unit

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-}
     {$if __GPC_RELEASE__ < 20030412}
     {$error This unit requires GPC release 20030412 or newer.}
     {$endif}

     unit Turbo3;

     interface

     import GPC only (AssignTFDD);
            System (MemAvail => System_MemAvail,
                    MaxAvail => System_MaxAvail);
            CRT (LowVideo  => CRT_LowVideo,
                 HighVideo => CRT_HighVideo);

     var
       Kbd: Text;
       CBreak: Boolean absolute CheckBreak;

     procedure AssignKbd (var f: AnyFile);
     function  MemAvail: Integer;
     function  MaxAvail: Integer;
     function  LongFileSize (var f: AnyFile): Real;
     function  LongFilePos  (var f: AnyFile): Real;
     procedure LongSeek     (var f: AnyFile; aPosition: Real);
     procedure LowVideo;
     procedure HighVideo;


File: gpc.info,  Node: WinDos,  Prev: Turbo3,  Up: GPC Units

6.15.21 BP compatibility: WinDos
--------------------------------

The following listing contains the interface of the WinDos unit.

   This is a portable implementation of most routines from BP's
`WinDos' unit. A few routines that are Dos - or even IA32 real mode -
specific, are only available if `__BP_UNPORTABLE_ROUTINES__' is defined,
*Note BP Incompatibilities::.

   The same functionality and much more is available in the Run Time
System, *Note Run Time System::. The RTS routines usually have
different names and/or easier and less limiting interfaces (e.g.
`ReadDir' etc. vs. `FindFirst' etc.), and are often more efficient.

   Therefore, using this unit is not recommended in newly written
programs.

     { Mostly BP compatible portable WinDos unit

       This unit supports most, but not all, of the routines and
       declarations of BP's WinDos unit.

       Notes:

       - The procedures GetIntVec and SetIntVec are not supported since
         they make only sense for Dos real-mode programs (and GPC
         compiled programs do not run in real-mode, even on IA32 under
         Dos). The procedures Intr and MsDos are only supported under
         DJGPP if `__BP_UNPORTABLE_ROUTINES__' is defined (with the
         `-D__BP_UNPORTABLE_ROUTINES__' option). A few other routines are
         also only supported with this define, but on all platforms (but
         they are crude hacks, that's why they are not supported without
         this define).

       - The internal structure of file variables (TFileRec and TTextRec)
         is different in GPC. However, as far as TFDDs are concerned,
         there are other ways to achieve the same in GPC, see the GPC
         unit.

       Copyright (C) 1998-2006 Free Software Foundation, Inc.

       Author: Frank Heckenbach <frank@pascal.gnu.de>

       This file is part of GNU Pascal.

       GNU Pascal is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published
       by the Free Software Foundation; either version 2, or (at your
       option) any later version.

       GNU Pascal is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License
       along with GNU Pascal; see the file COPYING. If not, write to the
       Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
       02111-1307, USA.

       As a special exception, if you link this file with files compiled
       with a GNU compiler to produce an executable, this does not cause
       the resulting executable to be covered by the GNU General Public
       License. This exception does not however invalidate any other
       reasons why the executable file might be covered by the GNU
       General Public License. }

     {$gnu-pascal,I-,maximum-field-alignment 0}
     {$if __GPC_RELEASE__ < 20030412}
     {$error This unit requires GPC release 20030412 or newer.}
     {$endif}

     module WinDos;

     export WinDos = all (FCarry, FParity, FAuxiliary, FZero, FSign,
       FOverflow,
                          DosError, GetDate, GetTime, GetCBreak,
       SetCBreak,
                          GetVerify, SetVerify, DiskFree, DiskSize,
                          GetFAttr, SetFAttr, GetFTime, SetFTime,
                          UnpackTime, PackTime,
                          {$ifdef __BP_UNPORTABLE_ROUTINES__}
                          {$ifdef __GO32__}
                          Intr, MsDos,
                          {$endif}
                          DosVersion, SetDate, SetTime,
                          {$endif}
                          CStringGetEnv => GetEnvVar);

     import GPC (MaxLongInt => GPC_Orig_MaxLongInt);
            System;
            Dos (FindFirst => Dos_FindFirst,
                 FindNext  => Dos_FindNext,
                 FindClose => Dos_FindClose);

     const
       { File attribute constants }
       faReadOnly  = ReadOnly;
       faHidden    = Hidden;    { set for dot files except `.' and `..' }
       faSysFile   = SysFile;   { not supported }
       faVolumeID  = VolumeID;  { not supported }
       faDirectory = Directory;
       faArchive   = Archive;   { means: not executable }
       faAnyFile   = AnyFile;

       { Maximum file name component string lengths }
       fsPathName  = 79;
       fsDirectory = 67;
       fsFileName  = 8;
       fsExtension = 4;

       { FileSplit return flags }
       fcExtension = 1;
       fcFileName  = 2;
       fcDirectory = 4;
       fcWildcards = 8;

     type
       PTextBuf = ^TTextBuf;
       TTextBuf = TextBuf;

       { Search record used by FindFirst and FindNext }
       TSearchRec = record
         Fill: SearchRecFill;
         Attr: Byte8;
         Time, Size: LongInt;
         Name: {$ifdef __BP_TYPE_SIZES__}
               packed array [0 .. 12] of Char
               {$else}
               TStringBuf
               {$endif};
         Reserved: SearchRec
       end;

       { Date and time record used by PackTime and UnpackTime }
       TDateTime = DateTime;

       { 8086 CPU registers -- only used by the unportable Dos routines }
       TRegisters = Registers;

     { FindFirst and FindNext are quite inefficient since they emulate
       all the brain-dead Dos stuff. If at all possible, the standard
       routines OpenDir, ReadDir and CloseDir (in the GPC unit) should be
       used instead. }
     procedure FindFirst (Path: PChar; Attr: Word; var SR: TSearchRec);
     procedure FindNext  (var SR: TSearchRec);
     procedure FindClose (var SR: TSearchRec);
     function  FileSearch (Dest, FileName, List: PChar): PChar;
     function  FileExpand (Dest, FileName: PChar): PChar;
     function  FileSplit (Path, Dir, BaseName, Ext: PChar) = Res: Word;
     function  GetCurDir (Dir: PChar; Drive: Byte): PChar;
     procedure SetCurDir (Dir: PChar);
     procedure CreateDir (Dir: PChar);
     procedure RemoveDir (Dir: PChar);
     function  GetArgCount: Integer;
     function  GetArgStr (Dest: PChar; ArgIndex: Integer; MaxLen: Word):
       PChar;


File: gpc.info,  Node: Borland Pascal,  Next: Reference,  Prev: Programming,  Up: Top

7 A QuickStart Guide from Borland Pascal to GNU Pascal.
*******************************************************

This chapter is intended to be a QuickStart guide for programmers who
are familiar with Borland Pascal.

   Throughout the manual, we talk of "Borland Pascal" or "BP" for
short, to refer to Borland Pascal version 7 for Dos protected mode.
Other versions of Borland Pascal and Turbo Pascall don't differ too
much, but this one was the very last Dos version Borland has published,
so in most if not all cases, you can safely substitute the version
you're familiar with.

   "Borland Pascal" and "Turbo Pascal" are registered trademarks of
Borland Inc.

* Menu:

* BP Compatibility::
* BP Incompatibilities::
* IDE versus command line::
* Comments::
* BP Compatible Compiler Directives::
* Units; GPI files and Automake::
* Optimization::
* Debugging::
* Objects::
* Strings in BP and GPC::
* Typed Constants::
* Bit; Byte and Memory Manipulation::
* User-defined Operators in GPC::
* Data Types in BP and GPC::
* BP Procedural Types::
* Files::
* Built-in Constants::
* Built-in Operators in BP and GPC::
* Built-in Procedures and Functions::
* Special Parameters::
* Miscellaneous::
* BP and Extended Pascal::
* Portability hints::


File: gpc.info,  Node: BP Compatibility,  Next: BP Incompatibilities,  Up: Borland Pascal

7.1 BP Compatibility
====================

GNU Pascal (GPC) is compatible to version 7 of Borland Pascal (BP) to a
large extent and comes with portable replacements of the BP standard
units.

   However, BP is a 16-bit compiler while GPC is a 32/64-bit compiler,
so the size of the `Integer' type, for instance, is 16 bits in BP, but
at least 32 bits in GPC. If a BP program has been designed with
portability in mind from the ground up, it may work with GPC without
any change. Programs which rely on byte order, on the internals or
sizes of data types or which use unportable things like interrupts and
assembler code, will need to be changed. The following section lists
the possible problems with solutions.

   The GPC Run Time System (RTS) is fairly complete, and you can use
all libraries written for GNU C from GNU Pascal, so there is much less
need to use unportable constructs than there was in BP. (For example,
BP's Turbo Vision library uses assembler to call a local procedure
through a pointer. With GPC you can do this in Pascal just as with
global procedures.) Please do not throw away the advantage of full
portability by sticking to those workarounds.

   We have successfully ported real-world projects (with several 10000s
of lines) from BP to GPC, so this is possible for you, too.


File: gpc.info,  Node: BP Incompatibilities,  Next: IDE versus command line,  Prev: BP Compatibility,  Up: Borland Pascal

7.2 BP Incompatibilities
========================

This sections lists the remaining incompatibilities of GPC to BP, and
the problems you might encounter when porting BP programs from 16-bit
Dos to other platforms, and gives solutions for them.

   By "incompatibilites" we mean problems that can arise when trying to
compile a valid BP program with GPC. Of course, there are many features
in GPC that BP doesn't know, but we call them extensions unless they
can break valid BP programs, so they are not mentioned here. The
subsequent sections of the `Borland Pascal' chapter mention a number of
useful extensions that you might want to know about but which will not
break your BP code.

* Menu:

* String type::
* Qualified identifiers::
* Assembler::
* Move; FillChar::
* Real type::
* Graph unit::
* OOP units::
* Keep; GetIntVec; SetIntVec::
* TFDDs::
* Mem; Port; Ptr; Seg; Ofs; PrefixSeg; etc.::
* Endianness assumptions::

   Some of the differences can be "overcome" by command-line switches.
As a summary:

     --borland-pascal -w --uses=System -D__BP_TYPE_SIZES__ --pack-struct
     -D__BP_RANDOM__ -D__BP_UNPORTABLE_ROUTINES__ -D__BP_PARAMSTR_0__

   But please read the following notes, and don't use these switches
indiscriminately when not necessary. There are reasons why they are not
GPC's defaults.

* Menu:

* - -borland-pascal - disable GPC extensions::
* -w - disable all warnings::
* - -uses=System - Swap; HeapError; etc.::
* -D__BP_TYPE_SIZES__ - small integer types etc.::
* - -pack-struct - disable structure alignment::
* -D__BP_RANDOM__ - BP compatible pseudo random number generator::
* -D__BP_UNPORTABLE_ROUTINES__ - Intr; DosVersion; etc.::
* -D__BP_PARAMSTR_0__ - BP compatible ParamStr (0) behaviour::


File: gpc.info,  Node: String type,  Next: Qualified identifiers,  Up: BP Incompatibilities

7.2.1 String type
-----------------

GPC's internal string format (Extended Pascal string schema) is
different from BP's. BP compatible "short strings" will be implemented
in GPC soon, but in the meantime, you'll have to live with the
difference. In general, GPC's format has many advantages (no length
limit of 255 characters, constant and reference parameters always know
about their capacity, etc.), but you will see differences if you:

   - declare a variable as `String' without a capacity. However, GPC
     will assume 255 then (like BP) and only warn about it (and not even
     this when using `--borland-pascal', see below), so that's not a
     real problem. The "clean" way, however, is to declare `String
     [255]' when you mean so (but perhaps you'll prefer `String
     (2000)'? :-).

   - access "character 0" which happens to hold the length in BP. This
     does not work with string schemata. Use `Length' to get the
     length, and `SetLength' to modify it.

   - try to `FillChar' a string, e.g.  `FillChar (StringVar, 256, 0);',
     which would overwrite the `Capacity' field. Using `FillChar
     (StringVar[1], ...);' is alright since it accesses the characters
     of the string, not the `Capacity' and `Length' fields. If you want
     to set the length to zero, use `SetLength' (see above) or simply
     assign an empty string (`StringVar := '''). This is more efficient
     than clearing all the characters, anyway, and has the same effect
     for all normal purposes.

   - try to read or write strings from/to _binary_ files (`Text' files
     are no problem). You will have to rewrite the code. If you also
     want to get rid of the 255 character limit and handle endianness
     issues (see below) in one go, you can use the
     `ReadStringLittleEndian' etc. routines (*note Run Time System::),
     but if you need BP compatible strings (i.e., with a one-byte
     length field) in data files, you cannot use them (but you can
     easily modify them for this purpose).


File: gpc.info,  Node: Qualified identifiers,  Next: Assembler,  Prev: String type,  Up: BP Incompatibilities

7.2.2 Qualified identifiers
---------------------------

GPC supports "qualified identifiers", liek BP does. (In addition, it
also supports Extended Pascal style qualified identifiers which behave
a little differently for units and modules imported with `import'
rather than `uses'.)


File: gpc.info,  Node: Assembler,  Next: Move; FillChar,  Prev: Qualified identifiers,  Up: BP Incompatibilities

7.2.3 Assembler
---------------

GPC's inline assembler is not compatible to BP's. It uses "AT&T
syntax", supports a large variety of processors and works together with
GPC's optimizer. So, either convert your inline assembly to AT&T
syntax, or (usually better) to Pascal, or put it into an external file
which you can assemble with your favourite (32 bit) assembler. A
tutorial for using the GPC inline assembler is available at
`http://www.gnu-pascal.de/contrib/misc/gpcasm.zip'

   Since many things you usually do with assembler in BP are provided
by GPC's Run Time System (RTS), you will not need the inline assembler
as often as in BP. (See *Note Portability hints::.)

   The same applies to BP's `inline' directive for hand-written machine
code. GPC's `inline' directive works for Pascal routines (*note
Miscellaneous::), so you'll have to convert any hand-written machine
code to Pascal (and thereby make it more readable, portable and easier
to maintain while still getting the performance of inline code).


File: gpc.info,  Node: Move; FillChar,  Next: Real type,  Prev: Assembler,  Up: BP Incompatibilities

7.2.4 Move; FillChar
--------------------

GPC supports `Move' and `FillChar', and they're fully BP compatible.
However, some data structures have different internal formats which may
become relevant when using these procedures. E.g., using `Move' on file
variables does not work in GPC (there are reasons why assigning file
variables with `:=' is not allowed in Pascal, and circumventing this
restriction with `Move' is not a good idea). For other examples, see
*Note String type::, *Note Real type::, and *Note Endianness
assumptions::.


File: gpc.info,  Node: Real type,  Next: Graph unit,  Prev: Move; FillChar,  Up: BP Incompatibilities

7.2.5 Real type
---------------

GPC does not support BP's 6-byte `Real' type. It supports `Single',
`Double' and `Extended' which, at least on the IA32 and some other
processors, are compatible to BP.

   For BP's 6-byte `Real' type, GPC's `System' unit provides an
emulation, called `BPReal', as well as conversion routines to GPC's
`Real' type (which is the same as `Double'), called `RealToBPReal' and
`BPRealToReal'. You'll probably only need them when reading or writing
binary files containing values of the BP 6-byte real type. There are no
operators (e.g., `+') available for `BPReal', but since GPC supports
operator overloading, you could define them yourself (e.g., convert to
`Real', do the operation, and convert back). Needless to say that this
is very inefficient and should not be done for any serious
computations. Better convert your data after reading them from the file
and before writing them back, or simply convert your data files once
(the other types are more efficient even with BP on any non-prehistoric
processor, anyway).


File: gpc.info,  Node: Graph unit,  Next: OOP units,  Prev: Real type,  Up: BP Incompatibilities

7.2.6 Graph unit
----------------

A mostly BP compatible `Graph' unit exists as part of the `GRX'
package. It is known to work under DJGPP, Cygwin, mingw, Linux/IA32
with svgalib, and should work under any Unix system with X11 (tested
under Linux, Solaris, AIX, etc.).

   There is a small difference in the color numbering, but it should be
easy to work-around: You can't assume, e.g., that color 1 is always
blue, and 2 is green, etc. On a system with 15 or more bits of color
depth (i.e., 32768 or more colors, which most PCs today have), they
will all be very dark shades of blue. This is not really a bug, but
simply a property of modern high-color modes (whereas BP's `Graph' unit
was only designed for 16 and 256 color modes).

   However, the names `Blue', `Green' etc. stand for the correct colors
in the `Graph' unit of GRX. They are no constants, but functions
(because the color depth is in general not known until runtime), so you
can't use them in contexts where constants are expected. Also, they
might conflict with the identifiers of the `CRT' unit if you use both
units at the same time. If you want to use computed color values in the
range 0 ... 15, you can translate them to the correct colors using the
`EGAColor' function.


File: gpc.info,  Node: OOP units,  Next: Keep; GetIntVec; SetIntVec,  Prev: Graph unit,  Up: BP Incompatibilities

7.2.7 OOP units
---------------

The OOP stuff (Turbo Vision etc.) is not yet completed, but work on
several projects is underway. If you want information about the current
status or access to development source, please contact the GPC mailing
list.


File: gpc.info,  Node: Keep; GetIntVec; SetIntVec,  Next: TFDDs,  Prev: OOP units,  Up: BP Incompatibilities

7.2.8 Keep; GetIntVec; SetIntVec
--------------------------------

The routines `Keep', `GetIntVec' and `SetIntVec' in the `Dos' unit do
not even make sense on DJGPP (32 bit Dos extender). If your program
uses these, it is either a low-level Dos utility for which porting to a
32 bit environment might cause bigger problems (because the internal
issues of DPMI become relevant which are usually hidden by DJGPP), or
it installs interrupt handlers which will have to be thought about more
carefully because of things like locking memory, knowing about and
handling the differences between real and protected mode interrupts,
etc. For these kinds of things, we refer you to the DJGPP FAQ (*note
DJGPP FAQ: (djgppfaq)Top.).


File: gpc.info,  Node: TFDDs,  Next: Mem; Port; Ptr; Seg; Ofs; PrefixSeg; etc.,  Prev: Keep; GetIntVec; SetIntVec,  Up: BP Incompatibilities

7.2.9 TFDDs
-----------

The internal structure of file variables (`FileRec' and `TextRec' in
BP's `Dos' unit and `TFileRec' and `TTextRec' in BP's `WinDos' unit) is
different in GPC.  However, as far as "Text File Device Drivers"
(TFDDs) are concerned, GPC offers a more powerful mechanism. Please see
the RTS reference (*note Run Time System::), under `AssignTFDD'.


File: gpc.info,  Node: Mem; Port; Ptr; Seg; Ofs; PrefixSeg; etc.,  Next: Endianness assumptions,  Prev: TFDDs,  Up: BP Incompatibilities

7.2.10 Mem; Port; Ptr; Seg; Ofs; PrefixSeg; etc.
------------------------------------------------

Those few routines in the `System' unit that deal with segmented
pointers (e.g., `Ptr') are emulated in such a way that such ugly BP
constructs like
     PInteger (Ptr (Seg (a), Ofs (a) + 6 * SizeOf (Integer)))^ = 42
   work in GPC, but they do not provide access to absolute memory
addresses. Neither do `absolute' variables (which take a simple address
in the program's address space in GPC, rather than a segmented
address), and the `Mem' and `Port' arrays don't exist in GPC.

   As a replacement for `Port' on IA32 processors, you can use the
routines provided in the `Ports' unit, *Note Ports::. If you want to
access absolute memory addresses in the first megabyte under DJGPP, you
can't do this with normal pointers because DJGPP programs run in a
protected memory environment, unless you use a dirty trick called "near
pointer hack". Please see the DJGPP FAQ (*note DJGPP FAQ:
(djgppfaq)Top.) for this and for other ways.

   For similar reasons, the variable `PrefixSeg' in the `System' unit
is not supported. Apart from "TSR"s, its only meaningful use in BP
might be the setting of environment variables.  GPC provides the
`SetEnv' and `UnSetEnv' procedures for this purpose which you can use
instead of any BP equivalents based on `PrefixSeg'. (However note that
they will modify the program's own and its childs' environment, not its
parent's environment. This is a property - most people call it a
feature - of the environments, including DJGPP, that GPC compiled
programs run in.)


File: gpc.info,  Node: Endianness assumptions,  Next: - -borland-pascal - disable GPC extensions,  Prev: Mem; Port; Ptr; Seg; Ofs; PrefixSeg; etc.,  Up: BP Incompatibilities

7.2.11 Endianness assumptions
-----------------------------

GPC also runs on big-endian systems (*note Endianness::). This is, of
course, a feature of GPC, but might affect your programs when running
on a big-endian system if they make assumptions about endianness, e.g.,
by using type casts (or `absolute' declarations or variant records
misused as type casts) in certain ways. Please see the demo program
`absdemo.pas' for an example and how to solve it.

   Endianness is also relevant (the more common case) when exchanging
data between different machines, e.g. via binary files or over a
network. Since the latter is not easily possible in BP, and the
techniques to solve the problems are mostly the same as for files, we
concentrate on files here.

   First, you have to choose the endianness to use for the file. Most
known data formats have a specified endianness (usually that of the
processor on which the format was originally created). If you define
your own binary data format, you're free to choose the endianness to
use.

   Then, when reading or writing values larger than one byte from/to
the file, you have to convert them. GPC's Run Time System supports this
by some routines. E.g., you can read an array from a little-endian file
with the procedure `BlockReadLittleEndian', or write one to a
big-endian file with `BlockWriteBigEndian'.  _Note:_ The endianness in
the procedure names refers to the file, not the system - the routines
know about the endianness of the system they run on, but you have to
tell them the endianness of the file to use. This means you do not have
to (and must not) use an `ifdef' to use the version matching the
system's endianness.

   When reading or writing records or other more complicated
structures, either read/write them field by field using
`BlockReadBigEndian' etc., or read/write them with the regular
`BlockRead' and `BlockWrite' procedures and convert each field after
reading or before writing using procedures like `ConvertFromBigEndian'
or `ConvertToLittleEndian' (but remember, when writing, to undo the
conversion afterwards, if you want to keep using the data - this is not
necessary with `BlockWriteLittleEndian' etc.).

   Especially for strings, there are ready-made procedures like
`ReadStringBigEndian' or `WriteStringLittleEndian' which will
read/write the length as a 64 bit value (much space for really long
strings :-) in the given endianness, followed by the characters (which
have no endianness problem).

   All these routines are described in detail in the RTS reference
(*note Run Time System::), under `endianness'. The demo program
`endiandemo.pas' contains an example on how to use these routines.


File: gpc.info,  Node: - -borland-pascal - disable GPC extensions,  Next: -w - disable all warnings,  Prev: Endianness assumptions,  Up: BP Incompatibilities

7.2.12 - -borland-pascal - disable GPC extensions
-------------------------------------------------

GPC warns about some BP constructs which are especially "dirty", like
misusing typed constants as initialized variables. GPC also supports
some features that may conflict with BP code, like macros.  The command
line option `--borland-pascal' disables both, so you might want to use
it for a first attempt to compile your BP code under GPC. However, we
suggest you try compiling without this switch and fixing any resulting
problems as soon as you've become acquainted with GPC.


File: gpc.info,  Node: -w - disable all warnings,  Next: - -uses=System - Swap; HeapError; etc.,  Prev: - -borland-pascal - disable GPC extensions,  Up: BP Incompatibilities

7.2.13 -w - disable all warnings
--------------------------------

Even in `--borland-pascal' mode, GPC may warn about some dangerous
things. To disable *all* warnings, you can use the `-w' option (note:
lower-case `w'!). This is not recommended at all, but you may consider
it more BP compatible ...


File: gpc.info,  Node: - -uses=System - Swap; HeapError; etc.,  Next: -D__BP_TYPE_SIZES__ - small integer types etc.,  Prev: -w - disable all warnings,  Up: BP Incompatibilities

7.2.14 - -uses=System - Swap; HeapError; etc.
---------------------------------------------

A few exotic BP routines and declarations (e.g., `Swap' and
`HeapError') are contained in a `System' unit, *Note System::, which
GPC (unlike BP) does not automatically use in each program. To use it,
you can add a `uses System;' clause to your program. If you don't want
to change your code, the command line option `--uses=System' will do
the same.


File: gpc.info,  Node: -D__BP_TYPE_SIZES__ - small integer types etc.,  Next: - -pack-struct - disable structure alignment,  Prev: - -uses=System - Swap; HeapError; etc.,  Up: BP Incompatibilities

7.2.15 -D__BP_TYPE_SIZES__ - small integer types etc.
-----------------------------------------------------

Since GPC runs on 32 and 64 bit platforms, integer types have larger
sizes than in BP. However, if you use the `System' unit (*note -
-uses=System - Swap; HeapError; etc.::) and define the symbol
`__BP_TYPE_SIZES__' (by giving `-D__BP_TYPE_SIZES__' on the command
line), it will redeclare the types to the sizes used by BP. This is
less efficient and more limiting, but might be necessary if your
program relies on the exact type sizes.


File: gpc.info,  Node: - -pack-struct - disable structure alignment,  Next: -D__BP_RANDOM__ - BP compatible pseudo random number generator,  Prev: -D__BP_TYPE_SIZES__ - small integer types etc.,  Up: BP Incompatibilities

7.2.16 - -pack-struct - disable structure alignment
---------------------------------------------------

GPC by default aligns fields of records and arrays suitably for higher
performance, while BP doesn't. If you don't want the alignment (e.g.,
because the program relies on the internal format of your structures),
give the `--pack-struct' option.


File: gpc.info,  Node: -D__BP_RANDOM__ - BP compatible pseudo random number generator,  Next: -D__BP_UNPORTABLE_ROUTINES__ - Intr; DosVersion; etc.,  Prev: - -pack-struct - disable structure alignment,  Up: BP Incompatibilities

7.2.17 -D__BP_RANDOM__ - BP compatible pseudo random number generator
---------------------------------------------------------------------

GPC uses a more elaborate pseudo random number generator than BP does.
Using the `Random' and `Randomize' functions works the same way, but
there is no `RandSeed' variable (but a `SeedRandom' procedure).
However, if you use the `System' unit (*note - -uses=System - Swap;
HeapError; etc.::) and define the symbol `__BP_RANDOM__' (by giving
`-D__BP_RANDOM__' on the command line), it will provide a 100% BP
compatible pseudo random number generator, including the `RandSeed'
variable, which will produce exactly the same sequence of pseudo random
numbers that BP's pseudo random number generator does. Even the
`Randomize' function will then behave exactly like in BP.


File: gpc.info,  Node: -D__BP_UNPORTABLE_ROUTINES__ - Intr; DosVersion; etc.,  Next: -D__BP_PARAMSTR_0__ - BP compatible ParamStr (0) behaviour,  Prev: -D__BP_RANDOM__ - BP compatible pseudo random number generator,  Up: BP Incompatibilities

7.2.18 -D__BP_UNPORTABLE_ROUTINES__ - Intr; DosVersion; etc.
------------------------------------------------------------

A few more routines in the `Dos' and `WinDos' units besides the ones
mentioned under *Note Keep; GetIntVec; SetIntVec::, like `Intr' or
`DosVersion', are meaningless on non-Dos systems. By default, the `Dos'
unit does not provide these routines (it only provides those that are
meaningful on all systems, which are most of its routines, including
the most commonly used ones). If you need the unportable ones, you get
them by using the `System' unit (*note - -uses=System - Swap;
HeapError; etc.::) and defining the symbol `__BP_UNPORTABLE_ROUTINES__'
(by giving `-D__BP_UNPORTABLE_ROUTINES__' on the command line). If you
use `Intr' or `MsDos', your program will only compile under DJGPP then.
Other routines, e.g. `DosVersion' are emulated quite roughly on other
systems. Please see the notes in the `Dos' unit (*note Dos::) for
details.


File: gpc.info,  Node: -D__BP_PARAMSTR_0__ - BP compatible ParamStr (0) behaviour,  Prev: -D__BP_UNPORTABLE_ROUTINES__ - Intr; DosVersion; etc.,  Up: BP Incompatibilities

7.2.19 -D__BP_PARAMSTR_0__ - BP compatible ParamStr (0) behaviour
-----------------------------------------------------------------

In BP (or under Dos), `ParamStr (0)' always contains the full path of
the current executable. Under GPC, by default it contains what was
passed by the caller as the 0th argument - which is often the name of
the executable, but that's merely a convention, and it usually does not
include the path.

   If you use the `System' unit (*note - -uses=System - Swap;
HeapError; etc.::) and define the symbol `__BP_PARAMSTR_0__' (by giving
`-D__BP_PARAMSTR_0__' on the command line), it will change the value of
`ParamStr (0)' to that of `ExecutablePath', overwriting the value
actually passed by the caller, to imitate BP's/Dos's behaviour.
*However note:* On most systems, `ExecutablePath' is *not* guaranteed to
return the full path, so defining this symbol doesn't change anything.
In general, you *cannot* expect to find the full executable path, so
better don't even try it, or your program will (at best) run on some
systems. For most cases where BP programs access their own executable,
there are cleaner alternatives available.


File: gpc.info,  Node: IDE versus command line,  Next: Comments,  Prev: BP Incompatibilities,  Up: Borland Pascal

7.3 IDE versus command line
===========================

On the Dos (DJGPP) and Linux platforms, you can use RHIDE for GNU
Pascal; check the subdirectories of your DJGPP distribution.

   Unfortunately, there is no IDE which would run on all platforms. We
are working on it, but this will take some time. Please be patient - or
offer your help!

   Without an IDE, the GNU Pascal Compiler, GPC, is called about like
the command-line version of the Borland Pascal Compiler, BPC. Edit your
source file(s) with your favorite ASCII editor, then call GNU Pascal
with a command line like

     C:\GNU-PAS> gpc hello.pas -o hello.exe

on your Dos or OS/2 box or

     myhost:/home/joe/gnu-pascal> gpc hello.pas -o hello

on your Unix (or Unix-compatible) system.

   Don't omit the `.pas' suffix: GPC is a common interface for a Pascal
compiler, a C, ObjC and C++ compiler, an assembler, a linker, and
perhaps an Ada and a FORTRAN compiler. From the extension of your
source file GPC figures out which compiler to run. GPC recognizes
Pascal sources by the extension `.pas', `.p', `.pp' or `.dpr'.

   The `-o' is a command line option which tells GPC how the executable
has to be named. If not given, the executable will be called `a.out'
(Unix) or `a.exe' (Dos). However, you can use the
`--executable-file-name' to tell GPC to always call the executable like
the source (with the extension removed under Unix and changed to `.exe'
under Dos).

   Note that GPC is case-sensitive concerning file names and options,
so it will _not_ work if you type

     C:\GNU-PAS> GPC HELLO.PAS -O HELLO.EXE

   GPC is a very quiet compiler and doesn't print anything on the
screen unless you request it or there is an error. If you want to see
what is going on, invoke GPC with additional options:

     -Q            "don't be quiet"  (or: Quassel-Modus in German)

(with _capital_ `Q'!) means that GPC prints out the names of procedures
and functions it processes, and

     --verbose

or abbreviated

     -v

means that GPC informs you about the stages of compilation, i.e.
preprocessing, compiling, assembling, and linking.

   One example (this time for OS/2):

     [C:\GNU-Pascal] gpc --verbose -Q hello.pas

   Throughout this chapter, we will tell you about a lot of
command-line switches. They are all invoked this way.

   After compilation, there will be an executable `hello' file in the
current directory. (`hello.exe' on Dos or OS/2.) Just run it and enjoy.
If you're new to Unix, please note that the current directory is not on
the PATH in most installations, so you might have to run your program
as `./hello'. This also helps to avoid name conflicts with other
programs. Such conflicts are especially common with the program name
`test' which happens to be a standard utility under Unix that does not
print any output. If you call your program `test.pas', compile it, and
then invoke `test', you will usually not run your program, but the
utility which leads to mysterious problems. So, invoke your program as
`./test' or, better yet, avoid the name `test' for your programs.

   If there are compilation errors, GNU Pascal will not stop
compilation after the first one - as Borland Pascal does - but try to
catch all errors in one compilation. If you get more error messages
than your screen can hold, you can catch them in a file (e.g.
`gpc.out') or pipe them to a program like `more' in the following way:

     gpc hello.pas 2> gpc.out

   This works with OS/2 and any bash-like shell under Unix; for Dos you
must get a replacement for `command.com' which supports this kind of
redirection, or use the `redir' utility (see also the DJGPP FAQ, *Note
DJGPP FAQ: (djgppfaq)Top.):

     C:\GNU-PAS> redir -eo gpc hello.pas -o hello.exe | more

   You can also use Borland's IDE for GNU Pascal on the Dos platform:
Install the GNU Pascal Compiler in the Tools menu (via Options/Tools).

     Name:       GNU Pascal
     Path:       gpc
     Arguments:  $SAVE ALL --executable-file-name $NAME($EDNAME).pas
     HotKey:     Shift+F9

   Note once more that GPC is case-sensitive, so it is important to
specify `.pas' instead of the `.PAS' Borland Pascal would append
otherwise!

   You can include more command-line arguments to GNU Pascal (e.g.
`--automake'; see below) as you will learn more about them.

   Since Borland Pascal will try to recompile your program if you use
its `Run' menu function, you will need another tool to run your program:

     Name:       Run Program
     Path:       command.com
     Arguments:  /c $NAME($EDNAME)
     HotKey:     Shift+F10


File: gpc.info,  Node: Comments,  Next: BP Compatible Compiler Directives,  Prev: IDE versus command line,  Up: Borland Pascal

7.4 Comments
============

GPC supports comments surrounded by `{ }' and `(* *)', just like BP
does. According to the ISO 7185 and ISO 10206 standards, Pascal allows
comments opened with `(*' and closed with `}'. Borland Pascal does not
support such "mixed" comments, so you might have sources where passages
containing comments are "commented out" using the other kind of comment
delimiters. GPC's default behaviour is (like BP) not to allow mixed
comments, so you don't need to worry about this. However, if you happen
to like mixed comments, you can turn them on either by a command-line
option, or by a compiler directive:

     --mixed-comments     {$mixed-comments}    (*$mixed-comments*)

   GPC supports nested comments (e.g., `{ foo { bar } baz }'), but they
are disabled by default (compatible to BP which doesn't know nested
comments at all). You can enable them with the option
`--nested-comments' (or the equivalent compiler directive)

   GPC also supports Delphi style comments starting with `//' and
extending until the end of the line. This comment style is activated by
default unless one of the `--classic-pascal', `--extended-pascal',
`--object-pascal' or `--borland-pascal' dialect options is given. You
can turn them on or off with the `--[no-]delphi-comments' option.


File: gpc.info,  Node: BP Compatible Compiler Directives,  Next: Units; GPI files and Automake,  Prev: Comments,  Up: Borland Pascal

7.5 BP Compatible Compiler Directives
=====================================

All of BP's one-letter compiler directives (except H, P, Q, R, V) are
supported by GPC, though some of them are ignored because they are not
necessary under GPC. Besides, GPC supports a lot more directives. For
an overview, see *Note Compiler Directives::.


File: gpc.info,  Node: Units; GPI files and Automake,  Next: Optimization,  Prev: BP Compatible Compiler Directives,  Up: Borland Pascal

7.6 Units, GPI files and Automake
=================================

You can use units in the same way as in Borland Pascal. However, there
are some additional features.

   Concerning the syntax of a unit, you can, if you want, use Extended
Pascal syntax to specify a unit initializer, i.e., instead of writing

     begin
       ...
     end.

at the end of the unit, you can get the same result with

     to begin do
       begin
         ...
       end;

and there also exists

     to end do
       begin
         ...
       end;

which specifies a finalization routine. You can use this instead of
Borland Pascal's exit procedures, but for compatibility, the included
`System' unit also provides the `ExitProc' variable. The `to begin do'
and/or `to end do' parts must be followed by the final `end.'. See
*Note Modules::, for information about Extended Pascal modules, an
alternative to units.

   When GPC compiles a unit, it produces two files: an `.o' object file
(compatible with other GNU compilers such as GNU C) plus a `.gpi' file
which describes the interface.

   If you are interested in the internal format of GPI file, see *Note
GPI files::.

   If you want to compile a program that uses units, you must "make"
the project. (This is the command-line switch `-M' or the IDE keystroke
`F9' in BP.) For this purpose, GPC provides the command-line switch
`--automake':

     gpc --automake hello.pas

   If you want to force everything to be rebuilt rather than only
recompile changed files (`-B' or "build" in BP), use `--autobuild'
instead of `--automake':

     gpc --autobuild hello.pas

   For more information about the automake mechanism, see *Note
Automake::.

   If you do not want to use the automake mechanism for whatever
reason, you can also compile every unit manually and then link
everything together.

   GPC does not automatically recognize that something is a unit and
cannot be linked; you have to tell this by a command line switch:

     -c            only compile, don't link.

   (If you omit this switch when compiling a unit, you only get a
linker error message `undefined reference to `main''.  Nothing serious.)

   For example, to compile two units, use:

     gpc -c myunit1.pas myunit2.pas

   When you have compiled all units, you can compile a program that
uses them without using `--automake':

     gpc hello.pas

   However, using `--automake' is recommended, since it will recompile
units that were modified.

   You could also specify the program and the units in one command line:

     gpc hello.pas myunit1.pas myunit2.pas

   One of the purposes of writing units is to compile them separately.
However, GNU Pascal allows you to have one or more units in the same
source file (producing only one `.o' file but separate `.gpi' files).
You even can have a program and one or more units in one source file;
in this case, no `.o' file is produced at all.


File: gpc.info,  Node: Optimization,  Next: Debugging,  Prev: Units; GPI files and Automake,  Up: Borland Pascal

7.7 Optimization
================

GNU Pascal is a 32/64 bit compiler with excellent optimization
algorithms (which are identically the same as those of GNU C). There
are six optimization levels, specified by the command line options
`-O', `-O2', ..., `-O6'.

   One example:

     program OptimizationDemo;

     procedure Foo;
     var
       A, B: Integer;
     begin
       A := 3;
       B := 4;
       WriteLn (A + B)
     end;

     begin
       Foo
     end.

   When GNU Pascal compiles this program with optimization (`-O3'), it
recognizes that the argument to `WriteLn' is the constant 7 - and
optimizes away the variables `A' and `B'. If the variables were global,
they would not be optimized away because they might be accessed from
other places, but the constant 7 would still be optimized.

   For more about optimization, see the GNU C documentation.


File: gpc.info,  Node: Debugging,  Next: Objects,  Prev: Optimization,  Up: Borland Pascal

7.8 Debugging
=============

The command line option `-g' specifies generation of debugging
information for GDB, the GNU debugger. GDB comes with its own
documentation. Currently, GDB does not understand Pascal syntax, so you
should be familiar with C expressions if you want to use it.

   See also "Notes for debugging" in the "Programming" chapter; see
*Note Notes for Debugging::.

   Sometimes it is nice to have a look at the assembler output of the
compiler. You can do this in a debugger or disassembler (which is the
only way to do it in BP), but you can also tell GPC to produce
assembler code directly: When you specify the `-S' command line option,
GPC produces an `.s' file instead of an `.o' file.  The `.s' file
contains assembler source for your program. More about this in the next
section.


File: gpc.info,  Node: Objects,  Next: Strings in BP and GPC,  Prev: Debugging,  Up: Borland Pascal

7.9 Objects
===========

Objects in the Borland Pascal 7.0 notation are implemented into GNU
Pascal with the following differences:

   * the `private', `protected', `public' and `published' directives
     are recognized but ignored,

   * data fields and methods may be mixed:
          type
            MyObj = object
              x: Integer;
              procedure Foo; virtual;
              y: Real;
              function Bar: Char;
            end;


File: gpc.info,  Node: Strings in BP and GPC,  Next: Typed Constants,  Prev: Objects,  Up: Borland Pascal

7.10 Strings in BP and GPC
==========================

Strings are "Schema types" in GNU Pascal which is something more
advanced than Borland-style strings. For variables, you cannot specify
just `String' as a type like in Borland Pascal; for parameters and
pointer types you can. There is no 255 characters length limit.
According to Extended Pascal, the maximum string length must be in
(parentheses); GNU Pascal accepts [brackets], too, however, like BP.

   For more about strings and schema types see *Note Schema Types::.

   GPC supports Borland Pascal's string handling functions and some
more (see *Note String Operations::):

Borland Pascal           GNU Pascal
Length                   Length
Pos                      Pos, Index (1)
Str                      Str, WriteStr (1) (2)
Val                      Val, ReadStr (2)
Copy                     Copy, SubStr, MyStr[2 .. 7] (3)
Insert                   Insert
Delete                   Delete
MyStr[0] := #7           SetLength (MyStr, 7)
=, <>, <, <=, >, >=      =, <>, <, <=, >, >= (4)
                         EQ, NE, LT, LE, GT, GE
n/a                      Trim

   Notes:

   (1) The order of parameters of the Extended Pascal routines
(`Index', `WriteStr') is different from the Borland Pascal routines.

   (2) `ReadStr' and `WriteStr' allow an arbitrary number of arguments,
and the arguments are not limited to numbers.  `WriteStr' also allows
comfortable formatting like `WriteLn' does, e.g.  `WriteStr (Dest, Foo
: 20, Bar, 1/3 : 10 : 2)'.

   (3) `SubStr' reports a runtime error if the requested substring does
not fit in the given string, `Copy' does not (like in BP).

   (4) By default, the string operators behave like in BP. However, if
you use the option `--no-exact-compare-strings' or `--extended-pascal',
they ignore differences of trailing blanks, so, e.g., `'foo'' and `'foo
 '' are considered equal. The corresponding functions (`EQ', ...)
always do exact comparisons.


File: gpc.info,  Node: Typed Constants,  Next: Bit; Byte and Memory Manipulation,  Prev: Strings in BP and GPC,  Up: Borland Pascal

7.11 Typed Constants
====================

GNU Pascal supports Borland Pascal's "typed constants" but also
Extended Pascal's initialized variables:

     var
       x: Integer value 7;

   or

     var
       x: Integer = 7;

   When a typed constant is misused as an initialized variable, a
warning is given unless you specify `--borland-pascal'.

   When you want a local variable to preserve its value, define it as
`static' instead of using a typed constant. Typed constants also become
static automatically for Borland Pascal compatibility, but it's better
not to rely on this "feature" in new programs.  Initialized variables
do not become static automatically.

     program StaticDemo;

     procedure Foo;
     { x keeps its value between two calls to this procedure }
     var
       x: Integer = 0; attribute (static);
     begin
       WriteLn (x);
       Inc (x)
     end;

     begin
       Foo;
       Foo;
       Foo;
     end.

   For records and arrays, GPC supports both BP style and Extended
Pascal style initializers. When you initialize a record, you may omit
the field names. When you initialize an array, you may provide indices
with a `:'. However, this additional information is ignored completely,
so perhaps it's best for the moment to only provide the values ...

     program BPInitVarDemo;
     const
       A: Integer = 7;
       B: array [1 .. 3] of Char = ('F', 'o', 'o');
       C: array [1 .. 3] of Char = 'Bar';
       Foo: record
         x, y: Integer;
       end = (x: 3; y: 4);
     begin
     end.


File: gpc.info,  Node: Bit; Byte and Memory Manipulation,  Next: User-defined Operators in GPC,  Prev: Typed Constants,  Up: Borland Pascal

7.12 Bit, Byte and Memory Manipulation
======================================

The bitwise operators `shl', `shr', `and', `or', `xor' and `not' work
in GNU Pascal like in Borland Pascal.  As an extension, you can use
them as procedures, for example

     program AndProcedureDemo;
     var x: Integer;
     begin
       and (x, $0000ffff);
     end.

   as an alternative to

     program AndOperatorDemo;
     var x: Integer;
     begin
       x := x and $0000ffff;
     end.

   GPC accepts the BP style notation `$abcd' for hexadecimal numbers,
but you also can use Extended Pascal notation:

     program EPBaseDemo;
     const
       Binary =  2#11111111;
       Octal  =  8#177;
       Hex    = 16#ff;
     begin
     end.

   and so on up to a basis of 36. Of course, you can mix the notations
as you like, e.g.:

     program BPEPBaseDemo;
     begin
       WriteLn ($cafe = 2#1100101011111110)
     end.

   `Inc' and `Dec' are implemented like in Borland Pascal.  `Pred' and
`Succ' are generalized according to Extended Pascal and can have a
second (optional) parameter:

     procedure SuccDemo;
     var a: Integer = 42;
     begin
       a := Succ (a, 5);
       WriteLn (a) { 47 }
     end.

   BP style `absolute' variables work in the context of overloading
other variables as well as in the context of specifying an absolute
address, but the latter is highly unportable and not very useful even
in Dos protected mode.

     program BPAbsoluteDemo;

     type
       TString = String (80);
       TTypeChoice = (t_Integer, t_Char, t_String);

     { @@ WARNING: BAD STYLE! }
     procedure ReadVar (var x: Void; TypeChoice: TTypeChoice);
     var
       xInt: Integer absolute x;
       xChar: Char absolute x;
       xStr: TString absolute x;
     begin
       case TypeChoice of
         t_Integer: ReadLn (xInt);
         t_Char   : ReadLn (xChar);
         t_String : ReadLn (xStr);
       end
     end;

     var
       i: Integer;
       c: Char;
       s: TString;

     begin
       ReadVar (i, t_Integer);
       ReadVar (c, t_Char);
       ReadVar (s, t_String);
       WriteLn (i, ' ', c, ' ', s)
     end.

   GNU Pascal knows Borland Pascal's procedures `FillChar' and `Move'.
However, their use can be dangerous because it often makes implicit
unportable assumptions about type sizes, endianness, internal
structures or similar things. Therefore, avoid them whenever possible.
E.g., if you want to clear an array of strings, don't `FillChar' the
whole array with zeros (this would overwrite the Schema discriminants,
see *Note Strings::), but rather use a `for' loop to assign the empty
string to each string. In fact, this is also more efficient than
`FillChar', since it only has to set the length field of each string to
zero.


File: gpc.info,  Node: User-defined Operators in GPC,  Next: Data Types in BP and GPC,  Prev: Bit; Byte and Memory Manipulation,  Up: Borland Pascal

7.13 User-defined Operators in GPC
==================================

GNU Pascal allows the user to define operators according to the
Pascal-SC syntax:

     program PXSCOperatorDemo;

     type
       Point = record
         x, y: Real;
       end;

     operator + (a, b: Point) c: Point;
     begin
       c.x := a.x + b.x;
       c.y := a.y + b.y;
     end;

     var
       a, b, c: Point = (42, 0.5);

     begin
       c := a + b
     end.

   The Pascal-SC operators `+>', `+<', etc. for exact numerical
calculations are not implemented, but you can define them.


File: gpc.info,  Node: Data Types in BP and GPC,  Next: BP Procedural Types,  Prev: User-defined Operators in GPC,  Up: Borland Pascal

7.14 Data Types in BP and GPC
=============================

   * Integer types have different sizes in Borland and GNU Pascal:

     Borland Pascal      GNU Pascal         Bits (1)     Signed
     ShortInt            ByteInt             8           yes
     Integer             ShortInt           16           yes
     LongInt             Integer            32           yes
     Comp                LongInt, Comp      64           yes
     Byte                Byte                8           no
     Word                ShortWord          16           no
     n/a                 Word               32           no
     n/a                 LongWord           64           no

     (1) The size of the GNU Pascal types may depend on the platform.
     The sizes above apply to 32 bit platforms, including the IA32.

     If you care for types with exactly the same size as in Borland
     Pascal, take a look at the `System' unit and read its comments.

     You can get the size of a type with `SizeOf' in bytes (like in
     Borland Pascal) and with `BitSizeOf' in bits, and you can declare
     types with a specific size (given in bits), e.g.:

          program IntegerSizeDemo;
          type
            MyInt  = Integer attribute (Size = 42);  { 42 bits, signed }
            MyWord = Word attribute (Size = 2);      { 2 bits, unsigned,
                                                        i.e., 0 .. 3 }
            MyCard = Cardinal attribute (Size = 2);  { the same }

            HalfInt = Integer attribute (Size = BitSizeOf (Integer) div 2);
              { A signed integer type which is half as big as the normal
                `Integer' type, regardless of how big `Integer' is
                on any platform the program is compiled on. }

          begin
          end.

   * Borland's real (floating point) types are supported except for the
     6-byte software Real type (but the `System' unit provides
     conversion routines for it). GNU Pascals's `Real' type has 8 bytes
     on the IA32 and is the same as `Double'. In addition there are
     alternative names for real types:

     Borland Pascal      GNU Pascal
     Single              Single, ShortReal
     Real                n/a (1)
     Double              Double, Real
     Extended            Extended, LongReal
     Comp                LongInt, Comp (see above)

     (1) But see `BPReal', `RealToBPReal' and `BPRealToReal' in GPC's
     `System' unit.

   * Complex numbers: According to Extended Pascal, GNU Pascal has
     built-in complex numbers and supports a number of mathematical
     functions on them, e.g. `Abs', `Sqr', `SqRt', `Exp', `Ln', `Sin',
     `Cos', `ArcTan'.

   * Record types: GNU Pascal by default aligns 32-bit fields on 4-byte
     addresses because this improves performance. So, e.g., the record
          type
            MyRec = record
              f, o, oo: Boolean;
              Bar: Integer
            end;
     has 8 bytes, not 7. Use the `--pack-struct' option or declare the
     record as `packed' to force GPC to pack it to 7 bytes.  However,
     note that this produces somewhat less efficient code on the IA32
     and far less efficient code on certain other processors.  Packing
     records and arrays is mostly useful only when using large
     structures where memory usage is a real concern, or when reading or
     writing them from/to binary files where the exact layout matters.



File: gpc.info,  Node: BP Procedural Types,  Next: Files,  Prev: Data Types in BP and GPC,  Up: Borland Pascal

7.15 BP Procedural Types
========================

In addition to BP's procedural types, GNU Pascal has pointers to
procedures:

     type
       FuncPtr = ^function (Real): Real;

   The differences between procedure pointers and procedural types are
only syntactical:

   * In the first case, one can pass/assign a procedure/function with
     `@myproc', in the latter case just with `myproc' (which can lead
     to confusion in the case of functions - though GPC should always
     recognize the situation and not try to call the function).

   * In the first case, one can call the routine via `myprocptr^', in
     the latter case just with `myprocvar'.

   * To retrieve the address of a procedure stored in a variable, one
     can use `myprocptr' in the first case and `@myprocvar' in the
     latter.

   * If, for some reason, one needs the address of the variable itself,
     in the first case, that's obtained with `@myprocptr', in the
     second case with `@@myprocvar'!

   * Bottom line: BP style procedural types are simpler to use in normal
     cases, but somewhat strange in the last example.

   One can use both kinds in the same program, of course, though it is
recommended to stick to one kind throughout to avoid maximum confusion.

   GNU Pascal also supports Standard Pascal's procedural parameters
(*note Special Parameters::).

   Furthermore, GNU Pascal allows you to call even local procedures
through procedural pointers, variables or parameters without reverting
to any dirty tricks such as assembler (which is necessary in BP).

   The differences between the various kinds of procedural types,
pointers and parameters are demonstrated in the demo program
`procvardemo.pas'. An example for calling local routines through
procedural parameters can be found in the demo program
`iteratordemo.pas'.


File: gpc.info,  Node: Files,  Next: Built-in Constants,  Prev: BP Procedural Types,  Up: Borland Pascal

7.16 Files
==========

   * GPC supports files like in Borland Pascal, including untyped files,
     `BlockRead', `BlockWrite' and `Assign'. Instead of `Assign', you
     can also use the `Bind' mechanism of Extended Pascal.

     Besides the routines supproted by BP, there are many more routines
     available that deal with files, file names and similar things in a
     portable way. In contrast to Borland Pascal, you don't have to use
     any platform-specific units to do these kinds of things, though
     portable emulations of those units (e.g., of the `Dos' and
     `WinDos' units) are also available for compatibility.



File: gpc.info,  Node: Built-in Constants,  Next: Built-in Operators in BP and GPC,  Prev: Files,  Up: Borland Pascal

7.17 Built-in Constants
=======================

   * The `MaxInt', `MaxLongInt', `Pi' constants are supported like in
     BP.

   * Other built-in constants: GNU Pascal has `MaxChar', `MaxReal',
     `MinReal', `EpsReal' and a number of other useful constants.


File: gpc.info,  Node: Built-in Operators in BP and GPC,  Next: Built-in Procedures and Functions,  Prev: Built-in Constants,  Up: Borland Pascal

7.18 Built-in Operators in BP and GPC
=====================================

Besides the operators found in Borland Pascal, GNU Pascal supports the
following operators:

   * Exponentiation: According to Extended Pascal, GNU Pascal supports
     the exponentiation operators `pow' and `**' which do not exist in
     Borland Pascal. You can use `x pow y' for integer and `x ** y' for
     real or complex exponents. The basis may be integer, real or
     complex in both cases.

   * GNU Pascal has a symmetric set difference operator `set1 >< set2'.
     For more about this, see *Note Set Operations::.


File: gpc.info,  Node: Built-in Procedures and Functions,  Next: Special Parameters,  Prev: Built-in Operators in BP and GPC,  Up: Borland Pascal

7.19 Built-in Procedures and Functions
======================================

   * `GetMem' and `FreeMem' are supported like in BP.

     The second parameter to `FreeMem' is ignored by GNU Pascal and may
     be omitted. Memory blocks are always freed with the same size they
     were allocated with.

     Remark: Extended Pascal Schema types provide a cleaner approach to
     most of the applications of `GetMem' and `FreeMem'.

   * `Min' and `Max': GNU Pascal has built-in `Min' and `Max' functions
     (two arguments) which work for all ordinal types (`Integer',
     `Char', ...) plus `Real'.

   * `UpCase', `High', `Low' and similar functions are built-in. In
     contrast to Borland Pascal, GNU Pascal's `UpCase' function is
     aware of non-ASCII characters of certain languages (e.g., accented
     letters and "umlauts"), but for compatibility this feature is
     disables in `--borland-pascal' mode. There is also a `LoCase'
     function.

   * `Lo', `Hi', `Swap' functions: not built-in, but available in the
     `System' unit.


File: gpc.info,  Node: Special Parameters,  Next: Miscellaneous,  Prev: Built-in Procedures and Functions,  Up: Borland Pascal

7.20 Special Parameters
=======================

   * Untyped reference parameters can be denoted by

          procedure Foo (var x);

     like in Borland Pascal. In GNU Pascal, you can also use

          procedure Foo (var x: Void);

   * GNU Pascal defines "ellipsis" parameters for variable argument
     lists:

          procedure Foo (a: Integer; ...);

     However, GPC does not (yet) provide a portable mechanism to access
     the additional arguments.

   * Structured function result types: According to Extended Pascal, GNU
     Pascal allows functions to return records and arrays.

   * BP style "open array parameters"
          procedure Foo (a: array of Integer);
     are implemented. However, Standard Pascal `conformant array
     parameters' are usually a cleaner mechanism to pass arrays of
     variable size.

   * Besides BP compatible procedural types and procedure pointers
     (*note BP Procedural Types::), GNU Pascal supports Standard
     Pascal's procedural parameters:

          procedure DrawGraph (function f (x: Real): Real);


File: gpc.info,  Node: Miscellaneous,  Next: BP and Extended Pascal,  Prev: Special Parameters,  Up: Borland Pascal

7.21 Miscellaneous
==================

   * Headlines: According to Extended Pascal, a program headline must
     contain the program's parameters:

          program Foo (Input, Output);
          begin
          end.

     In GNU Pascal, headline parameters are optional. If the headline is
     omitted entirely, a warning is given unless you have specified
     `--borland-pascal' in the command line.

   * `case' statements: In a `case' statement, GNU Pascal allows
     `otherwise' (according to Extended Pascal) as an alternative to
     `else':

          program CaseOtherwiseDemo;
          var x: Integer;
          begin
            ReadLn (x);
            case x of
              1: WriteLn ('one');
              2: WriteLn ('two');
              otherwise
                 WriteLn ('many')
            end
          end.

     Note: In the absence of a `case' or `otherwise' branch, missing
     cases labels cause an error in Extended Pascal (which goes
     unnoticed in Borland Pascal). GPC does not give this error, but a
     warning if the `-Wswitch' option is given, however only for
     enumeration types.

   * Character constants: BP compatible character constants like `^M'
     as well as `#13' are implemented into GNU Pascal.

   * Sets: GNU Pascal has a `Card' function for sets which counts their
     elements. Unlike Borland Pascal, GNU Pascal does not limit sets to
     the range 0 .. 255.

   * Inline: GNU Pascal allows "inline" Pascal procedures and
     functions, while Borland Pascal only allows machine code to be
     inlined:

     Borland Pascal:

          function Max (x, y: Integer): Integer;
            inline ($58 / $59 / $3b / $c1 / $7f / $01 / $91);

     GNU Pascal:

          program InlineDemo;

          function Max (x, y: Integer): Integer; attribute (inline);
          begin
            if x > y then
              Max := x
            else
              Max := y
          end;

          begin
            WriteLn (Max (42, 17), ' ', Max (-4, -2))
          end.

     (Actually, a more general `Max' function is already built in.)

     This feature is not so important as it might seem because in
     optimization level 3 or higher (*note GPC Options::), GNU Pascal
     automatically inlines short procedures and functions.


File: gpc.info,  Node: BP and Extended Pascal,  Next: Portability hints,  Prev: Miscellaneous,  Up: Borland Pascal

7.22 BP and Extended Pascal
===========================

Pascal is a well-known programming language and hardly needs to be
described here. Note, however, that there is a large difference between
the language used by the BP compiler and the Pascal Standards.

   Extended Pascal is a standardized language based on the original
Standard Pascal, but with significant extensions. Unfortunately,
Borland Pascal does not conform to any of the Pascal standards.
Writing a program that both complies to Extended Pascal (or even
Standard Pascal) and compiles with BP is almost impossible for any
non-trivial task.

   On the other hand, BP has some nice features that make it very
powerful in the environments in which it runs. However, some of those
features are of little use on non-Dos systems and would not be good
candidates for standardization.

   There are also several BP features which are semantically similar to
features in Standard Pascal or Extended Pascal, but syntactically
different.

   Therefore, in order to be useful to users coming from either side,
GPC supports both the standards and the BP dialect as good as possible.
By default, GPC allows features from any dialect it knows.  By giving a
dialect option such as `--borland-pascal' or `--extended-pascal', you
can tell GPC to disable the features not found in that dialect, and to
adjust its warning behaviour to the dialect.

   The different sets of reserved words are a little problem, but GPC
solves it by making the words in question only "conditionally reserved"
which works transparently without problems in most cases. Still, giving
a dialect option will disable all keywords not part of this dialect.

   Apart from this, there are surprisingly few real conflicts between
the dialects. Therefore, you can usually compile your BP code without
the `--borland-pascal' option and make use of all of GPC's features.
You might be surprised, though, when GPC accepts things you didn't know
were allowed. :-)

   Finally, if you want to make use of some of GPC's extensions
(compared to BP) and still keep the code compileable with BP without
using `ifdef's all over the place, we suggest you look at the unit
`gpc-bp.pas', shipped with GPC, which contains BP versions of some of
GPC's features. Please read the comments at the beginning of the unit
to find out more about it.


File: gpc.info,  Node: Portability hints,  Prev: BP and Extended Pascal,  Up: Borland Pascal

7.23 Portability hints
======================

GPC offers you the possibility to make your code fully portable to each
of the many platforms supported by GPC. It would be a pity not to make
use of this.

   This section lists some known pitfalls that often hinder otherwise
well-written programs to take full advantage of GPC. If you have never
used any compiler but Borland Pascal and similar compilers, some of the
advices might look strange to you. But this is just the same level of
strangeness that your old programs will have for you once you have
understood the principles of cross-platform portability. Remember that
many tricks you have always been applying almost automatically in
Borland Pascal were necessary to overcome certain limitations of the
Dos platform and to compensate for the compiler's missing optimization.
Programming with an optimizing compiler like GPC for platforms without
a 64 kB limit is a completely new experience - and perhaps it is among
the reasons why you are now working with GPC in the first place?

Portability - why?
------------------

_Okay - but why should I bother and make my program portable?  I know
that all who want to use my program are running WXYZ-OS anyway._

   Yes, but that's the result of a self-fulfilling prophecy. It depends
on *you* whether it will always remain like this or not.  Consider a
program ABC written for a single platform, WXYZ-OS.  Naturally, only
WXYZ-OS-users get interested in ABC. The author gets feedback only from
WXYZ-OS users and does not see any reason to make the program
cross-platform. Then people realize that if they want to run ABC they
must move to WXYZ-OS. The author concludes that people only want
WXYZ-OS programs, and so on.

   To break out, just create a portable version of your program *now*.
Then all OSes have equal chances to show their abilities when running
your program, and your customers can choose their OS. Then, maybe, they
decide to use your program just for the reason that they can be sure
that it will run on all present and future platforms and not only on a
specific one - who knows?

   _My program is a tool specifically designed to make the best of the
STUV feature of WXYZ-OS. There is no point in making it portable._

   How much do you know about non-WXYZ-OSes? Just ask an expert how the
STUV feature is named elsewhere. Be sure, if it is of value, it exists
almost everywhere.

Low-level features
------------------

_I am using a lot of low-level stuff in my programs, so they cannot be
portable._

   You do not use those low-level routines directly in your high-level
routines, do you? There should always be a layer "in-between" that
encapsulates the low-level routines and present an API to your program
that exactly reflects the needs of your application.  This "API in
between" is the point where you can exchange the low-level routines by
portable calls to GPC's Run Time System.

   If you do not have such a layer in-between, then the API of the
low-level routines you call are your first approximation for such a
layer.  If you have ever thought "it would be great if that API
function had that additional parameter", then your own extended version
of that API function that *has* that parameter can become part of your
"API in between".  But then don't stop here: Certainly the API of the
OS is *not* ideal for your program's needs. Just create more routines
that encapsulate all OS-specific stuff ...

   When the low-level stuff in question consists of interrupts,
assembler and similar things, then the first thing you need is a
portable replacement of the functionality. Fortunately, GPC covers many
things already in Pascal that require assembler in Borland Pascal:

   * GPC's units and libraries come with source. You do not need to
     learn assembler and to write a complete replacement for the CRT
     unit if you only want to adapt some tiny detail in the behavior of
     CRT to your personal needs.

   * GPC's Run Time System is fairly complete. For example, to extract
     the assigned name of a `File' variable, you do not need to mess
     around with the internal representation of those variables, but you
     can type `uses GPC' and then use the `FileName' function.  In the
     same unit, you will find a `FileExists' function and much more.

   * Manually "constructing" an object is covered by the `SetType'
     procedure in GPC. This is where Turbo Vision uses assembler to load
     an object from a stream.

   * Calling local procedures and functions via pointers simply works in
     GPC. This is another place where, for instance, Turbo Vision's
     `ForEach' method uses assembler, while GPC lets you do the same
     thing in Pascal.

   * Interfacing with the OS can be done through library calls. GPC's
     built-in functions and the GPC unit offer a rather complete set of
     routines. And again: You have the source of all this.

   * Using `FillChar' and `Move' does not necessarily speed up your
     programs. Using them to circumvent restrictions of the language
     (e.g. for direct assignments between variables of object or file
     type) is asking for trouble. `FillChar' was created in UCSD Pascal
     to set consecutive chars in a string to the same value, and `Move'
     was created to move the chars within the same string.  Better do
     not use them for other purposes.



File: gpc.info,  Node: Reference,  Next: Keywords,  Prev: Borland Pascal,  Up: Top

8 The Alphabetical GPC Language Reference
*****************************************

*This chapter is still under development. All keywords and built-in
identifiers are listed, but not all with explanations.*

   This chapter contains an alphabetical list of all keywords (reserved
words) and built-in identifiers of the GNU Pascal compiler. For
detailed and comprehensive description of syntax and reserved words,
see *Note Programming::. This chapter explains only built-in procedures
and functions in detail.

   It does not cover extensions provided by external units and
libraries which are supposed to come with their own documentation.  For
the interfaces of the units that come with GPC, see *Note GPC Units::.

* Menu:

* Abs::
* absolute::
* abstract::
* Addr::
* AlignOf::
* all::
* and::
* and then::
* and_then::
* AnsiChar::
* AnyFile::
* Append::
* ArcCos::
* ArcSin::
* ArcTan::
* Arg::
* array::
* as::
* asm::
* asmname::
* Assert::
* Assign::
* Assigned::
* attribute::
* begin::
* Bind::
* bindable::
* Binding::
* BindingType::
* BitSizeOf::
* BlockRead::
* BlockWrite::
* Boolean::
* Break::
* Byte::
* ByteBool::
* ByteCard::
* ByteInt::
* c::
* Card::
* Cardinal::
* case::
* CBoolean::
* CCardinal::
* Char::
* ChDir::
* Chr::
* CInteger::
* c_language::
* class::
* Close::
* Cmplx::
* Comp::
* CompilerAssert::
* Complex::
* Concat::
* Conjugate::
* const::
* constructor::
* Continue::
* Copy::
* Cos::
* CString::
* CString2String::
* CStringCopyString::
* CurrentRoutineName::
* CWord::
* Cycle::
* Date::
* Dec::
* DefineSize::
* Delete::
* destructor::
* Discard::
* Dispose::
* div::
* do::
* Double::
* downto::
* else::
* Empty::
* end::
* EOF::
* EOLn::
* EpsReal::
* EQ::
* EQPad::
* Erase::
* except::
* Exclude::
* Exit::
* Exp::
* export::
* exports::
* Extend::
* Extended::
* external::
* Fail::
* False::
* far::
* file::
* FilePos::
* FileSize::
* FillChar::
* finalization::
* Finalize::
* finally::
* Flush::
* for::
* FormatString::
* forward::
* Frac::
* FrameAddress::
* FreeMem::
* function::
* GE::
* GEPad::
* Get::
* GetMem::
* GetTimeStamp::
* goto::
* GT::
* GTPad::
* Halt::
* High::
* if::
* Im::
* implementation::
* import::
* in::
* Inc::
* Include::
* Index::
* inherited::
* initialization::
* Initialize::
* InOutRes::
* Input::
* Insert::
* Int::
* Integer::
* interface::
* interrupt::
* IOResult::
* is::
* label::
* LastPosition::
* LE::
* Leave::
* Length::
* LEPad::
* library::
* Ln::
* LoCase::
* LongBool::
* LongCard::
* LongestBool::
* LongestCard::
* LongestInt::
* LongestReal::
* LongestWord::
* LongInt::
* LongReal::
* LongWord::
* Low::
* LT::
* LTPad::
* Mark::
* Max::
* MaxChar::
* MaxInt::
* MaxReal::
* MedBool::
* MedCard::
* MedInt::
* MedReal::
* MedWord::
* Min::
* MinReal::
* MkDir::
* mod::
* module::
* Move::
* MoveLeft::
* MoveRight::
* name::
* NE::
* near::
* NEPad::
* New::
* NewCString::
* nil::
* not::
* Null::
* object::
* Odd::
* of::
* on::
* only::
* operator::
* or::
* Ord::
* or else::
* or_else::
* otherwise::
* Output::
* overload::
* override::
* Pack::
* packed::
* Page::
* PAnsiChar::
* ParamCount::
* ParamStr::
* PChar::
* Pi::
* PObjectType::
* Pointer::
* Polar::
* Pos::
* Position::
* pow::
* Pred::
* private::
* procedure::
* program::
* property::
* protected::
* PtrCard::
* PtrDiffType::
* PtrInt::
* PtrWord::
* public::
* published::
* Put::
* qualified::
* raise::
* Random::
* Randomize::
* Re::
* Read::
* ReadLn::
* ReadStr::
* Real::
* record::
* Release::
* Rename::
* repeat::
* Reset::
* resident::
* restricted::
* Result::
* Return::
* ReturnAddress::
* Rewrite::
* RmDir::
* Round::
* RunError::
* Seek::
* SeekEOF::
* SeekEOLn::
* SeekRead::
* SeekUpdate::
* SeekWrite::
* segment::
* Self::
* set::
* SetFileTime::
* SetLength::
* SetType::
* shl::
* ShortBool::
* ShortCard::
* ShortInt::
* ShortReal::
* ShortWord::
* shr::
* Sin::
* Single::
* SizeOf::
* SizeType::
* SmallInt::
* Sqr::
* SqRt::
* StandardError::
* StandardInput::
* StandardOutput::
* StdErr::
* Str::
* String::
* String2CString::
* SubStr::
* Succ::
* Text::
* then::
* Time::
* TimeStamp::
* to::
* to begin do::
* to end do::
* Trim::
* True::
* Trunc::
* Truncate::
* try::
* type::
* type of::
* TypeOf::
* Unbind::
* unit::
* Unpack::
* until::
* UpCase::
* Update::
* uses::
* Val::
* value::
* var::
* view::
* virtual::
* Void::
* while::
* with::
* Word::
* WordBool::
* Write::
* WriteLn::
* WriteStr::
* xor::


File: gpc.info,  Node: Abs,  Next: absolute,  Up: Reference

Abs
===

Synopsis
--------

     function Abs (i: INTEGER_TYPE): INTEGER_TYPE;
or
     function Abs (x: REAL_TYPE): REAL_TYPE;
   or
     function Abs (z: COMPLEX_TYPE): REAL_TYPE;

Description
-----------

Returns the absolute value of the argument. For integer or real values
of `x', the definition is

     function Abs (x: INTEGER_OR_REAL_TYPE): INTEGER_OR_REAL_TYPE;
     begin
       if x < 0 then
         Abs := -x
       else
         Abs := x
     end;

whereas for complex values it is

     function Abs (x: Complex): Real;
     begin
       Abs := SqRt (x * Conjugate (x))
     end;

Conforming to
-------------

The function `Abs' is defined in ISO 7185 Pascal; its application to
complex values is defined in ISO 10206 Extended Pascal.

Example
-------

     program AbsDemo;
     var
       i1: Complex;
     begin
       WriteLn (Abs (42));             { 42 }
       WriteLn (Abs (-42));            { 42 }
       WriteLn (Abs (-12.1) : 0 : 1);  { 12.1 }
       i1 := Cmplx (1, 1);             { 1 + i }
       WriteLn (Abs (i1) : 0 : 3)      { 1.414, i.e. SqRt (2) }
     end.

See also
--------

*Note Sqr::.


File: gpc.info,  Node: absolute,  Next: abstract,  Prev: Abs,  Up: Reference

absolute
========

Synopsis
--------

     var
       VARIABLE_NAME: DATA_TYPE absolute VARIABLE_REFERENCE;
or
     var
       VARIABLE_NAME: DATA_TYPE absolute INTEGER_EXPRESSION;

Description
-----------

The first meaning of the `absolute' directive allows to put a variable
to the address of another one and thus provides a type-casting
mechanism.

   In most cases, VARIABLE_REFERENCE will be just a variable name, but
GPC also allows arbitrary pointer expressions here. If
VARIABLE_REFERENCE has neither a constant address nor is a variable
parameter, GPC prints a warning. This warning is suppressed in
"extended syntax" mode which is switched on by the `--extended-syntax'
option or the `{$X+}' compiler directive.

   GPC also allows explicit type casts. Variant records (as defined in
ISO 7185 Pascal), however, have no _guaranteed_ overlaying and are
therefore _not_ suitable for type casts.

   The second meaning of `absolute' places a variable at a specified
address. This is useful on machines without virtual memory addressing
for doing certain low-level operations, but should be avoided on
systems with memory protection such as Unix-like systems.  GPC does not
check whether the specified virtual address makes any sense and does
not provide a built-in mechanism to map it to a real address.

   GPC warns about this second use of `absolute' unless "extended
syntax" has been requested.

Conforming to
-------------

`absolute' is a Borland Pascal extension.

   Borland Pascal has a slightly different syntax for the second
meaning related to the addressing scheme of IA32 processors working in
real mode.

   Allowing arbitrary memory references instead of just variable names
in the first meaning of `absolute' is a GNU Pascal extension.

Example
-------

     program AbsoluteDemo;

     {$X+}

     const
       IOMem = $f0000000;
       MaxVarSize = MaxInt div 8;

     var
       Mem: array [0 .. MaxVarSize - 1] of Byte absolute 0;

       { This address has no actual meaning }
       MyPort: Byte absolute IOMem + $c030;

     { Beware: Using any of the variables above will crash
       your program unless you know exactly what you do!
       That's why GPC warns about it without the $X+ directive. }

     var
       x: Real;
       a: array [1 .. SizeOf (Real)] of Byte absolute x;
       i: Integer;
       b: Byte absolute a[i];  { GNU Pascal extension:
                                  non-constant memory reference. }

     begin
       x := 3.14;

       { Look at the internal representation of a real variable. }
       for i := 1 to SizeOf (Real) do
         Write (a[i] : 4);
       WriteLn;

       { The same again, more ugly ... }
       for i := 1 to SizeOf (Real) do
         Write (b : 4);
       WriteLn;

       { And yes, there's an even more ugly way to do it ... }
       for i := 1 to SizeOf (Real) do
         Write (Mem[PtrCard (@x) + i - 1] : 4);
       WriteLn
     end.

See also
--------

*Note Keywords::, *Note record::, *Note Type Casts::.


File: gpc.info,  Node: abstract,  Next: Addr,  Prev: absolute,  Up: Reference

abstract
========

Not yet implemented.

Synopsis
--------

Description
-----------

Abstract object type or method declaration.

Conforming to
-------------

`abstract' is an Object Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Addr,  Next: AlignOf,  Prev: abstract,  Up: Reference

Addr
====

Synopsis
--------

     function Addr (const Foo): Pointer;

Description
-----------

`Addr' returns the address of its argument. It is equivalent to the
address operator.

   Note: In BP, `Addr' returns an untyped pointer. GPC does this only
with `--borland-pascal'. Otherwise it returns a typed pointer. `Addr'
never depends on the `--[no]-typed-address' option/compiler directive,
unlike the address operator. (It is recommended you never rely on
untyped pointer results, but use a type-cast if really necessary.)

Conforming to
-------------

`Addr' is a Borland Pascal extension.

Example
-------

     program AddrDemo;
     var
       Foo: ^Integer;
       Bar: Integer;
     begin
       Foo := Addr (Bar);  { Let `Foo' point to `Bar'. }
       Bar := 17;
       Foo^ := 42;  { Change the value of `Bar' to 42 }
       WriteLn (Bar)
     end.

See also
--------

*Note Operators::.


File: gpc.info,  Node: AlignOf,  Next: all,  Prev: Addr,  Up: Reference

AlignOf
=======

Synopsis
--------

     function AlignOf (var x): Integer;

Description
-----------

Returns the alignment of a type or variable in bytes.

Conforming to
-------------

`AlignOf' is a GNU Pascal extension.

Example
-------

     program AlignOfDemo;
     var
       a: Integer;
       b: array [1 .. 8] of Char;
     begin
       WriteLn (AlignOf (a));  { Alignment of `Integer', e.g. 4 bytes. }
       WriteLn (AlignOf (Integer));  { The same. }
       WriteLn (AlignOf (b));  { Alignment of `Char'; usually 1 byte. }
     end.

   Although the array is bigger than a single char, it is accessed char
by char, so there usually is no need to align it on a 4 byte boundary or
such. (This may be false on some platforms.)

See also
--------

*Note SizeOf::, *Note BitSizeOf::, *Note TypeOf::.


File: gpc.info,  Node: all,  Next: and,  Prev: AlignOf,  Up: Reference

all
===

(Under construction.)

Synopsis
--------

Description
-----------

`export' extension (`export foo = all').

Conforming to
-------------

`all' is a GNU Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: and,  Next: and then,  Prev: all,  Up: Reference

and
===

Synopsis
--------

     operator and (operand1, operand2: Boolean) = Result: Boolean;
or
     operator and (operand1, operand2: INTEGER_TYPE) = Result: INTEGER_TYPE;
   or
     procedure and (var operand1: INTEGER_TYPE; operand2: INTEGER_TYPE);

Description
-----------

In GNU Pascal, `and' has three built-in meanings:

  1. Logical "and" between two `Boolean'-type expressions.  The result
     of the operation is of `Boolean' type.

     By default, `and' acts as a short-circuit operator in GPC: If the
     first operand is `False', the second operand is not evaluated
     because the result is already known to be `False'.  You can change
     this to complete evaluation using the `--no-short-circuit'
     command-line option or the `{$B+}' compiler directive.

  2. Bitwise "and" between two integer-type expressions.  The result is
     of the common integer type of both expressions.

  3. Use as a "procedure": `operand1' is "and"ed bitwise with
     `operand2'; the result is stored in `operand1'.


Conforming to
-------------

The logical `and' operator is defined in ISO 7185 Pascal.

   According to ISO, you cannot rely on `and' being a short-circuit
operator. On the other hand, GPC's default behaviour does _not_
contradict the ISO standard. (See *Note and_then::.)  However, since it
seems to be a de-facto standard among ISO Pascal compilers to evaluate
both operands of `and', GPC switches to `--no-short-circuit' mode if
one of the language dialect options selecting ISO Pascal, for instance
`--extended-pascal', is given. Use `--short-circuit' to override.

   Use of `and' as a bitwise operator for integers is a Borland Pascal
extension.

   Use of `and' as a "procedure" is a GNU Pascal extension.

Example
-------

     program AndDemo;
     var
       a, b, c: Integer;
     begin
       if (a = 0) and (b = 0) then  { logical `and' }
         c := 1
       else if (a and b) = 0 then  { bitwise `and' }
         c := 2
       else
         and (c, a)  { same as `c := c and a' }
     end.

   Note the difference between the logical `and' and the bitwise `and':
When `a' is 2 and `b' is 4, then `a and b' is 0.  *Beware:* `a and b =
0' has nothing to do with `(a = 0) and (b = 0)'!

   Since bitwise `and' has a higher priority than the `=' operator,
parentheses are needed in `if (a = 0) and (b = 0)' because otherwise `0
and b' would be calculated first, and the remainder would cause a parse
error.

See also
--------

*Note Keywords::, *Note and_then::, *Note and then::, *Note or::, *Note
xor::, *Note Operators::.


File: gpc.info,  Node: and then,  Next: and_then,  Prev: and,  Up: Reference

and then
========

Synopsis
--------

     { `and then' is built in. A user-defined operator cannot consist of
        two words. }
     operator and then (operand1, operand2: Boolean) = Result: Boolean;

Description
-----------

`and then' is an alias for the short-circuit logical operator
`and_then'.

Conforming to
-------------

While `and_then' is defined in ISO 10206 Extended Pascal, `and then' is
a GNU Pascal extension.

Example
-------

     program AndThenDemo;
     var
       p: ^Integer;
     begin
       New (p);
       ReadLn (p^);
       if (p <> nil) and then (p^ < 42) then  { This is safe. }
         WriteLn (p^, ' is less than 42')
     end.

See also
--------

*Note Keywords::, *Note and_then::, *Note and::, *Note or else::.


File: gpc.info,  Node: and_then,  Next: AnsiChar,  Prev: and then,  Up: Reference

and_then
========

Synopsis
--------

     operator and_then (operand1, operand2: Boolean) = Result: Boolean;

Description
-----------

The `and_then' short-circuit logical operator performs the same
operation as the logical operator `and'. But while the ISO standard
does not specify anything about the evaluation of the operands of `and'
- they may be evaluated in any order, or not at all - `and_then' has a
well-defined behaviour: It evaluates the first operand. If the result
is `False', `and_then' returns `False' without evaluating the second
operand. If it is `True', the second operand is evaluated and returned.

   Since the behaviour described above is the most efficient way to
implement `and', GPC by default treats `and' and `and_then' exactly the
same. If you want, for some reason, to have both operands of `and'
evaluated completely, you must assign both to temporary variables and
then use `and' - or `and_then', it does not matter.

Conforming to
-------------

`and_then' is an ISO 10206 Extended Pascal extension.

   Some people think that the ISO standard requires both operands of
`and' to be evaluated. This is false. What the ISO standard _does_ say
is that you cannot rely on a certain order of evaluation of the
operands of `and'; in particular things like the following program can
crash according to ISO Pascal, although they cannot crash when compiled
with GNU Pascal running in default mode.

     program AndBug;
     var
       p: ^Integer;
     begin
       New (p);
       ReadLn (p^);
       if (p <> nil) and (p^ < 42) then  { This is NOT safe! }
         WriteLn ('You''re lucky. But the test could have crashed ...')
     end.

Example
-------

     program And_ThenDemo;
     var
       p: ^Integer;
     begin
       New (p);
       ReadLn (p^);
       if (p <> nil) and_then (p^ < 42) then  { This is safe. }
         WriteLn (p^, ' is less than 42')
     end.

See also
--------

*Note Keywords::, *Note and then::, *Note and::, *Note or_else::.


File: gpc.info,  Node: AnsiChar,  Next: AnyFile,  Prev: and_then,  Up: Reference

AnsiChar
========

Synopsis
--------

     type
       AnsiChar = Char;

Description
-----------

`AnsiChar' is an 8 bit char type. Currently, it is the same as `Char',
but this might change in the future, once `wide chars' (16 bit chars)
will be introduced into GPC. Depending on the platform, `Char' might be
either `AnsiChar' or `WideChar' then.

Conforming to
-------------

`AnsiChar' is a Borland Delphi extension.

Example
-------

     program AnsiCharDemo;
     var
       A: AnsiChar;  { There is nothing special with `AnsiChar'. }
       B: Char;
     begin
       A := 'A';
       A := B
     end.

See also
--------

*Note PAnsiChar::, *Note Char::.


File: gpc.info,  Node: AnyFile,  Next: Append,  Prev: AnsiChar,  Up: Reference

AnyFile
=======

Synopsis
--------

     type
       AnyFile  { built-in type }

Description
-----------

`AnyFile' is a built-in type that can only be used for parameters and
pointer targets. Any kind of file variable (`Text', untyped and typed
`file') can be passed to such a parameter and their address assigned to
such a pointer. On the other side, only generic file operations are
possible with `AnyFile' parameters/pointer targets.

   This type is useful for implementing generic file handling routines.
Also some built-in file routines use this type for their parameters,
e.g. `IOSelectRead' (*note Run Time System::).

   `BlockRead' (*note BlockRead::) and `BlockWrite' (*note
BlockWrite::) treat `AnyFile' specially, in that they accept all
`AnyFile's as arguments (even if the actual file is a typed or `Text'
file) and always use a block size of 1 (even if the actual file is an
untyped file with different block size or a typed file of a type with
size not equal to one). This is the only way to reliably read/write a
certain amount of data from/to an `AnyFile'.

   `AnyFile' pointers cannot be allocated with `New' (because it would
be unspecified which kind of file to create).

Conforming to
-------------

`AnyFile' is a GNU Pascal extension.

Example
-------

     program AnyFileDemo;

     procedure Test (var f: AnyFile);
     var v: ^AnyFile;
     begin
       { Generic file operations are allowed for `AnyFile' }
       Rewrite (f);

       { `AnyFile' can also be accessed via pointers }
       v := @f;
       Close (v^)
     end;

     var
       t: Text;
       f: file;
       g: file of Integer;

     begin
       { Any kind of file variable can be passed as `AnyFile' }
       Test (t);
       Test (f);
       Test (g)
     end.

See also
--------

*Note Text::, *Note file::.


File: gpc.info,  Node: Append,  Next: ArcCos,  Prev: AnyFile,  Up: Reference

Append
======

Synopsis
--------

     procedure Append (var F: ANY_FILE; [FileName: String;]
                                         [BlockSize: Cardinal]);

Description
-----------

`Append' opens a file for writing. If the file does not exist, it is
created. If it does exist, the file pointer is positioned after the
last element.

   Like `Rewrite', `Reset' and `Extend' do, `Reset' accepts an optional
second parameter for the name of the file in the filesystem and a third
parameter for the block size of the file. The third parameter is
allowed only (and by default also required) for untyped files. For
details, see *Note Rewrite::.

Conforming to
-------------

`Append', including the `BlockSize' parameter, is a Borland Pascal
extension. ISO 10206 Extended Pascal has *Note Extend:: instead.  The
`FileName' parameter is a GNU Pascal extension.

Example
-------

     program AppendDemo;
     var
       Sample: Text;
     begin
       Assign (Sample, 'sample.txt');
       Rewrite (Sample);
       WriteLn (Sample, 'Hello, World!');  { `sample.txt' now has one line }
       Close (Sample);

       { ... }

       Append (Sample);
       WriteLn (Sample, 'Hello again!');  { `sample.txt' now has two lines }
       Close (Sample)
     end.

See also
--------

*Note Assign::, *Note Reset::, *Note Rewrite::, *Note Update::, *Note
Extend::.


File: gpc.info,  Node: ArcCos,  Next: ArcSin,  Prev: Append,  Up: Reference

ArcCos
======

Synopsis
--------

     function ArcCos (x: Real): Real;
or
     function ArcCos (z: Complex): Complex;

Description
-----------

`ArcCos' returns the (principal value of the) arcus cosine of the
argument. The result is in the range `0 < ArcCos (x) < Pi' for real
arguments.

Conforming to
-------------

`ArcCos' is a GNU Pascal extension.

Example
-------

     program ArcCosDemo;
     begin
       { yields 3.14159 as ArcCos (0.5) = Pi / 3 }
       WriteLn (3 * ArcCos (0.5) : 0 : 5)
     end.

See also
--------

*Note ArcSin::, *Note ArcTan::, *Note Sin::, *Note Cos::, *Note Ln::,
*Note Arg::.


File: gpc.info,  Node: ArcSin,  Next: ArcTan,  Prev: ArcCos,  Up: Reference

ArcSin
======

Synopsis
--------

     function ArcSin (x: Real): Real;
or
     function ArcSin (z: Complex): Complex;

Description
-----------

`ArcSin' returns the (principal value of the) arcus sine of the
argument. The result is in the range `-Pi / 2 < ArcSin (x) < Pi / 2'
for real arguments.

Conforming to
-------------

`ArcSin' is a GNU Pascal extension.

Example
-------

     program ArcSinDemo;
     begin
       { yields 3.14159 as ArcSin (0.5) = Pi / 6 }
       WriteLn (6 * ArcSin (0.5) : 0 : 5)
     end.

See also
--------

*Note ArcCos::, *Note ArcTan::, *Note Sin::, *Note Cos::, *Note Ln::,
*Note Arg::.


File: gpc.info,  Node: ArcTan,  Next: Arg,  Prev: ArcSin,  Up: Reference

ArcTan
======

Synopsis
--------

     function ArcTan (x: Real): Real;
or
     function ArcTan (z: Complex): Complex;

Description
-----------

`ArcTan' returns the (principal value of the) arcus tangent of the
argument. The result is in the range `-Pi / 2 < ArcTan (x) < Pi / 2'
for real arguments.

Conforming to
-------------

`ArcTan' is defined in ISO 7185 Pascal; its application to complex
values is defined in ISO 10206 Extended Pascal.

Example
-------

     program ArcTanDemo;
     begin
       { yields 3.14159 as ArcTan (1) = Pi / 4 }
       WriteLn (4 * ArcTan (1) : 0 : 5)
     end.

See also
--------

*Note ArcSin::, *Note ArcCos::, *Note Sin::, *Note Cos::, *Note Ln::,
*Note Arg::.


File: gpc.info,  Node: Arg,  Next: array,  Prev: ArcTan,  Up: Reference

Arg
===

Synopsis
--------

     function Arg (z: Complex): Real;

Description
-----------

`Arg' returns the complex "argument", i.e. the angle (in radian) in the
complex plane with respect to the real axis, of its parameter `z'. The
result is in the range of `-Pi < Arg (z) <= Pi'.

Conforming to
-------------

`Arg' is an ISO 10206 Extended Pascal extension.

Example
-------

     program ArgDemo;
     var
       z: Complex;
     begin
       z := Cmplx (1, 1);  { 1 + i }
       WriteLn (Arg (z) : 0 : 5)  { yields 0.78540, i.e. Pi / 4 }
     end.

See also
--------

*Note ArcTan::, *Note Ln::, *Note Polar::.


File: gpc.info,  Node: array,  Next: as,  Prev: Arg,  Up: Reference

array
=====

Synopsis
--------

In type definitions:
     array [INDEX_TYPE] of ELEMENT_TYPE
   or
     array [INDEX_TYPE, ..., INDEX_TYPE] of ELEMENT_TYPE

   In parameter list declarations:
     array of ELEMENT_TYPE

Description
-----------

The reserved word `array' is used to define an array type.

   @@conformant/open arrays

Conforming to
-------------

Array types are defined in ISO 7185 Pascal.

Example
-------

     program ArrayDemo;
     type
       IntArray = array [1 .. 20] of Integer;
       WeekDayChars = array [(Mon, Tue, Wed, Thu, Fri, Sat, Sun)] of Char;
       Foo = array [0 .. 9, 'a' .. 'z', (Baz, Glork1, Fred)] of Real;
       TwoDimIntArray = array [1 .. 10] of IntArray;
       { is equivalent to: }
       TwoDimIntArray2 = array [1 .. 10, 1 .. 20] of Integer;

     procedure PrintChars (F: array of Char);
     var
       i: Integer;
     begin
       for i := Low (F) to High (F) do
         WriteLn (F[i])
     end;

     var
       Waldo: WeekDayChars;

     begin
       Waldo := 'HiWorld';
       PrintChars (Waldo)
     end.

See also
--------

*Note Keywords::, *Note Array Types::, *Note High::, *Note Low::


File: gpc.info,  Node: as,  Next: asm,  Prev: array,  Up: Reference

as
==

(Under construction.)

Synopsis
--------

Description
-----------

Object type membership test and conversion.

Conforming to
-------------

`as' is an Object Pascal and a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::, *Note is::, *Note TypeOf::, *Note OOP::.


File: gpc.info,  Node: asm,  Next: asmname,  Prev: as,  Up: Reference

asm
===

(Under construction.)

Synopsis
--------

Description
-----------

See `http://www.gnu-pascal.de/contrib/misc/gpcasm.zip'.

Conforming to
-------------

`asm', as implemented in GPC, is a GNU Pascal extension. It is mostly
compatible to GCC's `asm', but not compatible to that of Borland Pascal.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: asmname,  Next: Assert,  Prev: asm,  Up: Reference

asmname
=======

Synopsis
--------

Description
-----------

*Deprecated*! Use `external name' now.

Conforming to
-------------

Example
-------

See also
--------

*Note Keywords::, *Note external::, *Note name::, *Note Importing
Libraries from Other Languages::.


File: gpc.info,  Node: Assert,  Next: Assign,  Prev: asmname,  Up: Reference

Assert
======

Synopsis
--------

     procedure Assert (Condition: Boolean);
or
     procedure Assert (Condition: Boolean; const Message: String);

Description
-----------

`Assert' checks the given `Condition' at run-time. If it is true, it
does nothing. If it is false, it raises a runtime error, using the
second argument for the message if given.

   However, if the switch `--no-assertions' is given (*note GPC Command
Line Options::), `Assert' is deactivated. It still evaluates the
condition if it has side effects, but never raises a runtime error.

Conforming to
-------------

`Assert' is a Borland Delphi extension.

Example
-------

See also
--------

*Note CompilerAssert::.


File: gpc.info,  Node: Assign,  Next: Assigned,  Prev: Assert,  Up: Reference

Assign
======

(Under contruction.)

Synopsis
--------

     procedure Assign (var F: ANY_FILE; FileName: String);

Description
-----------

Conforming to
-------------

`Assign' is a Borland Pascal extension.

Example
-------

See also
--------

*Note Reset::, *Note Rewrite::, *Note Update::, *Note Extend::, *Note
Append::.


File: gpc.info,  Node: Assigned,  Next: attribute,  Prev: Assign,  Up: Reference

Assigned
========

(Under construction.)

Synopsis
--------

     function Assigned (p: Pointer): Boolean;
or
     function Assigned (p: PROCEDURAL_TYPE): Boolean;

Description
-----------

The `Assigned' function returns `True' if the pointer parameter or the
address of the procedural parameter is not `nil'; it returns `False' if
it is `nil'.

Conforming to
-------------

`Assigned' is a Borland Pascal extension.

Example
-------

     program AssignedDemo;
     type
       PInt = ^Integer;

     procedure TellIfOdd (p: PInt);
     begin
       if Assigned (p) and then Odd (p^) then
         WriteLn ('The pointer p points to an odd value.')
     end;

     var
       foo: Integer;
     begin
       TellIfOdd (nil);
       foo := 1;
       TellIfOdd (@foo);
       foo := 2;
       TellIfOdd (@foo)
     end.

See also
--------

*Note Null::, *Note nil::, *Note Pointer::.


File: gpc.info,  Node: attribute,  Next: begin,  Prev: Assigned,  Up: Reference

attribute
=========

(Under construction.)

Synopsis
--------

     DECLARATION attribute (NAME);

   or

     DECLARATION attribute (NAME = PARAMETER);

   or

     DECLARATION attribute (NAME (PARAMETER, PARAMETER ...));

Description
-----------

Several attributes can be given in one `attribute' directive, separated
with `,', or in several `attribute' directives.

   Besides the attributes that GCC supports (*note Attribute Syntax:
(gcc)Attribute Syntax.), GPC allows the following attributes for
variables:

   * static

   * register

   * volatile

   * const

   * external

   * name (with a string constant parameter)

   For routines it allows the following additional attributes:

   * ignorable

   * inline

   * iocritical

   * name (with a string constant parameter)

   * noinline

   For types it allows the following additional attributes:

   * iocritical (for procedural [pointer] types)

   * size (with an integer constant parameter)

   `Size' can be applied to integer and Boolean types to produce types
with a specified size in bits; for example

     type
       Card16 = Cardinal attribute (Size = 16);

defines an unsigned integer type with 16 bits.

   Variable and routine attributes are preceded by a `;', type
attributes are not. So, e.g., in the following example, the `Size'
attribute applies to the type, and the `static' attribute to the
variable.
     var a: Integer attribute (Size = 64); attribute (static);

Conforming to
-------------

`attribute' is a GNU Pascal extension.

Example
-------

     program AttributeDemo;

     { Demo for `iocritical' attribute. }

     { Program will abort with a runtime error! }

     {$I-}
     procedure p; attribute (iocritical);
     var t: Text;
     begin
       Reset (t)  { Will not cause a runtime error here because I/O
                    checking is off, but leave InOutRes set. }
     end;
     {$I+}

     begin

       p;
       { Since `p' was declared `iocritical', and I/O checking is now on,
         InOutRes is checked immediately after the call to p, and a
         runtime error raised. }

       { So this statement is never reached. }
       InOutRes := 0;

       { Neither this one, which would be reached without the
         `iocritical' attribute. }
       WriteLn ('never gets here')

     end.

See also
--------

*Note Keywords::, *Note external::.


File: gpc.info,  Node: begin,  Next: Bind,  Prev: attribute,  Up: Reference

begin
=====

Synopsis
--------

     begin
       STATEMENT;
       STATEMENT;
       ...
       STATEMENT
     end;

Description
-----------

The reserved word `begin' opens a `begin ... end' statement which joins
several STATEMENTS to one compound statement.

Conforming to
-------------

`begin' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program BeginDemo;
     begin
       if True then
         WriteLn ('single statement');
       if True then
         begin                     { clamp statement1 ... }
           WriteLn ('statement1');
           WriteLn ('statement2')
         end                       { ... to statement2 }
     end.

See also
--------

*Note Keywords::, *Note begin end Compound Statement::, *Note end::


File: gpc.info,  Node: Bind,  Next: bindable,  Prev: begin,  Up: Reference

Bind
====

(Under construction.)

Synopsis
--------

     procedure Bind (var F: ANY_FILE; B: BindingType);

Description
-----------

Conforming to
-------------

`Bind' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Unbind::, *Note Binding::, *Note BindingType::, *Note bindable::.


File: gpc.info,  Node: bindable,  Next: Binding,  Prev: Bind,  Up: Reference

bindable
========

(Under construction.)

Synopsis
--------

Description
-----------

External bindability of files.

Conforming to
-------------

`bindable' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Keywords::, *Note Bind::, *Note Unbind::, *Note Binding::, *Note
BindingType::.


File: gpc.info,  Node: Binding,  Next: BindingType,  Prev: bindable,  Up: Reference

Binding
=======

(Under construction.)

Synopsis
--------

     function Binding (F: ANY_FILE): BindingType;

Description
-----------

Conforming to
-------------

`Binding' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Bind::, *Note Unbind::, *Note BindingType::, *Note bindable::.


File: gpc.info,  Node: BindingType,  Next: BitSizeOf,  Prev: Binding,  Up: Reference

BindingType
===========

(Under construction.)

Synopsis
--------

     type
       UnixTimeType = LongInt;
       BindingType = packed record
         Bound,
         Force,                     { Can be set to allow binding to
                                      directories or inaccessible files }
         Extensions_Valid,
         Readable,
         Writable,
         Executable,
         Existing,                  { Binding points to an existing file }
         Directory,                 { Binding points to an existing
                                      directory; `Existing' is False
                                      in this case }
         Special,                   { Binding points to an existing
                                      special file (device, pipe, socket,
                                      etc.); `Existing' is False in
                                      this case }
         SymLink: Boolean;          { Binding points to a symbolic link }
         Size: FileSizeType;        { Size of file, or -1 if unknown }
         AccessTime,                { Time of last access }
         ModificationTime,          { Time of last modification }
         ChangeTime: UnixTimeType;  { Time of last change }
         User,                      { User ID of owner }
         Group,                     { Group ID of owner }
         Mode,                      { Access permissions, cf. ChMod }
         Device,                    { Device the file is on }
         INode,                     { Unix INode number }
         Links: Integer;            { Number of hard links }
         TextBinary: Boolean;       { Open a Text file in binary mode }
         Handle: Integer;           { Can be set to bind a Pascal file to
                                      a given file handle }
         CloseFlag: Boolean;        { If Handle is used, tell whether to
                                      close it when file is closed }
         Name: String (BindingNameLength)
       end;

   `BindingNameLength' is an implementation-defined constant.

Description
-----------

Conforming to
-------------

`BindingType' is an ISO 10206 Extended Pascal extension. The fields
`Bound' and `Name' are required by Extended Pascal, the other ones are
GNU Pascal extensions.

Example
-------

See also
--------

*Note Bind::, *Note Unbind::, *Note Binding::, *Note bindable::.


File: gpc.info,  Node: BitSizeOf,  Next: BlockRead,  Prev: BindingType,  Up: Reference

BitSizeOf
=========

Synopsis
--------

     function BitSizeOf (var x): SizeType;

Description
-----------

Returns the size of a type or variable in bits.

Conforming to
-------------

`BitSizeOf' is a GNU Pascal extension.

Example
-------

     program BitSizeOfDemo;
     type
       Int12 = Integer attribute (Size = 12);
     var
       a: Integer;
       b: array [1 .. 8] of Char;
       c: Int12;
       d: packed record
            x: Int12;
            y: 0 .. 3
          end;
     begin
       WriteLn (BitSizeOf (a));    { Size of an `Integer'; usually 32 bits. }
       WriteLn (BitSizeOf (Integer));  { The same. }
       WriteLn (BitSizeOf (b));    { Size of eight `Char's; usually 64 bits. }
       WriteLn (BitSizeOf (c));    { e.g. 16 bits (smallest addressable
                                      space holding a 12 bit integer). }
       WriteLn (BitSizeOf (d));    { e.g. 16 }
       WriteLn (BitSizeOf (d.x));  { 12 }
       WriteLn (BitSizeOf (d.y))   { 2 }
     end.

See also
--------

*Note SizeOf::, *Note AlignOf::, *Note TypeOf::.


File: gpc.info,  Node: BlockRead,  Next: BlockWrite,  Prev: BitSizeOf,  Up: Reference

BlockRead
=========

(Under construction.)

Synopsis
--------

     procedure BlockRead (var F: File; var Buffer; Blocks: Integer);
or
     procedure BlockRead (var F: File; var Buffer; Blocks: Integer;
                          var BlocksRead: Integer);

Description
-----------

Conforming to
-------------

`BlockRead' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: BlockWrite,  Next: Boolean,  Prev: BlockRead,  Up: Reference

BlockWrite
==========

(Under construction.)

Synopsis
--------

     procedure BlockWrite (var F: File; const Buffer; Blocks: Integer);
or
     procedure BlockWrite (var F: File; const Buffer; Blocks: Integer;
                           var BlocksWritten: Integer);

Description
-----------

Conforming to
-------------

`BlockWrite' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Boolean,  Next: Break,  Prev: BlockWrite,  Up: Reference

Boolean
=======

Synopsis
--------

     type
       Boolean = (False, True); { built-in type }

Description
-----------

The intrinsic `Boolean' represents boolean values, i.e. it can only
assume the two values `True' and `False' (which are predefined
constants).

Conforming to
-------------

`Boolean' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

     program BooleanDemo;
     var
       a: Boolean;
     begin
       a := True;
       WriteLn (a)
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note True::, *Note False::, *Note
CBoolean::, *Note ByteBool::, *Note ShortBool::, *Note MedBool::, *Note
WordBool::, *Note LongBool::, *Note LongestBool::.


File: gpc.info,  Node: Break,  Next: Byte,  Prev: Boolean,  Up: Reference

Break
=====

Synopsis
--------

     Break  { simple statement }

Description
-----------

With `Break' you can exit the body of the current loop instantly. It
can only be used within a `while', `repeat' or a `for' loop.

Conforming to
-------------

`Break' is a Borland Pascal extension. Mac Pascal has `Leave' instead.

Example
-------

     program BreakDemo;
     var
       Foo: Integer;
     begin
       while True do
         begin
           repeat
             WriteLn ('Enter a number less than 100:');
             ReadLn (Foo);
             if Foo < 100 then
               Break;  { Exits `repeat' loop }
             WriteLn (Foo, ' is not exactly less than 100! Try again ...')
           until False;
           if Foo > 50 then
             Break;  { Exits `while' loop }
           WriteLn ('The number entered was not greater than 50.')
         end
     end.

See also
--------

*Note Loop Control Statements::, *Note Continue::, *Note Cycle::, *Note
Exit::, *Note Halt::, *Note Leave::, *Note Return::, *Note goto::.


File: gpc.info,  Node: Byte,  Next: ByteBool,  Prev: Break,  Up: Reference

Byte
====

Synopsis
--------

     type
       Byte  { built-in type }

Description
-----------

`Byte' is an unsigned integer type which is one "unit" wide.  On most
platforms one unit has 8 bits, therefore the type is named "byte" and
usually has a range of `0 .. 255'. (It is the same as *Note ByteCard::.)

   `Byte' in GNU Pascal is compatible to `unsigned char' in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`Byte' is a Borland Pascal extension. (For something equivalent in ISO
Pascal, see *Note Subrange Types::.)

Example
-------

     program ByteDemo;
     var
       a: Byte;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: ByteBool,  Next: ByteCard,  Prev: Byte,  Up: Reference

ByteBool
========

Synopsis
--------

     type
       ByteBool = Boolean attribute (Size = BitSizeOf (Byte));

Description
-----------

The intrinsic `ByteBool' represents boolean values, but occupies the
same memory space as a `Byte'.  It is used when you need to define a
parameter or record that conforms to some external library or system
specification.

Conforming to
-------------

`ByteBool' is a Borland Pascal extension.

Example
-------

     program ByteBoolDemo;
     var
       a: ByteBool;
     begin
       Byte (a) := 1;
       if a then WriteLn ('Ord (True) = 1')
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note Boolean::, *Note True::, *Note
False::, *Note CBoolean::, *Note ShortBool::, *Note MedBool::, *Note
WordBool::, *Note LongBool::, *Note LongestBool::.


File: gpc.info,  Node: ByteCard,  Next: ByteInt,  Prev: ByteBool,  Up: Reference

ByteCard
========

Synopsis
--------

     type
       ByteCard = Cardinal attribute (Size = BitSizeOf (Byte));

Description
-----------

`ByteCard' is an unsigned integer type which is one "unit" wide.  On
most platforms one unit has 8 bits, therefore the type is prefixed
"byte-" and usually has a range of `0 .. 255'.

   `ByteCard' in GNU Pascal is compatible to `unsigned char' in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`ByteCard' is a GNU Pascal extension.

Example
-------

     program ByteCardDemo;
     var
       a: ByteCard;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: ByteInt,  Next: c,  Prev: ByteCard,  Up: Reference

ByteInt
=======

Synopsis
--------

     type
       ByteInt = Integer attribute (Size = BitSizeOf (Byte));

Description
-----------

`ByteInt' is a signed integer type which is one "unit" wide.  On most
platforms one unit has 8 bits, therefore the type is prefixed "byte-"
and usually has a range of `-128 .. 127'.

   `ByteInt' in GNU Pascal is compatible to `signed char' in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`ByteInt' is a GNU Pascal extension.

   `ByteInt' in GNU Pascal corresponds to *Note ShortInt:: in Borland
Pascal.

Example
-------

     program ByteIntDemo;
     var
       a: ByteInt;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: c,  Next: Card,  Prev: ByteInt,  Up: Reference

c
=

Synopsis
--------

Description
-----------

*Deprecated*! Use `external' now.

Conforming to
-------------

Example
-------

See also
--------

*Note Keywords::, *Note Importing Libraries from Other Languages::,
*Note external::.


File: gpc.info,  Node: Card,  Next: Cardinal,  Prev: c,  Up: Reference

Card
====

Synopsis
--------

     function Card (S: ANY_SET): Integer;

Description
-----------

The function `Card (S)' returns the number of elements in the set `S'.

Conforming to
-------------

`Card' is an ISO 10206 Extended Pascal extension.

Example
-------

     program CardDemo;
     var
       Foo: set of 1 .. 100;
     begin
       Foo := [1, 2, 3, 5, 1, 1, 1, 2, 2, 2, 3, 3, 5, 5];  { four elements }
       WriteLn ('foo consists of ', Card (Foo), ' elements')
     end.

See also
--------

*Note set::


File: gpc.info,  Node: Cardinal,  Next: case,  Prev: Card,  Up: Reference

Cardinal
========

Synopsis
--------

     type
       Cardinal  { built-in type }

Description
-----------

`Cardinal' is the "natural" unsigned integer type in GNU Pascal. On
some platforms it is 32 bits wide and thus has a range of `0 ..
4294967295'. Use it whenever you need a general-purpose unsigned
integer type and don't need to care about compatibility to other Pascal
dialects.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`Cardinal' is not defined in ISO Pascal, but several Pascal compilers
support it as an extension. In Borland Delphi, for instance, it is an
unsigned 16-bit in version 1.0, an unsigned 31-bit integer from version
2.0 on, and an unsigned 32-bit integer from version 4.0 on.

Example
-------

     program CardinalDemo;
     var
       a: Cardinal;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: case,  Next: CBoolean,  Prev: Cardinal,  Up: Reference

case
====

Synopsis
--------

     case EXPRESSION of
       SELECTOR: STATEMENT;
       ...
       SELECTOR: STATEMENT;
     end;
or, with alternative statement sequence:
     case EXPRESSION of
       SELECTOR: STATEMENT;
       ...
       SELECTOR: STATEMENT;
     otherwise  { ``else'' instead of ``otherwise'' is allowed }
       STATEMENT;
       ...
       STATEMENT;
     end;
   or, as part of the invariant `record' type definition:
     foo = record
       FIELD_DECLARATIONS
     case bar: VARIANT_TYPE of
       SELECTOR: (FIELD_DECLARATIONS);
       SELECTOR: (FIELD_DECLARATIONS);
       ...
     end;
   or, without a variant selector field,
     foo = record
       FIELD_DECLARATIONS
     case VARIANT_TYPE of
       SELECTOR: (FIELD_DECLARATIONS);
       SELECTOR: (FIELD_DECLARATIONS);
       ...
     end;

Description
-----------

`case' opens a case statement. For further description see *Note case
Statement::.

   For `case' in a variant record type definition, see *Note Record
Types::.

Conforming to
-------------

The `case' statement is defined in ISO 7185 Pascal and supported by all
known Pascal variants.

   According to ISO 7185 Pascal, the selector type must be a named
type. UCSD Pascal and Borland Pascal allow any ordinal type here.

   The alternative statement execution with `otherwise' it is an
Extended Pascal extension; with `else' it is a Borland Pascal
extension. In GNU Pascal, both are allowed.

Example
-------

     program CaseDemo;
     var
       Foo: String (10);
       Bar: Integer;
     begin
       WriteLn ('Enter up to ten arbitrary characters:');
       ReadLn (Foo);
       for Bar := 1 to Length (Foo) do
         begin
           Write (Foo[Bar], ' is ');
           case Foo[Bar] of
             'A' .. 'Z', 'a' .. 'z':
               WriteLn ('an English letter');
             '0' .. '9':
               WriteLn ('a number');
           otherwise
             WriteLn ('an unrecognized character')
           end
         end
     end.

See also
--------

*Note Keywords::, *Note if Statement::, *Note Record Types::, *Note
else::, *Note otherwise::


File: gpc.info,  Node: CBoolean,  Next: CCardinal,  Prev: case,  Up: Reference

CBoolean
========

(Under construction.)

Synopsis
--------

     type
       CBoolean  { built-in type }

Description
-----------

`CBoolean' is a Boolean type. In GNU Pascal it is compatible to `_Bool'
in GNU C (which is defined as `bool' in `stdbool.h'). This
compatibility is the reason why `CBoolean' exists.

Conforming to
-------------

`CBoolean' is a GNU Pascal extension.

Example
-------

     program CBooleanDemo;
     var
       a: CBoolean;
     begin
       a := True;
       if Ord (a) = 1 then WriteLn ('Ord (True) = 1')
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note Integer Types::, *Note Boolean::,
*Note True::, *Note False::, *Note ByteBool::, *Note ShortBool::, *Note
MedBool::, *Note WordBool::, *Note LongBool::, *Note LongestBool::.


File: gpc.info,  Node: CCardinal,  Next: Char,  Prev: CBoolean,  Up: Reference

CCardinal
=========

Synopsis
--------

     type
       CCardinal  { built-in type }

Description
-----------

`CCardinal' is an unsigned integer type. On some platforms it is 32
bits wide and thus has a range of `0 .. 4294967295'.

   `CCardinal' in GNU Pascal is compatible to `unsigned int' in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`CCardinal' is a GNU Pascal extension.

Example
-------

     program CCardinalDemo;
     var
       a: CCardinal;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: Char,  Next: ChDir,  Prev: CCardinal,  Up: Reference

Char
====

Synopsis
--------

     type
       Char  { built-in type }

Description
-----------

The built-in type `Char' holds elements of the operating system's
character set (usually ASCII). The `Char' type is a special case of
ordinal type. Conversion between character types and ordinal types is
possible with the built-in functions `Ord' and `Chr'.

Conforming to
-------------

`Char' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program CharDemo;
     var
       a: Char;
     begin
       a := 'x';
       WriteLn (a)
     end.

See also
--------

*Note Character Types::, *Note Ordinal Types::, *Note Type Casts::,
*Note Ord::, *Note Chr::.


File: gpc.info,  Node: ChDir,  Next: Chr,  Prev: Char,  Up: Reference

ChDir
=====

Synopsis
--------

     procedure ChDir (Directory: String);

Description
-----------

`ChDir' changes the current directory to DIRECTORY, if its argument is
a valid parameter to the related operating system's function.
Otherwise, a runtime error is caused.

Conforming to
-------------

`ChDir' is a Borland Pascal extension.

Example
-------

     program ChDirDemo;
     var
       Foo: String (127);
     begin
       WriteLn ('Enter directory name to change to:');
       ReadLn (Foo);
       {$I-}  { Don't abort the program on error }
       ChDir (Foo);
       if IOResult <> 0 then
         WriteLn ('Cannot change to directory `', Foo, '''.')
       else
         WriteLn ('Okay.')
     end.

See also
--------

*Note MkDir::, *Note RmDir::


File: gpc.info,  Node: Chr,  Next: CInteger,  Prev: ChDir,  Up: Reference

Chr
===

Synopsis
--------

     function Chr (AsciiCode: Integer): Char;

Description
-----------

`Chr' returns a character whose ASCII code corresponds to the value
given by `AsciiCode'.

Conforming to
-------------

`Chr' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program ChrDemo;
     var
       x: Integer;
     begin
       for x := 32 to 122 do
         Write (Chr (x))
     end.

See also
--------

*Note Character Types::, *Note Ord::, *Note Char::


File: gpc.info,  Node: CInteger,  Next: c_language,  Prev: Chr,  Up: Reference

CInteger
========

Synopsis
--------

     type
       CInteger  { built-in type }

Description
-----------

`CInteger' is a signed integer type. On some platforms it is 32 bits
wide and thus has a range of `-2147483648 .. 2147483647'.

   `CInteger' in GNU Pascal is compatible to `int' in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`CInteger' is a GNU Pascal extension.

Example
-------

     program CIntegerDemo;
     var
       a: CInteger;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: c_language,  Next: class,  Prev: CInteger,  Up: Reference

c_language
==========

Synopsis
--------

Description
-----------

*Deprecated*! Use `external' now.

Conforming to
-------------

Example
-------

See also
--------

*Note Keywords::, *Note Importing Libraries from Other Languages::,
*Note external::.


File: gpc.info,  Node: class,  Next: Close,  Prev: c_language,  Up: Reference

class
=====

Not yet implemented.

Synopsis
--------

Description
-----------

OOE/Delphi style object class.

Conforming to
-------------

`class' is an Object Pascal and a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Close,  Next: Cmplx,  Prev: class,  Up: Reference

Close
=====

(Under construction.)

Synopsis
--------

     procedure Close (var F: ANY_FILE);

Description
-----------

Conforming to
-------------

`Close' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Cmplx,  Next: Comp,  Prev: Close,  Up: Reference

Cmplx
=====

Synopsis
--------

     function Cmplx (RealPart, ImaginaryPart: Real): Complex;

Description
-----------

`Cmplx' makes a complex number from `RealPart' and `ImaginaryPart'.

Conforming to
-------------

`Cmplx' is an ISO 10206 Extended Pascal extension.

Example
-------

     program CmplxDemo;
     var
       z: Complex;
       x, y: Real;
     begin
       z := Cmplx (x, y)  { z := x + iy }
     end.

See also
--------

*Note Re::, *Note Im::, *Note Polar::, *Note Arg::


File: gpc.info,  Node: Comp,  Next: CompilerAssert,  Prev: Cmplx,  Up: Reference

Comp
====

Synopsis
--------

     type
       Comp = LongInt;

Description
-----------

`Comp' is a signed integer type which is longer than `Integer'. On some
platforms it is 64 bits wide and thus has a range of
`-9223372036854775808 .. 9223372036854775807'.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`Comp' is a Borland Pascal extension.

   In some contexts, Borland Pascal treats `Comp' as a "real" type -
this behaviour is not supported by GPC.

Example
-------

     program CompDemo;
     var
       a: Comp;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: CompilerAssert,  Next: Complex,  Prev: Comp,  Up: Reference

CompilerAssert
==============

Synopsis
--------

     procedure CompilerAssert (Condition: Boolean);
or
     function CompilerAssert (Condition: Boolean): Boolean;
   or
     function CompilerAssert (Condition: Boolean;
                ResultValue: ANY_TYPE): type of ResultValue;

Description
-----------

`CompilerAssert' checks the given `Condition' at compile-time. If it is
a compile-time constant of Boolean type with the value `True', it
returns `ResultValue', or if called with only one argument, it returns
`True' or nothing if used as a procedure.

   If `Condition' cannot be evaluated at compile-time or does not have
the value `True', it causes a compile-time error.

   So it can be used to make sure that certain assumptions hold before
relying on them.

   `CompilerAssert' does not depend on the `--[no-]assertions' options.
It does not generate any run-time code.

Conforming to
-------------

`CompilerAssert' is a GNU Pascal extension.

Example
-------

     program CompilerAssertDemo;

     var
       a: LongInt;

     const
       { Make sure that the highest value a can hold is larger than
         MaxInt, and set b to that value. }
       b = CompilerAssert (High (a) > MaxInt, High (a));

       { Do a similar check for the minimum value, setting c to True
         (which can be ignored). }
       c = CompilerAssert (Low (a) < Low (Integer));

     begin
       { Procedure-like use of CompilerAssert in the statement part. }
       CompilerAssert (MaxInt >= 100000);

       WriteLn (b, ' ', c)
     end.

See also
--------

*Note Assert::.


File: gpc.info,  Node: Complex,  Next: Concat,  Prev: CompilerAssert,  Up: Reference

Complex
=======

(Under construction.)

Synopsis
--------

     type
       Internal_Complex = record  { not visible }
         RealPart, ImaginaryPart: Real
       end;
       Complex = restricted Internal_Complex;

Description
-----------

Conforming to
-------------

`Complex' is an ISO 10206 Extended Pascal extension.

Example
-------

     program ComplexDemo;
     var
       a: Complex;
     begin
       a := Cmplx (42, 3);
       WriteLn (Re (a), ' + ', Im (a), ' i')
     end.

See also
--------


File: gpc.info,  Node: Concat,  Next: Conjugate,  Prev: Complex,  Up: Reference

Concat
======

(Under construction.)

Synopsis
--------

     function Concat (S1, S2: String): String;
or
     function Concat (S1, S2, S3: String): String;
   or
     ...

Description
-----------

Conforming to
-------------

`Concat' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Conjugate,  Next: const,  Prev: Concat,  Up: Reference

Conjugate
=========

Synopsis
--------

     function Conjugate (z: Complex): Complex;

Description
-----------

`Conjugate' computes the complex conjugate of the complex number `z'

Conforming to
-------------

`Conjugate' is a GNU Pascal extension.

Example
-------

     program ConjugateDemo;
     var
       z: Complex;
     begin
       z := Cmplx (2, 3);  { z is 2 + i * 3 }
       WriteLn ('z = ', Re (z) : 0 : 5, ' + i * ', Im (z) : 0 : 5);
       z := Conjugate (z);  { z conjugate is 2 - i * 3 }
       WriteLn ('z conjugate = ', Re (z) : 0 : 5,' + i * ', Im (z) : 0 : 5)
     end.

See also
--------

*Note Cmplx::, *Note Re::, *Note Im::, *Note Abs::


File: gpc.info,  Node: const,  Next: constructor,  Prev: Conjugate,  Up: Reference

const
=====

(Under construction.)

Synopsis
--------

Description
-----------

Constant declaration or constant parameter declaration.

Conforming to
-------------

`const' is defined in ISO 7185 Pascal and supported by all known Pascal
variants. `const' parameters are a Borland Pascal extension. Pointers
to `const' are a GNU Pascal extension.

   Constant declarations allow you to define names for constant
(unchanging) values, such as using `SecondsPerHour' instead of 3600.
This can make your program much more readable and maintainable.

   GNU Pascal allows you to define constant strings, records and arrays
as well as simple numeric constants.

   GNU Pascal also implements the const parameter extension which
allows the compiler to pass parameters by reference while still
allowing you to pass constant values as inputs.  See *Note Subroutine
Parameter List Declaration:: for more information.

   @@ Pointers to `const' @@

Example
-------

     program ConstDemo;

     type
       Rec = record
         x: Integer;
         y: Integer;
       end;

     const
       a = 5;
       constr: Rec = (10, 12);

     procedure doit (const r: Rec; const s: String);
     begin
       WriteLn (r.x);
       WriteLn (r.y);
       WriteLn (s);
     end;

     var
       variabler: Rec;

     begin
       variabler.x := 16;
       variabler.y := 7;
       doit (variabler, 'Should be 16 and 7');
       doit (constr, 'Should be 10 and 12');
     end.

See also
--------

*Note Keywords::, *Note var::, *Note protected::, *Note Subroutine
Parameter List Declaration::.


File: gpc.info,  Node: constructor,  Next: Continue,  Prev: const,  Up: Reference

constructor
===========

(Under construction.) ;-)

Synopsis
--------

Description
-----------

Object constructor.

Conforming to
-------------

`constructor' is an Object Pascal and a Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Continue,  Next: Copy,  Prev: constructor,  Up: Reference

Continue
========

Synopsis
--------

     Continue  { simple statement }

Description
-----------

`Continue' goes on with loop iteration by jumping to the end of the
current loop body. Note: `Continue' can only stand within a `while',
`repeat' or a `for' loop.

Conforming to
-------------

`Continue' is a Borland Pascal extension, Mac Pascal has `Cycle'
instead.

Example
-------

     program ContinueDemo;
     var
       Foo, Bar: Integer;
     begin
       WriteLn ('Enter three numbers:');
       for Bar := 1 to 3 do
         begin
           ReadLn (Foo);
           if Foo < 5 then
             Continue;
           WriteLn ('Your number was greater than 5.')
         end
     end.

See also
--------

*Note Loop Control Statements::, *Note Break::, *Note Cycle::, *Note
Exit::, *Note Halt::, *Note Leave::, *Note Return::, *Note goto::.


File: gpc.info,  Node: Copy,  Next: Cos,  Prev: Continue,  Up: Reference

Copy
====

Synopsis
--------

     function Copy (S: String; FirstChar, Count: Integer): String;
or
     function Copy (S: String; FirstChar: Integer): String;

Description
-----------

`Copy' returns a sub-string of `S' starting with the character at
position FIRSTCHAR. If COUNT is given, such many characters will be
copied into the sub-string. If COUNT is omitted, the sub-string will
range to the end of S.

   If `Count' is too large for the sub-string to fit in S, the result
will be truncated at the end of S. If `FirstChar' exceeds the length of
S, the empty string will be returned. (For a function which does not
truncate but triggers a runtime error instead, see *Note SubStr::.)

   Please note that GPC's strings may be longer than 255 characters. If
you want to isolate the second half of a string S starting with the
third character, use `Copy (S, 3)' instead of `Copy (S, 3, 255)'.

Conforming to
-------------

`Copy' is a UCSD Pascal extension. The possibility to omit the third
parameter is a GNU Pascal extension.

Example
-------

     program CopyDemo;
     var
       S: String (42);
     begin
       S := 'Hello';
       WriteLn (Copy (S, 2, 3));  { yields `ell' }
       WriteLn (Copy (S, 3));     { yields `llo' }
       WriteLn (Copy (S, 4, 7));  { yields `lo' }
       WriteLn (Copy (S, 42))     { yields the empty string }
     end.

See also
--------

*Note SubStr::, *Note String Slice Access::.


File: gpc.info,  Node: Cos,  Next: CString,  Prev: Copy,  Up: Reference

Cos
===

Synopsis
--------

     function Cos (x: Real): Real;
or
     function Cos (z: Complex): Complex;

Description
-----------

`Cos' returns the cosine of the argument.  The result is in the range
`-1 < Cos (x) < 1' for real arguments.

Conforming to
-------------

The function `Cos' is defined in ISO 7185 Pascal; its application to
complex values is defined in ISO 10206 Extended Pascal.

Example
-------

     program CosDemo;
     begin
       { yields 0.5 since Cos (Pi / 3) = 0.5 }
       WriteLn (Cos (Pi / 3) : 0 : 5)
     end.

See also
--------

*Note ArcTan::, *Note Sin::, *Note Ln::, *Note Arg::.


File: gpc.info,  Node: CString,  Next: CString2String,  Prev: Cos,  Up: Reference

CString
=======

(Under construction.)

Synopsis
--------

     type
       CString = ^Char;

Description
-----------

Conforming to
-------------

`CString' is a GNU Pascal extension.

Example
-------

     program CStringDemo;
     var
       s: CString;
     begin
       s := 'Hello, world!';
       {$X+}
       WriteLn (s)
     end.

See also
--------


File: gpc.info,  Node: CString2String,  Next: CStringCopyString,  Prev: CString,  Up: Reference

CString2String
==============

(Under construction.)

Synopsis
--------

     function CString2String (S: CString): String;

Description
-----------

Conforming to
-------------

`CString2String' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: CStringCopyString,  Next: CurrentRoutineName,  Prev: CString2String,  Up: Reference

CStringCopyString
=================

(Under construction.)

Synopsis
--------

     function CStringCopyString (Dest: CString; const Source: String): CString;

Description
-----------

Conforming to
-------------

`CStringCopyString' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: CurrentRoutineName,  Next: CWord,  Prev: CStringCopyString,  Up: Reference

CurrentRoutineName
==================

Synopsis
--------

     function CurrentRoutineName: String;

Description
-----------

`CurrentRoutineName' returns the name of the current routine from where
it's called.

Conforming to
-------------

`CurrentRoutineName' is a GNU Pascal extension.

Example
-------

     program CurrentRoutineNameDemo;

     procedure FooBar;
     begin
       WriteLn (CurrentRoutineName)  { `FooBar' }
     end;

     begin
       WriteLn (CurrentRoutineName);  { `main program' }
       FooBar
     end.

See also
--------


File: gpc.info,  Node: CWord,  Next: Cycle,  Prev: CurrentRoutineName,  Up: Reference

CWord
=====

Synopsis
--------

     type
       CWord = CCardinal;

Description
-----------

`CCardinal' is an unsigned integer type. On some platforms it is 32
bits wide and thus has a range of `0 .. 4294967295'. It is the same as
*Note CCardinal::.

   `CWord' in GNU Pascal is compatible to `unsigned int' in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`CWord' is a GNU Pascal extension.

Example
-------

     program CWordDemo;
     var
       a: CWord;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note CCardinal::, *Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: Cycle,  Next: Date,  Prev: CWord,  Up: Reference

Cycle
=====

Synopsis
--------

     Cycle  { simple statement }

Description
-----------

`Cycle' goes on with loop iteration by jumping to the end of the
current loop body. Note: `Cycle' can only stand within a `while',
`repeat' or a `for' loop.

Conforming to
-------------

`Cycle' is a Mac Pascal extension. Borland Pascal has `Continue'
instead.

Example
-------

     program CycleDemo;
     var
       Foo, Bar: Integer;
     begin
       WriteLn ('Enter three numbers:');
       for Bar := 1 to 3 do
         begin
           ReadLn (Foo);
           if Foo < 5 then
             Cycle;
           WriteLn ('Your number was greater than 5.')
         end
     end.

See also
--------

*Note Loop Control Statements::, *Note Break::, *Note Continue::, *Note
Exit::, *Note Halt::, *Note Leave::, *Note Return::, *Note goto::.


File: gpc.info,  Node: Date,  Next: Dec,  Prev: Cycle,  Up: Reference

Date
====

Synopsis
--------

     function Date (T: TimeStamp): packed array [1 .. DATE_LENGTH] of Char;

Description
-----------

Date takes a `TimeStamp' parameter and returns the date as a string (in
the form of a packed array of `Char').  DATE_LENGTH is an
implementation defined invisible constant.

Conforming to
-------------

`Date' is an ISO 10206 Extended Pascal extension.

Example
-------

Set *Note TimeStamp::.

See also
--------

*Note TimeStamp::, *Note GetTimeStamp::, *Note Time::, *Note Date And
Time Routines::.


File: gpc.info,  Node: Dec,  Next: DefineSize,  Prev: Date,  Up: Reference

Dec
===

Synopsis
--------

For ordinal types:
     procedure Dec (var x: ORDINAL_TYPE);
   or
     procedure Dec (var x: ORDINAL_TYPE; Amount: AND_INTEGER_TYPE);

   For pointer types:
     procedure Dec (var p: ANY_POINTER_TYPE);
   or
     procedure Dec (var p: ANY_POINTER_TYPE; Amount: AND_INTEGER_TYPE);

Description
-----------

For ordinal types, `Dec' decreases the value of `x' by one or by
`amount' if specified.

   If the argument `p' is pointing to a specified type (typed pointer),
`Dec' decreases the address of `p' by the size of the type `p' is
pointing to or by `amount' times that size respectively. If `p' is an
untyped pointer (i.e. `p' is of type *Note Pointer::), `p' is decreased
by one, otherwise by `amount' if specified.

Conforming to
-------------

`Dec' is a Borland Pascal extension. The combination of the second
argument with application to pointers is a GNU Pascal extension.

Example
-------

     program DecDemo;
     var
       x: Integer;
       y: array [1 .. 5] of Integer;
       p: ^Integer;
     begin
       x := 9;
       Dec (x, 10);  { yields -1 }
       {$X+}         { Turn on extended systax }
       p := @y[5];   { p points to y[5] }
       Dec (p, 3)    { p points to y[2] }
     end.

See also
--------

*Note Inc::, *Note Pred::, *Note Succ::, *Note Pointer Arithmetics::.


File: gpc.info,  Node: DefineSize,  Next: Delete,  Prev: Dec,  Up: Reference

DefineSize
==========

(Under construction.)

Synopsis
--------

     procedure DefineSize (var F: ANY_FILE; NewSize: Integer);

Description
-----------

Conforming to
-------------

`DefineSize' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Delete,  Next: destructor,  Prev: DefineSize,  Up: Reference

Delete
======

(Under construction.)

Synopsis
--------

     procedure Delete (var S: String; FirstChar, Count: Integer);
or
     procedure Delete (var S: String; FirstChar: Integer);

Description
-----------

Conforming to
-------------

`Delete' is a UCSD Pascal extension. The possibility to omit the third
parameter is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: destructor,  Next: Discard,  Prev: Delete,  Up: Reference

destructor
==========

(Under construction.)

Synopsis
--------

Description
-----------

Object destructor.

Conforming to
-------------

`destructor' is an Object Pascal and a Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Discard,  Next: Dispose,  Prev: destructor,  Up: Reference

Discard
=======

Synopsis
--------

     Discard (Value);

Description
-----------

`Discard' does nothing, but tells the compiler that the value given as
an argument is not further used. It can be applied, e.g., to routine
parameters which are to be ignored, so no warning about them will be
given with `-Wunused', or when calling a function and ignore its result.

   An alternative for the latter case is to give the function the
`ignorable' attribute. This is useful is the function's result is
expected to be ignored regularly. If, however, a result is generally
meaningful and only to be ignored in a particular case, using `Discard'
is preferable.

Conforming to
-------------

`Discard' is a GNU Pascal extension.

Example
-------

program DiscardDemo;

   function Foo (a: Integer): Integer; begin   WriteLn (a);   Foo := a
+ 1 end;

   { Parameter `a' is there only to make the parameter list compatible
to that of function `Foo'. } function Bar (a: Integer): Integer; begin
 Discard (a);  { Tell the compiler that we intentionally do not
          use `a' in this function. }   Bar := a + 1 end;

   var   c: Char;   f: function (a: Integer): Integer;

   begin   Write ('With output? ');   ReadLn (c);   if LoCase (c) = 'y'
then     f := Foo   else     f := Bar;   Discard (f (42))  { Call the
function, but ignore its result } end.

See also
--------


File: gpc.info,  Node: Dispose,  Next: div,  Prev: Discard,  Up: Reference

Dispose
=======

(Under construction.)

Synopsis
--------

     Dispose (PointerVar: Pointer);
or
     Dispose (PointerVar: Pointer; TAG_FIELD_VALUES);
   or
     Dispose (ObjectPointerVar: Pointer; DESTRUCTOR_CALL);

Description
-----------

Conforming to
-------------

`Dispose' is defined in ISO 7185 Pascal and supported by most known
Pascal variants, but not by UCSD Pascal. Its use for objects is a
Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: div,  Next: do,  Prev: Dispose,  Up: Reference

div
===

Synopsis
--------

     operator div (p, q: Integer) = r: Integer;

Description
-----------

Integer division operator.

Conforming to
-------------

`div' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program DivDemo;

     var
       a, b: Integer;

     begin
       a := 16;
       b := 7;
       WriteLn (a div b);  { `2' }
     end.

See also
--------

*Note Keywords::.


File: gpc.info,  Node: do,  Next: Double,  Prev: div,  Up: Reference

do
==

Synopsis
--------

     for ... do
       STATEMENT
or
     while ... do
       STATEMENT
   or
     with ... do
       STATEMENT
   or
     to begin do
       STATEMENT
   or
     to end do
       STATEMENT

Description
-----------

The `do' reserved word is used in combination with other Pascal
keywords in many ways. For description and examples see the relevant
reference sections: `for', `while', `with', `to begin', `to end'.

Conforming to
-------------

`do' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See references.

See also
--------

*Note Keywords::, *Note for::, *Note while::, *Note with::, *Note to
begin do::, *Note to end do::.


File: gpc.info,  Node: Double,  Next: downto,  Prev: do,  Up: Reference

Double
======

(Under construction.)

Synopsis
--------

     type
       Double = Real;

Description
-----------

`Double' is a synonym for the `Real' data type and supported for
compatibility with other compilers.

Conforming to
-------------

`Double' is a Borland Pascal extension.

Example
-------

     program DoubleDemo;
     var
       A: Double;  { There is nothing special with `Double'. }
       B: Real;
     begin
       A := Pi;
       A := B
     end.

See also
--------


File: gpc.info,  Node: downto,  Next: else,  Prev: Double,  Up: Reference

downto
======

Synopsis
--------

     for VARIABLE := VALUE1 downto VALUE2 do
       STATEMENT

Description
-----------

The `downto' reserved word is used in combination with `for' to build a
`for' loop.

Conforming to
-------------

`downto' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

program DowntoDemo; var   i: Integer; begin   for i := 10 downto 1 do
WriteLn (i) end.

See also
--------

*Note Keywords::, *Note for::.


File: gpc.info,  Node: else,  Next: Empty,  Prev: downto,  Up: Reference

else
====

Synopsis
--------

As part of the `if' ... `then' ... `else' statement:
     if BOOLEAN_EXPRESSION then
       STATEMENT1
     else
       STATEMENT2
   or, as part of the `case' ... `else' statement:
     case EXPRESSION of
       SELECTOR: STATEMENT;
       ...
       SELECTOR: STATEMENT
     else  { ``otherwise'' instead of ``else'' is allowed }
       STATEMENT;
       ...
       STATEMENT
     end

Description
-----------

`else' is part of the `if ... then ... else' statement which provides a
possibility to execute statements alternatively. In the `case'
statement, `else' starts a series of statements which is executed if no
selector fit in EXPRESSION. In this situation, `else' is a synonym for
`otherwise'.

Conforming to
-------------

`else' in `if' statements is defined in ISO 7185 Pascal and supported
by all known Pascal variants. `else' in `case' statements is a Borland
Pascal extension; ISO 10206 Extended Pascal has `otherwise' instead.

Example
-------

     program ElseDemo;
     var
       i: Integer;
     begin
       Write ('Enter a number: ');
       ReadLn (i);
       if i > 42 then
         WriteLn ('The number is greater than 42')
       else
         WriteLn ('The number is not greater than 42')
     end.

See also
--------

*Note Keywords::, *Note if::, *Note case::, *Note otherwise::.


File: gpc.info,  Node: Empty,  Next: end,  Prev: else,  Up: Reference

Empty
=====

(Under construction.)

Synopsis
--------

     function Empty (var F: ANY_FILE): Boolean;

Description
-----------

Conforming to
-------------

`Empty' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: end,  Next: EOF,  Prev: Empty,  Up: Reference

end
===

Synopsis
--------

     begin
       STATEMENT;
       STATEMENT;
       ...
       STATEMENT
     end

Description
-----------

The reserved word `end' closes a `begin' ... `end'; statement which
joins several STATEMENTS together into one compound statement.

   @@ end of a `case' statement @@ end of a record or object declaration
@@ part of a `to end do' module destructor

Conforming to
-------------

`end' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program EndDemo;
     begin
       if True then
         WriteLn ('single statement');
       if True then
         begin  { clamp statement1 ... }
           WriteLn ('statement1');
           WriteLn ('statement2')
         end    { ... to statement2 }
     end.

See also
--------

*Note Keywords::, *Note begin end Compound Statement::, *Note begin::


File: gpc.info,  Node: EOF,  Next: EOLn,  Prev: end,  Up: Reference

EOF
===

(Under construction.)

Synopsis
--------

     function EOF ([var F: ANY_FILE]): Boolean;
or
     function EOF: Boolean;

Description
-----------

Conforming to
-------------

`EOF' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------


File: gpc.info,  Node: EOLn,  Next: EpsReal,  Prev: EOF,  Up: Reference

EOLn
====

(Under construction.)

Synopsis
--------

     function EOLn ([var F: Text]): Boolean;
or
     function EOLn: Boolean;

Description
-----------

Conforming to
-------------

`EOLn' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------


File: gpc.info,  Node: EpsReal,  Next: EQ,  Prev: EOLn,  Up: Reference

EpsReal
=======

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`EpsReal' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: EQ,  Next: EQPad,  Prev: EpsReal,  Up: Reference

EQ
==

(Under construction.)

Synopsis
--------

     function EQ (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`EQ' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: EQPad,  Next: Erase,  Prev: EQ,  Up: Reference

EQPad
=====

(Under construction.)

Synopsis
--------

     function EQPad (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`EQPad' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Erase,  Next: except,  Prev: EQPad,  Up: Reference

Erase
=====

(Under construction.)

Synopsis
--------

     procedure Erase (var F: ANY_FILE);

Description
-----------

Conforming to
-------------

`Erase' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: except,  Next: Exclude,  Prev: Erase,  Up: Reference

except
======

Not yet implemented.

Synopsis
--------

Conforming to
-------------

`except' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Exclude,  Next: Exit,  Prev: except,  Up: Reference

Exclude
=======

Synopsis
--------

     Exclude (SET_VARIABLE, ORDINAL_VALUE);

Description
-----------

Remove (subtract) a single element from a set.  ORDINAL_VALUE must be
compatible with the base type of SET_VARIABLE.  Exclude is equivalent
to:

     SET_VARIABLE := SET_VARIABLE - [ORDINAL_VALUE];

   If SET_VARIABLE does not contain ORDINAL_VALUE, nothing happens.

Conforming to
-------------

`Exclude' is a Borland Pascal extension.

Example
-------

     program ExcludeDemo;

     var
       Ch: Char;
       MyCharSet: set of Char;

     begin
       MyCharSet := ['P', 'N', 'L'];
       Exclude (MyCharSet , 'N')  { L, P }
     end.

   See other examples in *Note set:: and *Note Set Operations::.

See also
--------

*Note Keywords::, *Note Set Operations::, *Note set::, *Note in::,
*Note Include::.


File: gpc.info,  Node: Exit,  Next: Exp,  Prev: Exclude,  Up: Reference

Exit
====

Synopsis
--------

     procedure Exit;

   or

     procedure Exit (program);

   or

     procedure Exit (Identifier);

Description
-----------

`Exit' without an argument leaves the currently executed procedure or
function. Note: If `Exit' is called within the main program, it will be
terminated instantly.

   `Exit' with an argument that is `program' or the name of the current
program, terminates the program, and is equivalent to `Halt'.

   `Exit' with an argument that is the name of the current or an
encompassing routine leaves that routine.

Conforming to
-------------

`Exit' is a UCSD Pascal extension. Borland Pascal only allows it
without an argument.

Example
-------

     program ExitDemo;

     procedure Foo (Bar: Integer);
     var
       Baz, Fac: Integer;
     begin
       if Bar < 1 then
         Exit;  { Exit `Foo' }
       Fac := 1;
       for Baz := 1 to Bar do
         begin
           Fac := Fac * Baz;
           if Fac >= Bar then
             Exit;  { Exit `Foo' }
           WriteLn (Bar,' is greater than ', Baz, '!, which is equal to ', Fac)
       end
     end;

     begin
       Foo (-1);
       Foo (789);
       Exit;            { Terminates program }
       Foo (987654321)  { This is not executed anymore }
     end.

See also
--------

*Note Break::, *Note Continue::, *Note Halt::.


File: gpc.info,  Node: Exp,  Next: export,  Prev: Exit,  Up: Reference

Exp
===

Synopsis
--------

     function Exp (x: Real): Real;
or
     function Exp (z: Complex): Complex;

Description
-----------

The exponential function `Exp' computes the value of e to the power of
x, where the Euler number e = Exp (1) is the base of the natural
logarithm.

Conforming to
-------------

The function `Exp' is defined in ISO 7185 Pascal; its application to
complex values is defined in ISO 10206 Extended Pascal.

Example
-------

     program ExpDemo;
     var
       z: Complex;
     begin
       z := Cmplx (1, - 2 * Pi);  { z = 1 - 2 pi i }
       z := Exp (z);  { yields e = Exp (1), since Exp ix = Cos x + i Sin x }
       WriteLn (Ln (Re (z)) : 0 : 5)  { prints 1 = Ln (Exp (1)) }
     end.

See also
--------

*Note Ln::


File: gpc.info,  Node: export,  Next: exports,  Prev: Exp,  Up: Reference

export
======

(Under construction.)

Synopsis
--------

     export `interface_name' = (IDENTIFIER, IDENTIFIER, ...);

   or

     export `interface_name' = all;

Description
-----------

Interface export for Extended Pascal modules.

   `all' means to automatically export all identifiers declared in the
interface module.

Conforming to
-------------

`export' is an ISO 10206 Extended Pascal extension. It also exists in
Borland Pascal, but with a different meaning, not (yet) supported by
GPC.

   `export all' is a GNU Pascal extension.

Example
-------

     program ExportDemo;

     import AllInterface in 'somemodule.pas';

     begin
       Bar (a);
       WriteLn (b)
     end.

     module SomeModule interface;

     export
       SomeInterface = (a);
       AllInterface = all;  { Same as `AllInterface = (a, b, Bar);' }

     var
       a, b: Integer;

     procedure Bar (i: Integer);

     end.

     module SomeModule implementation;

     procedure Bar (i: Integer);
     begin
       b := a
     end;

     to begin do
       a := 42;

     end.

See also
--------

*Note Keywords::, *Note Modules::.


File: gpc.info,  Node: exports,  Next: Extend,  Prev: export,  Up: Reference

exports
=======

Not yet implemented.

Synopsis
--------

Description
-----------

Library export.

Conforming to
-------------

`exports' is a Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Extend,  Next: Extended,  Prev: exports,  Up: Reference

Extend
======

(Under construction.)

Synopsis
--------

     procedure Extend (var F: ANY_FILE; [FileName: String;]
                                         [BlockSize: Cardinal]);

Description
-----------

`Extend' opens a file for writing. If the file does not exist, it is
created. If it does exist, the file pointer is positioned after the
last element.

   Like `Rewrite', `Reset' and `Append' do, `Reset' accepts an optional
second parameter for the name of the file in the filesystem and a third
parameter for the block size of the file. The third parameter is
allowed only (and by default also required) for untyped files. For
details, see *Note Rewrite::.

Conforming to
-------------

`Extend' is an ISO 10206 Extended extension. Borland Pascal has *Note
Append:: instead.  The `BlockSize' parameter is a Borland Pascal
extension.  The `FileName' parameter is a GNU Pascal extension.

Example
-------

     program ExtendDemo;
     var
       Sample: Text;
     begin
       Assign (Sample, 'sample.txt');
       Rewrite (Sample);
       WriteLn (Sample, 'Hello, World!');  { `sample.txt' now has one line }
       Close (Sample);

       { ... }

       Extend (Sample);
       WriteLn (Sample, 'Hello again!');  { `sample.txt' now has two lines }
       Close (Sample)
     end.

See also
--------

*Note Assign::, *Note Reset::, *Note Rewrite::, *Note Update::, *Note
Append::.


File: gpc.info,  Node: Extended,  Next: external,  Prev: Extend,  Up: Reference

Extended
========

(Under construction.)

Synopsis
--------

     type
       Extended = LongReal;

Description
-----------

Conforming to
-------------

`Extended' is a Borland Pascal extension.

Example
-------

     program ExtendedDemo;
     var
       a: Extended;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------


File: gpc.info,  Node: external,  Next: Fail,  Prev: Extended,  Up: Reference

external
========

(Under construction.)

Synopsis
--------

     DECLARATION external;

   or

     DECLARATION external name LINKER_NAME;

Description
-----------

Declaration of external object.

Conforming to
-------------

`external' is a UCSD Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Fail,  Next: False,  Prev: external,  Up: Reference

Fail
====

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`Fail' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: False,  Next: far,  Prev: Fail,  Up: Reference

False
=====

Synopsis
--------

     type
       Boolean = (False, True);  { built-in type }

Description
-----------

`False' is one of the two Boolean values and is used to represent a
condition which is never fullfilled. For example, the expression, `1 =
2' always yields `False'. It is the opposite of `True'. `False' has the
ordinal value 0.

Conforming to
-------------

`False' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program FalseDemo;

     var
       a: Boolean;

     begin
       a := 1 = 2;  { yields False }
       WriteLn (Ord (False));  { 0 }
       WriteLn (a);  { False }
       if False then WriteLn ('This is not executed.')
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note True::, *Note Boolean::.


File: gpc.info,  Node: far,  Next: file,  Prev: False,  Up: Reference

far
===

Synopsis
--------

Description
-----------

The `far' directive can be appended to a procedure or function heading
but is ignored by GPC. It is there for Borland compatibility, only.
(Since the GNU compilers provide a flat memory model, the distinction
between `near' and `far' pointers is void.)

Conforming to
-------------

`far' is a Borland Pascal extension.

Example
-------

     program FarDemo;

     var
       p: procedure;

     {$W no-near-far}  { Don't warn about the uselessness of `far' }

     procedure Foo; far;  { `far' has no effect in GPC }
     begin
       WriteLn ('Foo')
     end;

     begin
       p := Foo;  { Would also work without `far' in GPC. }
       p
     end.

See also
--------

*Note Keywords::, *Note near::.


File: gpc.info,  Node: file,  Next: FilePos,  Prev: far,  Up: Reference

file
====

(Under construction.)

Synopsis
--------

In type definitions:
     file of TYPE
   or
     file

Description
-----------

Non-text file type declaration.

Conforming to
-------------

Typed files (`file of TYPE') are defined in ISO 7185 Pascal and
supported by all known Pascal variants. Untyped files (`file') are a
Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::, *Note Text::, *Note AnyFile::.


File: gpc.info,  Node: FilePos,  Next: FileSize,  Prev: file,  Up: Reference

FilePos
=======

(Under construction.)

Synopsis
--------

     function FilePos (var F: ANY_FILE): Integer;

Description
-----------

Conforming to
-------------

`FilePos' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: FileSize,  Next: FillChar,  Prev: FilePos,  Up: Reference

FileSize
========

(Under construction.)

Synopsis
--------

     function FileSize (var F: ANY_FILE): Integer;

Description
-----------

Conforming to
-------------

`FileSize' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: FillChar,  Next: finalization,  Prev: FileSize,  Up: Reference

FillChar
========

(Under construction.)

Synopsis
--------

     procedure FillChar (var Dest; Count: SizeType; Val: Char);
or
     procedure FillChar (var Dest; Count: SizeType; Val: Byte);

Description
-----------

Conforming to
-------------

`FillChar' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: finalization,  Next: Finalize,  Prev: FillChar,  Up: Reference

finalization
============

(Under construction.)

Synopsis
--------

Description
-----------

Unit finalization.

   It is equivalent to Extended Pascal's `to end do'.

Conforming to
-------------

`finalization' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::, *Note initialization::, *Note to end do::.


File: gpc.info,  Node: Finalize,  Next: finally,  Prev: finalization,  Up: Reference

Finalize
========

(Under construction.)

Synopsis
--------

     procedure Finalize (var Aynthing);

Description
-----------

`Finalize' does all necessary clean-ups for the parameter. This is
normally done automatically when a variable goes out of scope, so you
need to call `Finalize' only in special situations, e.g.  when you
deallocate a dynamic variable with `FreeMem' rather than `Dispose'.

   Using a variable after applying `Finalize' to it (and without
applying `Initialize' to it again) is invalid and produces undefined
results.

Conforming to
-------------

`Finalize' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Initialize::, *Note Dispose::, *Note FreeMem::.


File: gpc.info,  Node: finally,  Next: Flush,  Prev: Finalize,  Up: Reference

finally
=======

Not yet implemented.

Synopsis
--------

Conforming to
-------------

`finally' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Flush,  Next: for,  Prev: finally,  Up: Reference

Flush
=====

(Under construction.)

Synopsis
--------

     procedure Flush (var F: ANY_FILE);

Description
-----------

Conforming to
-------------

`Flush' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: for,  Next: FormatString,  Prev: Flush,  Up: Reference

for
===

Synopsis
--------

For ordinal index variables:
     for ORDINAL_VARIABLE := INITIAL_VALUE to FINAL_VALUE do
       STATEMENT
   or
     for ORDINAL_VARIABLE := INITIAL_VALUE downto FINAL_VALUE do
       STATEMENT

   For sets:
     for SET_ELEMENT_TYPE_VARIABLE in SOME_SET do
       STATEMENT

   For pointer index variables:
     for POINTER_VARIABLE := INITIAL_ADDRESS to FINAL_ADDRESS do
       STATEMENT
   or
     for POINTER_VARIABLE := INITIAL_ADDRESS downto FINAL_ADDRESS do
       STATEMENT

   @@ Set member iteration

Description
-----------

The `for' statement is a count loop. For further information see *Note
for Statement::.

Conforming to
-------------

`for' is defined in ISO 7185 Pascal and supported by all known Pascal
variants. Iteration of Pointers is a Borland Pascal extension. Set
member iteration is an ISO 10206 Extended Pascal extension.

Example
-------

     program ForDemo;
     var
       CharSet: set of Char;
       c: Char;
       n: Integer;
       Fac: array [0 .. 10] of Integer;
       PInt: ^Integer;
     begin
       CharSet := ['g', 'p', 'c'];
       for c in CharSet do
         WriteLn (c);  { prints `c', `g', `p' in three lines }
       Fac[0] := 1;
       for n := 1 to 10 do  { computes the factorial of n for n = 0 .. 10 }
         Fac[n] := Fac[n - 1] * n;
       {$X+}
       { prints n! for n = 0 .. 10 }
       for PInt := @Fac[0] to @Fac[10] do
         WriteLn (PInt - @Fac[0], '! = ', PInt^)
     end.

See also
--------

*Note Keywords::, *Note Set Types::, *Note Pointer Arithmetics::


File: gpc.info,  Node: FormatString,  Next: forward,  Prev: for,  Up: Reference

FormatString
============

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`FormatString' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: forward,  Next: Frac,  Prev: FormatString,  Up: Reference

forward
=======

(Under construction.)

Synopsis
--------

Description
-----------

Declaration of a routine whose definition follows below.

Conforming to
-------------

`forward' is a UCSD Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Frac,  Next: FrameAddress,  Prev: forward,  Up: Reference

Frac
====

Synopsis
--------

     function Frac (x: Real): Real;

Description
-----------

`Frac' returns the fractional part of a floating point number.

Conforming to
-------------

`Frac' is a Borland Pascal extension.

Example
-------

     program FracDemo;

     begin
       WriteLn (Frac (12.345) : 1 : 5);  { 0.34500 }
       WriteLn (Int (12.345) : 1 : 5);  { 12.00000 }
       WriteLn (Round (12.345) : 1);  { 12 }
       WriteLn (Trunc (12.345) : 1);  { 12 }

       WriteLn (Frac (-12.345) : 1 : 5);  { -0.34500 }
       WriteLn (Int (-12.345) : 1 : 5);  { -12.00000 }
       WriteLn (Round (-12.345) : 1);  { -12 }
       WriteLn (Trunc (-12.345) : 1);  { -12 }

       WriteLn (Frac (12.543) : 1 : 5);  { 0.54300 }
       WriteLn (Int (12.543) : 1 : 5);  { 12.00000 }
       WriteLn (Round (12.543) : 1);  { 13 }
       WriteLn (Trunc (12.543) : 1);  { 12 }

       WriteLn (Frac (-12.543) : 1 : 5);  { -0.54300 }
       WriteLn (Int (-12.543) : 1 : 5);  { -12.00000 }
       WriteLn (Round (-12.543) : 1);  { -13 }
       WriteLn (Trunc (-12.543) : 1);  { -12 }
     end.

See also
--------

*Note Real Types::, *Note Real::, *Note Int::, *Note Round::, *Note
Trunc::.


File: gpc.info,  Node: FrameAddress,  Next: FreeMem,  Prev: Frac,  Up: Reference

FrameAddress
============

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`FrameAddress' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: FreeMem,  Next: function,  Prev: FrameAddress,  Up: Reference

FreeMem
=======

Synopsis
--------

     procedure FreeMem (var p: Pointer; Size: Cardinal);
or
     procedure FreeMem (var p: Pointer);

Description
-----------

Releases a chunk of memory previously allocated using `GetMem'.  The
parameter SIZE is optional. Its value is currently ignored.

   Since Extended Pascal's schemata provide a cleaner way to implement
dynamical arrays and such, we recommend using `GetMem' and `FreeMem'
only for low-level applications or for interfacing with other languages.

Conforming to
-------------

`FreeMem' is a Borland Pascal extension. `FreeMem' with only one
parameter is a GNU Pascal extension.

Example
-------

*Note GetMem::.

See also
--------

*Note GetMem::, *Note Schema Types::, *Note Dispose::, *Note Mark::,
*Note Release::.


File: gpc.info,  Node: function,  Next: GE,  Prev: FreeMem,  Up: Reference

function
========

(Under construction.)

Synopsis
--------

Description
-----------

Function declaration.

Conforming to
-------------

`function' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: GE,  Next: GEPad,  Prev: function,  Up: Reference

GE
==

(Under construction.)

Synopsis
--------

     function GE (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`GE' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: GEPad,  Next: Get,  Prev: GE,  Up: Reference

GEPad
=====

(Under construction.)

Synopsis
--------

     function GEPad (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`GEPad' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Get,  Next: GetMem,  Prev: GEPad,  Up: Reference

Get
===

(Under construction.)

Synopsis
--------

     procedure Get (var F: TYPED_FILE);

Description
-----------

Conforming to
-------------

`Get' is defined in ISO 7185 Pascal and supported by all known Pascal
variants except UCSD/Borland Pascal and its variants.

Example
-------

See also
--------


File: gpc.info,  Node: GetMem,  Next: GetTimeStamp,  Prev: Get,  Up: Reference

GetMem
======

Synopsis
--------

     procedure GetMem (var p: Pointeger; Size: Cardinal);

Description
-----------

Allocates dynamical storage on the heap and returns a pointer to it in
`p'.

   Since Extended Pascal's schemata provide a cleaner way to implement
dynamical arrays and such, we recommend using `GetMem' and `FreeMem'
only for low-level applications.

Conforming to
-------------

`GetMem' is a Borland Pascal extension.

Example
-------

The Borland-comatibility unit `Graph' from the `BPcompat' package
supports a `GetImage' and a `PutImage' procedure which need a variable
of size `ImageSize' as a buffer. Since these are "black box" routines,
the buffer can't reasonably be a schema providing a dynamical array.
Instead, we have to use `GetMem' and `FreeMem' for dynamical memory
allocation.

     program GetMemDemo;
     var
       Buffer: Pointer;
       Size: Cardinal;
     begin
       Size := Random (10000);  { the size can be determined at run time }
       GetMem (Buffer, Size);
       { Do something with Buffer }
       FreeMem (Buffer)  { or: FreeMem (Buffer, Size) }
     end.

See also
--------

*Note FreeMem::, *Note New::, *Note Schema Types::.


File: gpc.info,  Node: GetTimeStamp,  Next: goto,  Prev: GetMem,  Up: Reference

GetTimeStamp
============

Synopsis
--------

     procedure GetTimeStamp (var T: TimeStamp);

Description
-----------

GetTimeStamp gets the current local date and time as a `TimeStamp'
record containing the Year, Month, Day, Hour, Minute, Second, and so on.

Conforming to
-------------

`GetTimeStamp' is an ISO 10206 Extended Pascal extension.

Example
-------

Set *Note TimeStamp::.

See also
--------

*Note TimeStamp::, *Note Date::, *Note Time::, *Note Date And Time
Routines::.


File: gpc.info,  Node: goto,  Next: GT,  Prev: GetTimeStamp,  Up: Reference

goto
====

(Under construction.)

Synopsis
--------

     goto LABEL

Description
-----------

The `goto' statement transfers control to statement with the label
`label'.

Conforming to
-------------

`goto' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: GT,  Next: GTPad,  Prev: goto,  Up: Reference

GT
==

(Under construction.)

Synopsis
--------

     function GT (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`GT' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: GTPad,  Next: Halt,  Prev: GT,  Up: Reference

GTPad
=====

(Under construction.)

Synopsis
--------

     function GTPad (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`GTPad' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Halt,  Next: High,  Prev: GTPad,  Up: Reference

Halt
====

Synopsis
--------

     Halt;
or
     Halt (ExitCode: Integer);

Description
-----------

`Halt' terminates the program with exitcode 0. If `ExitCode', is
specified, it is returned by `Halt' on exit.

Conforming to
-------------

`Halt' is an Extended Pascal and a UCSD Pascal extension.

Example
-------

     program HaltDemo;
     begin
       WriteLn ('This string will always be this program''s output.');
       Halt;  { Terminate right here and right now. }
       WriteLn ('And this string won''t ever!')
     end.

See also
--------

*Note Break::, *Note Continue::, *Note Exit::, *Note Return::, *Note
goto::.


File: gpc.info,  Node: High,  Next: if,  Prev: Halt,  Up: Reference

High
====

Synopsis
--------

     function High (ORDINAL_TYPE_OR_VARIABLE): ORDINAL_TYPE;
or
     function High (ARRAY_TYPE_OR_VARIABLE): ARRAY_INDEX_TYPE;
   or
     function High (STRING_VARIABLE): Integer;

Description
-----------

For ordinal types or variables of that type, `High' returns the highest
value a variable of that type can assume.

   For array types or variables of that type, `High' returns the
highest index a variable of that type can assume. Note: the result is of
the same type as the array index is. If the array has more than one
dimension, `High' returns the highest index in the first dimension.

   If the argument is a string variable, `High' returns the
discriminant of the string type (i.e. its capacity).

Conforming to
-------------

`High' is a Borland Pascal extension.

Example
-------

     program HighDemo;
     type
       Colors = (Red, Green, Blue);
     var
       Col: array [Colors] of (Love, Hope, Faithfulness);
       Foo: Colors;
       Bar: Integer;
       Baz: String (123);
     begin
       Foo := High (Col);             { yields Blue }
       Bar := Ord (High (Col[Foo]));  { yields Ord (Faithfulness), i.e., 2 }
       Bar := High (Integer);         { highest possible value of `Integer' }
       Bar := High (Baz)              { returns 123 }
     end.

See also
--------

*Note Low::


File: gpc.info,  Node: if,  Next: Im,  Prev: High,  Up: Reference

if
==

Synopsis
--------

     if BOOLEAN_EXPRESSION then
       STATEMENT
or with an alternative statement:
     if BOOLEAN_EXPRESSION then
       STATEMENT1
     else
       STATEMENT2

Description
-----------

The `if ... then' statement executes STATEMENT1 depending on `Boolean
expression' being true. If `else' is specified, it continues executing
STATEMENT2 instead.

Conforming to
-------------

`if' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program IfDemo;
     var
       Foo, Bar: Boolean;
     begin
       Foo := True;
       Bar := False;
       if ((1 = 1) or (2 = 3)) and (Foo = not Bar) then
         begin
           { This is executed if either Foo is true but not Bar or vice versa }
           WriteLn ('Either Foo or Bar is true.');
           if Bar then
             WriteLn ('You will see this text if Bar is true.')
         end
       else  { This whole `else' branch is not executed }
         if 1 = 1 then
           if True = False then
             WriteLn ('This text is never written on screen.')
           else  { Note: This ``else'' belongs to ``if True = False'' }
             WriteLn ('This text is never written on screen as well.')
         else  { Note: This ``else'' belongs to ``if 1 = 1'' }
           WriteLn ('Nor is this.')
     end.

See also
--------

*Note Keywords::, *Note if Statement::, *Note else::, *Note then::


File: gpc.info,  Node: Im,  Next: implementation,  Prev: if,  Up: Reference

Im
==

Synopsis
--------

     function Im (z: Complex): Real;

Description
-----------

`Im' extracts the imaginary part of the complex number `z'.  The result
is a real value.

Conforming to
-------------

`Im' is an ISO 10206 Extended Pascal extension.

Example
-------

     program ImDemo;
     var
       z: Complex;
     begin
       z := Cmplx (1, 2);  { 1 + i * 2 }
       WriteLn (Im (z) : 0 : 5)  { 2.00000 }
     end.

See also
--------

*Note Cmplx::, *Note Re::, *Note Arg::.


File: gpc.info,  Node: implementation,  Next: import,  Prev: Im,  Up: Reference

implementation
==============

(Under construction.)

Synopsis
--------

Description
-----------

Module or unit implementation part.

Conforming to
-------------

`implementation' is an Extended Pascal and a UCSD Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: import,  Next: in,  Prev: implementation,  Up: Reference

import
======

Synopsis
--------

     program @@fragment foo;

     import
       bar1;
       bar3 (baz1 => glork1) in 'baz.pas';
       bar2 only (baz2, baz3 => glork2);
       bar4 qualified;

     [...]

   In module:

     module @@fragment Bar;

     import
       bar1;
       bar3 (baz1 => glork1) in 'baz.pas';
       bar2 only (baz2, baz3 => glork2);
       bar4 qualified;

     [...]

Description
-----------

The reserved word `import' in the _import part_ of a program makes the
program import an interface.

   The `in' above tells GPC to look for the module in the specified
file; otherwise the file name is derived from the name of the interface
by adding first `.p', then `.pas' - which only works if the name of the
exported interface coincides with the file name.

   The symbol `=>' denotes import renaming: The entity which is
exported under the name `baz1' by the interface `bar3' will be known
under the new name `glork1' in the program.

   The `only' qualifier means that only the listed identifiers will be
imported from the interface. Renaming works together with `only', too.

   The `qualified' qualifier means "qualified import": The imported
identifiers will be accessible only trough a "qualified name". The
entity which is exported under the name `baz2' by the interface `bar4'
will be accessible as `bar4.baz2'.

   There must be at most one import part at the begining of a block.
Each module or function/procedure (and also main program) can have its
own import part. A single import part can import arbitrarly many
interfaces.

   The interfaces needn't be exported by Extended Pascal modules but
may be UCSD/Borland Pascal units as well. GPC also allows `import'
parts in units.

Conforming to
-------------

`import' and modules in general are an ISO 10206 Extended Pascal
extension.

Example
-------

See also
--------

*Note Keywords::, *Note module::, *Note unit::, *Note uses::.


File: gpc.info,  Node: in,  Next: Inc,  Prev: import,  Up: Reference

in
==

Synopsis
--------

As part of the `set' membership test, as a boolean expression:
     ORDINAL_VALUE in SET_EXPRESSION
   or, as part of a `for' loop iterating through a set:
     for ORDINAL_VARIABLE in SET_EXPRESSION do ...

Description
-----------

When `in' is used as a membership test, it acts as a binary operator
taking ORDINAL_VALUE as its left parameter and SET_EXPRESSION as its
right parameter and returning a boolean result which is true if
SET_EXPRESSION contains the element ORDINAL_VALUE.

   When `in' is used as part of a `for' loop, it iterates
ORDINAL_VARIABLE over the elements contained in SET_EXPRESSION, that is
every ORDINAL_VALUE that would return true if tested as `ORDINAL_VALUE
in SET_EXPRESSION'.

Conforming to
-------------

`in' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

Set *Note set::

See also
--------

*Note Keywords::, *Note Set Operations::, *Note set::, *Note Exclude::,
*Note Include::, *Note for::.


File: gpc.info,  Node: Inc,  Next: Include,  Prev: in,  Up: Reference

Inc
===

Synopsis
--------

For ordinal types:
     procedure Inc (var x: ORDINAL_TYPE);
   or
     procedure Inc (var x: ORDINAL_TYPE; Amount: AND_INTEGER_TYPE);

   For pointer types:
     procedure Inc (var p: ANY_POINTER_TYPE);
   or
     procedure Inc (var p: ANY_POINTER_TYPE; Amount: AND_INTEGER_TYPE);

Description
-----------

For ordinal types, `inc' increases the value of `x' by one or by
`amount' if it is given.

   If the argument `p' is pointing to a specified type (typed pointer),
`inc' increases the address of `p' by the size of the type `p' is
pointing to or by `amount' times that size respectively. If `p' is an
untyped pointer (i.e. `p' is of type *Note Pointer::), `p' is increased
by one.

Conforming to
-------------

`Inc' is a Borland Pascal extension.  Yet application of `Inc' to
pointers is defined in Borland Pascal.  The combination of the second
argument with application to pointers is a GNU Pascal extension.

Example
-------

     program IncDemo;
     var
       Foo: Integer;
       Bar: array [1 .. 5] of Integer;
       Baz: ^Integer;
     begin
       Foo := 4;
       Inc (Foo, 5);      { yields 9 }
       {$X+}            { Turn on extended systax }
       Baz := @Bar[1];   { Baz points to y[1] }
       Inc (Baz, 2);      { Baz points to y[3] }
     end.

See also
--------

*Note Dec::, *Note Pred::, *Note Succ::, *Note Pointer Arithmetics::.


File: gpc.info,  Node: Include,  Next: Index,  Prev: Inc,  Up: Reference

Include
=======

Synopsis
--------

     Include (SET_VARIABLE, ORDINAL_VALUE);

Description
-----------

Add (join) a single element to a set. ORDINAL_VALUE must be compatible
with the base type of SET_VARIABLE.  Include is equivalent to:

     SET_VARIABLE := SET_VARIABLE + [ORDINAL_VALUE];

   If SET_VARIABLE already contains ORDINAL_VALUE, nothing happens.

Conforming to
-------------

`Include' is a Borland Pascal extension.

Example
-------

     program IncludeDemo;

     var
       Ch: Char;
       MyCharSet: set of Char;

     begin
       MyCharSet := ['P', 'N', 'L'];
       Include (MyCharSet , 'A')  { A, L, N, P }
     end.

   See other examples in *Note set:: and *Note Set Operations::.

See also
--------

*Note Keywords::, *Note Set Operations::, *Note set::, *Note in::,
*Note Exclude::.


File: gpc.info,  Node: Index,  Next: inherited,  Prev: Include,  Up: Reference

Index
=====

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`Index' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: inherited,  Next: initialization,  Prev: Index,  Up: Reference

inherited
=========

(Under construction.)

Synopsis
--------

Description
-----------

Reference to methods of ancestor object types.

Conforming to
-------------

`inherited' is an Object Pascal, Borland Pascal and traditional
Macintosh Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: initialization,  Next: Initialize,  Prev: inherited,  Up: Reference

initialization
==============

(Under construction.)

Synopsis
--------

Description
-----------

Unit initialization.

   It is equivalent to Extended Pascal's `to begin do'.

Conforming to
-------------

`initialization' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::, *Note finalization::, *Note to begin do::.


File: gpc.info,  Node: Initialize,  Next: InOutRes,  Prev: initialization,  Up: Reference

Initialize
==========

(Under construction.)

Synopsis
--------

     procedure Initialize (var Aynthing);

Description
-----------

`Initialize' does all necessary initializations for the parameter
(e.g., setting of string and schema discriminants, and object VMT
pointers, initialization of file variables). This is normally done
automatically at the start of the lifetime of a variable, so you need
to call `Initialize' only in special situations, e.g. when you allocate
a dynamic variable with `GetMem' rather than `New'.

Conforming to
-------------

`Initialize' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Finalize::, *Note New::, *Note GetMem::.


File: gpc.info,  Node: InOutRes,  Next: Input,  Prev: Initialize,  Up: Reference

InOutRes
========

(Under construction.)

Synopsis
--------

     var
       InOutRes: Integer;

Description
-----------

Conforming to
-------------

`InOutRes' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Input,  Next: Insert,  Prev: InOutRes,  Up: Reference

Input
=====

(Under construction.)

Synopsis
--------

     var
       Input: Text;

Description
-----------

Conforming to
-------------

`Input' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------


File: gpc.info,  Node: Insert,  Next: Int,  Prev: Input,  Up: Reference

Insert
======

(Under construction.)

Synopsis
--------

     procedure Insert (Source: String; var Dest: String; Position: Integer);

Description
-----------

Conforming to
-------------

`Insert' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Int,  Next: Integer,  Prev: Insert,  Up: Reference

Int
===

Synopsis
--------

     function Int (x: Real): Real;

Description
-----------

`Int' returns the integer part of a floating point number as a floating
point number. Use `Trunc' to get the integer part as an integer.

Conforming to
-------------

`Int' is a UCSD Pascal extension.

Example
-------

     program IntDemo;

     begin
       WriteLn (Frac (12.345) : 1 : 5);  { 0.34500 }
       WriteLn (Int (12.345) : 1 : 5);  { 12.00000 }
       WriteLn (Round (12.345) : 1);  { 12 }
       WriteLn (Trunc (12.345) : 1);  { 12 }

       WriteLn (Frac (-12.345) : 1 : 5);  { -0.34500 }
       WriteLn (Int (-12.345) : 1 : 5);  { -12.00000 }
       WriteLn (Round (-12.345) : 1);  { -12 }
       WriteLn (Trunc (-12.345) : 1);  { -12 }

       WriteLn (Frac (12.543) : 1 : 5);  { 0.54300 }
       WriteLn (Int (12.543) : 1 : 5);  { 12.00000 }
       WriteLn (Round (12.543) : 1);  { 13 }
       WriteLn (Trunc (12.543) : 1);  { 12 }

       WriteLn (Frac (-12.543) : 1 : 5);  { -0.54300 }
       WriteLn (Int (-12.543) : 1 : 5);  { -12.00000 }
       WriteLn (Round (-12.543) : 1);  { -13 }
       WriteLn (Trunc (-12.543) : 1);  { -12 }
     end.

See also
--------

*Note Real Types::, *Note Real::, *Note Frac::, *Note Round::, *Note
Trunc::.


File: gpc.info,  Node: Integer,  Next: interface,  Prev: Int,  Up: Reference

Integer
=======

Synopsis
--------

     type
       Integer  { built-in type }

Description
-----------

`Integer' is the "natural" signed integer type in GNU Pascal.  On some
platforms it is 32 bits wide and thus has a range of `-2147483648 ..
2147483647'. Use it whenever you need a general-purpose signed integer
type.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

In ISO Pascal, `Integer' is the only built-in integer type.  (However
see *Note Subrange Types::.)

Example
-------

     program IntegerDemo;
     var
       a: Integer;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: interface,  Next: interrupt,  Prev: Integer,  Up: Reference

interface
=========

(Under construction.)

Synopsis
--------

Description
-----------

Module or unit interface part.

Conforming to
-------------

`interface' is an Extended Pascal and a UCSD Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: interrupt,  Next: IOResult,  Prev: interface,  Up: Reference

interrupt
=========

Not yet implemented.

Synopsis
--------

Description
-----------

Interrupt handler declaration (not yet implemented).

Conforming to
-------------

`interrupt' is a Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: IOResult,  Next: is,  Prev: interrupt,  Up: Reference

IOResult
========

(Under construction.)

Synopsis
--------

     function IOResult: Integer;

Description
-----------

Conforming to
-------------

`IOResult' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: is,  Next: label,  Prev: IOResult,  Up: Reference

is
==

Synopsis
--------

Description
-----------

Object type membership test.

Conforming to
-------------

`is' is an Object Pascal and a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::, *Note as::, *Note TypeOf::, *Note OOP::.


File: gpc.info,  Node: label,  Next: LastPosition,  Prev: is,  Up: Reference

label
=====

(Under construction.)

Synopsis
--------

Description
-----------

Label declaration for a `goto' statement.

Conforming to
-------------

`label' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: LastPosition,  Next: LE,  Prev: label,  Up: Reference

LastPosition
============

(Under construction.)

Synopsis
--------

     function LastPosition (var F: TYPED_FILE): INDEX_TYPE;

Description
-----------

Conforming to
-------------

`LastPosition' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: LE,  Next: Leave,  Prev: LastPosition,  Up: Reference

LE
==

(Under construction.)

Synopsis
--------

     function LE (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`LE' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Leave,  Next: Length,  Prev: LE,  Up: Reference

Leave
=====

Synopsis
--------

     Leave  { simple statement }

Description
-----------

With `Leave' you can exit the body of the current loop instantly. It
can only be used within a `while', `repeat' or a `for' loop.

Conforming to
-------------

`Leave' is a Mac Pascal extension. Borland Pascal has `Break' instead.

Example
-------

     program LeaveDemo;
     var
       Foo: Integer;
     begin
       while True do
         begin
           repeat
             WriteLn ('Enter a number less than 100:');
             ReadLn (Foo);
             if Foo < 100 then
               Leave;  { Exits `repeat' loop }
             WriteLn (Foo, ' is not exactly less than 100! Try again ...')
           until False;
           if Foo > 50 then
             Leave;  { Exits `while' loop }
           WriteLn ('The number entered was not greater than 50.')
         end
     end.

See also
--------

*Note Loop Control Statements::, *Note Break::, *Note Continue::, *Note
Cycle::, *Note Exit::, *Note Halt::, *Note Return::, *Note goto::.


File: gpc.info,  Node: Length,  Next: LEPad,  Prev: Leave,  Up: Reference

Length
======

(Under construction.)

Synopsis
--------

     function Length (S: String): Integer;

Description
-----------

Conforming to
-------------

`Length' is an Extended Pascal and a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: LEPad,  Next: library,  Prev: Length,  Up: Reference

LEPad
=====

(Under construction.)

Synopsis
--------

     function LEPad (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`LEPad' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: library,  Next: Ln,  Prev: LEPad,  Up: Reference

library
=======

Not yet implemented.

Synopsis
--------

Description
-----------

Library declaration.

Conforming to
-------------

`library' is a Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Ln,  Next: LoCase,  Prev: library,  Up: Reference

Ln
==

Synopsis
--------

     function Ln (x: Real): Real;
or
     function Ln (z: Complex): Complex;

Description
-----------

The natural logarith `Ln' is the logarithm with base e, where e is the
Euler number e = Exp (1) = 2.718281828...

Conforming to
-------------

The function `Ln' is defined in ISO 7185 Pascal; its application to
complex values is defined in ISO 10206 Extended Pascal.

Example
-------

     program LnDemo;
     var
       z: Complex;
     begin
       z := Cmplx (1, 1);
       z := Ln (z)  { yields Ln (SqRt (2)) + i * Pi / 4 }
                    { since Ln (i * x) = Ln Abs (x) + i * Arg (x) }
     end.

See also
--------


File: gpc.info,  Node: LoCase,  Next: LongBool,  Prev: Ln,  Up: Reference

LoCase
======

(Under construction.)

Synopsis
--------

     function LoCase (Ch: Char): Char;

Description
-----------

Conforming to
-------------

`LoCase' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: LongBool,  Next: LongCard,  Prev: LoCase,  Up: Reference

LongBool
========

Synopsis
--------

     type
       LongBool = Boolean attribute (Size = BitSizeOf (LongInt));

Description
-----------

The intrinsic `LongBool' represents boolean values, but occupies the
same memory space as a `LongInt'.  It is used when you need to define a
parameter or record that conforms to some external library or system
specification.

Conforming to
-------------

`LongBool' is a Borland Pascal extension.

Example
-------

     program LongBoolDemo;
     var
       a: LongBool;
     begin
       LongInt (a) := 1;
       if a then WriteLn ('Ord (True) = 1')
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note Boolean::, *Note True::, *Note
False::, *Note CBoolean::, *Note ByteBool::, *Note ShortBool::, *Note
MedBool::, *Note WordBool::, *Note LongestBool::.


File: gpc.info,  Node: LongCard,  Next: LongestBool,  Prev: LongBool,  Up: Reference

LongCard
========

Synopsis
--------

     type
       LongCard = Cardinal attribute (Size = BitSizeOf (LongInt));

Description
-----------

`LongCard' is an unsigned integer type which is longer than `Cardinal'.
On some platforms it is 64 bits wide and thus has a range of `0 ..
18446744073709551615'.

   `LongCard' in GNU Pascal is compatible to `long long unsigned int'
in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`LongCard' is a GNU Pascal extension.

Example
-------

     program LongCardDemo;
     var
       a: LongCard;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: LongestBool,  Next: LongestCard,  Prev: LongCard,  Up: Reference

LongestBool
===========

Synopsis
--------

     type
       LongestBool = Boolean attribute (Size = BitSizeOf (LongestInt));

Description
-----------

The intrinsic `LongestBool' represents boolean values, but occupies the
same memory space as a `LongestInt'.  It is used when you need to
define a parameter or record that conforms to some external library or
system specification.

Conforming to
-------------

`LongestBool' is a GNU Pascal extension.

Example
-------

     program LongestBoolDemo;
     var
       a: LongestBool;
     begin
       LongestInt (a) := 1;
       if a then WriteLn ('Ord (True) = 1')
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note Boolean::, *Note True::, *Note
False::, *Note CBoolean::, *Note ByteBool::, *Note ShortBool::, *Note
MedBool::, *Note WordBool::, *Note LongBool::.


File: gpc.info,  Node: LongestCard,  Next: LongestInt,  Prev: LongestBool,  Up: Reference

LongestCard
===========

Synopsis
--------

     type
       LongestCard = Cardinal attribute (Size = BitSizeOf (LongestInt));

Description
-----------

`LongestCard' is GPC's longest-possible unsigned integer type.
Currently, this is the same as *Note LongCard::.  On some platforms it
is 64 bits wide and thus has a range of `0 .. 18446744073709551615'.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`LongestCard' is a GNU Pascal extension.

Example
-------

     program LongestCardDemo;
     var
       a: LongestCard;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: LongestInt,  Next: LongestReal,  Prev: LongestCard,  Up: Reference

LongestInt
==========

Synopsis
--------

     type
       LongestInt = LongInt;  { might get bigger than LongInt someday }

Description
-----------

`LongestInt' is GPC's longest-possible signed integer type.  Currently,
this is the same as *Note LongInt::. On some platforms it is 64 bits
wide and thus has a range of `-9223372036854775808 ..
9223372036854775807'.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`LongestInt' is a GNU Pascal extension.

Example
-------

     program LongestIntDemo;
     var
       a: LongestInt;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: LongestReal,  Next: LongestWord,  Prev: LongestInt,  Up: Reference

LongestReal
===========

(Under construction.)

Synopsis
--------

     type
       LongestReal = LongReal;  { might get bigger than LongReal someday }

Description
-----------

Conforming to
-------------

`LongestReal' is a GNU Pascal extension.

Example
-------

     program LongestRealDemo;
     var
       a: LongestReal;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------


File: gpc.info,  Node: LongestWord,  Next: LongInt,  Prev: LongestReal,  Up: Reference

LongestWord
===========

Synopsis
--------

     type
       LongestWord = LongestCard;

Description
-----------

`LongestWord' is GPC's longest-possible unsigned integer type.
Currently, this is the same as *Note LongWord::. On some platforms it
is 64 bits wide and thus has a range of `0 ..  18446744073709551615'.
(It is the same as *Note LongestCard::.)

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`LongestWord' is a GNU Pascal extension.

Example
-------

     program LongestWordDemo;
     var
       a: LongestWord;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note LongestCard::, *Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: LongInt,  Next: LongReal,  Prev: LongestWord,  Up: Reference

LongInt
=======

Synopsis
--------

     type
       LongInt  { built-in type }

Description
-----------

`LongInt' is a signed integer type which is longer than `Integer'. On
some platforms it is 64 bits wide and thus has a range of
`-9223372036854775808 .. 9223372036854775807'.

   `LongInt' in GNU Pascal is compatible to `long long int' in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`LongInt' is a Borland Pascal extension. Borland Pascal defines
`LongInt' as a 32-bit signed integer type (*Note Integer:: in GNU
Pascal).

Example
-------

     program LongIntDemo;
     var
       a: LongInt;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: LongReal,  Next: LongWord,  Prev: LongInt,  Up: Reference

LongReal
========

(Under construction.)

Synopsis
--------

     type
       LongReal  { built-in type }

Description
-----------

Conforming to
-------------

`LongReal' is a GNU Pascal extension.

Example
-------

     program LongRealDemo;
     var
       a: LongReal;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------


File: gpc.info,  Node: LongWord,  Next: Low,  Prev: LongReal,  Up: Reference

LongWord
========

Synopsis
--------

     type
       LongWord = LongCard;

Description
-----------

`LongWord' is an unsigned integer type which is larger than `Word'. On
some platforms it is 64 bits wide and thus has a range of `0 ..
18446744073709551615'. It is the same as *Note LongCard::.

   `LongWord' in GNU Pascal is compatible to `long long unsigned int'
in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`LongWord' is a GNU Pascal extension.

Example
-------

     program LongWordDemo;
     var
       a: LongWord;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note LongCard::, *Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: Low,  Next: LT,  Prev: LongWord,  Up: Reference

Low
===

Synopsis
--------

     function Low (ORDINAL_TYPE_OR_VARIABLE): ORDINAL_TYPE;
or
     function Low (ARRAY_TYPE_OR_VARIABLE): ARRAY_ELEMENT_TYPE;
   or
     function Low (STRING_VARIABLE): Integer;

Description
-----------

For ordinal types or variables of that type, `Low' returns the lowest
value a variable of that type can assume.

   For array types or variables of that type, `Low' returns the lowest
index a variable of that type can assume. Note: the result is of the
same type as the array index is. If the array has more than one
dimension, `Low' returns the lowest index in the first dimension.

   If the argument is a string variable, `Low' returns one.

Conforming to
-------------

`Low' is a Borland Pascal extension.

Example
-------

     program LowDemo;
     type
       Colors = (Red, Green, Blue);
     var
       Col: array [12 .. 20] of Colors;
       Foo: 12 .. 20;
       Bar: Integer;
     begin
       Foo := Low (Col);            { returns 12 }
       Col[Foo] := Low (Col[Foo]);  { returns Red }
       Bar := Low (Integer)         { lowest possible value of `Integer' }
     end.

See also
--------

*Note High::


File: gpc.info,  Node: LT,  Next: LTPad,  Prev: Low,  Up: Reference

LT
==

(Under construction.)

Synopsis
--------

     function LT (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`LT' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: LTPad,  Next: Mark,  Prev: LT,  Up: Reference

LTPad
=====

(Under construction.)

Synopsis
--------

     function LTPad (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`LTPad' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Mark,  Next: Max,  Prev: LTPad,  Up: Reference

Mark
====

(Under construction.)

Synopsis
--------

     procedure Mark (var P: Pointer);

Description
-----------

Conforming to
-------------

`Mark' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Max,  Next: MaxChar,  Prev: Mark,  Up: Reference

Max
===

(Under construction.)

Synopsis
--------

     function Max (x1, x2: ORDINAL_OR_REAL_TYPE): SAME_TYPE;

Description
-----------

Conforming to
-------------

`Max' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: MaxChar,  Next: MaxInt,  Prev: Max,  Up: Reference

MaxChar
=======

(Under construction.)

Synopsis
--------

Description
-----------

The value of `MaxChar' is the largest value of `Char'.

Conforming to
-------------

`MaxChar' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: MaxInt,  Next: MaxReal,  Prev: MaxChar,  Up: Reference

MaxInt
======

(Under construction.)

Synopsis
--------

Description
-----------

The `MaxInt' constant defines the maximum value of `Integer'. This
constant is a built-in compiler value.

Conforming to
-------------

`MaxInt' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

See also
--------


File: gpc.info,  Node: MaxReal,  Next: MedBool,  Prev: MaxInt,  Up: Reference

MaxReal
=======

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`MaxReal' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note MinReal::.


File: gpc.info,  Node: MedBool,  Next: MedCard,  Prev: MaxReal,  Up: Reference

MedBool
=======

Synopsis
--------

     type
       MedBool = Boolean attribute (Size = BitSizeOf (MedInt));

Description
-----------

The intrinsic `MedBool' represents boolean values, but occupies the
same memory space as a `MedInt'.  It is used when you need to define a
parameter or record that conforms to some external library or system
specification.

Conforming to
-------------

`MedBool' is a GNU Pascal extension.

Example
-------

     program MedBoolDemo;
     var
       a: MedBool;
     begin
       MedInt (a) := 1;
       if a then WriteLn ('Ord (True) = 1')
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note Boolean::, *Note True::, *Note
False::, *Note CBoolean::, *Note ByteBool::, *Note ShortBool::, *Note
WordBool::, *Note LongBool::, *Note LongestBool::.


File: gpc.info,  Node: MedCard,  Next: MedInt,  Prev: MedBool,  Up: Reference

MedCard
=======

Synopsis
--------

     type
       MedCard = Cardinal attribute (Size = BitSizeOf (MedInt));

Description
-----------

`MedCard' is an unsigned integer type which is not smaller than
`Cardinal'. On some platforms it actually is the same as `Cardinal' and
32 bits wide and thus has a range of `0 .. 4294967295'.

   `MedCard' in GNU Pascal is compatible to `long unsigned int' in GNU
C. This compatibility is the reason why `MedCard' exists.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`MedCard' is a GNU Pascal extension.

Example
-------

     program MedCardDemo;
     var
       a: MedCard;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: MedInt,  Next: MedReal,  Prev: MedCard,  Up: Reference

MedInt
======

Synopsis
--------

     type
       MedInt  { built-in type }

Description
-----------

`MedInt' is a signed integer type which is not smaller than `Integer'.
On some platforms it actually is the same as `Integer' and 32 bits wide
and thus has a range of `-2147483648 .. 2147483647'.

   `MedInt' in GNU Pascal is compatible to `long int' in GNU C. This
compatibility is the reason why `MedInt' exists.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`MedInt' is a GNU Pascal extension.

Example
-------

     program MedIntDemo;
     var
       a: MedInt;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: MedReal,  Next: MedWord,  Prev: MedInt,  Up: Reference

MedReal
=======

(Under construction.)

Synopsis
--------

     type
       MedReal = Real;

Description
-----------

Conforming to
-------------

`MedReal' is a GNU Pascal extension.

Example
-------

     program MedRealDemo;
     var
       a: MedReal;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------


File: gpc.info,  Node: MedWord,  Next: Min,  Prev: MedReal,  Up: Reference

MedWord
=======

Synopsis
--------

     type
       MedWord = MedCard;

Description
-----------

`MedWord' is an unsigned integer type which is not smaller than `Word'.
On some platforms it actually is the same as `Word' and 32 bits wide
and thus has a range of `0 .. 4294967295'. It is the same as *Note
MedCard::.

   `MedWord' in GNU Pascal is compatible to `long unsigned int' in GNU
C. This compatibility is the reason why `MedWord' exists.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`MedWord' is a GNU Pascal extension.

Example
-------

     program MedWordDemo;
     var
       a: MedWord;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note MedCard::, *Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: Min,  Next: MinReal,  Prev: MedWord,  Up: Reference

Min
===

(Under construction.)

Synopsis
--------

     function Min (x1, x2: ORDINAL_OR_REAL_TYPE): SAME_TYPE;

Description
-----------

Conforming to
-------------

`Min' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: MinReal,  Next: MkDir,  Prev: Min,  Up: Reference

MinReal
=======

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`MinReal' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note MaxReal::.


File: gpc.info,  Node: MkDir,  Next: mod,  Prev: MinReal,  Up: Reference

MkDir
=====

Synopsis
--------

     procedure MkDir (Directory: String);

Description
-----------

`MkDir' creates the given DIRECTORY, if its argument is a valid
parameter to the related operating system's function.  Otherwise a
runtime error is caused.

Conforming to
-------------

`MkDir' is a Borland Pascal extension.

Example
-------

     program MkDirDemo;
     var
       Foo: String (127);
     begin
       WriteLn ('Enter directory name to create:');
       ReadLn (Foo);
       {$I-}  { Don't abort program on error }
       MkDir (Foo);
       if IOResult <> 0 then
         WriteLn ('Directory `', Foo, ''' could not be created')
       else
         WriteLn ('Okay')
     end.

See also
--------

*Note ChDir::, *Note RmDir::


File: gpc.info,  Node: mod,  Next: module,  Prev: MkDir,  Up: Reference

mod
===

(Under construction.)

Synopsis
--------

     operator mod (p, q: Integer) = r: Integer;

Description
-----------

Integer remainder operator.

Conforming to
-------------

`mod' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: module,  Next: Move,  Prev: mod,  Up: Reference

module
======

(Under construction.)

Synopsis
--------

Description
-----------

EP style or PXSC style module.

Conforming to
-------------

`module' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Move,  Next: MoveLeft,  Prev: module,  Up: Reference

Move
====

(Under construction.)

Synopsis
--------

     procedure Move (const Source; var Dest; Count: Integer);

Description
-----------

Conforming to
-------------

`Move' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: MoveLeft,  Next: MoveRight,  Prev: Move,  Up: Reference

MoveLeft
========

(Under construction.)

Synopsis
--------

     procedure MoveLeft (const Source; var Dest; Count: Integer);

Description
-----------

Conforming to
-------------

`MoveLeft' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: MoveRight,  Next: name,  Prev: MoveLeft,  Up: Reference

MoveRight
=========

(Under construction.)

Synopsis
--------

     procedure MoveRight (const Source; var Dest; count: Integer);

Description
-----------

Conforming to
-------------

`MoveRight' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: name,  Next: NE,  Prev: MoveRight,  Up: Reference

name
====

(Under construction.)

Synopsis
--------

PROCEDURE/FUNCTION_HEADER; external name NAME;

   PROCEDURE/FUNCTION_HEADER; attribute (name = NAME);

   or

   VARIABLE_DECLARATION; external name NAME;

   VARIABLE_DECLARATION; attribute (name = NAME);

   or

   unit NAME; attribute (name = NAME);

Description
-----------

The `name' directive declares the external name of a procedure,
function or variable. It can be used after `external' or within
`attribute'.

   This directive declares the external name of a procedure, function
or variable. The external name of the routine is given explicitly as a
case-sensitive constant string expression. This is useful when
interfacing with libraries written in other languages.

   With this extension it is possible to access all external functions,
for example the X11 interface functions, and not only those written in
lowercase.

   `name' can also be applied to units and module interfaces. In this
case it denotes the _prefix_ prepended to the external name of the
initializer of the unit: While it is normally called `init_Modulename',
it is called `init_NAME_Modulename' when `name' is given.

   This is not of interest under normal circumstances since the
initializers are called automatically. It can help avoiding conflicts
when there are several units of the same name within one program.
Again, this does not happen normally, but e.g., when a program uses a
unit/module that has the same name as one of the units the RTS consists
of: The RTS uses `GPC' as the name for its units to avoid conflicts.

   In the future, a `name' directive applied to units, modules and
programs (the latter is recognized syntactically already, but has no
effect yet) will also affect the default external name of routines and
variables which have no `name' directive themselves. Again, this is
mostly useful for libraries etc., and will not be necessary for normal
units, modules and programs.

Conforming to
-------------

`name' is a Borland Pascal extension. `attribute' and the application
of `name' to units, modules and programs are GNU Pascal extensions.

Example
-------

     program NameDemo;

     { Make two variables aliases of each other by using `name'.
       This is not good style. If you must have aliases for any reason,
       `absolute' declarations may be the lesser evil ... }
     var
       Foo: Integer; attribute (name = 'Foo_Bar');
       Bar: Integer; external name 'Foo_Bar';

     { A function from the C library }
     function PutS (Str: CString): Integer; external name 'puts';

     var
       Result: Integer;
     begin
       Result := PutS ('Hello World!');
       WriteLn ('puts wrote ', Result, ' characters (including a newline).');
       Foo := 42;
       WriteLn ('Foo = ', Foo);
       Bar := 17;
       WriteLn ('Setting Bar to 17.');
       WriteLn ('Now, Foo = ', Foo, '!!!')
     end.

See also
--------

*Note Keywords::, *Note attribute::, *Note external::, *Note Importing
Libraries from Other Languages::.


File: gpc.info,  Node: NE,  Next: near,  Prev: name,  Up: Reference

NE
==

(Under construction.)

Synopsis
--------

     function NE (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`NE' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: near,  Next: NEPad,  Prev: NE,  Up: Reference

near
====

Synopsis
--------

Description
-----------

The `near' directive can be appended to a procedure or function heading
but is ignored by GPC. It is there for Borland compatibility, only.
(Since the GNU compilers provide a flat memory model, the distinction
between `near' and `far' pointers is void.)

Conforming to
-------------

`near' is a Borland Pascal extension.

Example
-------

     program NearDemo;

     var
       p: procedure;

     {$W no-near-far}  { Don't warn about the uselessness of `near' }

     procedure Foo; near;  { `near' has no effect in GPC }
     begin
       WriteLn ('Foo')
     end;

     begin
       p := Foo;  { Works, despite the `near'. }
       p
     end.

See also
--------

*Note Keywords::, *Note far::.


File: gpc.info,  Node: NEPad,  Next: New,  Prev: near,  Up: Reference

NEPad
=====

(Under construction.)

Synopsis
--------

     function NEPad (S1, S2: String): Boolean;

Description
-----------

Conforming to
-------------

`NEPad' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: New,  Next: NewCString,  Prev: NEPad,  Up: Reference

New
===

(Under construction.)

Synopsis
--------

     procedure New (var P: ANY_POINTER);
or
     procedure New (var P: POINTER_TO_A_VARIANT_RECORD; TAG_FIELDS);
   or
     procedure New (var P: POINTER_TO_A_SCHEMA; DISCRIMINANTS);
   or
     procedure New (var P: POINTER_TO_AN_OBJECT; CONSTRUCTOR_CALL);
   or
     function New (ANY_POINTER_TYPE): SAME_TYPE;
   or
     function New (VARIANT_RECORD_POINTER_TYPE;
                   TAG_FIELDS): SAME_TYPE;
   or
     function New (SCHEMA_POINTER_TYPE;
                   DISCRIMINANTS): SAME_TYPE;
   or
     function New (OBJECT_POINTER_TYPE;
                   CONSTRUCTOR_CALL): SAME_TYPE;

Description
-----------

Conforming to
-------------

`New' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------


File: gpc.info,  Node: NewCString,  Next: nil,  Prev: New,  Up: Reference

NewCString
==========

(Under construction.)

Synopsis
--------

     function NewCString (const S: String): CString;

Description
-----------

Conforming to
-------------

`NewCString' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: nil,  Next: not,  Prev: NewCString,  Up: Reference

nil
===

Synopsis
--------

`nil' is a predefined constant

Description
-----------

`nil' is a predefined pointer constant that indicates an unassigned
pointer. "nil" stands for "not in list". _Every_ pointer type can be
associated with this constant.

Conforming to
-------------

`nil' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program NilDemo;
     const
       NodeNum = 10;
     type
       PNode = ^TNode;
       TNode = record
         Key: Integer;
         Next: PNode
       end;
     var
       Root, Node: PNode;
       Foo: Integer;
     begin
       New (Root);
       Root^.Key := 1;             { Set root key }
       Node := Root;
       for Foo := 2 to NodeNum do  { Create linked list with NODE_NUM nodes }
         begin
           New (Node^.Next);
           Node := Node^.Next;
           Node^.Key := Foo        { Set key }
         end;
       Node^.Next := nil;          { Mark end of linked list }
       { Shorten list by removing its first element until list is empty }
       while Root <> nil do
         begin
           Node := Root;
           WriteLn ('Current key:', Root^.Key);
           Root := Root^.Next;
           Dispose (Node);
           Node := nil             { Indicate old node is not assigned }
         end
     end.

See also
--------

*Note Keywords::, *Note Assigned::, *Note Pointer::


File: gpc.info,  Node: not,  Next: Null,  Prev: nil,  Up: Reference

not
===

(Under construction.)

Synopsis
--------

     operator not (b1, b2: Boolean) = Result: Boolean;
or
     operator not (i1, i2: INTEGER_TYPE) = Result: INTEGER_TYPE;

Description
-----------

Boolean or bitwise negation operator.

Conforming to
-------------

`not' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Null,  Next: object,  Prev: not,  Up: Reference

Null
====

Synopsis
--------

     var
       Null: Void absolute 0;

Description
-----------

`Null' is a predefined variable at address `nil'.  `Null' can be passed
as a "void" argument to a procedure, function or operator expecting a
"var" parameter. _Note_: Make sure they can handle this case, otherwise
this is likely to cause an exception and the program will be
terminated. Since `Null' is an L-value, it can be taken as
"nil-reference".

Conforming to
-------------

`Null' is a Borland Delphi extension.

Example
-------

     program NullDemo;
     type
       PString = ^String;
     var
       Com1: String (25) = 'This is an amazing number';
       Com2: String (25) = 'This is a boring number';

     procedure FooBar (Foo: Integer; var Comment: PString);
     begin
       if Odd (Foo) then
         WriteLn ('FooBar:', Foo, ' is odd')
        else
         WriteLn ('FooBar:', Foo, ' is even');
       if @Comment <> nil then
         if not Odd (Foo) then
           Comment := @Com1
         else
           Comment := @Com2
     end;

     var
       S: String (25);
       P: PString value @S;

     begin
       { FooBar allows you to leave out variables
         for any information you might not need }
       FooBar (1, Null);
       { But FooBar is flexible, after all }
       FooBar (6, P);
       WriteLn ('FooBar said about 6: `', P^, '''')
     end.

See also
--------

*Note nil::


File: gpc.info,  Node: object,  Next: Odd,  Prev: Null,  Up: Reference

object
======

Synopsis
--------

Description
-----------

The keyword `object' is used to declare a new object type:

     type
       foo = object
         a: Integer;
         constructor Init;
         procedure Bar (x: Integer); virtual;
       end;

   (For a longer example, see *Note OOP::.)

Conforming to
-------------

GNU Pascal follows the Borland Pascal 7.0 object model.

   ISO Pascal does not support Object-oriented programming. There is an
ANSI draft for an "Object Pascal" language which is not yet supported
by GPC, but planned. The Delphi language, also called "Object Pascal"
by Borland, is currently not supported by GPC either.

Example
-------

See also
--------

*Note Keywords::, *Note OOP::, *Note record::.


File: gpc.info,  Node: Odd,  Next: of,  Prev: object,  Up: Reference

Odd
===

Synopsis
--------

     function Odd (i: Integer): Boolean;

Description
-----------

`Odd' checks the parity of its argument `i'. It returns `True' if the
argument is odd, `False' if it is even.

Conforming to
-------------

`Odd' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program OddDemo;
     var
       Foo: Integer;
     begin
       Write ('Please enter an odd number: ');
       ReadLn (Foo);
       if not Odd (Foo) then
         WriteLn ('Odd''s not even! Something''s odd out there ...')
       else
         WriteLn (Foo, ' is pretty odd.')
     end.

See also
--------


File: gpc.info,  Node: of,  Next: on,  Prev: Odd,  Up: Reference

of
==

(Under construction.)

Synopsis
--------

Description
-----------

Part of an `array', `set' or typed `file' type declaration, a `case'
statement, a variant `record' type or a `type of' type inquiry.

Conforming to
-------------

`of' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: on,  Next: only,  Prev: of,  Up: Reference

on
==

Not yet implemented.

Synopsis
--------

Conforming to
-------------

`on' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: only,  Next: operator,  Prev: on,  Up: Reference

only
====

(Under construction.)

Synopsis
--------

Description
-----------

Import specification.

Conforming to
-------------

`only' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: operator,  Next: or,  Prev: only,  Up: Reference

operator
========

(Under construction.)

Synopsis
--------

Description
-----------

Operator declaration.

Conforming to
-------------

`operator' is PASCAL_SC extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: or,  Next: Ord,  Prev: operator,  Up: Reference

or
==

Synopsis
--------

     operator or (operand1, operand2: Boolean) = Result: Boolean;
or
     operator or (operand1, operand2: INTEGER_TYPE) = Result: INTEGER_TYPE;
   or
     procedure or (var operand1: INTEGER_TYPE; operand2: INTEGER_TYPE);

Description
-----------

In GNU Pascal, `or' has three built-in meanings:

  1. Logical "or" between two `Boolean'-type expressions.  The result
     of the operation is of `Boolean' type.

     By default, `or' acts as a short-circuit operator in GPC: If the
     first operand is `True', the second operand is not evaluated
     because the result is already known to be `True'. You can change
     this to complete evaluation using the `--no-short-circuit'
     command-line option or the `{$B+}' compiler directive.

  2. Bitwise "or" between two integer-type expressions.  The result is
     of the common integer type of both expressions.

  3. Use as a "procedure": `operand1' is "or"ed bitwise with
     `operand2'; the result is stored in `operand1'.


Conforming to
-------------

The logical `or' operator is defined in ISO 7185 Pascal.

   According to ISO, you cannot rely on `or' being a short-circuit
operator. On the other hand, GPC's default behaviour does _not_
contradict the ISO standard. (See *Note or_else::.) However, since it
seems to be a de-facto standard among ISO Pascal compilers to evaluate
both operands of `or', GPC switches to `--no-short-circuit' mode if one
of the language dialect options selecting ISO Pascal, for instance
`--extended-pascal', is given. Use `--short-circuit' to override.

   Use of `or' as a bitwise operator for integers is a Borland Pascal
extension.

   Use of `or' as a "procedure" is a GNU Pascal extension.

Example
-------

     program OrDemo;
     var
       a, b, c: Integer;
     begin
       if (a = 0) or (b = 0) then  { logical `or' }
         c := 1
       else if (a or b) = 0 then  { bitwise `or' }
         c := 2
       else
         or (c, a)  { same as `c := c or a' }
     end.

   Note the difference between the logical `or' and the bitwise `or':
When `a' is 2 and `b' is 4, then `a or b' is 6. *Beware:* `a or b = 0'
happens to mean the same as `(a = 0) and (b = 0)'. (Note the `and'!)

   Since bitwise `or' has a higher priority than the `=' operator,
parentheses are needed in `if (a = 0) or (b = 0)' because otherwise `0
or b' would be calculated first, and the remainder would cause a parse
error.

See also
--------

*Note Keywords::, *Note and::, *Note xor::, *Note Operators::.


File: gpc.info,  Node: Ord,  Next: or else,  Prev: or,  Up: Reference

Ord
===

Synopsis
--------

     function Ord (ORDINAL_VALUE): Integer;

Description
-----------

`Ord' returns the ordinal value of any ordinal variable or constant.
For characters, this would be the ASCII code corresponding to the
character. For enumerated types, this would be the ordinal value of the
constant or variable (remember that ordinal value of enumerated
constants start from zero).

Conforming to
-------------

`Ord' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program OrdDemo;
     var
       Ch: Char;
       Day: (Monday, Tuesday, Wednesday, Thursday, Friday);
     begin
       Ch := 'A';
       WriteLn (Ord (Ch));  { 65 }
       Day := Thursday;
       WriteLn (Ord (Day));  { 3 }
     end.

See also
--------

*Note Character Types::, *Note Ordinal Types::, *Note Chr::, *Note
Char::


File: gpc.info,  Node: or else,  Next: or_else,  Prev: Ord,  Up: Reference

or else
=======

Synopsis
--------

     { `or else' is built in. A user-defined operator cannot consist of
        two words. }
     operator or else (operand1, operand2: Boolean) = Result: Boolean;

Description
-----------

`or else' is an alias for the short-circuit logical operator `or_else'.

Conforming to
-------------

While `or_else' is defined in ISO 10206 Extended Pascal, `or else' is a
GNU Pascal extension.

Example
-------

     program OrElseDemo;
     var
       a: Integer;
     begin
       ReadLn (a);
       if (a = 0) or else (100 div a > 42) then  { This is safe. }
         WriteLn ('100 div a > 42')
     end.

See also
--------

*Note Keywords::, *Note or_else::, *Note or::, *Note and then::.


File: gpc.info,  Node: or_else,  Next: otherwise,  Prev: or else,  Up: Reference

or_else
=======

Synopsis
--------

     operator or_else (operand1, operand2: Boolean) = Result: Boolean;

Description
-----------

The `or_else' short-circuit logical operator performs the same
operation as the logical operator `or'. But while the ISO standard does
not specify anything about the evaluation of the operands of `or' -
they may be evaluated in any order, or not at all - `or_else' has a
well-defined behaviour: It evaluates the first operand. If the result
is `True', `or_else' returns `True' without evaluating the second
operand. If it is `False', the second operand is evaluated and returned.

   GPC by default treats `or' and `or_else' exactly the same.  If you
want, for some reason, to have both operands of `or' evaluated
completely, you must assign both to temporary variables and then use
`or' - or `or_else', it does not matter.

Conforming to
-------------

`or_else' is an ISO 10206 Extended Pascal extension.

   Some people think that the ISO standard requires both operands of
`or' to be evaluated. This is false. What the ISO standard _does_ say
is that you cannot rely on a certain order of evaluation of the
operands of `or'; in particular things like the following program can
crash according to ISO Pascal, although they cannot crash when compiled
with GNU Pascal running in default mode.

     program OrBug;
     var
       a: Integer;
     begin
       ReadLn (a);
       if (a = 0) or (100 div a > 42) then  { This is *not* safe! }
         WriteLn ('You''re lucky. But the test could have crashed ...')
     end.

Example
-------

     program Or_ElseDemo;
     var
       a: Integer;
     begin
       ReadLn (a);
       if (a = 0) or_else (100 div a > 42) then  { This is safe. }
         WriteLn ('100 div a > 42')
     end.

See also
--------

*Note Keywords::, *Note or else::, *Note or::, *Note and_then::.


File: gpc.info,  Node: otherwise,  Next: Output,  Prev: or_else,  Up: Reference

otherwise
=========

Synopsis
--------

Default `case' branch as part of the `case' ...  `otherwise' statement:
     case EXPRESSION of
       SELECTOR: STATEMENT;
       ...
       SELECTOR: STATEMENT
     otherwise  { ``else'' instead of ``otherwise'' is allowed }
       STATEMENT;
       ...
       STATEMENT
     end

   Use in a structured value of `array' type:
     [INDEX1: VALUE1; INDEX2: VALUE2
      otherwise VALUE_OTHERWISE]

Description
-----------

`otherwise' starts a series of statements which is executed if no
selector matches EXPRESSION. In this situation, `else' is a synonym for
`otherwise'.

   `otherwise' also defines the default value in an Extended Pascal
structured values of array type.

Conforming to
-------------

`otherwise' is an ISO 10206 Extended Pascal extension.

Example
-------

     program OtherwiseDemo;

     var
       i: Integer;
       a: array [1 .. 10] of Integer value [1: 2; 4: 5 otherwise 3];

     begin
       for i := 1 to 10 do
         case a[i] of
           2:        WriteLn ('a[', i, '] has value two.');
           3:        WriteLn ('a[', i, '] has value three.');
           otherwise WriteLn ('a[', i, '] has neither value two nor three.')
         end
     end.

See also
--------

*Note Keywords::, *Note case Statement::, *Note case::, *Note else::.


File: gpc.info,  Node: Output,  Next: overload,  Prev: otherwise,  Up: Reference

Output
======

(Under construction.)

Synopsis
--------

     var
       Output: Text;

Description
-----------

Conforming to
-------------

`Output' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

See also
--------


File: gpc.info,  Node: overload,  Next: override,  Prev: Output,  Up: Reference

overload
========

Not yet implemented.

Synopsis
--------

Conforming to
-------------

`overload' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: override,  Next: Pack,  Prev: overload,  Up: Reference

override
========

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`override' directive is defined in OOE draft and supported by Delphi
and Mac Pascal

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Pack,  Next: packed,  Prev: override,  Up: Reference

Pack
====

(Under construction.)

Synopsis
--------

Description
-----------

     procedure Pack (Source: UNPACKED_ARRAY;
                     FirstElement: INDEX_TYPE;
                     var Dest: PACKED_ARRAY);

Conforming to
-------------

`Pack' is defined in ISO 7185 Pascal and supported by all known Pascal
variants except UCSD/Borland Pascal and its variants.

Example
-------

See also
--------


File: gpc.info,  Node: packed,  Next: Page,  Prev: Pack,  Up: Reference

packed
======

Synopsis
--------

Description
-----------

`packed' is a reserved word. According to ISO 7185 Pascal it can
precede `array' and `record' type definitions to indicate that memory
usage should be minimized for variables of this type, possibly at the
expense of loss of speed.

   As a GNU Pascal extension, `packed' can also be applied to *Note
Subrange Types::.

Conforming to
-------------

The reserved word `packed' is defined in ISO 7185 Pascal.

   According to ISO standard, only _packed_ arrays of char with lower
bound 1 qualify as strings of fixed length. GNU Pascal neither requires
`packed' nor the lower bound of 1 here.

Example
-------

     program PackedDemo;

     type
       MonthInt = packed 1 .. 12;  { needs one byte }
       FastMonthInt = 1 .. 12;     { needs e.g. four bytes }

       FixString10 = packed array [1 .. 10] of Char;
       FoxyString10 = array [0 .. 9] of Char;

       Flags = packed array [1 .. 32] of Boolean;  { needs four bytes }

       Int15 = Integer attribute (Size = 15);
       DateRec = packed record
         Day: 1 .. 31;       { five bits }
         Month: MonthInt;    { four bits }
         Year: Int15         { 15 bits = -16384 .. 16383 }
       end;

       Dates = array [1 .. 1000] of DateRec;

     var
       S: FixString10;
       T: FoxyString10;

     begin
       S := 'Hello!';  { blank padded }
       WriteLn (S);

       T := 'GNU Pascal';  { GPC extension: this also works. }
       WriteLn (T)
     end.

   `DateRec' has 24 bits = 3 bytes in total; `Dates' has 3000 bytes.

See also
--------

*Note Keywords::, *Note Pack::, *Note Unpack::, *Note SizeOf::, *Note
AlignOf::, *Note BitSizeOf::.


File: gpc.info,  Node: Page,  Next: PAnsiChar,  Prev: packed,  Up: Reference

Page
====

(Under construction.)

Synopsis
--------

     procedure Page ([var F: Text]);
or
     procedure Page;

Description
-----------

Conforming to
-------------

`Page' is defined in ISO 7185 Pascal, but missing in Borland Pascal.

Example
-------

See also
--------


File: gpc.info,  Node: PAnsiChar,  Next: ParamCount,  Prev: Page,  Up: Reference

PAnsiChar
=========

(Under construction.)

Synopsis
--------

     type
       PAnsiChar = ^AnsiChar;

Description
-----------

Conforming to
-------------

`PAnsiChar' is a Borland Delphi extension.

Example
-------

     program PAnsiCharDemo;
     var
       s: PAnsiChar;
     begin
       s := 'Hello, world!';
       {$X+}
       WriteLn (s)
     end.

See also
--------


File: gpc.info,  Node: ParamCount,  Next: ParamStr,  Prev: PAnsiChar,  Up: Reference

ParamCount
==========

Synopsis
--------

     function ParamCount: Integer;

Description
-----------

`ParamCount' returns the number of command-line arguments given to the
program. `ParamCount' returns 0 if no arguments have been given to the
program; the name of the program as an implicit argument is not counted.

Conforming to
-------------

`ParamCount' is a Borland Pascal extension.

Example
-------

     program ParamCountDemo;

     var
       i: Integer;

     begin
       WriteLn ('You have invoked this program with ',
                ParamCount, ' arguments.');
       WriteLn ('These are:');
       for i := 1 to ParamCount do
         WriteLn (ParamStr (i))
     end.

See also
--------

*Note ParamStr::.


File: gpc.info,  Node: ParamStr,  Next: PChar,  Prev: ParamCount,  Up: Reference

ParamStr
========

(Under construction.)

Synopsis
--------

     function ParamStr (ParmNumber: Integer): String;

Description
-----------

*Please note:* If you are using the Dos (DJGPP) or MS-Windows (mingw32)
version of GPC and are getting unexpected results from `ParamStr',
please see the section "Command-line Arguments Handling in DJGPP" of
the DJGPP FAQ list.

Conforming to
-------------

`ParamStr' is a Borland Pascal extension.

Example
-------

     program ParamStrDemo;

     var
       i: Integer;

     begin
       WriteLn ('You have invoked this program with ',
                ParamCount, ' arguments.');
       WriteLn ('These are:');
       for i := 1 to ParamCount do
         WriteLn (ParamStr (i))
     end.

See also
--------


File: gpc.info,  Node: PChar,  Next: Pi,  Prev: ParamStr,  Up: Reference

PChar
=====

(Under construction.)

Synopsis
--------

     type
       PChar = ^Char;
or
     type
       PChar = CString;

Description
-----------

Conforming to
-------------

`PChar' is a Borland Pascal extension.

Example
-------

     program PCharDemo;
     var
       s: PChar;
     begin
       s := 'Hello, world!';
       {$X+}
       WriteLn (s)
     end.

See also
--------


File: gpc.info,  Node: Pi,  Next: PObjectType,  Prev: PChar,  Up: Reference

Pi
==

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`Pi' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: PObjectType,  Next: Pointer,  Prev: Pi,  Up: Reference

PObjectType
===========

Synopsis
--------

     type
       InternalSignedSizeType =
         Integer attribute (Size = BitSizeOf (SizeType));
       PObjectType = ^const record
         Size:        SizeType;
         NegatedSize: InternalSignedSizeType;
         Parent:      PObjectType;
         Name:        ^const String
       end;

   (Note: `^record' is not valid syntax. It is just used here in the
explanation because the record type has no name by itself.  Because of
the added method pointers (see below), there is no useful usage of the
record type.)

Description
-----------

`PObjectType' is the type returned by `TypeOf' and required by
`SetType'. In fact, the record pointed to (the "VMT", "virtual method
table") also contains pointers to the virtual methods. However, these
are not declared in `PObjectType' because they vary from object type to
object type. The fields declared here are those that are shared by every
object type and can be accessed via `TypeOf'.

   `Size' contains the size of the object type, `NegatedSize' contains
the size negated (for runtime checks). `Parent' contains a pointer to
the parent type's VMT (or nil if the type has no parent). `Name' points
to a string containing the type's name.

Conforming to
-------------

`PObjectType' is a GNU Pascal extension.

Example
-------

See also
--------

*Note TypeOf::, *Note SetType::, *Note OOP::.


File: gpc.info,  Node: Pointer,  Next: Polar,  Prev: PObjectType,  Up: Reference

Pointer
=======

(Under construction.)

Synopsis
--------

     type
       Pointer  { built-in type }

Description
-----------

Conforming to
-------------

`Pointer' is a Borland Pascal extension.

Example
-------

     program PointerDemo;
     var
       a: Integer;
       b: Boolean;
       p: Pointer;
     begin
       p := nil;
       p := @a;
       p := @b
     end.

See also
--------


File: gpc.info,  Node: Polar,  Next: Pos,  Prev: Pointer,  Up: Reference

Polar
=====

(Under construction.)

Synopsis
--------

     function Polar (rho, phi: Real): Complex;

Description
-----------

Conforming to
-------------

`Polar' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Pos,  Next: Position,  Prev: Polar,  Up: Reference

Pos
===

(Under construction.)

Synopsis
--------

     function Pos (SearchPattern, Source: String): Integer;

Description
-----------

Conforming to
-------------

`Pos' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Position,  Next: pow,  Prev: Pos,  Up: Reference

Position
========

(Under construction.)

Synopsis
--------

     function Position (var F: TYPED_FILE): INDEX_TYPE;

Description
-----------

Conforming to
-------------

`Position' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: pow,  Next: Pred,  Prev: Position,  Up: Reference

pow
===

(Under construction.)

Synopsis
--------

     operator pow (base: Real; exponent: Integer) = power: Real;
or
     operator pow (base: Complex; exponent: Integer) = power: Complex;

Description
-----------

Exponentiation operator with integer exponent.

Conforming to
-------------

`pow' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Pred,  Next: private,  Prev: pow,  Up: Reference

Pred
====

Synopsis
--------

     function Pred (i: ORDINAL_TYPE): ORDINAL_TYPE;
or
     function Pred (i: ORDINAL_TYPE; j: AND_INTEGER_TYPE): ORDINAL_TYPE;

   or, with extended syntax (`--extended-syntax' or `{$X+}'),

     function Pred (p: POINTER_TYPE): POINTER_TYPE;
   or
     function Pred (p: POINTER_TYPE; j: AND_INTEGER_TYPE): POINTER_TYPE;

Description
-----------

Returns the predecessor of the ORDINAL_TYPE value `i', or, if the
second argument `j' is given, its `j'th predecessor. For integer values
`i', this is `i - 1' (or `i - j'). (No, `Pred' does _not_ work faster
than plain subtraction. Both are optimized the same way, often to a
single machine instruction.)

   If extended syntax is on, the argument may also be a pointer value.
In this case, the address is decremented by the size of the variable
pointed to, or, if `j' is given, by `j' times the size of the variable
pointed to. If `p' points to an element of an array, the returned
pointer will point to the (`j'th) previous element of the array.

Conforming to
-------------

The `Pred' function is defined in ISO 7185 Pascal. The optional second
parameter is defined in ISO 10206 Extended Pascal.  Application of
`Pred' to pointers is defined in Borland Pascal.  The combination of
the second argument with application to pointers is a GNU Pascal
extension.

Example
-------

     program PredDemo;

     type
       Metasyntactical = (foo, bar, baz);

     var
       m: Metasyntactical;
       c: Char;
       a: array [1 .. 7] of Integer;
       p: ^Integer;

     begin
       m := Pred (bar);     { foo }
       c := Pred ('Z', 2);  { 'X' }
       a[1] := 42;
       a[4] := Pred (a[1]);     { 41 }
       a[5] := Pred (a[4], 3);  { 38 }
       {$X+}
       p := @a[5];
       p := Pred (p);     { now p points to a[4] }
       p := Pred (p, 3);  { now p points to a[1] }
     end.

See also
--------

*Note Succ::, *Note Dec::, *Note Pointer Arithmetics::.


File: gpc.info,  Node: private,  Next: procedure,  Prev: Pred,  Up: Reference

private
=======

(Under construction.)

Synopsis
--------

Description
-----------

GPC currently accepts but ignores the `private' directive in object
type declarations.

Conforming to
-------------

`private' is a Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::, *Note protected::, *Note public::, *Note published::.


File: gpc.info,  Node: procedure,  Next: program,  Prev: private,  Up: Reference

procedure
=========

(Under construction.)

Synopsis
--------

Description
-----------

Procedure declaration.

Conforming to
-------------

`procedure' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: program,  Next: property,  Prev: procedure,  Up: Reference

program
=======

(Under construction.)

Synopsis
--------

Description
-----------

Start of a Pascal program.

Conforming to
-------------

`program' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: property,  Next: protected,  Prev: program,  Up: Reference

property
========

Not yet implemented.

Synopsis
--------

Description
-----------

Object properties.

Conforming to
-------------

`property' is an Object Pascal and a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: protected,  Next: PtrCard,  Prev: property,  Up: Reference

protected
=========

(Under construction.)

Synopsis
--------

Description
-----------

The Extended Pascal meaning of `protected' is supported by GPC.

   GPC currently accepts but ignores the `protected' directive in
object type declarations.

Conforming to
-------------

Extended Pascal and Borland Pascal, but with different meanings.

Example
-------

See also
--------

*Note Keywords::, *Note const::, *Note import::, *Note private::, *Note
public::, *Note published::.


File: gpc.info,  Node: PtrCard,  Next: PtrDiffType,  Prev: protected,  Up: Reference

PtrCard
=======

(Under construction.)

Synopsis
--------

     type
       PtrCard = Cardinal attribute (Size = BitSizeOf (Pointer));

Description
-----------

An unsigned integer type of the same size as a pointer.

Conforming to
-------------

`PtrCard' is a GNU Pascal extension.

Example
-------

     program PtrCardDemo;
     var
       a: PtrCard;
       p: Pointer;
     begin
       GetMem (p, 10);
       a := PtrCard (p);
       Inc (a);
       p := Pointer (a)
     end.

See also
--------


File: gpc.info,  Node: PtrDiffType,  Next: PtrInt,  Prev: PtrCard,  Up: Reference

PtrDiffType
===========

(Under construction.)

Synopsis
--------

     type
       PtrDiffType  { built-in type }

Description
-----------

`PtrDiffType' is a (signed) integer type to represent the difference
between two positions in memory. It is not needed except for rather
low-level purposes.

Conforming to
-------------

`PtrDiffType' is a GNU Pascal extension.

Example
-------

     program PtrDiffTypeDemo;
     var
       a: array [1 .. 10] of Integer;
       d: PtrDiffType;
       p, q: ^Integer;
     begin
       p := @a[1];
       q := @a[4];
       {$X+}
       d := q - p
     end.

See also
--------


File: gpc.info,  Node: PtrInt,  Next: PtrWord,  Prev: PtrDiffType,  Up: Reference

PtrInt
======

(Under construction.)

Synopsis
--------

     type
       PtrInt = Integer attribute (Size = BitSizeOf (Pointer));

Description
-----------

A signed integer type of the same size as a pointer.

Conforming to
-------------

`PtrInt' is a GNU Pascal extension.

Example
-------

     program PtrIntDemo;
     var
       a: PtrInt;
       p: Pointer;
     begin
       GetMem (p, 10);
       a := PtrInt (p);
       Inc (a);
       p := Pointer (a)
     end.

See also
--------


File: gpc.info,  Node: PtrWord,  Next: public,  Prev: PtrInt,  Up: Reference

PtrWord
=======

(Under construction.)

Synopsis
--------

     type
       PtrWord = PtrCard;

Description
-----------

An unsigned integer type of the same size as a pointer.

Conforming to
-------------

`PtrWord' is a GNU Pascal extension.

Example
-------

     program PtrWordDemo;
     var
       a: PtrWord;
       p: Pointer;
     begin
       GetMem (p, 10);
       a := PtrWord (p);
       Inc (a);
       p := Pointer (a)
     end.

See also
--------

*Note PtrCard::, *Note Integer Types::.


File: gpc.info,  Node: public,  Next: published,  Prev: PtrWord,  Up: Reference

public
======

(Under construction.)

Synopsis
--------

Description
-----------

GPC currently accepts but ignores the `public' directive in object type
declarations.

Conforming to
-------------

`public' is a Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::, *Note private::, *Note protected::, *Note published::.


File: gpc.info,  Node: published,  Next: Put,  Prev: public,  Up: Reference

published
=========

(Under construction.)

Synopsis
--------

Description
-----------

GPC currently accepts but ignores the `published' directive in object
type declarations.

Conforming to
-------------

`published' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::, *Note private::, *Note protected::, *Note public::.


File: gpc.info,  Node: Put,  Next: qualified,  Prev: published,  Up: Reference

Put
===

(Under construction.)

Synopsis
--------

     procedure Put (var F: TYPED_FILE);

Description
-----------

Conforming to
-------------

`Put' is defined in ISO 7185 Pascal and supported by all known Pascal
variants except UCSD/Borland Pascal and its variants.

Example
-------

See also
--------


File: gpc.info,  Node: qualified,  Next: raise,  Prev: Put,  Up: Reference

qualified
=========

(Under construction.)

Synopsis
--------

Description
-----------

Import specification.

Conforming to
-------------

`qualified' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: raise,  Next: Random,  Prev: qualified,  Up: Reference

raise
=====

Not yet implemented.

Synopsis
--------

Conforming to
-------------

`overload' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Random,  Next: Randomize,  Prev: raise,  Up: Reference

Random
======

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`Random' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Randomize,  Next: Re,  Prev: Random,  Up: Reference

Randomize
=========

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`Randomize' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Re,  Next: Read,  Prev: Randomize,  Up: Reference

Re
==

Synopsis
--------

     function Re (z: Complex): Real;

Description
-----------

`Re' extracts the real part of the complex number `z'.

Conforming to
-------------

`Re' is an ISO 10206 Extended Pascal extension.

Example
-------

     program ReDemo;
     var
       z: Complex;
     begin
       z := Cmplx (1, 2);
       WriteLn (Re (z) : 0 : 5)
     end.

See also
--------

*Note Cmplx::, *Note Im::, *Note Arg::


File: gpc.info,  Node: Read,  Next: ReadLn,  Prev: Re,  Up: Reference

Read
====

(Under construction.)

Synopsis
--------

     procedure Read (var F: TYPED_FILE; VARIABLE);
or
     procedure Read (var F: Text; VARIABLES);
   or
     procedure Read (VARIABLES);

Description
-----------

Conforming to
-------------

`Read' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------


File: gpc.info,  Node: ReadLn,  Next: ReadStr,  Prev: Read,  Up: Reference

ReadLn
======

(Under construction.)

Synopsis
--------

     procedure ReadLn (var F: Text; VARIABLES);
or
     procedure ReadLn (VARIABLES);

Description
-----------

Conforming to
-------------

`ReadLn' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

See also
--------


File: gpc.info,  Node: ReadStr,  Next: Real,  Prev: ReadLn,  Up: Reference

ReadStr
=======

(Under construction.)

Synopsis
--------

     procedure ReadStr (const S: String; VARIABLES);

Description
-----------

Conforming to
-------------

`ReadStr' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Real,  Next: record,  Prev: ReadStr,  Up: Reference

Real
====

(Under construction.)

Synopsis
--------

     type
       Real  { built-in type }

Description
-----------

Conforming to
-------------

`Real' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program RealDemo;
     var
       a: Real;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Real Types::, *Note Int::, *Note Frac::, *Note Round::, *Note
Trunc::.


File: gpc.info,  Node: record,  Next: Release,  Prev: Real,  Up: Reference

record
======

Synopsis
--------

In type definitions:
     RECORD_TYPE_IDENTIFIER = record
       FIELD_IDENTIFIER: TYPE_DEFINITION
       ...
       FIELD_IDENTIFIER: TYPE_DEFINITION
     end;

   or, with a variant part,

     RECORD_TYPE_IDENTIFIER = record
       FIELD_IDENTIFIER: TYPE_DEFINITION
       ...
       FIELD_IDENTIFIER: TYPE_DEFINITION
       case bar: VARIANT_TYPE of
         SELECTOR: (FIELD_DECLARATIONS);
         SELECTOR: (FIELD_DECLARATIONS);
         ...
     end;

   or, without a variant selector field,

     RECORD_TYPE_IDENTIFIER = record
       FIELD_IDENTIFIER: TYPE_DEFINITION
       ...
       FIELD_IDENTIFIER: TYPE_DEFINITION
       case VARIANT_TYPE of
         SELECTOR: (FIELD_DECLARATIONS);
         SELECTOR: (FIELD_DECLARATIONS);
         ...
     end;

Description
-----------

The reserved word `record' starts the definition of a new record type.

   Records can be `packed' to save memory usage at the expense of speed.

   The variants of a variant record may - but are not required to -
share one location in memory (inside the record).

   Sometimes variant records are used to emulate type casting in ISO
7185 Pascal. This is in fact a violation of the standard and not
portable. There is intentionally _no_ possibility in ISO 7185 Pascal to
emulate type casting.

Conforming to
-------------

The reserved word `record' and record types are defined in ISO 7185
Pascal.

   According to ISO Pascal, the variant type must be an identifier.
GNU Pascal, like UCSD and Borland Pascal, also allows a subrange here.

   Subranges in the variant fields, e.g. `case Integer of 2 .. 5', are
a GPC extension.

Example
-------

     program RecordDemo;

     type
       FooPtr = ^Foo;

       Foo = record
         Bar: Integer;
         NextFoo: FooPtr;
         case Choice: 1 .. 3 of
           1: (a: Integer);  { These three choices may share }
           2: (b: Real);     { one location in memory. }
           3: (c: Char;
               d: Boolean);
       end;

       Int5 = Integer attribute (Size = 5);
       SmallFoo = packed record
         b: 0 .. 3;
         a: Int5;
         r: Boolean
       end;  { needs 1 byte }

     var
       f: Foo;

     begin
       f.b := 3.14;
       WriteLn (f.a)  { yields some strange number which is part of the   }
                      { internal representation of the real number `f.b'. }
     end.

See also
--------

*Note Keywords::, *Note packed::, *Note case Statement::


File: gpc.info,  Node: Release,  Next: Rename,  Prev: record,  Up: Reference

Release
=======

(Under construction.)

Synopsis
--------

     procedure Release (P: Pointer);

Description
-----------

Conforming to
-------------

`Release' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Rename,  Next: repeat,  Prev: Release,  Up: Reference

Rename
======

(Under construction.)

Synopsis
--------

     procedure Rename (var F: ANY_FILE; NewName: String);

Description
-----------

Conforming to
-------------

`Rename' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: repeat,  Next: Reset,  Prev: Rename,  Up: Reference

repeat
======

Synopsis
--------

     repeat
       STATEMENT;
       ...
       STATEMENT;
     until BOOLEAN_EXPRESSION;

Description
-----------

The `repeat ... until' statement declares a loop. For further
description see *Note repeat Statement::.

Conforming to
-------------

`repeat' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

     program RepeatDemo;
     var
       Number, Sum: Integer;
     begin
       WriteLn ('Black Jack for beginners.');
       WriteLn ('You can choose your cards yourself. :-)');
       Sum := 0;
       repeat
         Write ('Your card (number)? ');
         ReadLn (Number);
         Inc (Sum, Number);
         WriteLn ('You have ', Sum, '.')
       until Sum >= 21;
       if Sum = 21 then
         WriteLn ('You win!')
       else
         WriteLn ('You lose.')
     end.

See also
--------

*Note Keywords::, *Note while Statement::, *Note for Statement::.


File: gpc.info,  Node: Reset,  Next: resident,  Prev: repeat,  Up: Reference

Reset
=====

(Under construction.)

Synopsis
--------

     procedure Reset (var F: ANY_FILE; [FileName: String;]
                                         [BlockSize: Cardinal]);

Description
-----------

`Reset' opens an existing file for reading. The file pointer is
positioned at the beginning of the file.

   Like `Rewrite', `Append' and `Extend' do, `Reset' accepts an
optional second parameter for the name of the file in the filesystem
and a third parameter for the block size of the file. The third
parameter is allowed only (and by default also required) for untyped
files. For details, see *Note Rewrite::.

Conforming to
-------------

`Reset' is defined in ISO 7185 Pascal.  The `BlockSize' parameter is a
Borland Pascal extension.  The `FileName' parameter is a GNU Pascal
extension.

Example
-------

     program ResetDemo;
     var
       Sample: Text;
       s: String (42);
     begin
       Rewrite (Sample);  { Open an internal file for writing }
       WriteLn (Sample, 'Hello, World!');
       Reset (Sample);  { Open it again for reading }
       ReadLn (Sample, s);
       WriteLn (s);
       Close (Sample)
     end.

See also
--------

*Note Assign::, *Note Rewrite::, *Note Append::, *Note Extend::.


File: gpc.info,  Node: resident,  Next: restricted,  Prev: Reset,  Up: Reference

resident
========

Not yet implemented.

Synopsis
--------

Description
-----------

Library export specification.

Conforming to
-------------

`resident' is a Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: restricted,  Next: Result,  Prev: resident,  Up: Reference

restricted
==========

(Under construction.)

Synopsis
--------

Description
-----------

Restricted type specification.

Conforming to
-------------

`restricted' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Result,  Next: Return,  Prev: restricted,  Up: Reference

Result
======

(Under construction.)

Synopsis
--------

Description
-----------

*Please note:* GPC _deactivates_ `Result' by default because it is
incompatible with standard program semantics.  Only in `--delphi' mode
or with the option `--implicit-result', it is activated. Explicit
result variables provide a safer alternative that works in default mode.

Conforming to
-------------

`Result' is a Borland Delphi extension.

Example
-------

See also
--------


File: gpc.info,  Node: Return,  Next: ReturnAddress,  Prev: Result,  Up: Reference

Return
======

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`Return' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: ReturnAddress,  Next: Rewrite,  Prev: Return,  Up: Reference

ReturnAddress
=============

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`ReturnAddress' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Rewrite,  Next: RmDir,  Prev: ReturnAddress,  Up: Reference

Rewrite
=======

(Under construction.)

Synopsis
--------

     procedure Rewrite (var F: ANY_FILE; [FileName: String;]
                                         [BlockSize: Cardinal]);

Description
-----------

`Rewrite' opens a file for writing. If the file does not exist, it is
created. The file pointer is positioned at the beginning of the file.

   Like `Reset', `Append' and `Extend' do, `Rewrite' accepts an
optional second and third parameter.

   The second parameter can specify the name of the file in the
filesystem. If it is omitted, the following alternative ways can be
used to specify the name. There are so many different ways in order to
be compatible to the idiosyncrasies of as many other Pascal compilers
as possible. (If you know about yet other ways, let us know ...)

   - The `Assign' procedure (*note Assign::)

   - The `Bind' procedure (*note Bind::)

   The following ways are only available if the file is external, i.e.
a global variable which is mentioned in the program header.  Otherwise,
the file will be internal, i.e. get no name in the file system (it may
get a name temporarily, but will then be erased automatically again).
This is useful to store some data and read them back within a program
without the need for permanent storage.

   - A command-line parameter of the form `--gpc-rts=-nF:NAME' where F
     is the identifier of the file variable.

   - If the file was mentioned in the program header and the option
     `--transparent file names' (*note GPC Command Line Options::) was
     set, the file name will be identical to the identifier converted
     to lower-case.

   - Otherwise, the user will be prompted for a file name.

   The last optional parameter determines the block size of the file.
It is valid only for untyped files. Often 1 is a reasonable value here.
However, the existence of this parameter is a BP compatibility feature,
and in BP it defaults to 128 because of historic misdesign.  Therefore,
GPC requires this parameter to be present. In `--borland-pascal' mode,
it makes it optional (like BP does), but warns about the strange
default if omitted.

Conforming to
-------------

`Rewrite' is defined in ISO 7185 Pascal.  The `BlockSize' parameter is
a Borland Pascal extension.  The `FileName' parameter is a GNU Pascal
extension.

Example
-------

     program RewriteDemo;
     var
       Sample: Text;
     begin
       Assign (Sample, 'sample.txt');
       Rewrite (Sample);
       WriteLn (Sample, 'Hello, World!');
       Close (Sample)
     end.

See also
--------

*Note Assign::, *Note Reset::, *Note Append::, *Note Extend::, *Note
Update::.


File: gpc.info,  Node: RmDir,  Next: Round,  Prev: Rewrite,  Up: Reference

RmDir
=====

Synopsis
--------

     procedure RmDir (Directory: String);

Description
-----------

`RmDir' removes the given DIRECTORY if its argument is a valid
parameter to the related operating system's function. Otherwise a
runtime error is caused.

Conforming to
-------------

`RmDir' is a Borland Pascal extension.

Example
-------

     program RmDirDemo;
     var
       Foo: String (127);
     begin
       WriteLn ('Enter directory name to remove: ');
       ReadLn (Foo);
       {$I-}  { Don't abort on I/O errors }
       RmDir (Foo);
       if IOResult <> 0 then
         WriteLn ('Directory ', Foo, ' could not be removed.')
       else
         WriteLn ('Okay.')
     end.

See also
--------

*Note ChDir::, *Note MkDir::


File: gpc.info,  Node: Round,  Next: RunError,  Prev: RmDir,  Up: Reference

Round
=====

Synopsis
--------

     function Round (x: Real): Integer;

Description
-----------

`Round' returns the nearest integer to `x'. The result is of type
integer. In the case of equidistance, the result is machine-dependent
(or depends on the behaviour of the processor).

Conforming to
-------------

`Round' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program RoundDemo;
     var
       Foo: Real;
     begin
       Foo := 9.876543;
       WriteLn (Round (Foo));  { Prints 10 }
       Foo := 3.456789;
       WriteLn (Round (Foo));  { Prints 3 }

       WriteLn (Frac (12.345) : 1 : 5);  { 0.34500 }
       WriteLn (Int (12.345) : 1 : 5);  { 12.00000 }
       WriteLn (Round (12.345) : 1);  { 12 }
       WriteLn (Trunc (12.345) : 1);  { 12 }

       WriteLn (Frac (-12.345) : 1 : 5);  { -0.34500 }
       WriteLn (Int (-12.345) : 1 : 5);  { -12.00000 }
       WriteLn (Round (-12.345) : 1);  { -12 }
       WriteLn (Trunc (-12.345) : 1);  { -12 }

       WriteLn (Frac (12.543) : 1 : 5);  { 0.54300 }
       WriteLn (Int (12.543) : 1 : 5);  { 12.00000 }
       WriteLn (Round (12.543) : 1);  { 13 }
       WriteLn (Trunc (12.543) : 1);  { 12 }

       WriteLn (Frac (-12.543) : 1 : 5);  { -0.54300 }
       WriteLn (Int (-12.543) : 1 : 5);  { -12.00000 }
       WriteLn (Round (-12.543) : 1);  { -13 }
       WriteLn (Trunc (-12.543) : 1);  { -12 }
     end.

See also
--------

*Note Real Types::, *Note Real::, *Note Int::, *Note Frac::, *Note
Trunc::.


File: gpc.info,  Node: RunError,  Next: Seek,  Prev: Round,  Up: Reference

RunError
========

(Under construction.)

Synopsis
--------

     procedure RunError (ErrorCode: Integer);

Description
-----------

Conforming to
-------------

`RunError' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Seek,  Next: SeekEOF,  Prev: RunError,  Up: Reference

Seek
====

(Under construction.)

Synopsis
--------

     procedure Seek (var F: TYPED_FILE; NewPosition: INDEX_TYPE);

Description
-----------

Conforming to
-------------

`Seek' is a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: SeekEOF,  Next: SeekEOLn,  Prev: Seek,  Up: Reference

SeekEOF
=======

(Under construction.)

Synopsis
--------

     function SeekEOF ([var F: Text]): Boolean;

Description
-----------

Conforming to
-------------

`SeekEOF' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: SeekEOLn,  Next: SeekRead,  Prev: SeekEOF,  Up: Reference

SeekEOLn
========

(Under construction.)

Synopsis
--------

     function SeekEOLn ([var F: Text]): Boolean;

Description
-----------

Conforming to
-------------

`SeekEOLn' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: SeekRead,  Next: SeekUpdate,  Prev: SeekEOLn,  Up: Reference

SeekRead
========

(Under construction.)

Synopsis
--------

     procedure SeekRead (var F: TYPED_FILE; NewPosition: INDEX_TYPE);

Description
-----------

Conforming to
-------------

`SeekRead' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: SeekUpdate,  Next: SeekWrite,  Prev: SeekRead,  Up: Reference

SeekUpdate
==========

(Under construction.)

Synopsis
--------

     procedure SeekUpdate (var F: TYPED_FILE; NewPosition: INDEX_TYPE);

Description
-----------

Conforming to
-------------

`SeekUpdate' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: SeekWrite,  Next: segment,  Prev: SeekUpdate,  Up: Reference

SeekWrite
=========

(Under construction.)

Synopsis
--------

     procedure SeekWrite (var F: TYPED_FILE; NewPosition: INDEX_TYPE);

Description
-----------

Conforming to
-------------

`SeekWrite' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: segment,  Next: Self,  Prev: SeekWrite,  Up: Reference

segment
=======

Not yet implemented.

Synopsis
--------

Description
-----------

Segment specification.

Conforming to
-------------

`segment' is a UCSD Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Self,  Next: set,  Prev: segment,  Up: Reference

Self
====

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`Self' is an Object Pascal and a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: set,  Next: SetFileTime,  Prev: Self,  Up: Reference

set
===

Synopsis
--------

In type definitions:
     set of ORDINAL_TYPE  { built-in type class }

Description
-----------

A set contains zero or more elements from an ordinal type, e.g.  Char,
a subrange of Char, or a subrange of an enumerated type or integers.
The elements of a sets do not have any ordering (that is a set
containing 'B' and 'A' is the same as a set containing 'A' and 'B'),
nor can an element be included more than once. Sets simply store the
information about which elements are included in the set.

Conforming to
-------------

`set' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program SetDemo;

     type
       TCharSet = set of Char;

     var
       Ch: Char;
       MyCharSet: TCharSet;
     begin
       MyCharSet := ['P','N','L'];
       if 'A' in MyCharSet then
         WriteLn ('Wrong: A in set MyCharSet')
       else
         WriteLn ('Right: A is not in set MyCharSet');
       Include (MyCharSet, 'A');  { A, L, N, P }
       Exclude (MyCharSet, 'N');  { A, L, P }
       MyCharSet := MyCharSet + ['B','C'];  { A, B, C, L, P }
       MyCharSet := MyCharSet - ['C','D'];  { A, B, L, P }
       WriteLn ('set MyCharSet contains:');
       for Ch in MyCharSet do
         WriteLn (Ch);
     end.

   Set also *Note Set Operations:: or examples of some of the many set
operations.

See also
--------

*Note Keywords::, *Note Set Operations::, *Note in::, *Note Exclude::,
*Note Include::.


File: gpc.info,  Node: SetFileTime,  Next: SetLength,  Prev: set,  Up: Reference

SetFileTime
===========

     procedure SetFileTime (var f: ANY_FILE;
                            AccessTime, ModificationTime: UnixTimeType);

Synopsis
--------

Description
-----------

Conforming to
-------------

`SetFileTime' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: SetLength,  Next: SetType,  Prev: SetFileTime,  Up: Reference

SetLength
=========

Synopsis
--------

     procedure SetLength (var S: String; NewLength: Integer);

Description
-----------

`SetLength' explicitly assigns a new length `NewLength' to the string
parameter `S'. The contents of the string elements (characters) are
_not_ changed; if the operation increases the length of the string, the
characters appended at the end are _undefined_.

Conforming to
-------------

`SetLength' is a Borland Delphi 2.0 extension.

Example
-------

     program SetLengthDemo;

     var
       S: String (26);

     begin
       S := 'Hello, world!';
       SetLength (S, Length ('Hello'));
       WriteLn (S);                                           { 'Hello' }

       SetLength (S, 26);
       WriteLn (S);                     { 'Hello, world!(%$xy"!#&~+(/]' }
                                 { undefined characters ^^^^^^^^^^^^^^  }

       { SetLength (S, 42);  GPC detects this overflow at compile time. }
     end.

See also
--------

*Note Length::, *Note String::.


File: gpc.info,  Node: SetType,  Next: shl,  Prev: SetLength,  Up: Reference

SetType
=======

Synopsis
--------

     procedure SetType (var SomeObject; VMT: PObjectType);

Description
-----------

The procedure `SetType' explicitly assigns a value to the implicit VMT
field of an object. This is normally done implicitly when a constructor
is called.

   You can use this to write a polymorphic I/O routine which reads an
object from a file. In this case, you cannot reasonably use `New' to
allocate the storage, but you `GetMem' it and initialize the object
manually using `SetType' before calling the constructor explicitly.

   The only values you should assign to an object via `SetType' are
actual VMT pointers that were obtained via `TypeOf'. In particular,
declaring a record like the one shown in the description of
`PObjectType' and assigning a pointer to it to an object via `SetType'
will usually not work because the virtual method pointers are missing.

   Since `SetType' is a dangerous feature, it yields a warning unless
`{$X+}' is given.

Conforming to
-------------

`SetType' is a GNU Pascal extension.

Example
-------

     program SetTypeDemo;

     type
       BasePtr = ^BaseObj;

       BaseObj = object
         constructor Load;
       end;

       ChildObj = object (BaseObj)
         constructor Load;
       end;

     constructor BaseObj.Load;
     begin
     end;

     constructor ChildObj.Load;
     begin
     end;

     {$X+}

     { This is somewhat fragmentary code. }
     function GetObject (var InputFile: File) = Result: BasePtr;
     const
       VMTTable: array [1 .. 2] of PObjectType =
         (TypeOf (BaseObj), TypeOf (ChildObj));
     var
       Size: Cardinal;
       TypeID: Integer;
       VMT: PObjectType;
     begin
       { Read the size of the object from some file and store it in `Size'. }
       BlockRead (InputFile, Size, SizeOf (Size));

       { Allocate memory for the object. }
       GetMem (Result, Size);

       { Read some ID from some file. }
       BlockRead (InputFile, TypeID, SizeOf (TypeID));

       { Look up the `VMT' from some table. }
       { Explicit range checking wouldn't be a bad idea here ... }
       { Without it, a wrong value just leads to a runtime error. }
       VMT := VMTTable[TypeID];

       SetType (Result^, VMT);

       { Now the object is ready, and the constructor can be called. }
       { Look up the correct constructor from some table and call it. }
     end;

     begin
     end.

See also
--------

*Note PObjectType::, *Note TypeOf::, *Note OOP::.


File: gpc.info,  Node: shl,  Next: ShortBool,  Prev: SetType,  Up: Reference

shl
===

Synopsis
--------

     operator shl (operand1, operand2: INTEGER_TYPE) = Result: INTEGER_TYPE;
or
     procedure shl (var operand1: INTEGER_TYPE; operand2: INTEGER_TYPE);

Description
-----------

In GNU Pascal, `shl' has two built-in meanings:

  1. Bitwise shift left of an integer-type expression by another
     integer value.  The result is of the type of the first operand.

  2. Use as a "procedure": `operand1' is shifted left by `operand2';
     the result is stored in `operand1'.


Conforming to
-------------

`shl' is a Borland Pascal extension.

   Use of `shl' as a "procedure" is a GNU Pascal extension.

Example
-------

     program ShlDemo;
     var
       a: Integer;
     begin
       a := 1 shl 7;  { yields 128 = 2 pow 7 }
       shl (a, 4)  { same as `a := a shl 4' }
     end.

See also
--------

*Note Keywords::, *Note shr::, *Note Operators::.


File: gpc.info,  Node: ShortBool,  Next: ShortCard,  Prev: shl,  Up: Reference

ShortBool
=========

Synopsis
--------

     type
       ShortBool = Boolean attribute (Size = BitSizeOf (ShortInt));

Description
-----------

The intrinsic `ShortBool' represents boolean values, but occupies the
same memory space as a `ShortInt'.  It is used when you need to define
a parameter or record that conforms to some external library or system
specification.

Conforming to
-------------

`ShortBool' is a GNU Pascal extension.

Example
-------

     program ShortBoolDemo;
     var
       a: ShortBool;
     begin
       ShortInt (a) := 1;
       if a then WriteLn ('Ord (True) = 1')
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note Boolean::, *Note True::, *Note
False::, *Note CBoolean::, *Note ByteBool::, *Note MedBool::, *Note
WordBool::, *Note LongBool::, *Note LongestBool::.


File: gpc.info,  Node: ShortCard,  Next: ShortInt,  Prev: ShortBool,  Up: Reference

ShortCard
=========

Synopsis
--------

     type
       ShortCard = Cardinal attribute (Size = BitSizeOf (ShortInt));

Description
-----------

`ShortCard' is an unsigned integer type which is not larger than
`Cardinal'. On some platforms it is 16 bits wide and thus has a range
of `0 .. 65535'.

   `ShortCard' in GNU Pascal is compatible to `short unsigned int' in
GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`ShortCard' is a GNU Pascal extension.

Example
-------

     program ShortCardDemo;
     var
       a: ShortCard;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: ShortInt,  Next: ShortReal,  Prev: ShortCard,  Up: Reference

ShortInt
========

Synopsis
--------

     type
       ShortInt  { built-in type }

Description
-----------

`ShortInt' is a signed integer type which is not larger than `Integer'.
On some platforms it is 16 bits wide and thus has a range of `-32768 ..
32767'.

   `ShortInt' in GNU Pascal is compatible to `short int' in GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`ShortInt' is a Borland Pascal extension. In Borland Pascal, `ShortInt'
is an 8-bit signed integer type (`ByteInt' in GNU Pascal).

Example
-------

     program ShortIntDemo;
     var
       a: ShortInt;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: ShortReal,  Next: ShortWord,  Prev: ShortInt,  Up: Reference

ShortReal
=========

(Under construction.)

Synopsis
--------

     type
       ShortReal  { built-in type }

Description
-----------

Conforming to
-------------

`ShortReal' is a GNU Pascal extension.

Example
-------

     program ShortRealDemo;
     var
       a: ShortReal;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------


File: gpc.info,  Node: ShortWord,  Next: shr,  Prev: ShortReal,  Up: Reference

ShortWord
=========

Synopsis
--------

     type
       ShortWord = ShortCard;

Description
-----------

`ShortWord' is an unsigned integer type which is not larger than
`Word'. On some platforms it is 16 bits wide and thus has a range of `0
.. 65535'. It is the same as *Note ShortCard::.

   `ShortWord' in GNU Pascal is compatible to `short unsigned int' in
GNU C.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`ShortWord' is a GNU Pascal extension.

   `ShortWord' in GNU Pascal essentially corresponds to `Word' in
Borland Pascal and Delphi where it is a 16-bit unsigned integer type.

Example
-------

     program ShortWordDemo;
     var
       a: ShortWord;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note ShortCard::, *Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: shr,  Next: Sin,  Prev: ShortWord,  Up: Reference

shr
===

Synopsis
--------

     operator shr (operand1, operand2: INTEGER_TYPE) = Result: INTEGER_TYPE;
or
     procedure shr (var operand1: INTEGER_TYPE; operand2: INTEGER_TYPE);

Description
-----------

In GNU Pascal, `shr' has two built-in meanings:

  1. Bitwise shift right of an integer-type expression by another
     integer value.  The result is of the type of the first operand.

  2. Use as a "procedure": `operand1' is shifted right by `operand2';
     the result is stored in `operand1'.


Conforming to
-------------

`shr' is a Borland Pascal extension.

   Unlike the Borland compilers, GNU Pascal cares about the signedness
of the first operand: If a signed integer with a negative value is
shifted right, "one" bits are filled in from the left.

   Use of `shr' as a "procedure" is a GNU Pascal extension.

Example
-------

     program ShrDemo;
     var
       a: Integer;
     begin
       a := 1024 shr 4;  { yields 64 }
       a := -127 shr 4;  { yields -8 }
       shr (a, 2)  { same as `a := a shr 2' }
     end.

See also
--------

*Note Keywords::, *Note shl::, *Note Operators::.


File: gpc.info,  Node: Sin,  Next: Single,  Prev: shr,  Up: Reference

Sin
===

Synopsis
--------

     function Sin (x: Real): Real;
or
     function Sin (z: Complex): Complex;

Description
-----------

`Sin' returns the sine of the argument.  The result is in the range `-1
<= Sin (x) <= 1' for real arguments.

Conforming to
-------------

The function `Sin' is defined in ISO 7185 Pascal; its application to
complex values is defined in ISO 10206 Extended Pascal.

Example
-------

     program SinDemo;
     begin
       { yields 0.5 since Sin (Pi / 6) = 0.5 }
       WriteLn (Sin (Pi / 6) : 0 : 5)
     end.

See also
--------

*Note ArcTan::, *Note Cos::, *Note Ln::, *Note Arg::.


File: gpc.info,  Node: Single,  Next: SizeOf,  Prev: Sin,  Up: Reference

Single
======

(Under construction.)

Synopsis
--------

     type
       Single = ShortReal;

Description
-----------

Conforming to
-------------

`Single' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: SizeOf,  Next: SizeType,  Prev: Single,  Up: Reference

SizeOf
======

Synopsis
--------

     function SizeOf (var x): SizeType;

Description
-----------

Returns the size of a type or variable in bytes.

   `SizeOf' can be applied to expressions and type names. If the
argument is a polymorphic object, the size of its actual type is
returned.

Conforming to
-------------

`SizeOf' is a UCSD Pascal extension.

Example
-------

     program SizeOfDemo;
     var
       a: Integer;
       b: array [1 .. 8] of Char;
     begin
       WriteLn (SizeOf (a));        { Size of an `Integer'; often 4 bytes. }
       WriteLn (SizeOf (Integer));  { The same. }
       WriteLn (SizeOf (b))         { Size of eight `Char's; usually 8 bytes. }
     end.

See also
--------

*Note BitSizeOf::, *Note AlignOf::, *Note TypeOf::.


File: gpc.info,  Node: SizeType,  Next: SmallInt,  Prev: SizeOf,  Up: Reference

SizeType
========

Synopsis
--------

     type
       SizeType  { built-in type }

Description
-----------

`SizeType' is an integer type (usually unsigned) to represent the size
of objects in memory.

Conforming to
-------------

`SizeType' is a GNU Pascal extension.

Example
-------

     program SizeTypeDemo;
     var
       a: array [1 .. 10] of Integer;
       Size: SizeType;
     begin
       Size := SizeOf (a);
       WriteLn (Size)
     end.

See also
--------


File: gpc.info,  Node: SmallInt,  Next: Sqr,  Prev: SizeType,  Up: Reference

SmallInt
========

Synopsis
--------

     type
       SmallInt = ShortInt;

Description
-----------

`SmallInt' is a signed integer type which is not larger than `Integer'.
On some platforms it is 16 bits wide and thus has a range of `-32768 ..
32767'. It is the same as `ShortInt' (see *Note ShortInt::).

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`SmallInt' is a Borland Delphi 2.0 extension.

Example
-------

     program SmallIntDemo;
     var
       a: SmallInt;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note ShortInt::, *Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: Sqr,  Next: SqRt,  Prev: SmallInt,  Up: Reference

Sqr
===

Synopsis
--------

     function Sqr (i: INTEGER_TYPE): INTEGER_TYPE;
or
     function Sqr (x: REAL_TYPE): REAL_TYPE;
   or
     function Sqr (z: COMPLEX_TYPE): COMPLEX_TYPE;

Description
-----------

Returns the square of the argument:

     function Sqr (x: SOME_TYPE): SOME_TYPE;
     begin
       Sqr := x * x  { or: x pow 2 }
     end;

Conforming to
-------------

The function `Sqr' is defined in ISO 7185 Pascal; its application to
complex values is defined in ISO 10206 Extended Pascal.

Example
-------

     program SqrDemo;

     var
       i: Complex;

     begin
       i := Cmplx (0, 1);
       WriteLn (Re (Sqr (i)) : 0 : 3)  { yields -1.000 }
     end.

See also
--------

*Note pow::, *Note SqRt::, *Note Abs::, *Note Operators::.


File: gpc.info,  Node: SqRt,  Next: StandardError,  Prev: Sqr,  Up: Reference

SqRt
====

Synopsis
--------

     function SqRt (x: REAL_TYPE): REAL_TYPE;
or
     function SqRt (z: COMPLEX_TYPE): COMPLEX_TYPE;

Description
-----------

Returns the positive square root of the argument.

   For real arguments, it is an error if the argument is negative.

   For complex arguments, `SqRt' returns the principal value of the
root of the argument, i.e. the root with positive real part, or, if the
real part is zero, that one with positive imaginary part.

Conforming to
-------------

The function `SqRt' is defined in ISO 7185 Pascal; its application to
complex values is defined in ISO 10206 Extended Pascal.

Example
-------

     program SqRtDemo;

     var
       m1: Complex;

     begin
       m1 := Cmplx (-1, 0);  { -1 }
       WriteLn (Re (SqRt (m1)) : 6 : 3, Im (SqRt (m1)) : 6 : 3);
         { yields 1.000 -1.000, i.e. the imaginary unit, i }
     end.

See also
--------

*Note pow::, *Note Sqr::, *Note Operators::.


File: gpc.info,  Node: StandardError,  Next: StandardInput,  Prev: SqRt,  Up: Reference

StandardError
=============

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`StandardError' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: StandardInput,  Next: StandardOutput,  Prev: StandardError,  Up: Reference

StandardInput
=============

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`StandardInput' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: StandardOutput,  Next: StdErr,  Prev: StandardInput,  Up: Reference

StandardOutput
==============

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`StandardOutput' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: StdErr,  Next: Str,  Prev: StandardOutput,  Up: Reference

StdErr
======

Synopsis
--------

     var
       StdErr: Text;

Description
-----------

The `StdErr' variable is connected to the standard error file handle.
To report errors, you should prefer `WriteLn (StdErr, 'everything
wrong')' over `WriteLn ('everything wrong')'.

Conforming to
-------------

`StdErr' is a GNU Pascal extension.

Example
-------

     program StdErrDemo;
     var
       Denominator: Integer;
     begin
       ReadLn (Denominator);
       if Denominator = 0 then
         WriteLn (StdErr, ParamStr (0), ': division by zero')
       else
         WriteLn ('1 / ', Denominator, ' = ', 1 / Denominator)
     end.

See also
--------

*Note StandardError::, *Note Output::, *Note Input::.


File: gpc.info,  Node: Str,  Next: String,  Prev: StdErr,  Up: Reference

Str
===

(Under construction.)

Synopsis
--------

     procedure Str (x: INTEGER_OR_REAL; var Dest: String);
or
     procedure Str (x: INTEGER_OR_REAL : FIELD_WIDTH; var Dest: String);
   or
     procedure Str (x: Real : FIELD_WIDTH : PRECISION; var Dest: String);
   or
     procedure Str (REPEATED_CONSTRUCTS_AS_DESCRIBED_ABOVE; var Dest: String);

Description
-----------

Conforming to
-------------

`Str' is a UCSD Pascal extension, generalized by Borland Pascal. The
possibility to handle more than one variable in one `Str' statement is
a GNU Pascal extension.

   ISO 10206 Extended Pascal defines `WriteStr' instead of `Str'.

Example
-------

See also
--------

*Note WriteStr::.


File: gpc.info,  Node: String,  Next: String2CString,  Prev: Str,  Up: Reference

String
======

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`String' is an Extended Pascal and a UCSD Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: String2CString,  Next: SubStr,  Prev: String,  Up: Reference

String2CString
==============

(Under construction.)

Synopsis
--------

     function String2CString (const S: String): CString;

Description
-----------

Conforming to
-------------

`String2CString' is a GNU Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: SubStr,  Next: Succ,  Prev: String2CString,  Up: Reference

SubStr
======

Synopsis
--------

     function SubStr (S: String; FirstChar: Integer): String;
or
     function SubStr (S: String; FirstChar, Count: Integer): String;

Description
-----------

`SubStr' returns a sub-string of S starting with the character at
position FIRSTCHAR. If COUNT is given, such many characters will be
copied into the sub-string. If COUNT is omitted, the sub-string will
range to the end of S.

   If `Count' is too large for the sub-string to fit in S or if
`FirstChar' exceeds the length of S, `SubStr' triggers a runtime error.
(For a function returning the empty string instead, see *Note Copy::.)

Conforming to
-------------

`SubStr' is an ISO 10206 Extended Pascal extension.

Example
-------

     program SubStrDemo;
     var
       S: String (42);
     begin
       S := 'Hello';
       WriteLn (SubStr (S, 2, 3));   { yields `ell' }
       WriteLn (SubStr (S, 3));      { yields `llo' }
       WriteLn (SubStr (S, 4, 7));   { yields a runtime error }
       WriteLn (SubStr (S, 42));     { yields a runtime error }
     end.

See also
--------

*Note Copy::, *Note String Slice Access::.


File: gpc.info,  Node: Succ,  Next: Text,  Prev: SubStr,  Up: Reference

Succ
====

Synopsis
--------

     function Succ (i: ORDINAL_TYPE): ORDINAL_TYPE;
or
     function Succ (i: ORDINAL_TYPE; j: AND_INTEGER_TYPE): ORDINAL_TYPE;

   or, with extended syntax (`--extended-syntax' or `{$X+}'),

     function Succ (p: POINTER_TYPE): POINTER_TYPE;
   or
     function Succ (p: POINTER_TYPE; j: AND_INTEGER_TYPE): POINTER_TYPE;

Description
-----------

Returns the successor of the ORDINAL_TYPE value `i', or, if the second
argument `j' is given, its `j'th successor.  For integer values `i',
this is `i + 1' (or `i + j').  (No, `Succ' does _not_ work faster than
plain addition.  Both are optimized the same way, often to a single
machine instruction.)

   If extended syntax is on, the argument may also be a pointer value.
In this case, the address is incremented by the size of the variable
pointed to, or, if `j' is given, by `j' times the size of the variable
pointed to. If `p' points to an element of an array, the returned
pointer will point to the (`j'th) next element of the array.

Conforming to
-------------

The `Succ' function is defined in ISO 7185 Pascal. The optional second
parameter is defined in ISO 10206 Extended Pascal.  Application of
`Succ' to pointers is defined in Borland Pascal.  The combination of
the second argument with application to pointers is a GNU Pascal
extension.

Example
-------

     program SuccDemo;

     type
       Metasyntactical = (foo, bar, baz);

     var
       m: Metasyntactical;
       c: Char;
       a: array [1 .. 7] of Integer;
       p: ^Integer;

     begin
       m := Succ (foo);     { bar }
       c := Succ ('A', 4);  { 'E' }
       a[1] := 42;
       a[2] := Succ (a[1]);     { 43 }
       a[5] := Succ (a[2], 7);  { 50 }
       {$X+}
       p := @a[1];
       p := Succ (p);     { points to `a[2]' now }
       p := Succ (p, 3);  { points to `a[5]' now }
     end.

See also
--------

*Note Pred::, *Note Inc::, *Note Pointer Arithmetics::.


File: gpc.info,  Node: Text,  Next: then,  Prev: Succ,  Up: Reference

Text
====

(Under construction.)

Synopsis
--------

     type
       Text  { built-in type }

Description
-----------

Conforming to
-------------

`Text' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program TextDemo;
     var
       t: Text;
     begin
       Rewrite (t, 'hello.txt');
       WriteLn (t, 'Hello, world!')
     end.

See also
--------

*Note file::, *Note AnyFile::.


File: gpc.info,  Node: then,  Next: Time,  Prev: Text,  Up: Reference

then
====

(Under construction.)

Synopsis
--------

Description
-----------

Part of an `if' statement or part of the `and then' operator.

Conforming to
-------------

`then' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program ThenDemo;
     var
       i: Integer;
     begin
       Write ('Enter a number: ');
       ReadLn (i);
       if i > 42 then
         WriteLn ('The number is greater than 42')
     end.

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Time,  Next: TimeStamp,  Prev: then,  Up: Reference

Time
====

Synopsis
--------

     function Time (T: TimeStamp): packed array [1 .. TIME_LENGTH] of Char;

Description
-----------

Date takes a `TimeStamp' parameter and returns the time as a string (in
the form of a packed array of `Char').  TIME_LENGTH is an
implementation defined invisible constant.

Conforming to
-------------

`Time' is an ISO 10206 Extended Pascal extension.

Example
-------

Set *Note TimeStamp::.

See also
--------

*Note TimeStamp::, *Note GetTimeStamp::, *Note Date::, *Note Date And
Time Routines::.


File: gpc.info,  Node: TimeStamp,  Next: to,  Prev: Time,  Up: Reference

TimeStamp
=========

Synopsis
--------

     type
       TimeStamp = packed record
         DateValid,
         TimeValid  : Boolean;
         Year       : Integer;
         Month      : 1 .. 12;
         Day        : 1 .. 31;
         DayOfWeek  : 0 .. 6;   { 0 means Sunday }
         Hour       : 0 .. 23;
         Minute     : 0 .. 59;
         Second     : 0 .. 61;  { to allow for leap seconds }
         MicroSecond: 0 .. 999999;
         TimeZone   : Integer;  { in seconds east of UTC }
         DST        : Boolean;
         TZName1,
         TZName2    : String (32);
       end;

Description
-----------

The `TimeStamp' record holds all the information about a particular
time. You can get the current time with `GetTimeStamp' and you can get
the date or time in a printable form using the `Date' and `Time'
functions.

Conforming to
-------------

`TimeStamp' is an ISO 10206 Extended Pascal extension. The fields
`DateValid', `TimeValid', `Year', `Month', `Day', `Hour', `Minute',
`Second' are required by Extended Pascal, the other ones are GNU Pascal
extensions.

Example
-------

     program TimeStampDemo;

     var
       t: TimeStamp;

     begin
       GetTimeStamp (t);
       WriteLn ('DateValid: ', t.DateValid);
       WriteLn ('TimeValid: ', t.TimeValid);
       WriteLn ('Year: ', t.Year);
       WriteLn ('Month: ', t.Month);
       WriteLn ('Day: ', t.Day);
       WriteLn ('DayOfWeek (0 .. 6, 0=Sunday): ', t.DayOfWeek);
       WriteLn ('Hour (0 .. 23): ', t.Hour);
       WriteLn ('Minute (0 .. 59): ', t.Minute);
       WriteLn ('Second (0 .. 61): ', t.Second);
       WriteLn ('MicroSecond (0 .. 999999): ', t.MicroSecond);
       WriteLn ('TimeZone (in seconds east of UTC): ', t.TimeZone);
       WriteLn ('DST: ', t.DST);
       WriteLn ('TZName1: ', t.TZName1);
       WriteLn ('TZName2: ', t.TZName2);
       WriteLn;
       WriteLn ('Date is: ', Date (t));
       WriteLn ('Time is: ', Time (t));
     end.

See also
--------

*Note GetTimeStamp::, *Note Date::, *Note Time::, *Note Date And Time
Routines::.


File: gpc.info,  Node: to,  Next: to begin do,  Prev: TimeStamp,  Up: Reference

to
==

(Under construction.)

Synopsis
--------

Description
-----------

Part of a `for' loop counting upwards or a `to begin do' or `to end do'
module constructor or destructor.

Conforming to
-------------

`to' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: to begin do,  Next: to end do,  Prev: to,  Up: Reference

to begin do
===========

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`to begin do' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: to end do,  Next: Trim,  Prev: to begin do,  Up: Reference

to end do
=========

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

`to begin end' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Trim,  Next: True,  Prev: to end do,  Up: Reference

Trim
====

(Under construction.)

Synopsis
--------

     function Trim (S: String): String;

Description
-----------

Conforming to
-------------

`Trim' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: True,  Next: Trunc,  Prev: Trim,  Up: Reference

True
====

Synopsis
--------

     type
       Boolean = (False, True);  { built-in type }

Description
-----------

`True' is one of the two Boolean values and is used to represent a
condition which is always fullfilled. For example, the expression `1 =
1' always yields the value `True'. It is the opposite of `False'.
`True' has the ordinal value 1.

Conforming to
-------------

`True' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program TrueDemo;

     var
       a: Boolean;

     begin
       a := 1 = 1;  { yields True }
       WriteLn (Ord (True));  { 1 }
       WriteLn (a);  { True }
       if True then WriteLn ('This is executed.')
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note False::, *Note Boolean::.


File: gpc.info,  Node: Trunc,  Next: Truncate,  Prev: True,  Up: Reference

Trunc
=====

Synopsis
--------

     function Trunc (x: Real): Integer;

Description
-----------

`Trunc' returns the integer part of a floating point number as an
integer. Use `Int' to get the integer part as a floating point number.

Conforming to
-------------

`Trunc' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program TruncDemo;

     begin
       WriteLn (Frac (12.345) : 1 : 5);  { 0.34500 }
       WriteLn (Int (12.345) : 1 : 5);  { 12.00000 }
       WriteLn (Round (12.345) : 1);  { 12 }
       WriteLn (Trunc (12.345) : 1);  { 12 }

       WriteLn (Frac (-12.345) : 1 : 5);  { -0.34500 }
       WriteLn (Int (-12.345) : 1 : 5);  { -12.00000 }
       WriteLn (Round (-12.345) : 1);  { -12 }
       WriteLn (Trunc (-12.345) : 1);  { -12 }

       WriteLn (Frac (12.543) : 1 : 5);  { 0.54300 }
       WriteLn (Int (12.543) : 1 : 5);  { 12.00000 }
       WriteLn (Round (12.543) : 1);  { 13 }
       WriteLn (Trunc (12.543) : 1);  { 12 }

       WriteLn (Frac (-12.543) : 1 : 5);  { -0.54300 }
       WriteLn (Int (-12.543) : 1 : 5);  { -12.00000 }
       WriteLn (Round (-12.543) : 1);  { -13 }
       WriteLn (Trunc (-12.543) : 1);  { -12 }
     end.

See also
--------

*Note Real Types::, *Note Real::, *Note Int::, *Note Frac::, *Note
Round::.


File: gpc.info,  Node: Truncate,  Next: try,  Prev: Trunc,  Up: Reference

Truncate
========

(Under construction.)

Synopsis
--------

     procedure Truncate (var F: ANY_FILE);

Description
-----------

Conforming to
-------------

`Truncate' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: try,  Next: type,  Prev: Truncate,  Up: Reference

try
===

Not yet implemented.

Synopsis
--------

Conforming to
-------------

`try' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: type,  Next: type of,  Prev: try,  Up: Reference

type
====

Synopsis
--------

As a type declaration:
     type
       TYPE_INDENTIFIER = TYPE_DEFINITION;
   or with initialization:
     type
       TYPE_INDENTIFIER = TYPE_DEFINITION value CONSTANT_EXPRESSION;

Description
-----------

The reserved word `type' starts the declaration of a TYPE IDENTIFIER
which is defined by TYPE_DEFINITION. For further description see *Note
Type Declaration::, *Note Type Declaration::, *Note Type Definition::,
*Note Data Types::.

Conforming to
-------------

`type' is defined in ISO 7185 Pascal and supported by all known Pascal
variants. Initializers are an ISO 10206 Extended Pascal extension.

Example
-------

     program TypeDemo;
     type
       { This side is the }    { That side is the }
       { type declaration }    { type definition  }

       { array type }
       ArrayType                  = array [0 .. 9] of Integer;

       { record type }
       RecordType                 = record
                                      Bar: Integer
                                    end;

       { subrange type }
       SubrangeType               = -123 .. 456;

       { enumeration type }
       EnumeratedType             = (Mon, Tue, Wed, Thu, Fri, Sat, Sun);

       { set type }
       CharSetType                = set of Char;

       { object type }
       ObjectType                 = object
                                      constructor Init;
                                      procedure Method;
                                      destructor Done
                                    end;

       { pointer type to another type identifier }
       PArrayType                 = ^ArrayType;

       { an alias name for another type identifier }
       IntegerType                = Integer;

       { an integer which is initialized by 123 }
       InitializedInt             = Integer value 123;

       { a schema with discriminants x and y of type Integer }
       SchemaType (x, y: Integer) = array [x .. y] of Integer;

     { Dummy methods of the object type }
     constructor ObjectType.Init;
     begin
     end;

     procedure ObjectType.Method;
     begin
     end;

     destructor ObjectType.Done;
     begin
     end;

     begin
     end.

See also
--------

*Note Keywords::, *Note Type Declaration::, *Note Type Definition::,
*Note Data Types::, *Note Variable Declaration::, *Note array::, *Note
record::, *Note object::, *Note set::, *Note Pointer::, *Note value::.


File: gpc.info,  Node: type of,  Next: TypeOf,  Prev: type,  Up: Reference

type of
=======

(Under construction.)

Synopsis
--------

Description
-----------

Conforming to
-------------

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: TypeOf,  Next: Unbind,  Prev: type of,  Up: Reference

TypeOf
======

Synopsis
--------

     function TypeOf (var x): PObjectType;

Description
-----------

Returns a pointer to the VMT of an _object_ type or variable.  This
pointer can be used to identify the type of an object.

   `TypeOf' can be applied to expressions of object type and to object
type names. In the former case, the actual type of polymorphic objects
is returned.

Conforming to
-------------

`TypeOf' is a Borland Pascal extension.

Example
-------

     program TypeOfDemo;
     type
       FooPtr = ^Foo;
       BarPtr = ^Bar;

       Foo = object         { Has a VMT, though it doesn't }
         x: Integer;        { contain virtual methods.     }
         constructor Init;
       end;

       Bar = object (Foo)
         y: Integer;
       end;

     constructor Foo.Init;
     begin
     end;

     var
       MyFoo: FooPtr;

     begin
       MyFoo := New (BarPtr, Init);
       if TypeOf (MyFoo^) = TypeOf (Bar) then  { True }
         WriteLn ('OK')
     end.

See also
--------

*Note BitSizeOf::, *Note AlignOf::, *Note PObjectType::, *Note
SetType::, *Note SizeOf::, *Note OOP::.


File: gpc.info,  Node: Unbind,  Next: unit,  Prev: TypeOf,  Up: Reference

Unbind
======

(Under construction.)

Synopsis
--------

     procedure Unbind (var F: ANY_FILE);

Description
-----------

Conforming to
-------------

`Unbind' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------

*Note Bind::, *Note Binding::, *Note BindingType::, *Note bindable::.


File: gpc.info,  Node: unit,  Next: Unpack,  Prev: Unbind,  Up: Reference

unit
====

(Under construction.)

Synopsis
--------

Description
-----------

UCSD and BP style unit declaration.

Conforming to
-------------

`unit' is a UCSD Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Unpack,  Next: until,  Prev: unit,  Up: Reference

Unpack
======

(Under construction.)

Synopsis
--------

     procedure Unpack (Source: PACKED_ARRAY;
                       var Dest: UNPACKED_ARRAY;
                       FirstElement: INDEX_TYPE);

Description
-----------

Conforming to
-------------

`Unpack' is defined in ISO 7185 Pascal and supported by all known
Pascal variants except UCSD/Borland Pascal and its variants.

Example
-------

See also
--------


File: gpc.info,  Node: until,  Next: UpCase,  Prev: Unpack,  Up: Reference

until
=====

(Under construction.)

Synopsis
--------

Description
-----------

`until' is part of the `repeat ... until' loop statement.

Conforming to
-------------

`until' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------

*Note Keywords::, *Note repeat::, *Note while::, *Note for::.


File: gpc.info,  Node: UpCase,  Next: Update,  Prev: until,  Up: Reference

UpCase
======

(Under construction.)

Synopsis
--------

     function UpCase (Ch: Char): Char;

Description
-----------

Conforming to
-------------

`UpCase' is a Borland Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: Update,  Next: uses,  Prev: UpCase,  Up: Reference

Update
======

(Under construction.)

Synopsis
--------

     procedure Update (var F: ANY_FILE);

Description
-----------

Conforming to
-------------

`Update' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: uses,  Next: Val,  Prev: Update,  Up: Reference

uses
====

Synopsis
--------

In a program:

     program @@fragment foo;

     uses
       bar1,
       bar2 in 'baz.pas',
       bar3;

     [...]

   In a unit:

     unit @@fragment Bar3;

     interface

     uses
       bar1,
       bar2 in 'baz.pas';

     [...]

     implementation

     uses
       bar3,
       bar4 in 'qux.pas';

     [...]

Description
-----------

The reserved word `uses' in the _import part_ of a program or unit
makes the program or unit import an interface.

   The keyword `in' tells GPC to look for the `unit' in the specified
file; otherwise the file name is derived from the name of the
interface, coverted to lower-case, by adding first `.p', then `.pas'.

   In BP, there must be at most one `uses' part in a program, and in a
unit, there can be one import part in the interface part and one in the
implementation part. GPC, as an extention, allows for several `uses'
parts, and also allows `uses' parts in a module.

   The imported interface needn't be a UCSD/Borland Pascal unit, it may
be an interface exported by an Extended Pascal module as well.

Conforming to
-------------

ISO Pascal does not define `uses' and units at all. UCSD and Borland
Pascal do, but without the `in' extension. Delphi supports `uses' like
described above.

Example
-------

See also
--------

*Note Keywords::, *Note unit::, *Note module::, *Note import::.


File: gpc.info,  Node: Val,  Next: value,  Prev: uses,  Up: Reference

Val
===

(Under construction.)

Synopsis
--------

     procedure Val (const Source: String; var x: INTEGER_OR_REAL;
                    var ErrorPosition: Integer);

Description
-----------

`Val' converts the integer or real number that is represented by the
characters in the string `Source' and places it into `x'.

   The `Source' string can have a base prefix (`$' for hexadecimal or
`Base#'). The optional `ErrorCode' will be set to the position of the
first invalid character, or to a 0 if the entire string represents a
valid number. In case an invalid character occurrs in `Source', `x'
will be undefined.

Conforming to
-------------

`Val' is a Borland Pascal extension.

Example
-------

     program ValDemo;
     var
       x, ec: Integer;
       l: LongInt;
       r: Real;
     begin
       Val ('123', x, ec);                { x :=            123; ec := 0; }
       Val ('-123', x, ec);               { x :=           -123; ec := 0; }
       Val ('123.456', r, ec);            { r :=        123.456; ec := 0; }
       Val ('$ffff', x, ec);              { x :=          65535; ec := 0; }
       Val ('$F000', x, ec);              { x :=          61440; ec := 0; }
       Val ('-$ffff', x, ec);             { x :=         -65535; ec := 0; }
       Val ('12#100', x, ec);             { x :=            144; ec := 0; }
       Val ('-2#11111111', x, ec);        { x :=           -255; ec := 0; }
       { here we have the invalid character 'X' for base 16 }
       Val ('$fffeX', x, ec);             { x :=    <undefined>; ec := 6; }
       Val ('12#100invalid', x, ec);      { x :=    <undefined>; ec := 7; }
       Val ('36#Jerusalem', l, ec);       { l := 54758821170910; ec := 0; }
     end.

See also
--------

*Note ReadLn::, *Note ReadStr::, *Note WriteLn::, *Note WriteStr::,
*Note Str::.


File: gpc.info,  Node: value,  Next: var,  Prev: Val,  Up: Reference

value
=====

Synopsis
--------

Description
-----------

The reserved word `value' is part of a type or var declaration.  It can
be replaced by `:=' or `='.

Conforming to
-------------

`value' is an ISO 10206 Extended Pascal extension. `:=' in this context
is a VAX Pascal extension, and `=' is a Borland Delphi extension.

Example
-------

See also
--------

*Note Keywords::, *Note var::, *Note type::, *Note Variable
Declaration::, *Note Type Declaration::.


File: gpc.info,  Node: var,  Next: view,  Prev: value,  Up: Reference

var
===

Synopsis
--------

As part of a variable declaration part or in a statement block:
     var VARIABLE_IDENTIFIER: TYPE_IDENTIFIER;
   or
     var VARIABLE_IDENTIFIER: TYPE_DEFINITION;
   and with initializing value:
     var VARIABLE_IDENTIFIER: TYPE_IDENTIFIER value CONSTANT_EXPRESSION;
   or
     var VARIABLE_IDENTIFIER: TYPE_DEFINITION value CONSTANT_EXPRESSION;

As part of a parameter list (passing by reference):
     var VAR_PARAMETER: TYPE_IDENTIFIER;
   or without type declaration
     var VAR_PARAMETER;

or protected (i.e., the called routine can't modify the parameter):
     protected var VAR_PARAMETER: TYPE_IDENTIFIER;
   or without type declaration
     protected var VAR_PARAMETER;

Description
-----------

In a declaration part: The reserved word `var' declares a
VARIABLE_IDENTIFIER whose type is of TYPE_IDENTIFIER or which is
defined by TYPE_DEFINITION. For further description see *Note Variable
Declaration::, *Note Type Declaration::, *Note Type Definition::, *Note
Data Types::.

   In a parameter list: see *Note Subroutine Parameter List
Declaration::.

Conforming to
-------------

`var' is defined in ISO 7185 Pascal and supported by all known Pascal
variants. Untyped `var' parameters in parameter lists are a UCSD Pascal
extension. The ability to do `var' declarations in a statement block is
a GNU Pascal extension.

Example
-------

     program VarDemo;

     type
       FooType = Integer;

     var
       Bar: FooType;
       ArrayFoo: array [0 .. 9] of Integer;   { array var definition }
       FecordFoo: record                      { record var definition }
                    Bar: Integer
                  end;
       CharsetFoo: set of Char;               { set var }
       SubrangeFoo: -123 .. 456;              { subrange var }
       EnumeratedFoo: (Mon, Tue, Wed, Thu, Fri, Sat, Sun);  {enumerated var }
       PointerBar: ^FooType;                  { pointer var }

     procedure ReadFoo (var Foo: FooType);
     begin
       ReadLn (Foo)
     end;

     begin
       var Bar: Integer;  { GNU Pascal extension }
       Bar := 42
     end.

See also
--------

*Note Keywords::, *Note type::, *Note array::, *Note record::, *Note
set::, *Note Subrange Types::, *Note Pointer::, *Note protected::.


File: gpc.info,  Node: view,  Next: virtual,  Prev: var,  Up: Reference

view
====

(Under construction.)

Synopsis
--------

Description
-----------

Object class view.

Conforming to
-------------

`view' is an Object Pascal extension. Currently GPC only supports views
without parents.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: virtual,  Next: Void,  Prev: view,  Up: Reference

virtual
=======

(Under construction.)

Synopsis
--------

Description
-----------

Virtual object method declaration.

Conforming to
-------------

`virtual' is an Object Pascal and a Borland Pascal extension.

Example
-------

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Void,  Next: while,  Prev: virtual,  Up: Reference

Void
====

(Under construction.)

Synopsis
--------

     type
       Void  { built-in type }

Description
-----------

Conforming to
-------------

`Void' is a GNU Pascal extension.

Example
-------

     program VoidDemo;

     procedure p (var x: Void);
     begin
     end;

     var
       i: Integer;
       s: String (42);

     begin
       p (i);
       p (s)
     end.

See also
--------


File: gpc.info,  Node: while,  Next: with,  Prev: Void,  Up: Reference

while
=====

Synopsis
--------

     while BOOLEAN_EXPRESSION do
       STATEMENT

Description
-----------

The `while' statement declares a loop. For further description see
*Note while Statement::.

Conforming to
-------------

`while' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

     program WhileDemo;
     var
       Foo, Bar: Integer;
     begin
       WriteLn ('Enter an descending series of integer numbers.');
       WriteLn ('Terminate by breaking this rule.');
       WriteLn ('Enter start number: ');
       Bar := MaxInt;
       ReadLn (Foo);
       while Foo < Bar do
         begin
           Bar := Foo;
           ReadLn (Foo)
         end;
       WriteLn ('The last number of your series was: ', Bar)
     end.

See also
--------

*Note Keywords::, *Note repeat Statement::, *Note for Statement::.


File: gpc.info,  Node: with,  Next: Word,  Prev: while,  Up: Reference

with
====

(Under construction.)

Synopsis
--------

Description
-----------

Automatic `record' or object field access.

Conforming to
-------------

`with' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

...

   { Note bar is shadowed by foo.bar }  ...

See also
--------

*Note Keywords::.


File: gpc.info,  Node: Word,  Next: WordBool,  Prev: with,  Up: Reference

Word
====

Synopsis
--------

     type
       Word = Cardinal;

Description
-----------

`Word' is the "natural" unsigned integer type in GNU Pascal.  On some
platforms it is 32 bits wide and thus has a range of `0 .. 4294967295'.
It is the same as *Note Cardinal::, introduced for compatibility with
other Pascal compilers.

   There are lots of other integer types in GPC, see *Note Integer
Types::.

Conforming to
-------------

`Word' is defined in Borland Pascal and Borland Delphi, where it is a
16-bit unsigned integer type.

Example
-------

     program WordDemo;
     var
       a: Word;
     begin
       a := 42;
       WriteLn (a)
     end.

See also
--------

*Note Cardinal::, *Note Integer Types::, *Note Subrange Types::.


File: gpc.info,  Node: WordBool,  Next: Write,  Prev: Word,  Up: Reference

WordBool
========

Synopsis
--------

     type
       WordBool = Boolean attribute (Size = BitSizeOf (Word));

Description
-----------

The intrinsic `WordBool' represents boolean values, but occupies the
same memory space as a `Word'.  It is used when you need to define a
parameter or record that conforms to some external library or system
specification.

Conforming to
-------------

`WordBool' is a Borland Pascal extension.

Example
-------

     program WordBoolDemo;
     var
       a: WordBool;
     begin
       Word (a) := 1;
       if a then WriteLn ('Ord (True) = 1')
     end.

See also
--------

*Note Boolean (Intrinsic)::, *Note Boolean::, *Note True::, *Note
False::, *Note CBoolean::, *Note ByteBool::, *Note ShortBool::, *Note
MedBool::, *Note LongBool::, *Note LongestBool::.


File: gpc.info,  Node: Write,  Next: WriteLn,  Prev: WordBool,  Up: Reference

Write
=====

(Under construction.)

Synopsis
--------

     procedure Write (var F: TYPED_FILE; VARIABLE);
or
     procedure Write (var F: Text; VALUES_AND_FORMAT_SPECIFICATIONS);
   or
     procedure Write (VALUES_AND_FORMAT_SPECIFICATIONS);

Description
-----------

Conforming to
-------------

`Write' is defined in ISO 7185 Pascal and supported by all known Pascal
variants.

Example
-------

See also
--------


File: gpc.info,  Node: WriteLn,  Next: WriteStr,  Prev: Write,  Up: Reference

WriteLn
=======

(Under construction.)

Synopsis
--------

     procedure WriteLn (var F: Text; VALUES_AND_FORMAT_SPECIFICATIONS);
or
     procedure WriteLn (VALUES_AND_FORMAT_SPECIFICATIONS);

Description
-----------

Conforming to
-------------

`WriteLn' is defined in ISO 7185 Pascal and supported by all known
Pascal variants.

Example
-------

See also
--------


File: gpc.info,  Node: WriteStr,  Next: xor,  Prev: WriteLn,  Up: Reference

WriteStr
========

(Under construction.)

Synopsis
--------

     procedure WriteStr (var Dest: String; VALUES_AND_FORMAT_SPECIFICATIONS);

Description
-----------

Conforming to
-------------

`WriteStr' is an ISO 10206 Extended Pascal extension.

Example
-------

See also
--------


File: gpc.info,  Node: xor,  Prev: WriteStr,  Up: Reference

xor
===

Synopsis
--------

     operator xor (operand1, operand2: Boolean) = Result: Boolean;
or
     operator xor (operand1, operand2: INTEGER_TYPE) = Result: INTEGER_TYPE;
   or
     procedure xor (var operand1: INTEGER_TYPE; operand2: INTEGER_TYPE);

Description
-----------

In GNU Pascal, `xor' has three built-in meanings:

  1. Logical "exclusive or" between two `Boolean'-type expressions. The
     result of the operation is of `Boolean' type.  (Logical `foo xor
     bar' in fact has the same effect as `foo <> bar'.)

  2. Bitwise "exclusive or" between two integer-type expressions.  The
     result is of the common integer type of both expressions.

  3. Use as a "procedure": `operand1' is "xor"ed bitwise with
     `operand2'; the result is stored in `operand1'.


Conforming to
-------------

ISO Pascal does not define the `xor' operator; Borland Pascal and
Delphi do.

   Use of `xor' as a "procedure" is a GNU Pascal extension.

Example
-------

     program XorDemo;
     var
       a, b, c: Integer;
     begin
       if (a = 0) xor (b = 0) then
         c := 1  { happens if either `a' or `b' is zero,    }
                 { but not if both are zero or both nonzero }
       else if (a xor b) = 0 then  { bitwise xor }
         c := 2  { happens if a = b }
       else
         xor (c, a)  { same as `c := c xor a' }
     end.

See also
--------

*Note Keywords::, *Note and::, *Note or::, *Note Operators::.


File: gpc.info,  Node: Keywords,  Next: Support,  Prev: Reference,  Up: Top

9 Pascal keywords and operators supported by GNU Pascal.
********************************************************

This chapter lists all keywords understood by GNU Pascal. The keywords
are taken from the following standards and dialects:

   * ISO 7185 Pascal (CP)

   * ISO 10206 Extended Pascal (EP)

   * ANSI draft Object Pascal (OP)

   * UCSD Pascal (UCSD)

   * Borland Pascal 7.0 (BP)

   * Borland Delphi (BD)

   * Pascal-SC (PXSC, Pascal eXtensions for Scientific Calculations)

   * VAX Pascal (VP)

   * Sun Pascal (SP)

   * Traditional Macintosh Pascal (MP)

   * GNU Pascal extensions (GPC)

   The table below lists all known keywords with short descriptions.
The links point to the longer descriptions in the reference.

   By default (using GPC extensions) all keywords are enabled. Only
those are marked `GPC' in the table below that are valid _only_ in the
GPC extensions.

   All keywords that are specific to some dialects (i.e., not marked
"any") can also be used as identifiers (with a few exceptions, see
below). Then, however, they generally cannot be used as keywords
anymore. So you can compile code from dialects that use them as
keywords and code that uses them as identifiers, i.e., you do not have
to modify your correct ISO 7185 programs in order to compile them with
GPC without any dialect option. Some words can even be used as keywords
and identifiers in parallel, including `forward' (according to ISO 7185
Pascal), and `near' and `far' (according to Borland Pascal).

   The exceptions are:

   * The keyword `uses' can't be used _immediately_ after an `import'
     part: using `import' or `uses' consistently or putting some other
     declaration between `import' and  `uses' helps.

   A dialect option turns off all keywords that do not belong to this
dialect. Besides, any keyword can be enabled and disabled with the
compiler options `{$enable-keyword}' and `{$disable-keyword}'.

absolute (BP, BD) (*note absolute::)
     overloaded variable declaration

abstract (OP, BD) (*note abstract::)
     abstract object type or method declaration

all (all) (*note all::)
     `export' (*note export::) extension (`export foo = all')

and (any) (*note and::)
     Boolean or bitwise `and' operator or part of the `and then' (*note
     and then::) operator

and_then (EP, OP) (*note and_then::)
     short-circuit Boolean `and' (*note and::) operator

array (any) (*note array::)
     array type declaration

as (OP, BD, MP) (*note as::)
     object type membership test and conversion

asm (BP, BD) (*note asm::)
     GNU style inline assembler code

asmname (GPC) (*note asmname::)
     DEPRECATED! linker name of routines and variables

attribute (GPC) (*note attribute::)
     attributes of routines and variables

begin (any) (*note begin::)
     begin of a code block, part of a `to begin do' (*note to begin
     do::) module constructor

bindable (EP, OP) (*note bindable::)
     external bindability of files

c (GPC) (*note c::)
     DEPRECATED! declaration of external routine

c_language (GPC) (*note c_language::)
     DEPRECATED! declaration of external routine

case (any) (*note case::)
     multi-branch conditional statement or variant `record' (*note
     record::) type

class (OP, BD) (*note class::)
     OOE/Delphi class

const (any) (*note const::)
     constant declaration or constant parameter declaration

constructor (OP, BP, BD) (*note constructor::)
     object constructor

destructor (OP, BP, BD) (*note destructor::)
     object destructor

div (any) (*note div::)
     integer division operator

do (any) (*note do::)
     part of a `while' (*note while::) or `for' (*note for::) loop, a
     `with' (*note with::) statement, or a `to begin do' (*note to
     begin do::) or `to end do' (*note to end do::) module constructor
     or destructor

downto (any) (*note downto::)
     part of a `for' (*note for::) loop counting downwards

else (any) (*note else::)
     alternative part of an `if' (*note if::) statement, default `case'
     (*note case::) branch, part of the `or else' (*note or else::)
     operator

end (any) (*note end::)
     end of a code block, end of a `case' (*note case::) statement, end
     of a `record' (*note record::) or `object' (*note object::)
     declaration, part of a `to end do' (*note to end do::) module
     destructor

except (BD) (*note except::)
     exception handler

export (export) (*note export::)
     module interface export

exports (BP, BD) (*note exports::)
     library export (not yet implemented)

external (UCSD, BP, BD, MP) (*note external::)
     declaration of an external object

far (BP, BD) (*note far::)
     BP directive (ignored)

file (any) (*note file::)
     non-text file type declaration

finalization (BD) (*note finalization::)
     unit finalization

finally (BD) (*note finally::)
     block finally

for (any) (*note for::)
     loop statement where the number of loops is known in advance

forward (any) (*note forward::)
     declaration of a routine whose definition follows below

function (any) (*note function::)
     function declaration

goto (any) (*note goto::)
     statement to jump to a `label' (*note label::)

if (any) (*note if::)
     conditional statement

implementation (all except CP) (*note implementation::)
     module or unit implementation part

import (EP, OP) (*note import::)
     module interface import

in (any) (*note in::)
     set membership test or part of a `for' (*note for::) loop
     iterating through sets

inherited (OP, BP, BD, MP) (*note inherited::)
     reference to methods of ancestor object types

initialization (BD) (*note initialization::)
     unit initialization

interface (interface) (*note interface::)
     module or unit interface part

interrupt (BP, BD) (*note interrupt::)
     interrupt handler declaration (not yet implemented)

is (OP, BD, MP) (*note is::)
     object type membership test

label (any) (*note label::)
     label declaration for a `goto' (*note goto::) statement

library (BP, BD) (*note library::)
     library declaration (not yet implemented)

mod (any) (*note mod::)
     integer remainder operator

module (module) (*note module::)
     EP style or PXSC style module

name (name) (*note name::)
     linker name

near (BP, BD) (*note near::)
     BP directive (ignored)

nil (any) (*note nil::)
     reserved value for unassigned pointers

not (any) (*note not::)
     Boolean or bitwise negation operator

object (BP, BD, MP) (*note object::)
     BP style object declaration

of (any) (*note of::)
     part of an `array' (*note array::), `set' (*note set::) or typed
     `file' (*note file::) type declaration, a `case' (*note case::)
     statement, a variant `record' (*note record::) type or a `type of'
     (*note type of::) type inquiry

on (BD) (*note on::)
     on clause

only (EP, OP) (*note only::)
     import specification

operator (PXSC) (*note operator::)
     operator declaration

or (any) (*note or::)
     Boolean or bitwise `or' operator or part of the `or else' (*note
     or else::) operator

or_else (EP, OP) (*note or_else::)
     short-circuit Boolean `or' (*note or::) operator

otherwise (EP, OP, MP) (*note otherwise::)
     default `case' (*note case::) branch, default value in a
     structured value of `array' (*note array::) type

overload (BD) (*note overload::)
     overload directive

override (OP, BD, MP) (*note override::)
     override directive

packed (any) (*note packed::)
     declaration of packed structured types (`record' (*note record::),
     `array' (*note array::), `set' (*note set::), `file' (*note
     file::)), also packed ordinal subranges

pow (EP, OP) (*note pow::)
     exponentiation operator with integer exponent

private (private) (*note private::)
     private object fields

procedure (any) (*note procedure::)
     procedure declaration

program (any) (*note program::)
     start of a Pascal program

property (OP, BD) (*note property::)
     OOE property classes/Delphi object properties (not yet implemented)

protected (protected) (*note protected::)
     read-only formal parameters or module export and protected object
     fields

public (public) (*note public::)
     public object fields

published (published) (*note published::)
     published object fields

qualified (EP, OP) (*note qualified::)
     import specification

raise (BD) (*note raise::)
     raise statement

record (any) (*note record::)
     record type declaration

repeat (any) (*note repeat::)
     loop statement

resident (BP, BD) (*note resident::)
     library export specification (not yet implemented)

restricted (EP, OP) (*note restricted::)
     restricted type specification

segment (UCSD) (*note segment::)
     segment specification (not yet implemented)

set (any) (*note set::)
     set type declaration

shl (BP, BD, MP) (*note shl::)
     bitwise left shift operator

shr (BP, BD, MP) (*note shr::)
     bitwise right shift operator

then (any) (*note then::)
     part of an `if' (*note if::) statement or part of the `and then'
     (*note and then::) operator

to (any) (*note to::)
     part of a `for' (*note for::) loop counting upwards or a `to begin
     do' (*note to begin do::) or `to end do' (*note to end do::)
     module constructor or destructor

try (BD) (*note try::)
     try statement

type (any) (*note type::)
     type declaration or part of a `type of' (*note type of::) type
     inquiry

unit (UCSD, BP, BD, MP) (*note unit::)
     UCSD and BP style unit declaration

until (any) (*note until::)
     end of a `repeat' (*note repeat::) statement

uses (UCSD, BP, BD, MP) (*note uses::)
     unit import

value (EP, OP) (*note value::)
     variable/type initializer

var (any) (*note var::)
     variable declaration or reference parameter declaration

view (OP) (*note view::)
     OOE class view

virtual (OP, BP, BD, MP) (*note virtual::)
     virtual object method declaration

while (any) (*note while::)
     loop statement

with (any) (*note with::)
     automatic `record' (*note record::) or object field access

xor (BP, BD, MP) (*note xor::)
     Boolean or bitwise `exclusive or' operator


File: gpc.info,  Node: Support,  Next: To Do,  Prev: Keywords,  Up: Top

10 Where to get support for GNU Pascal; how to report bugs.
***********************************************************

   Here you can find information on where to find the most up-to-date
information about GPC, how you can get support (professional or
voluntary), how to use GPC's Test Suite, and how to report new bugs you
might encounter.

   If you have problems with GNU Pascal, please read the relevant
sections of the GPC Manual. The most current version of the manual is
available at `http://www.gnu-pascal.de/gpc/index.html' for online
browsing.  You can also download the complete manual in HTML format
(tar.bz2) (`gpc-html.tar.bz2' on GPC's WWW home page).  The manual is
also available in PDF (`gpc.pdf' on GPC's WWW home page), PostScript
(compressed with bzip2) (`gpc.ps.bz2' on GPC's WWW home page) and DVI
(compressed with bzip2) (`gpc.dvi.bz2' on GPC's WWW home page) formats
for printing or online reading.

   If the manual doesn't help you, here is what we recommend you to do:

*Note FAQ::                Check the GPC FAQ

* Menu:

* Mailing List::           Join the GPC Mailing List
* Mailing List Archives::  Look in the Mailing List Archives
* Newsgroups::             Ask in a newsgroup
* Professional Support::   Get individual support for GPC
* Compiler Crashes::       If the compiler crashes ...
* Reporting Bugs::         Find out how to report GPC bugs
* Testing::                If you have GPC sources, learn how to run
                           the Test Suite to test your bugs reported


File: gpc.info,  Node: Mailing List,  Next: Mailing List Archives,  Up: Support

10.1 The GPC Mailing List
=========================

There is a mailing list devoted to GNU Pascal. You can write to the
mailing list, e.g. if you have problems installing GPC or if you found
a problem with GPC (please see *Note Reporting Bugs::). You can also
use it to discuss suggestions for improving GPC and, most welcome, to
offer your help or contribute code, documentation or other work. Mails
to the list should be in English.

   To subscribe to the mailing list, send the command
     subscribe gpc your@email.address
   in the body of a mail to <majordomo@gnu.de> (*not* to
`gpc@gnu.de'!). The subject is ignored. (Please replace
`your@email.address' with your real email address.) For more info, send
a line `help' to <majordomo@gnu.de>.

   After subscribing, you can send a message to the mailing list by
sending email to the list address <gpc@gnu.de> as if it were a person.

   To leave the mailing list, send the command
     unsubscribe gpc your@email.address
   to <majordomo@gnu.de>.

   You can reach a human moderator at _gpc-owner@gnu.de_.

   There is a separate mailing list for discussions about GPC
documentation, <gpc-doc@gnu.de>. To subscribe, send the command
     subscribe gpc-doc your@email.address
   to <majordomo@gnu.de>.

   There is also a (low-traffic) announce list, <gpc-announce@gnu.de>
that you can subscribe to stay up-to-date. To subscribe to the list,
write an email with
     subscribe gpc-announce your@email.address
   in the body to <majordomo@gnu.de>. If you like to announce a
contribution, a service or an event related to GPC, you are invited to
post to this list rather than `gpc@gnu.de', but please don't use the
announce list for questions or discussions. Please note that all mail
sent to the announce list is forwarded to the regular list, so you
won't have to subscribe to both lists if you don't want to miss
anything. For the same reason, please don't cross-post to both lists.

   There is also a German speaking mailing list, <gpc-de@gnu.de>. To
subscribe send the command
     subscribe gpc-de your@email.address
   in the body of a mail to <majordomo@gnu.de> (note the hints above).


File: gpc.info,  Node: Mailing List Archives,  Next: Newsgroups,  Prev: Mailing List,  Up: Support

10.2 The GPC Mailing List Archives
==================================

Perhaps your problem was already discussed on the list. There is a
searchable archive of the mailing list on the WWW. It can be browsed or
searched at
     `http://www.gnu-pascal.de/crystal/gpc/en/'

   The archive of the documentation list is at
     `http://www.gnu-pascal.de/crystal/gpc-doc/en/'

   The archive of the announce list is at
     `http://www.gnu-pascal.de/crystal/gpc-announce/en/'

   The archive of the German GPC list is at
     `http://www.gnu-pascal.de/crystal/gpc-de/de/'


File: gpc.info,  Node: Newsgroups,  Next: Professional Support,  Prev: Mailing List Archives,  Up: Support

10.3 Newsgroups relevant to GPC
===============================

To get support, you can also ask the Usenet newsgroups for help.  There
are several Pascal related newsgroups, but none is dedicated just to
GNU Pascal, so use the one which is most appropriate for your problem.
For general Pascal questions, we recommend the following one:

`news://comp.lang.pascal.misc'       Pascal in general and ungrouped
                                     Pascals.

   Pascal syntax related questions may be appropriate in:

`news://comp.lang.pascal.ansi-iso'   Pascal according to ANSI and ISO
                                     standards.

   The next newsgroup is a haven for beginners, answering questions
that would apply to almost any Pascal. However, if you have a
GPC-specific question don't post there - use the GPC mailing list.  And
when in doubt use the GPC mailing list.

`news://comp.lang.pascal.borland'    Borland Pascal questions.

   Don't forget to give back what you have obtained. None of us is
getting money for answering your questions (unless you pay us by
yourself). Please do your part by answering the questions of others
instead.


File: gpc.info,  Node: Professional Support,  Next: Compiler Crashes,  Prev: Newsgroups,  Up: Support

10.4 Where to get individual support for GPC
============================================

GPC is free software and comes *without any warranty*.

   If you want to get professional support, you can hire an individual
or a company for providing such a service.

   G-N-U GmbH (http://www.g-n-u.de) is doing large parts of the
development of GNU Pascal. This company offers special support for GPC
and can be contacted at <info@g-n-u.de>.

   More generally, to find a company or an individual who offers
support and other consulting services for free software, look into the
GNU Service Directory (http://www.gnu.org/prep/service.html).


File: gpc.info,  Node: Compiler Crashes,  Next: Reporting Bugs,  Prev: Professional Support,  Up: Support

10.5 If the compiler crashes ...
================================

If the compiler crashes, you have discovered a bug. A reliable compiler
never crashes. To help the maintainers fix this bug, it is important
that you send us a problem report.

   If you're on Unix, you can find out where the compiler crashed if
you enable coredumps, then load the compiler (`gpc1') plus the core
file in the debugger (`gdb /your_path_here/gpc1 core'), then type
`backtrace' to get a stacktrace. Include this stacktrace in your bug
report.


File: gpc.info,  Node: Reporting Bugs,  Next: Testing,  Prev: Compiler Crashes,  Up: Support

10.6 How to report GPC bugs
===========================

If you encounter a bug with GPC, please check whether it is one of the
known bugs (*note Known Bugs::). If not, please report it to the GNU
Pascal mailing list (*note Mailing List::). That way, they always reach
the maintainers. Please note the following points.

   * Please send a description of the problem. Try to give as much
     information as possible, with the full text of any error messages
     encountered, or a description of how some output varies from the
     expected output. Always specify the operating system type with
     version and the machine type (try `uname -a' if unsure) as well as
     the version of GPC which you get by typing `gpc -v'.

   * A good article on submitting bug reports can be found at either
     `http://www.chiark.greenend.org.uk/~sgtatham/bugs.html' or
     `http://freshmeat.net/news/2000/02/26/951627540.html'

     Another good article "How To Ask Questions The Smart Way" is
     available as `http://www.catb.org/~esr/faqs/smart-questions.html'

     *Please note that the authors of these articles have no relation
     to GPC and will not help you with your problems! The articles
     contain general hints about how to report problems well.*


   If the problem is with the compiler itself, not an installation
problem or something like this, please provide a test program to
reproduce the problem, and note the following hints. You can also
contribute test programs for features that are working in GPC to ensure
they will not break in future releases.

   * The test program should be as short as possible, but *by all
     means*, please send a *complete* program and *make sure* that it
     still reproduces the problem before you send it. Too often, users
     have sent code which contained obvious syntax errors far before
     the actual problem, or just code fragments that we could only make
     wild guesses about. This is unproductive for us and doesn't help
     you get your problem solved.


   The preferred form for test programs is the form that the automated
GPC Test Suite understands. Please, if at all possible, send your test
programs in this form which should be easy to do, so we won't have to
waste our time to bring them into this form, and can concentrate on
fixing the problem.

   * The file containing the main program _must_ have a name ending
     with `.pas' and contain the keyword `program' (case-insensitively)
     and a `;' in the same line to be recognized by the Test Suite at
     all. Other files whose name ends in `.pas' (e.g., units or modules
     needed by the program), must not contain this.

   * Since the Test Suite must run under very ... nah ... strange
     operating systems, too, file names must be distinguished in their
     first eight characters (case-insensitively) and should not contain
     anything but letters, numbers, hyphens, underscores and a single
     dot. Furthermore, any ancillary files (units, modules, includes,
     data files) should not be longer than "8+3" characters; the same
     applies to the names of unit/module interfaces (because GPC will
     create `.gpi' file names based on those). It is often a good idea
     to use your name, nickname or initials followed by a number as the
     file name.

   * If your test program needs any units or modules, don't give them
     (or their interfaces in case of modules) common names like `Test',
     `Foo' or `MyUnit', unless you have very special reasons to,
     because there might be subtle problems if several test programs
     use the same name. Instead, it is recommended to prefix the
     unit/module/interface names with the name of the main test program
     or an abbreviation of it (if necessary because of the file name
     restrictions). Furthermore, please avoid the use of units and
     modules at all if the bug is not specific to them, in order to keep
     the test as simple as possible.

   * The test program, when run, should produce a line of output
     consisting of the string `OK' (followed by a newline) if
     everything went as expected, and something else (e.g. `failed',
     possibly followed by the reason of failure) if something went
     wrong.  In the latter case you might want to output additional
     information such as the values of important variables or an
     indication in which place the program failed if there are several
     possible places.

   * However, if the program is intended to check whether GPC catches an
     (intentional) compile-time error in the program, place the string
     `WRONG' somewhere in the test program, preferably in a comment in
     the line that contains the intentional error. `WRONG' tests will
     be run with the option `-w' to suppress all warnings, so only real
     errors will be detected.

     *Please note:* While it is possible to combine several `OK' tests
     in a single test program (if you make sure that it outputs `OK'
     only if all tests pass), you cannot put several `WRONG' tests into
     one test program. This is because the compiler will fail (and the
     test therefore be regarded as successful) already if _one_ error
     occurs. So, for `WRONG' tests, do only one check per test program.
     Also, try to keep such a test program as small and simple as
     possible, to avoid the risk that it will fail because of other
     problems (and therefore the test be mistakenly considered
     successful).

   * If the test should merely provoke a GPC warning, use `WARN'
     instead of `WRONG'. This will run the test without `-w', but with
     `-Werror'. However, such tests will also appear to succeed if they
     produce a compiler error, not only a warning.  Therefore, when
     checking for a warning, it is often a good idea to provide a
     complementary test (with expected success) and with `-w' in `FLAG'
     or a compiler directive `{$W-}' to make sure that it's really just
     a warning, not an error.

   * Runtime errors must be detected by the test itself. One way to do
     so is to insert code like the following into your test program:

          uses GPC;

          procedure ExpectError;
          begin
            if ExitCode = 0 then
              WriteLn ('failed')
            else
              begin
                WriteLn ('OK');
                Halt (0)
              end
          end;

          begin
            AtExit (ExpectError);
            { Your code which should provoke a runtime error }
          end.

   * For a test that reproduces an existing problem (which is not
     expected to be fixed soon), please put a comment at the top that
     describes the problem in a few words, and start it with `BUG'.
     This is not required by the test scripts, it's just to make it
     easier for those who will try to fix the problem to see immediately
     what the test is about. Tests for new (planned) features should not
     say `BUG'.


   The following special features of the Test Suite may be helpful for
constructing slightly unusual tests:

   * If the expected output is something else than `OK', place it in a
     file `<basename>.out' (where `<basename>' is the name of the test
     program without the `.pas' extension).

   * If the test program expects some input, place it in a file
     `<basename>.in'. It will automatically be redirected to the
     program's standard input.

   * If the test needs some special flags to be given to the GPC command
     line, place them in a comment preceded by `FLAG', e.g.:

          { FLAG --extended-pascal -Werror }

   * If the test program creates a file, use `.dat' as a file name
     suffix and no directory (the Makefiles will remove such files in
     the `mostlyclean' etc. targets) and do not assume that this file
     exists, does not exist, or anything else about it when the test
     starts. If possible, use an internal (unnamed) file, so these
     issues will not apply.

   * The source file name of the test program will be passed as the
     first command-line argument to the test program run.

   * If a test needs to be run in a special way, you can accompany the
     program with a script `<basename>.run' that will do the actual
     test after the test program was compiled. This script will be run
     by `sh' (regardless of its first line). In order to be portable,
     it should only use standard tools and features present in all `sh'
     compatible shells (e.g., `ash', `bash', but not necessarily
     `csh'). The source file name of the test program will be passed as
     the first command-line argument to the run script in this case.
     The compiled file is called `./a.out' on most systems, but, e.g.,
     `./a.exe' on Cygwin. The environment variable `A_OUT' contains the
     base name (i.e., `a.out' or `a.exe', so you can always invoke the
     program as `./"$A_OUT"').

   * If a test needs to be compiled in a special way (e.g., to decide
     whether to skip the test), place the commands in a script
     (preferably called `<basename>.cmp'), and put the file name of the
     script (without directory) in a comment preceded by `COMPILE-CMD:'
     into the source of the test program. The compile script will be
     run *instead* of the compiler and any other action otherwise done
     for this test program, so it gives you maximum flexibility to do
     whatever you need to do. This script will be run by `sh'
     (regardless of its first line). In order to be portable, it should
     only use standard tools and features present in all `sh'
     compatible shells (see above). The first command-line argument to
     the compile script will be the compiler to use, including all
     options. The second argument will be the source file name of the
     test program. For some typical tests, there are standard compile
     scripts, e.g. `asmtest.cmp' which will skip the test unless run on
     a platform supported by the few tests that contain `asm'
     statements. Of course, it's generally better not to have to use
     such scripts when possible.

   * In some cases you may want to write _randomized_ tests. This is
     not usually recommended since it makes problems found harder to
     reproduce, but sometimes it might be useful (e.g., if you want to
     cover a large parameter space). In such a case, the following
     strategy can be used:

          ...

          uses GPC;

          var
            RandomSeed: Integer;

          begin
            RandomSeed := Random (MaxInt);
            SeedRandom (RandomSeed);

            ... { do your normal tests }

            { when printing an error message: }
            if ... then
              begin
                WriteLn ('failed (', RandomSeed, ') ',
                         ... { possibly additional information } );
                Halt
              end
          end.

     This is a little unnatural since a random number is used to
     (re-)seed the random number generator, but there's currently no way
     to retrieve the internal state of the random number generator (and
     in fact, it's not represented by a single number, but by a large
     array).

     Given the value of `RandomSeed' in an error message, it should
     then be possible to reproduce the problem by inserting this value
     in place of the `Random (MaxInt)'. Just be sure to print this
     value in *every* message of failure the program may produce.



File: gpc.info,  Node: Testing,  Prev: Reporting Bugs,  Up: Support

10.7 Running the GPC Test Suite
===============================

_Note:_ If you have installed a GPC binary distribution, you usually
don't have the Test Suite installed (you can download the GPC source
distribution to get it, however), so this section does not apply to
you. Still, you can find in the section `Contributing Tests to the Test
Suite' how to report GPC bugs in the form of new test programs so we
can fix them as fast as possible.

   The files in the test directory and subdirectories are for testing
GPC only and should not be of any other use.

   Note: A few of the tests do not make sense on all systems. They are
equipped with checks and will be skipped if they find the system not
suitable. Skipped tests do *not* indicate a GPC bug, unless you have a
reason to be sure that the particular test should make sense on your
system.

   * To run the whole Test Suite, type `make' in the test directory (or
     `make check' in the `p' object directory after building GPC).

   * The output will show all errors encountered (hopefully none) and
     tests skipped, and finally display a summary giving the number of
     successful, failed and skipped tests. Any failed test indicates a
     bug in GPC which should be reported to the GPC mailing list,
     <gpc@gnu.de>. Don't forget to mention the operating system you ran
     the test on and any other relevant information about what you did.

   * You can also type `make pascal.check-long' to get a long output
     which is a sequence of file names followed by `OK' for successful
     tests, `SKIPPED' for skipped tests (both in capital letters), and
     anything else for failed tests.

   * To run only some of the tests, you can type something like `make
     MASK="foo[1-7]*.pas"' or `make MASK="foo42.pas" pascal.check-long'.

   * To clean up after running the tests, type `make clean'.



File: gpc.info,  Node: To Do,  Next: Internals,  Prev: Support,  Up: Top

11 The GNU Pascal To-Do List.
*****************************

This is the To-Do list for the GNU Pascal Compiler.

   The GNU Pascal development team is constantly working on making GNU
Pascal more reliable and more comfortable. However, there are some
known bugs which will take some time to be fixed (any help welcome!),
and we do not want to hide them from you. You might also be interested
to know what features are planned to be implemented in the future. This
list is meant to keep track of the known bugs and wanted features of
GPC.

   If you want to report a new bug or suggest a new feature, the best
way to do it is in the mailing list. This way, other GPC users can
provide additional ideas, perhaps work-arounds for bugs, and the GPC
maintainers can sooner start to think about how to solve the problem.
The GPC mailing list is <gpc@gnu.de>. To subscribe, send the command
`subscribe gpc your@email.address' in the body of a mail to
<majordomo@gnu.de> (the subject is ignored). An archive of the mailing
list can be found at `http://www.gnu-pascal.de/crystal/gpc/en/'.

   The list changes regularly. The present version refers to the
current GPC snapshot, 20060325.

   This list is part of the GNU Pascal Manual, included in GPC
distributions and snapshots. You can always browse the most current
version of the list on GPC's WWW page. If you check the To-Do list
regularly you can decide if and when to try a new snapshort.

* Menu:

* Known Bugs::        Known bugs in GPC
* Planned Features::  Features planned for GPC
* Fixed Bugs::        Fixed bugs


File: gpc.info,  Node: Known Bugs,  Next: Planned Features,  Up: To Do

11.1 Known bugs in GPC
======================

In this section, you can find information about GPC bugs that are known
to the developers.

   If you encounter a bug with GPC, please check whether it is one of
the known bugs. If not, report it to the GNU Pascal mailing list.  (But
always report if you solve the problem! :-)

   Solved problems are moved to "Fixed Bugs" (*note Fixed Bugs::), and
implemented features to the "News" chapter (*note News::).

   A message ID (like `<42@foo.bar>') refers to a message in the GPC
mailing list or a newsgroup where the topic was discussed (often a bug
report). A note of the form `(xy20001231)' refers to an internal
message of the GPC developers. A file name like `(foo42.pas)' refers to
the according program in the GPC test suite included in the GPC source
distribution.

   * `setlimit' is applied when it shouldn't be ((a) variable/constant
     declarations, (b) `set of ShortCard') ???

   * dynamic sets don't work

   * there are some bugs with mathematical functions; GPC fails, for
     example, the Paranoia test
     (`http://www.netlib.org/paranoia/index.html')


File: gpc.info,  Node: Planned Features,  Next: Fixed Bugs,  Prev: Known Bugs,  Up: To Do

11.2 Features planned for GPC
=============================

In the following sections, you can find informations about features
which have been suggested and/or discussed for inclusion into GPC,
usually in the GPC mailing list. The division into the sections and the
names of the sections may change when this seems useful. The entries
within each section are in no particular order.

   Some of the entries may be a bit difficult to read. Double question
marks (`??') within the entries mean that it's not yet clear how to do
the thing. Triple question marks (`???') mean that it's not clear
whether to do it at all. ;-)

* Menu:

* Planned - Strings::            String types
* Planned - OOP::                Object oriented programming extensions
* Planned - Other types::        Other types
* Planned - Misc::               Miscellaneous GPC topics
* Planned - Utilities::          Useful utilities for GPC


File: gpc.info,  Node: Planned - Strings,  Next: Planned - OOP,  Up: Planned Features

11.2.1 Planned features: Strings
--------------------------------

   * const/var `AnyString' parameters and pointers (records internally,
     cf. gpc.pas) (GetCapacity; only for var parameters)

   * `SetLength' for non-Pascal string types; use truncate-flag

   * make work on all string types: string functions from
     `rts/string*.pas', `Concat'/`+' (Optimize `s := s + ch')
     (fh19971105)

   * option `--arrays-of-char-as-cstrings={none,zero-based,all}' to
     allow assigning [zero-based] arrays of char to cstring variables
     (warning otherwise) (cstrini2.pas); make padding of those arrays
     in initialized variables and in assignments dependent on this
     switch (fh19970921) (fjf57.pas, ok) and if the length matches
     exactly, give a warning (fh19971013) (cstrassign.pas); pass those
     arrays as cstrings in read*, write*, str (P_*STRING; current
     length=-1 in two places); compile time warning (and treatment as
     non-zero-based) if it's not clear at compile time if a conformant
     array or schema is zero-based or not, and an operation depends on
     this in the zero-based state

   * Short strings (Length, Capacity) and switches
     (tc19980326.2,tc19980327); allow `type x=string' (undiscriminated)
     when switch is set so that strings don't default to length 255
     (fh19971113) (cf. fjf97.pas); don't add a #0 terminator when
     passing as a CString parameter (automatically use String2CString)

   * automatically convert CStrings to Strings?

   * general switch `--bp-strings'

   * "wide" characters

   * open array/string parameters (`$P', `$V' in BP; undocumented
     `OpenString' identifier in BP)

   * variables of type undiscriminated schema/strings -> remove
     pointers to string constants; functions returning undiscriminated
     schemata (pg19980813.3)


File: gpc.info,  Node: Planned - OOP,  Next: Planned - Other types,  Prev: Planned - Strings,  Up: Planned Features

11.2.2 Planned features: OOP
----------------------------

   * Object Oriented Extensions draft, Delphi; `class'; allow classes
     and object types to inherit from each other;
     <01BD7A3A.6B187A20.prucha@helicon.co.at>; `obpascal.zip'

   * error/exception handling (Java, Delphi?)
     <01BD7A3A.6B187A20.prucha@helicon.co.at> (tc20000623)

   * method pointers/procedural variables (`procedure/function of
     object') (-> Delphi) ???

   * destructor: reset VMT link to nil ???

   * `CLASS is CLASS' (implemented in Pascal with `Parent')

   * BP compatible dynamic method dispatcher ?? ???

   * `New': Delphi syntax; Dispose?? (automatically?; set references
     automatically to nil) (-> FPC)

   * `--base-class=foo', `--base-object=bar' ???

   * properties <01BD7A3A.6B187A20.prucha@helicon.co.at>,
     <16131.199805071354@potter.cc.keele.ac.uk>

   * VMTs (also for local classes (EP modules???)!) in GPI files,
     written to assembler file by main program; `--cfiles=foo': .s file
     with VMTs for C/assembler??? (also .h???)

   * method overloading ??? ??

   * interfaces (cf. OOE, Java); `OBJ is INTERFACE' (not so easy?) ???;
     variables of type pointer to more than one interface [and class]
     (also possible!); VMT problem with interfaces (my solution??? also
     with dynamic linking???)

   * virtual constructors; in interfaces (load)???

   * VMT: Children: list of pVMT

   * VMT: object constants, class variables; virtual/static

   * VMT: ClassID (64/128 bits?) default 0, error when duplicated,
     warning when 0 and inherited from class with <>0 ?, not allowed
     for abstract classes!; ClassName (also for abstract classes?); [];
     ProgrammerID, BaseClassID at beginning of unit (redeclarable?);
     find class by ClassID/ClassName (implementable in Pascal with
     `Children'); store in GPI: whether ClassID used, ClassName used,
     which classes are instantiated ???


File: gpc.info,  Node: Planned - Other types,  Next: Planned - Misc,  Prev: Planned - OOP,  Up: Planned Features

11.2.3 Planned features: Other types
------------------------------------

   * variant records: EP: check that all values of tag-type have
     exactly one matching variant

   * automatically detected upper array bounds in structured
     constants/intialized variables (-> PXSC)

   * UCSD Pascal's `Integer[n]' ??? BCD?

   * `SELECTED_REAL_KIND' for real types (cf. Fortran, drf) ?? ???

   * general subtypes ???

   * type-cast operators ???

   * read/write operators ???

   * read Booleans and enum types from files, write enum types to files
     ???

   * sparse sets; sets of arbitrary types ?? ???

   * initalization and finalization code for arbitrary types (e.g. GMP
     types)

   * resize schemata (cf. `SetLength' in Delphi)

   * `ShortComplex', `LongComplex'
     <Pine.GSO.4.44.0207151258290.5058-100000@bonsai.fernuni-hagen.de>

   * keep files in FDRList while they live, not only while they're
     open, so `DoneFDR' can be applied to all of them ???

   * improve TFDDs

   * generic types (cf. OOE section C.1) (gentypes.pas) ???


File: gpc.info,  Node: Planned - Misc,  Next: Planned - Utilities,  Prev: Planned - Other types,  Up: Planned Features

11.2.4 Planned features: Misc
-----------------------------

   * checking of overflows, variants etc.; check that strings converted
     to CStrings don't contain #0 characters; initialize strings
     (length field), pointers, ordinal values and reals(?) with invalid
     values if checking is on

   * warn about using uninitialized variables (kevin2.pas), especially
     for strings, also for `for'-loop counters after the loop (EP 6.8.1)

   * transpose arrays (Fortran)? <918557$mke$1@nnrp1.deja.com>

   * inline functions in GPI files

   * options to warn about everything that could cause portability
     problems

   * libraries (static/shared; DLL)
     <Pine.HPP.3.96.971110183550.7996B-100000@tea.geophysik.tu-freiberg.de>

   * smart linking (split `foo.s', as `foo*.s', ar `foo*.o' or split
     `foo.o')

   * overloading of unary operators (`+', `-', `not') ???

   * function overloading (in units and static methods?? - with
     different parameters, override or overload?); linker name??
     (perhaps: first occurrence of a procedure with normal name (=> all
     non-overloaded procedures get normal names)?); cf. Delphi methods
     without `override'

   * `for var: type = foo to bar do' ???

   * default parameters (cf. OOE section C.4; Delphi 4?)
     (iniparm[12].pas) <E183vio-000IyH-00@f12.mail.ru>

   * variable number of arguments <32F9CFE7.5CB@lmemw.ericsson.se> ??
     ???

   * multithreading support ?? ???

   * `--wirth-pascal' :-)

   * PXSC standard ... (`pxsc.zip', `contrib/peter/pxsc') (??)

   * Pascal++ standard ... (??) ???

   * Delphi features: CompToCurrency, CurrencyToComp, Slice, TypeInfo
     ???, dynamic arrays (tc19991012)

   * output column numbers in error messages ??

   * debug info: `with' statements


File: gpc.info,  Node: Planned - Utilities,  Prev: Planned - Misc,  Up: Planned Features

11.2.5 Planned features: Utilities
----------------------------------

   * `gp' make utility to replace automake; `external LIB' like `$L'
     (-> BP, Delphi) ?? (fh19990325.2)

   * `pas2texi' <200301290441.FAA30843@goedel.fjf.gnu.de>

   * C header to Pascal translator

   * gdb: Pascal types (sets, files, subranges, schemata, ...)

   * `indent'-like source code formatter for Pascal

   * AT&T <-> Intel assembler syntax converter (-> BP BASM) ???


File: gpc.info,  Node: Fixed Bugs,  Prev: Planned Features,  Up: To Do

11.3 Problems that have been solved
===================================

This section lists the bugs fixed since the last (non alpha/beta) GPC
release, together with the date (YYYYMMDD) on which they were fixed, so
you can check if some problem has already been solved in a recent
release or developer version. For new features, see *Note News::.

   * 20060304: Do not allow passing strings to parameters of type array
     of char subrange (avoids passing out of range values).

   * 20060228: Use at least integer precision for arithmetic (avoids
     loss of precision due to overflow)

   * 20060225: Avoid ICE on some record types

   * 20060225: Avoid segfault in bison parser

   * 20060214: Avoid ICE on unimplemented operators (ice4.pas)

   * 20060214: Avoid ICE on bad forward declaration (ice3.pas)

   * 20060214: ISO-10206 requires at least one output parameter in
     `ReadStr' (rstr2a.pas)

   * 20060213: Allow side effects in arguments of `ReadStr' (rstr1.pas)

   * 20060213: Correctly pass substrings to `StringTFDD_Reset'
     (fjf1099.pas)

   * 20060213: Avoid ICE on multiple errors with set constants
     (constv2c.pas)

   * 20060213: Avoid ICE on bad parent class (delc.pas)

   * 20060212: fix passing of multiple string values to `const'
     conformant arrays (confa2.pas)

   * 20060212: Avoid ICE on invalid conformant arrays (confa3.pas)

   * 20060212: Avoid confusing initialized variant records with
     conformal arrays (confa1.pas)

   * 20060212: Avoid ICE on invalid set argument (sets16a.pas)

   * 20060212: Avoid ICE on incompatible arguments in binary operators

   * 20060212: gpc rejected some valid strings arguments (peter8.pas)

   * 20060208: In ISO modes check identifier scopes stricter in record
     types and parameter lists (gale7[a-m].pas, gale8[a-u].pas)

   * 20060203: Fix problems with strange characters in some versions of
     ncurses

   * 20060130: In ISO modes report out of range constants only at
     runtime (range1.pas)

   * 20060130: make set literals and packed sets compatible
     (sets17a.pas)

   * 20060128: check `type of' argument more strictly in ISO modes
     (gale9[abc].pas, gale10.pas, gale11[a-d].pas)

   * 20060128: in ISO-7185 mode require that program parameters are
     files (pparm1.pas)

   * 20060128: require digit after decimal point in ISO modes
     (real2.pas)

   * 20060128: in ISO modes allow sets inside packed records and arrays
     (pack13.pas)

   * 20060128: in ISO modes require parameters to `read' and `write'
     (read3.pas, write3.pas)

   * 20060127: allow string literals in ISO-7185 mode (const1.pas)

   * 20060127: allow empty ranges in set constructors (sets18.pas)

   * 20060127: correct comparison of sets (sets15.pas)

   * 20051118: avoid crash when preprocessing (prep1a.pas)

   * 20051118: define `__OS_DOS__' on Dos and Windows

   * 20051118: fix spurious warning about `-Wuninitialized'

   * 20051114: fix passing discriminated string schema

   * 20051105: constructor calls inside constructors and destructor
     calls inside destructors

   * 20051104: allow testing when different GPC version using the same
     backend is already installed

   * 20051025: correctly parse `import foo; uses qualified;'
     (waldek15.pas)

   * 20051021: accept `--no-methods-always-virtual'

   * 20051021: nonlocal jump fixes for 3.2.x and 3.3.x

   * 20051021: fix bootstrap with C++ and 3.3.x

   * 20051021: allow one element sets in non-iso dialects (delset.pas)

   * 20051021: do not crash on wrong open array parameter (waldek13.pas)

   * 20051014: `forward', `near' and `far' may be redeclared in all
     dialects

   * 20051014: Integer2StringBaseExt now works in 64-bit machines
     (mir048[cd].pas)

   * 20051014: do not crash on bad declarations (dimwit1.pas,
     dimwit3.pas, dimwit5.pas)

   * 20051014: avoid calling fcntl if not present (fjf1042b.pas,
     fjf1042c.pas on Mingw32)

   * 20051014: sorting set initializers used wrong comparison function
     (affected Solaris)

   * 20051014: avoid range-check failure in RTS on strict alignement
     machines (affected at least Sparc and HP)

   * 20051014: mod in schema initializer (modtest.pas)

   * 20051014: avoid spurious side effects in initializers do to
     range-checking (fjf1021[dh-k].pas)

   * 20051014: fix bootstrap with Ada and 3.4.x

   * 20051014: fix bootstrap with 3.2.x

   * 20050325: check initializers of unused types (fjf898*.pas)

   * 20050325: check identifier scopes stricter (az25.pas, fjf1059*.pas)

   * 20050321: in `--borland-pascal' give only a warning, not an error,
     for duplicate `case' elements (drf6*.pas)

   * 20050320: multi-dimensional `packed' arrays are not correctly
     packed (fjf149*.pas)

   * 20050316: check arithmetical overflow in constants somewhat better
     (fjf206*.pas)

   * 20050316: check duplicate external declarations stricter
     (fjf948.pas)

   * 20050312: check that actual discriminants match in parameters and
     assignments, and in strict EP mode, check that actual
     discriminants of parameters within one identifier list match
     (berend4.pas, fjf104[45]*.pas, typeof[2-4].pas)

   * 20050312: check pointer to schema types stricter (fjf130.pas,
     fjf614.pas, schema3a.pas affected)

   * 20050311: allow importing the same value as a result of distinct
     expressions under the same name for EP modules for ordinal,
     pointer, string and set constants (fjf1040*.pas, stef1.pas)

   * 20050307: allow attributes for procedural types (chief56.pas)

   * 20050307: problem with string operations and `goto' (contour0.pas,
     contourbug.pas, martin1.pas, berend3.pas)

   * 20050307: check `goto' targets more strictly
     <261020020000077022%gpaeper@empirenet.com>,
     <Pine.LNX.4.44.0210281004000.31943-100000@duch.mimuw.edu.pl>
     (az48.pas, fjf701*.pas, fjf1038*.pas, gale6.pas)

   * 20050307: `Result' is not completely Delphi compatible
     (fjf1022*.pas)

   * 20050307: problem if a `Write' or `WriteLn' argument calls a
     routine which writes to the same file (fjf1036.pas)

   * 20050302: `Update' as well as writing after reading or checking
     `EOF' can get the file position wrong in some cases (arp2*.pas,
     fjf159.pas, fjf160*.pas)

   * 20050217: declaring a procedure in the implementation with the
     same name as an imported procedure doesn't work (chief18.pas),
     detect name collisions between imported EP modules (mod9.pas)

   * 20050214: warn if an lhs cast decreases alignment (avo9.pas)

   * 20050214: don't require result variables in forward declarations
     except in strict ISO mode (marku10*.pas)

   * 20050213: writing to a file buffer at EOF doesn't work (eof1.pas)

   * 20050211: don't allow `f^' for unopened files `f' (pcerror[ij].pas)

   * 20050210: evalute initializers exactly as often as specified
     (fjf1019.pas)

   * 20050205: initialized types in record and object fields and in
     schemata (inirec[24].pas, fjf1016*.pas)

   * 20050130: in standard Pascal modes, `EOF' is false on an empty
     file (tom7.pas)

   * 20050127: wrong `arithmetical overflow' with `set of byte'
     (igor1.pas)

   * 20050119: types and initializers containing variable expressions,
     including schemata with non-constant discriminants and global
     variables of dynamic size (couper[45].pas, fjf186.pas, fjf548.pas,
     fjf612a.pas, fjf997*.pas, fjf1003*.pas, john1a.pas)

   * 20050117: `pow', `Trim', `Card', set operations (`-', `*', `><')
     and comparisons as well as string comparisons and array slices
     with constant arguments cannot be used in constants (fjf998*.pas,
     fjf1000*.pas, fjf1009*.pas)

   * 20050117: `ParamStr' evaluates its argument twice (fjf963b.pas)

   * 20050106: user-defined operators must not be applied to implicit
     operations (fjf991.pas and many other cases)

   * 20041203: accessing components of a constant (EP) constructor
     (indexed by a constant for arrays) must yield a constant again
     (dave3*.pas)

   * 20041202: GPC crashes when using two variables with
     identically-named fields in a single `with' statement (withbug.pas)

   * 20041125: GPC doesn't accept `case' statements without
     case-list-elements (fjf982*.pas)

   * 20041125: gcc-3.x: options are wrongly reordered (so, e.g.,
     `--gnu-pascal -Wno-underscore' doesn't work as expected) (avo7.pas)

   * 20041124: applying `not' to a function result in parentheses
     doesn't work (avo6.pas)

   * 20041123: packed array indices containing `mod' don't work
     (avo4.pas)

   * 20041120: GPC sometimes prints `???' instead of the actual file
     name in messages

   * 20041028: function results (of record type) must not be allowed as
     `with' elements (only a warning in `--delphi' and `--mac-pascal'
     modes for compatibility); fields of non-lvalue `with' elements
     must not be lvalues either (fjf493*.pas)

   * 20041022: value parameters of type `String' (undiscriminated) must
     take the capacity of the actual parameter, according to EP
     (waldek11*.pas)

   * 20041021: initialized types in arrays (fjf233.pas, fjf974*.pas)

   * 20041020: initializers are ignored in `New' and `Initialize'
     (fjf967[j-l].pas)

   * 20041020: the address of global routines is not allowed in
     initializers (avo2*.pas)

   * 20041015: `Index' and `Pos' cannot be used in constant expressions
     (fjf970*.pas)

   * 20041012: initializers of variant records don't work (fjf259.pas),
     (peter6.pas) <C1256791.0021F002.00@synln01.synstar.de>

   * 20041012: initializers of packed arrays don't work (emil5.pas)

   * 20041007: the `__FILE__' and `__BASE_FILE__' macros should return
     full paths

   * 20041006: `Sqr' sometimes evaluates its argument twice
     (fjf963a.pas)

   * 20041004: memory leak in routines with a local variable of file
     type that are left via `Exit' or `Return' (fjf962.pas)

   * 20040916: using a Boolean function as a condition in a `repeat'
     loop doesn't work correctly (artur1*.pas)

   * 20040913: overstrict type-checking in comparisons involving
     procedural types (fjf960*.pas)

   * 20040908: `Read', `Write' etc. evaluate its arguments in the wrong
     order (az43*.pas)

   * 20040908: `Read' etc. evaluate references to string parameters
     twice (fjf958.pas)

   * 20040907: on targets with 16 bit `Integer' type, the `MicroSecond'
     field of `TimeStamp' causes a compilation error

   * 20040907: character arrays indexed by non-integer ordinal types
     treated as strings cause internal compiler errors (fjf957*.pas)

   * 20040906: `-W[no-]cast-align' does not work (fjf956*.pas)

   * 20040903: in `FormatTime' `%Z' and `%z' unless provided by system
     library ignore DST

   * 20040710: powerpc: `--strength-reduce' doesn't work with `for'
     loops (was kludged before, fixed in gcc-3.3.3)

   * 20040710: AIX: `ReturnAddress' doesn't work after use of dynmamic
     variables (backend bug, fixed in gcc-3.3.3)

   * 20040622: functions returning sets are called twice if
     range-checking is on (inga1*.pas)

   * 20040512: `pow' and `**' are really EP conformant now (in
     particular `x pow y' and `x ** y' are an error if x = 0 and y <=
     0) (emil27*.pas)

   * 20040511: bug with `absolute' variables in strange situations
     (waldek8.pas)

   * 20040511: `protected var' parameters must only accept references
     (unlike `const' parameters) (gale5*.pas)

   * 20040507: `pack' must not pack the component type of arrays
     (fjf940[b-e].pas)

   * 20040507: in some circumstances packed fields are allowed as `var'
     parameters (fjf940a.pas)

   * 20040427: parameters of procedural types don't support Standard
     Pascal procedural parameters, conformant/open arrays and `type of'
     inquiries (fjf939*.pas)

   * 20040422: bugs with nonlocal gotos out of routines declaring file
     variables (nonloc*.pas) (fix involved a change in the internal
     representation of file variables)

   * 20040331: `'foo'#42' is rejected in `--borland-pascal'
     (chief53.pas)

   * 20040330: records/objects with many fields are handled slowly

   * 20040328: `--implementation-only' doesn't work correctly
     (bo4-19.pas)

   * 20040325: messages referring to object methods point to the end of
     the object type rather than the method declaration

   * 20040325: bug when slice-accessing a function result of type
     `Pointer' type-casted to `PString' (bo4-18.pas)

   * 20040210: incorrect errors with packed arrays and records
     (fb[12].pas, gale[34].pas)

   * 20040204: GPC crashes on `else' after a missing semicolon in some
     circumstances (fjf926.pas)

   * 20031007: spurious errors about `result types in forward declared
     functions' in `--extended-pascal' etc. (dave2.pas)

   * 20031004: do not allow disposing of `nil' pointers in standard
     Pascal modes (fjf917*.pas)

   * 20031001: arithmetic expressions don't work as lower
     array/subrange bounds (fjf204.pas, fjf248.pas, fjf293.pas,
     fjf336.pas, fjf346a.pas, fjf622.pas)

   * 20030925: initializers for types containing nested schemata don't
     work (fjf914*.pas)

   * 20030830: open internal files with `O_EXCL' on `Rewrite' (as a
     protection against symlink attacks)

   * 20030819: GPC accepts, but ignores, options with invalid suffixes
     (e.g. `--delphi-pascal')

   * 20030729: `pow' and `**' are EP conformant now (in particular `x
     pow y = (1 div x) pow (­y)' if `y' is negative and `x <> 0')
     (fjf908.pas)

   * 20030714: `--enable-keyword'/`--disable-keyword' on the
     command-line makes GPC crash (david5.pas)

   * 20030704: wrong type-error when applying `Inc' to a type-casted
     pointer (peter3.pas)

   * 20030702: with range checking enabled, check dynamic
     subrange/array size (fjf222*.pas, fjf813*.pas, fjf900*.pas)

   * 20030701: GPC allows modification of conformant array bounds,
     result of `High'/`Low' etc. (fjf897*.pas)

   * 20030626: don't allow linker names starting with a digit
     (fjf894.pas)

   * 20030625: `SubStr' with constant arguments doesn't work in
     constants (gale1.pas)

   * 20030617: handle `BitSizeOf' correctly for packed array fields,
     don't allow `SizeOf' on them (fjf891*.pas)

   * 20030612: System: `BPReal' must be a packed record
     <3EE8A26D.C919BE7D@flexim.de>

   * 20030610: schema types with initializers (drf1.pas, fjf886*.pas)

   * 20030610: `Return' doesn't work for sets (fjf885.pas)

   * 20030609: bug with arrays as fields of `packed' records
     (waldek6.pas)

   * 20030607: don't allow duplicate imports in a module interface and
     implementation (nick1b.pas)

   * 20030604: compensate for parser read-ahead in the lexer, so
     compiler directives don't become effective too early and error
     messages refer more closely to the correct source position

   * 20030603: bug when dividing two integers with `/' (fjf481.pas)

   * 20030509: don't allow `absolute' in type definitions

   * 20030502: subranges with variable limits (couper[23].pas)

   * 20030502: Sparc with gcc-2.95.x: `goto' jumping out of two
     procedure nesting levels doesn't work (GCC bug; fixed in gcc-3)
     <200111170922.KAA09125@goedel.fjf.gnu.de> (fjf558[op].pas) (fixed
     with gcc-3 or when using `--longjmp-all-nonlocal-labels')

   * 20030502: the parser does not always recover well after a parse
     error <199911040915.KAA11168@humulus.daimi.au.dk> (fixed the case
     given in this report; if there are other cases, please report)

   * 20030501: detect conflicts between object fields and local
     variables in methods

   * 20030430: packed array/record fields don't work in `Read' etc.
     (tom5.pas)

   * 20030430: file parameters must not automatically be bindable in
     `--extended-pascal' (fjf193[c-e].pas)

   * 20030423: give an error rather than a warning when casting between
     types of different size in `{$X-}'

   * 20030423: simplify code generated to compute size of dynamical
     variables if no bitfields are involved (ok with gcc-3)

   * 20030422: initialized object variables don't work (fjf445*.pas)

   * 20030422: declarations of a module interface are not visible in
     the implementation (kevin13.pas, mod12.pas)
     <Pine.BSI.3.96.971110210330.7570A-100000@malasada.lava.net>

   * 20030422: detect invalid array slice access with constant indices
     at compile-time (peter2*.pas)

   * 20030421: automatically close dynamically allocated files on
     `Dispose' and files declared in a statement block at the end of
     the statement block <6r9ir5$7v5$1@nntpd.lkg.dec.com>
     (fjf219[a-d].pas, fjf502.pas)

   * 20030421: initialize local static variables in the main
     constructor, not in each routine call (fjf458*.pas)

   * 20030421: check parameter and result variable names in repeated
     forward etc. declarations <20010321204051.A611@plato> (fjf284.pas,
     markus8.pas, fjf850*.pas)

   * 20030417: modifying `for'-loop counters within the loop or in a
     subroutine is not allowed <200005240807.EAA05355@mail.bcpl.net>,
     <Pine.LNX.4.44.0210281004000.31943-100000@duch.mimuw.edu.pl>
     (az47.pas, fjf837*.pas)

   * 20030417: possible stack overflow when using string concatenation
     in a loop (fjf419*.pas, fjf345e.pas, fjf460b.pas) - breaks
     berend3.pas (less important because strange test case, and just
     another instance of existing contourbug.pas)

   * 20030416: some functions in boolean shortcuts are always called
     (fjf226*.pas)

   * 20030414: label declarations must not be allowed in unit/module
     interfaces and module implementations (but in unit
     implementations, BP compatible, though we don't allow nonlocal
     `goto's into the constructor) (fjf835*.pas)

   * 20030321: variables declared in interfaces of modules are not
     initialized (capacity of strings etc.) (daj3.pas, sven14c.pas,
     nick1.pas)

   * 20030321: subranges whose size is exactly one or two bytes are not
     packed in packed arrays (daj14a.pas)

   * 20030321: `prior parameter's size depends on `Foo'' with `const'
     string parameters in module interfaces (fjf667.pas)

   * 20030313: operators don't always work across units (fjf803.pas)

   * 20030312: overloading `<=', `>=', `<>' and some certain words
     doesn't work (fjf789.pas, fjf794*.pas, fjf800.pas, fjf802.pas,
     fjf804.pas)

   * 20030311: when passing a schema variable as an untyped argument,
     the whole schema, including the discriminants is passed
     (fjf798.pas)

   * 20030302: discriminant identifiers as variant record selectors

   * 20030227: GPC crashes when taking the address of local variables
     in an initializer (nicola4*.pas)

   * 20030225: the warnings about uninitialized/unused variables don't
     work for strings, objects, etc. (fjf779*.pas)

   * 20030221: gcc-2.95.x: `configure --silent' doesn't work (passes
     wrong options to sub-configures, so the subsequent make fails)
     (GCC bug; fixed in 3.x)

   * 20030215: forward referencing pointers generate debug info that
     appears as generic pointers

   * 20030202: count of parameters in error messages should not include
     `Self' in methods or internal parameters for conformant or open
     arrays

   * 20030129: check for unresolved `forward', interface and method
     declarations (az32.pas, fjf758*.pas)

   * 20030129: several standard conformance bugs
     (az{1..24,26..42,44..46}*.pas, emil23*.pas)

   * 20030126: some bugs with complicated schema usage (emil22*.pas,
     fjf750*.pas)

   * 20030122: subtraction of unsigned types with a negative result
     doesn't work (ml4.pas)

   * 20021229: declaring huge enum types and exporting subranges of
     them is very slow (quadratic time behaviour); some bugs regarding
     exporting of subranges (fjf736*.pas)

   * 20021213: Linux: `crtscreen' should react to `SIGWINCH'

   * 20021120: `Card' doesn't work with set constructors; `Include' and
     `Exclude' should not accept set constructors (eike3*.pas)

   * 20021105: type initializers are not type-checked until a variable
     of the type is declared (fjf704.pas); with gcc-2.x: bug when
     variables of a type with initializer are declared locally in more
     than one routine (couper13.pas)

   * 20021105: `packed object' should not be allowed (fjf703.pas)

   * 20021101: bug when replacing a non-virtual method by a virtual one
     in a descendant object type (fjf702.pas)

   * 20021027: classic Pascal does not know the empty string
     <Pine.LNX.4.44.0210181332470.29475-100000@duch.mimuw.edu.pl>
     (fjf693*.pas)

   * 20021027: relational and exponentiation operators have no
     associativity
     <Pine.LNX.4.44.0210210807410.18095-100000@duch.mimuw.edu.pl>
     (fjf692.pas, fjf566[k-m].pas)

   * 20021002: `gpc -BDIR' requires a trailing dir separator

   * 20021001: constructors are accepted as the argument to `Dispose'
     (fjf674.pas)

   * 20021001: align file fields in packed records on machines with
     strict alignment requirements (chief38*.pas)

   * 20021001: bug on machines with strict alignment requirements
     <199906021618.MAA06228@sten27.software.mitel.com> (richard1.pas)

   * 20020930: duplicate variable declarations are allowed

   * 20020929: `attribute's of variables are ignored (fjf673.pas)

   * 20020929: `volatile' for `external' variables without `asmname' is
     ignored (fjf672.pas)

   * 20020926: numbers with base specifiers are allowed as labels
     (fjf417*.pas)

   * 20020923: System: `MemAvail'/`MaxAvail' can go into an endless loop

   * 20020920: the number of times the preprocessor is invoked by the
     automake mechanism might grow exponentially with the number of
     units involved <02091610572303.14626@dutw54.wbmt.tudelft.nl>

   * 20020918: importing `StandardOutput' etc. in the interface of a
     module doesn't work (sietse2*.pas)

   * 20020904: comparisons between signed and unsigned integers
     sometimes give wrong results (eike2.pas, fjf664.pas, martin5.pas)

   * 20020903: `IOSelect' fails with file handles >= 8 on some systems
     (e.g., Solaris) (fjf663.pas)

   * 20020831: GPC creates wrong debug info for many built-in types
     <200208280012.g7S0CWj07637@mail.bcpl.net>

   * 20020827: comparisons of `packed' subrange variables don't work
     right (martin4[ab].pas)

   * 20020824: operators defined in units don't always work (maur11.pas)

   * 20020824: object methods that contain an ISO style procedural
     parameter forget the implicit `with Self do' (fjf662a.pas)

   * 20020615: `if Pass[i] in 'A' .. 'Z'' makes GPC crash (miklos6.pas)

   * 20020603: compiling a program (not a unit or module) with
     `--interface-only' or `--syntax-only' segfaults (waldek1.pas)

   * 20020603: `--nested-comments' fails without `-Wall' (waldek2.pas)

   * 20020514: powerpc: `--strength-reduce' doesn't work with `for'
     loops [kludged now]

   * 20020514: guarantee complete evaluation in `{$B+}' mode
     (fjf552*.pas)

   * 20020514: spurious warning with `for' loops using a `ByteCard'
     counter (toby1.pas)


File: gpc.info,  Node: Internals,  Next: Copying,  Prev: To Do,  Up: Top

12 The GPC Source Reference
***************************

     "The Source will be with you. Always."

   This chapter describes internals of GPC. It is meant for GPC
developers and those who want to become developers, or just want to
know more about how the compiler works. It does not contain information
needed to just use GPC to compile programs.

   This chapter tells you how to look up additional information about
the GNU Pascal compiler from its source code.

   *Please note:* If you intend to modify GPC's source, please check
the top of each file you're going to modify. A number of files are
generated automatically by various tools. The top of these files will
tell you by which tool and from what file they were generated.
Modifying a generated file is pointless, since it will be overwritten
the next time the tool is run. Instead, modify the original source
(which will usually be easier in fact, e.g. a bison input file vs. the
generated C code). This also holds for various documentation and other
files.

   Proprietary compilers often come with a lot of technical information
about the internals of the compiler. This is necessary because their
vendors want to avoid to distribute the source of the compiler - which
is always the most definitive source of this technical information.

   With GNU compilers, on the other hand, you are free to get the
source code, look how your compiler works internally, customize it for
your own needs, and to re-distribute it in modified or unmodified form.
You may even take money for this redistribution.  (For details, see the
GNU General Public License, *Note Copying::.)

   The following subsections are your guide to the GNU Pascal source
code. If you have further questions, be welcome to ask them at the GNU
Pascal mailing list (see *Note Support::).

   All file paths mentioned in this chapter are relative to the GNU
Pascal source directory, a subdirectory `gcc/p' below the top-level GCC
source directory.

   The following sections roughly coincide with the order of the steps
a Pascal source passes through during compilation (omitting the code
generation which is the job of the GCC backend, and the assembler and
linker steps at the end which are done by the programs `as' and `ld' of
binutils and possibly other utilities like `collect2'). Also missing
here is the compiler driver `gpc' which behaves very similarly to `gcc'
and whose main job is to invoke the other parts in the right order,
with the right arguments etc.

   Note, this chapter docuemnts only selected parts of the compiler.
Many things are missing because nobody has yet had the time to write
something about them. In any case, for real understanding of the inner
workings, you should always refer to the source code.

* Menu:

* Preprocessor::         `gpcpp.c' -- The Pascal preprocessor
* Lexical analyzer::     `gpc-lex.c' -- How GPC reads your source.
* Syntax parsing::       `parse.y' -- ``Syntax diagrams'' as ``Bison'' source.
* Tree nodes::           `../tree.*' -- How GPC stores your program internally.
* Parameter passing::    `typecheck.c' -- How GPC passes parameters.
* GPI files::            `module.c' -- How GPC's precompiled module/unit interfaces work.
* Automake::             `module.c' -- How GPC automatically ``makes'' a large project.
* File Layout::          Files that make up GPC
* Planned::              Planned features

   For more information, see the manual of GCC internals, *Note Top:
(gccint)Top.


File: gpc.info,  Node: Preprocessor,  Next: Lexical analyzer,  Up: Internals

12.1 The Pascal preprocessor
============================

`gpc' contains integrated preprocessor. It is internally identical to
the former `gpcpp' standalone preprocessor, so it does everything
`gpcpp' did. In turn `gpcpp' is based on `cpp' so it has most
capabilities of `cpp' (see the cpp manual) and some more.  In
particular:

   * Comments like `cpp' does, but within `{ ... }' and `(* ... *)',
     also after `//' if `delphi-comments' is active, never within `/*
     ... */'.  Also mixed comments (`{ ... *)', `(* ... }') if enabled
     (`mixed-comments') and nested comments (e.g.  `{ ... { ... } ...
     }') if enabled (`nested-comments')

   * Macros and conditionals like `cpp' does, but both case sensitive
     and insensitive ones; `no-macros' to turn macro expansion off
     (e.g., for BP compatibility)

   * `ifopt' for short and long options

   * Include files like `cpp' does, but also with `{$I ...}' (BP
     style), which allows the file name extension to be omitted

   * Recognize Pascal strings (to avoid looking for comments and
     directives within strings) enclosed in single (like Standard
     Pascal) or double quotes (like C).

   * Option handling, sharing tables in `gpc-options.h' with the
     compiler:
        - Default option settings

        - Options can imply other options (e.g., `borland-pascal' ->
          `no-macros' etc.)

        - Short compiler directives

        - Short directive `W' (warnings) is disabled in
          `borland-pascal' and `delphi' because it has another meaning
          there

   * Compiler directives (`{$...}' or `(*$...*)'):
        - pass them through, so the compiler can handle them

        - keep track of them for `ifopt'

        - handle those that affect the preprocessor (e.g., about
          comments)

        - allow comments within compiler directives if nested comments
          are enabled

        - local directives

        - case insensitive

   * Slightly Pascal-like syntax for conditional compilation (`not' ->
     `!', `and' -> `&&', `or' -> `||', `xor' -> `!=', `shl' -> `<<',
     `shr' -> `>>', `False' -> `0', `True' -> `1', `<>' -> `!=', `=' ->
     `==')

   * Line directives like `cpp' does, but recognize BP style (`#42' or
     `#$f0') character constants and don't confuse them with line
     directives (the latter seem to always have a space after the `#')



File: gpc.info,  Node: Lexical analyzer,  Next: Syntax parsing,  Prev: Preprocessor,  Up: Internals

12.2 GPC's Lexical Analyzer
===========================

The source files `gpc-lex.c' and `pascal-lex.l' contain the so-called
_lexical analyzer_ of the GNU Pascal compiler.  The latter file is
processed with `flex' to produce `pascal-lex.c' which is not meant to
be read by a human, but compiled.

   This very first stage of the compiler is responsible for reading
what you have written and dividing it into _tokens_, the "atoms" of a
computer language. Here is, for example, where integer and real numbers
such as `42' and `3.14e-5', string constants, symbols, keywords and
identifiers etc. are recognized.

   The main entry point is the function `yylex' which calls the
flex-generated function `lexscan' which does the main work of token
separation.

* Menu:

* Lexer problems::
* BP character constants::
* Compiler directives internally::


File: gpc.info,  Node: Lexer problems,  Next: BP character constants,  Up: Lexical analyzer

12.2.1 Lexer problems
---------------------

Pascal is a language that's easy to lex and parse. Then came Borland ...

   A number of their ad-hoc syntax extensions cause lexing or parsing
problems, and even ambiguities. This lexer tries to solve them as well
as possible, sometimes with clever rules, other times with gross hacks
and with help from the parser. (And, BTW, it handles regular Pascal as
well. ;-)

   Some of the problems are (see also *note Parsing conflicts::):

   * Real constants with a trailing `.'. Problem: They make the
     character sequence `2.)' ambiguous. It could be interpreted as
     `2.0', followed by `)' or as `2' and `.)' (which is an alternative
     for `]'). This lexer chooses the latter interpretation, like BP
     does, and the standard requires. It would be possible to handle
     both, by keeping a stack of the currently open parentheses and
     brackets and chosing the matching closing one, but since BP does
     not do this, either, it doesn't seem worth the trouble. (Or maybe
     later ... ;-)

   * They also cause a little problem in the sequence `2..' (the start
     of an integer subrange), but this is easily solved by normal lexer
     look-ahead since a real constant can't be followed by a `.' in any
     Pascal dialect we know of.

   * Missing token separators between integer or real constants and a
     following keyword (e.g. `42to'). It gets worse with hex numbers
     (`$abcduntil'), but it's not really difficult to lex. However, we
     don't allow this with Extended Pascal non-decimal integer
     constants, e.g. `16#abcduntil' where it would be a little more
     difficult (because it would depend on the base whether or not `u'
     is a digit). Since BP does not even support EP non-decimal
     constants, there's no point in going to such troubles.

   * Character constants with `#'. They conflict with the Extended
     Pascal non-decimal integer number notation. `#13#10' could mean
     `Chr (13) + Chr (10)' or `Chr (13#10)'. This lexer chooses the
     former interpretation, since the latter one would be a mix of BP
     and Extended Pascal features.

   * Last (but not least - no, certainly worst): Character constants
     with `^' (was this "feature" meant as an AFJ or something???). GPC
     tries to make the best out of a stupid situation, see the next
     section (*note BP character constants::) for details.  It should
     be noted that BP itself fails in a number of situations involving
     such character constants, probably the clearest sign for a design
     bug.

   * But also GPC's extension `...' for variadic external function
     declarations causes a problem in the sequence `(...)' which could
     mean `(', `...', `)', i.e., a parameter list with only variadic
     arguments, or `(.', `.', `.)'.  Since the latter token sequence is
     meaningless in any Pascal dialect we know of, this lexer chooses
     the former one which is easily accomplished with normal look-ahead.


File: gpc.info,  Node: BP character constants,  Next: Compiler directives internally,  Prev: Lexer problems,  Up: Lexical analyzer

12.2.2 BP character constants
-----------------------------

Borland-style character constants of the form `^M' need special care.
For example look at the following type declaration:

     type
       X = Integer;
       Y = ^X;        { pointer type }
       Z = ^X .. ^Y;  { subrange type }

   One way one could attempt to resolve this is to let the parser tell
the lexer (via a global flag) whether a character constant or the
symbol `^' (to create pointer types or to dereference pointer
expressions) is suitable in the current context. This was done in
previous versions, but it had a number of disadvantages: First, any
dependency of the lexer on the parser (*note Lexical Tie-Ins:
(bison)Lexical Tie-Ins.) is problematic by itself since it must be
taken care of manually in each relevant parser rule. Furthermore, the
parser read-ahead must be taken into account, so the flag must usually
be changed apparently one token too early. Using GLR (*note GLR
Parsers: (bison)GLR Parsers.) makes this problem worse since it may
read many tokens while the parser is split before it can perform any
semantic action (which is where the flag could be modified). Secondly,
as the example above shows, there are contexts in which both meanings
are acceptable. So further look-ahead (within the lexer) was needed to
resolve the problem.

   Therefore, we now use another approach. When seeing `^X', the lexer
returns two tokens, a regular `^' and a special token
`LEX_CARET_LETTER' with semantic value `X'. The parser accepts
`LEX_CARET_LETTER' wherever an identifier is accepted, and turns it
into the identifier `X' via the nonterminal `caret_letter'.
Furthermore, it accepts the sequence `^', `LEX_CARET_LETTER' as a
string constant (whose value is a one-character string). Since
`LEX_CARET_LETTER' is only produced by the lexer immediately after `^',
with no white-space in between, this works (whereas otherwise, pasting
tokens in the parser is not reliable due to white-space, e.g. the token
sequence `:' and `=' could stand for `:=' (if `:=' weren't a token by
itself), but also for `: =' with a space in between). With this trick,
we can handle `^' followed by a single letter or underscore. The fact
that this doesn't cause any conflict in the grammar tell us that this
method works.

   However, BP even allows any other character after `^' as a char
constant. E.g., `^)' could be a pointer dereference after an expression
and followed by a closing parenthesis, or the character `i' (sic!).

   Some characters are unproblematic because they can never occur after
a `^' in its regular meaning, so the sequence can be lexed as a char
constant directly. These are all characters that are not part of any
Pascal tokens at all (which includes all control characters except
white-space, all non-ASCII characters and the characters `!', `&', `%',
`?', `\', ``', `|', `~' and `}' - the last one occurs at the end of
comments, but within a comment this issue doesn't occur, anyway) and
those characters that can only start constants because a constant can
never follow a `^' in Pascal; these are `#', `$', `'', `"' and the
digits.

   For `^' followed by whitespace, we return the token
`LEX_CARET_WHITE' which the parser accepts as either a string constant
or equivalent to `^' (because in the regular meaning, the white-space
is meaningless).

   If `^' is followed by one of the remaining characters (apart from
one, see below), namely `,', `.', `:', `;', `(', `)', `[', `]', `+',
`-', `*', `/', `<', `=', `>', `@', `^', the lexer just returns the
tokens regularly, and the parser accepts these sequences as a char
constant (besides the normal meaning of the tokens). (Again, since
white-space after `^' is already dealt with, this token pasting works
here.)

   But `^' can also be followed by a multi-character alphanumeric
sequence such as `^cto' which might be read as `^ cto' or `^c to'
(since BP also allows omitting white-space after constants), or by a
multi-character token such as `^<=' which could be `^ <=' or `^< ='.
Both could be solved with extra tokens, e.g. lexing `^<=' as `^',
`LEX_CARET_LESS', `=' and accepting `^', `LEX_CARET_LESS' in the parser
as a string constant and `LEX_CARET_LESS', `=' as equivalent to `<='
(relying on the fact that the lexer doesn't produce `LEX_CARET_LESS' if
there's white-space after the `<' because then the simple `^', `<' will
work, so justifying the token-pasting once again). This has not been
done yet (in the alphanumeric case, this might add a lot of special
tokens because of keywords etc., and it's doubtful whether that's worth
it).

   Finally, we have `^{' and `^(*'. This is so incredibly stupid (e.g.,
think of the construct `type c = Integer; foo = ^{ .. ^|; bar = {} c;'
which would become ambiguous then), that perhaps we should not attempt
to handle this ...

   (As a side-note, BP itself doesn't handle `^' character constants in
many situations, including many that GPC does handle with the
mechanisms described above, probably the clearest sign for a design
bug. But if we support them at all, we might just as well do it better
than BP ... :-)


File: gpc.info,  Node: Compiler directives internally,  Prev: BP character constants,  Up: Lexical analyzer

12.2.3 Compiler directives internally
-------------------------------------

Compiler directives are mostly handled in `options.c', mostly in common
with command-line options, using the definitions in `lang-options.h'
and the tables in `gpc-options.h'.

   A special problem is that the parser sometimes has to read tokens
before they're used to decide what to do next. LALR(1) parsers would
read at most one such token, but with GLR, the parser can split and
consume tokens while not doing any actions. The number of such tokens
is unbounded, though the relevant context can be determined by
analyzing the grammar.

   Reading look-ahead tokens is generally harmless, but if there is a
compiler directive before such a look-ahead token, it would be handled
apparently too early. This looks strange from the programmer's point of
view - even more so since the programmer cannot easily predict when the
parser needs to read ahead and when not, and therefore cannot be sure
where exactly to place the directive. This is particularly important
for local directives that are meant to have a scope as small as
possible.

   To solve this problem, GPC keeps those options that can be changed
by directives in a linked list of `struct options'. There are several
pointers into the list:

   `lexer_options' are the options current to the lexer. These are
always the ones read most recently. Compiler directives are applied
here when read. Each directive causes a new `struct options' to be
chained to the list.

   `compiler_options' points to the options current for the compiler,
i.e. seen before the last token handled in a parser rule.  To
facilitate this, we abuse Bison's location tracking feature (*note
Locations: (bison)Locations.) and refer to the options seen before a
token in the token's location (`yylloc'). Before each grammar rule is
handled, the compiler options are pointed to those of the last token
involved in the rules handled so far, using Bison's `YYLLOC_DEFAULT'
feature. Actual locations, used for error messages etc., are handled
the same way (according to the real purpose of Bison's location
tracking), also distinct for the lexer and compiler.

   _Please Note:_ Tokens are not always handled in order. E.g., in `2 +
3 * 4', first `3 * 4' is evaluated, then `2 + 12', i.e., the tokens `2'
and `+' are handled after the following ones. To avoid jumping back in
the options, we store a counter, rather than a pointer, in `yyloc', so
we can compare it to the current counter. This also allows us to free
any `struct options' that `compiler_options' has advanced beyond
because it can never go back.

   Finally, the pointer `co' points to the current options which is
`lexer_options' when we're in the lexer and `compiler_options'
otherwise. All routines that use or set options refer to `co', so there
is no problem when they may be called both from the lexer and from
other parts of the compiler.  (Previously, `lookup_name' was such a
routine, but now the lexer doesn't call it anymore.)

   _Please Note:_ Some of the options are flags declared in the
backend. Since we can't keep them in `struct option' directly, we have
to copy them back and forth in `activate_options'. This is a little
annoyance, but no real problem.


File: gpc.info,  Node: Syntax parsing,  Next: Tree nodes,  Prev: Lexical analyzer,  Up: Internals

12.3 Syntax parsing: GPC's Parser
=================================

The file `parse.y' contains the "bison" source code of GNU Pascal's
parser. This stage of the compilation analyzes and checks the syntax of
your Pascal program, and it generates an intermediate,
language-independent code which is then passed to the GNU back-end.

   The _bison_ language essentially is a machine-readable form of the
Backus-Naur Form, the symbolic notation of grammars of computer
languages. "Syntax diagrams" are a graphical variant of the Backus-Naur
Form.

   For details about the "bison" language, see the Bison manual (*note
Top: (bison)Top.). A short overview how to pick up some information you
might need for programming follows.

   Suppose you have forgotten how a variable is declared in Pascal.
After some searching in `parse.y' you have found the following:

     simple_decl_1:
         ...
       | p_var variable_declaration_list
           { [...] }
       ;

     variable_declaration_list:
         variable_declaration { }
       | variable_declaration_list variable_declaration
       ;

   Translated into English, this means: "A declaration can (amoung
other things like types and constants, omitted here) consist of the
keyword (lexical token) `var' followed by a `variable declaration
list'. A `variable declaration list' in turn consists of one or more
`variable declarations'." (The latter explanation requires that you
understand the recursive nature of the definition of
`variable_declaration_list'.)

   Now we can go on and search for `variable_declaration'.

     variable_declaration:
         id_list_limited ':' type_denoter_with_attributes
           { [...] }
         absolute_or_value_specification optional_variable_directive_list ';'
           { [...] }
       ;

   The `[...]' are placeholders for some C statements, the "semantic
actions" which (for the most part) aren't important for understanding
GPC's grammar.

   From this you can look up that a variable declaration in GNU Pascal
consists of an identifier list, followed by a colon, "type denoter with
attributes", an "absolute or value specification" and an "optional
variable directive list", terminated by a semicolon.  Some of these
parts are easy to understand, the others you can look up from
`parse.y'. Remember that the reserved word `var' precedes all this.

   Now you know how to get the exact grammar of the GNU Pascal language
from the source.

   The semantic actions, not shown above, are in some sense the most
important part of the bison source, because they are responsible for
the generation of the intermediate code of the GNU Pascal front-end,
the so-called _tree nodes_ (which are used to represent most things in
the compiler). For instance, the C code in "type denoter" returns
(assigns to `$$') information about the type in a variable of type
`tree'.

   The "variable declaration" gets this and other information in the
numbered arguments (`$1' etc.) and passes it to some C functions
declared in the other source files. Generally, those functions do the
real work, while the main job of the C statements in the parser is to
call them with the right arguments.

   This, the parser, is the place where it becomes Pascal.

* Menu:

* Parsing conflicts::  Conflicts in the Pascal syntax
* Parsing keywords::   So many keywords, so many problems ...
* forward near far::   `forward', `near' and `far' as weak keywords


File: gpc.info,  Node: Parsing conflicts,  Next: Parsing keywords,  Up: Syntax parsing

12.3.1 Conflicts in the Pascal syntax
-------------------------------------

Some problematic parts of Pascal syntax in various dialects (see also
*note Lexer problems::):

   * BP style initializers for variables (or "typed constants", as BP
     likes to call initialized variables even though they are not
     constant) with `=' rather than `value'. Problem: It makes
     initialized Boolean subrange variable declarations like `Foo:
     False .. True = False = False' ambiguous. They could be interpreted
     as `Foo: False .. (True = False) = False' or `Foo: False .. True =
     (False = False)'. This lexer, like BP, chooses the latter
     interpretation. To avoid conflicts in the parser, this is done with
     the `LEX_CONST_EQUAL' hack, counting parentheses and brackets so
     that in `Foo: False .. (True = False) = True' the *second* `='
     will become the LEX_CONST_EQUAL token.

   * BP style array initializers in `(', `)'. When they consist of a
     single entry (without an index as required in EP), they conflict
     with expressions in parentheses. This is resolved in the parser
     using GLR with `%dprec', and in the following processing of
     initializers.

   * Extended Pascal structured value constructors. The problem here is
     that identically looking constructs have different meaning:
     `foo[bar : baz]' may be a record or array constructor. Also
     `foo[bar]' may be an array access or a set constructor (and, as a
     Gnu extension also a record or array constructor). One problem is
     how to choose proper semantic action. Another is that the
     constucts involved (array access and record, array and set
     constructors) have different, but overlapping syntax. The problem
     is resolved using superset approach: the parser accepts anything
     resembling array access or a constructor and builds a tree
     representing its structure. Then semantic actions decide which
     construct is expected and verify that it is in fact well-formed
     (or report an error).

   * Extended Pascal (and many dialects) allow the lower bound of a
     subrange declaration to be an arbitrary expression (Standard Pascal
     allows only a plain constant). This makes things like `var Foo:
     (Bar ...' hard to parse, since `Bar' could be part of an
     expression in parentheses as the lower bound of a subrange, or the
     beginning of an enumeration type declaration. BP can't handle this
     situation. In GPC, this is now solved with the GLR parser. In fact,
     this case is rather easy to handle for GLR, as it does not even
     need `%dprec' or `%merge' since the presence or absence of `..'
     sooner or later makes one alternative fail.

   * Delphi's `external [LIBNAME] [name NAME]' construct where LIBNAME
     and NAME can be string expressions. Since `name' is not a reserved
     word, but an identifier, `external name name name' can be valid
     which is difficult to parse. It could be solved by the parser, by
     making `name' a special identifier whose special meaning is
     recognized after `external' only.


File: gpc.info,  Node: Parsing keywords,  Next: forward near far,  Prev: Parsing conflicts,  Up: Syntax parsing

12.3.2 So many keywords, so many problems ...
---------------------------------------------

Keywords can be potential problems since they are (generally) not
available for use as identifiers. Only those keywords that are defined
in ISO 7185 Pascal are unproblematic because no valid program should
ever use them as identifiers.

   To cope with this problem, GPC does several things:

   * If a dialect option is set, only keywords of the specified dialect
     are enabled. All possible keywords, together with their dialects,
     are defined in `predef.def'. However, compiling with dialect
     options is usually not recommended, so this is no good general
     solution.

   * The user can turn off individual keywords using the compiler
     directive `{$disable-keyword}'. This makes sure that every
     conflict with a user's identifier _can_ be avoided, but with extra
     work on the part of the user.

   * The parser used to enable and disable keywords in certain syntactic
     contexts. However, this was rather fragile since it interacts with
     the parser's read-ahead, and it requires attention on every related
     change in the parser. Therefore, this mechanism was removed.

   * All non-ISO-7185 keywords are now treated as "weak". This means,
     they are only recognized as keywords if no current declaration of
     this name exists. However, so that this can work, it must be
     possible to create new declarations of this name in the first place
     - at this point, no declaration exists yet, so the name is
     recognized as a keyword.

     This is solved by listing these keywords in the `new_identifier'
     rule of the parser. This means, first the lexer recognizes them as
     keywords, then the parser "turns them back" into identifiers. The
     advantage, compared to explicit enabling and disabling of
     keywords, is that bison automatically finds the places in which to
     apply the `new_identifier' rule, i.e. treat them as plain
     identifiers.

     Of course, there is a catch. Since the keyword tokens are listed in
     `new_identifier', they can conflict with occurrences of the actual
     keywords (bison will find such cases as S/R or R/R conflicts).
     Such conflicts have to be sorted out carefully and either removed
     or left to GLR handling. Fortunately, for many keywords, removing
     the conflicts turned out quite easy - in some cases no conflicts
     arose at all.


File: gpc.info,  Node: forward near far,  Prev: Parsing keywords,  Up: Syntax parsing

12.3.3 `forward', `near' and `far' as weak keywords
---------------------------------------------------

`forward' is a little special in ISO 7185 in that it is no keyword, so
it may be used as an identifier and a directive at the same time.
That's more than what our weak keywords allow.

   This problem would be easy to solve if we just parsed it as a plain
identifier (`LEX_ID') and then check that it was in fact `forward'.

   However, the same applies to the BP directives `near' and `far'. (At
least so it seems - the BP documentation claims they're reserved words,
but the compiler seems to think otherwise.)

   Parsing all the three together as an identifier and then checking
which one it was fails because `forward' is a remote directive, i.e. a
routine declared so has no body, while `near' and `far' are not. So it
makes a syntactical difference for what follows.

   So we lex the three like regular (non-weak) keywords, but throw
their tokens together with `LEX_ID' very early in the parser, in the
`id' rule which is used everywhere an existing identifier is expected.
But in the context of these three directives, no identifier is allowed,
so the three tokens can be used without conflicts between each other or
with `id'.


File: gpc.info,  Node: Tree nodes,  Next: Parameter passing,  Prev: Syntax parsing,  Up: Internals

12.4 Tree Nodes
===============

If you want really to understand how the GNU Pascal language front-end
works internally and perhaps want to improve the compiler, it is
important that you understand GPC's internal data structures.

   The data structure used by the language front-end to hold all
information about your Pascal program are the so-called "tree nodes".
(Well, it needn't be Pascal source - tree nodes are language
independent.) The tree nodes are kind of objects, connected to each
other via pointers. Since the GNU compiler is written in C and was
created at a time where nobody really thought about object-oriented
programming languages yet, a lot of effort has been taken to create
these "objects" in C.

   Here is an extract from the "object hierarchy". Omissions are marked
with "..."; nodes in parentheses are "abstract": They are never
instantiated and aren't really defined. They only appear here to
clarify the structure of the tree node hierarchy. The complete list is
in `../tree.def'; additional information can be found in `../tree.h'.

     (tree_node)
     |
     |--- ERROR_MARK  { enables GPC to continue after an error }
     |
     |--- (identifier)
     |    |
     |    |--- IDENTIFIER_NODE
     |    |
     |    \--- OP_IDENTIFIER
     |
     |--- TREE_LIST  { a list of nodes, also used as a
     |                  general-purpose "container object" }
     |
     |--- TREE_VEC
     |
     |--- BLOCK
     |
     |--- (type)  { information about types }
     |    |
     |    |--- VOID_TYPE
     |    |
     |    |--- INTEGER_TYPE
     |   ...
     |    |
     |    |--- RECORD_TYPE
     |    |
     |    |--- FUNCTION_TYPE
     |    |
     |    \--- LANG_TYPE  { for language-specific extensions }
     |
     |--- INTEGER_CST  { an integer constant }
     |
     |--- REAL_CST
     |
     |--- STRING_CST
     |
     |--- COMPLEX_CST
     |
     |--- (declaration)
     |    |
     |    |--- FUNCTION_DECL
     |   ...
     |    |
     |    |--- TYPE_DECL
     |    |
     |    \--- VAR_DECL
     |
     |--- (reference)
     |    |
     |    |--- COMPONENT_REF
     |   ...
     |    |
     |    \--- ARRAY_REF
     |
     |--- CONSTRUCTOR
     |
     \--- (expression)
          |
          |--- MODIFY_EXPR  { assignment }
          |
          |--- PLUS_EXPR  { addition }
         ...
          |
          |--- CALL_EXPR  { procedure/function call }
          |
          |--- GOTO_EXPR
          |
          \--- LOOP_EXPR  { for all loops }

   Most of these tree nodes - struct variables in fact - contain
pointers to other tree nodes. A `TREE_LIST' for instance has a
`TREE_VALUE' and a `TREE_PURPOSE' slot which can contain arbitrary
data; a third pointer `TREE_CHAIN' points to the next `TREE_LIST' node
and thus allows us to create linked lists of tree nodes.

   One example: When GPC reads the list of identifiers in a variable
declaration

     var
       Foo, Bar, Baz: Integer;

   the parser creates a chain of `TREE_LIST's whose `TREE_VALUE's hold
`IDENTIFIER_NODE's for the identifiers `Foo', `Bar', and `Baz'. The
function `declare_variables()' (declared in `declarations.c') gets this
tree list as a parameter, does some magic, and finally passes a chain
of `VAR_DECL' nodes to the back-end.

   The `VAR_DECL' nodes in turn have a pointer `TREE_TYPE' which holds
a `_TYPE' node - an `INTEGER_TYPE' node in the example above. Having
this, GPC can do type-checking when a variable is referenced.

   For another example, let's look at the following statement:

     Baz := Foo + Bar;

   Here the parser creates a `MODIFY_EXPR' tree node. This node has two
pointers, `TREE_OPERAND[0]' which holds a representation of `Baz', a
`VAR_DECL' node, and `TREE_OPERAND[1]' which holds a representation of
the sum `Foo + Bar'. The sum in turn is represented as a `PLUS_EXPR'
tree node whose `TREE_OPERAND[0]' is the `VAR_DECL' node `Foo', and
whose `TREE_OPERAND[1]' is the `VAR_DECL' node `Bar'. Passing this (the
`MODIFY_EXPR' node) to the back-end results in assembler code for the
assignment.

   If you want to have a closer look at these tree nodes, write a line
`{$debug-tree FooBar}' into your program with `FooBar' being some
identifier in your program. This tells GPC to output the contents of
the `IDENTIFIER_NODE' to the standard error file handle in
human-readable form.

   While hacking and debugging GPC, you will also wish to have a look
at these tree nodes in other cases. Use the `debug_tree()' function to
do so. (In fact `{$debug-tree FooBar}' does nothing else than to
`debug_tree()' the `IDENTIFIER_NODE' of the `Foobar' identifier node -
note the capitalization of the first character in the internal
representation.)


File: gpc.info,  Node: Parameter passing,  Next: GPI files,  Prev: Tree nodes,  Up: Internals

12.5 Parameter Passing
======================

GPC supports a lot of funny things in parameter lists: value and
reference, `protected' and `const' parameters, strings and other
schemata with specified or unspecified discriminants, conformant and
open arrays, objects, procedural parameters, untyped reference
parameters, etc. All this requires sophisticated type-checking; the
responsible function is `convert_arguments()' in the source file
`typecheck.c'.  Every detail can be looked up from there.

   Some short notes about the most interesting cases follow.

*Conformant arrays:*
     First, the array bounds are passed (an even number of parameters of
     an ordinal type), then the address(es) of the array(s) themselves.

*Procedural parameters:*
     These need special care because a function passed as a parameter
     can be confused with a call to the function whose result is then
     passed as a parameter. See also the functions
     `maybe_call_function()' and `probably_call_function()' in
     `expressions.c'.

*Chars:*
     According to ISO 10206 Extended Pascal, formal char parameters
     accept string values. GPC does the necessary conversion implicitly.
     The empty string produces a space.

*Strings and schemata:*
     Value parameter strings and schemata of known size are really
     passed by value. Value parameter strings and schemata of unknown
     size are passed by reference, and GPC creates temporary variable
     to hold a copy of the string.

*`CString' parameters:*
     GPC implicitly converts any string value such that the address of
     the actual string data is passed and appends a `Chr (0)'
     terminator when necessary.

*`const' parameters:*
     If a constant value is passed to a `const' parameter, GPC assigns
     the value to a temporary variable whose address is passed.
     Exception: Small types (whose size is known and not bigger than
     that of a pointer) as well as all integer, real and complex types
     are passed by value.

*Untyped parameters:*
     These are denoted by `var foo' or `var foo: Void' and are
     compatible to C's `void *' parameters; the size of such entities
     is _not_ passed. Maybe we will change this in the future and pass
     the size for `var foo' parameters whereas `var foo: Void' will
     remain compatible to C. (Same with `const' instead of `var'.)



File: gpc.info,  Node: GPI files,  Next: Automake,  Prev: Parameter passing,  Up: Internals

12.6 GPI files - GNU Pascal Interfaces
======================================

This section documents the mechanism how GPC transfers information from
the exporting modules and units to the program, module or unit which
imports (uses) the information.

   A GPI file contains a precompiled GNU Pascal interface.
"Precompiled" means in this context that the interface already has been
parsed (i.e. the front-end has done its work), but that no assembler
output has been produced yet.

   The GPI file format is an implementation-dependent (but not _too_
implementation-dependent ;-) file format for storing GNU Pascal
interfaces to be exported - Extended Pascal and PXSC module interfaces
as well as interface parts of UCSD/Borland Pascal units compiled with
GNU Pascal.

   To see what information is stored in or loaded from a GPI file, run
GPC with an additional command-line option `--debug-gpi'. Then, GPC
will write a human-readable version of what is being stored/loaded to
the standard error file handle. (See also: *Note Tree nodes::.) *Please
note:* This will usually produce _huge_ amounts of output!

   While parsing an interface, GPC stores the names of exported objects
in tree lists - look for `handle_autoexport' in the GPC source files.
At the end of the interface, everything is stored in one or more GPI
files. This is done in `module.c'. There you can find the source of
`create_gpi_files()' which documents the file format:

   First, a header of 33 bytes containing the string `GNU Pascal
unit/module interface' plus a newline.

   This is followed by an integer containing the "magic" value 12345678
(hexadecimal) to carry information about the endianness.  Note that,
though a single GPI file is always specific to a particular target
architecture, the host architecture (i.e., the system on which GPC
runs) can be different (cross-compilers).  Currently, GPC is not able
to convert endianness in GPI files "on the fly", but at least it will
detect and reject GPI files with the "wrong" endianness. When writing
GPI files, always the host's endianness is used (this seems to be a
good idea even when converting on the fly will be supported in the
future, since most often, GPI files created by a cross-compiler will be
read again by the same cross-compiler). "Integer" here and in the
following paragraphs means a `gpi_int' (which is currently defined as
`HOST_WIDE_INT').

   The rest of the GPI file consists of chunks. Each chunk starts with
a one-byte code that describes the type of the chunk. It is followed by
an integer that specifies the size of the chunk (excluding this chunk
header). The further contents depend on the type, as listed below.

   For the numeric values of the chunk type codes, please refer to
`GPI_CHUNKS' in `module.c'. Chunk types denoted with `(*)' must occur
exactly once in a GPI file. Other types may occur any number of times
(including zero times). The order of chunks is arbitrary. "String" here
simply means a character sequence whose length is the chunk's length
(so no terminator is needed).

`GPI_CHUNK_VERSION' (String) (*)
     The version of the GPI file which is the same as the GPC version.
     If `USE_GPI_DEBUG_KEY' is used (which will insert a "magic" value
     at the beginning of each node in the node table, see below, so
     errors in GPI files will be detected more reliably), ` D' is
     appended to this version string. (Currently, `USE_GPI_DEBUG_KEY'
     is used by default.) Furthermore, the GCC backend version is
     appended, since it also influences GPI files.

`GPI_CHUNK_TARGET' (String) (*)
     The target system the GPI file was compiled for.

`GPI_CHUNK_MODULE_NAME' (String) (*)
     The name of the unit/module.

`GPI_CHUNK_SRCFILE' (String) (*)
     The name of the primary source file of the unit/module.

`GPI_CHUNK_IMPORT'
     The name of an interface imported by the current interface. This
     chunk consists of a string followed by the checksum of the imported
     interface's nodes, so the chunk length is the length of the string
     plus the size of an integer. Again, no terminator of the string is
     needed.

     The checksum is currently a simple function of the contents of the
     `GPI_CHUNK_NODES' chunk's contents (see below). This might be
     replaced in the future by a MD5 hash or something else more
     elaborate.

`GPI_CHUNK_LINK' (String)
     The name of a file to link.

`GPI_CHUNK_LIB' (String)
     The name of a library to link (prefixed with `-l').

`GPI_CHUNK_INITIALIZER' (String)
     The name of a module initializer. For technical reasons, any such
     chunk must come _after_ the `GPI_CHUNK_MODULE_NAME' chunk.

`GPI_CHUNK_GPC_MAIN_NAME' (String)
     A `gpc-main' option given in this interface. (More than one
     occurrence is pointless.)

`GPI_CHUNK_NODES' (*)
     The exported names and the objects (i.e., constants, data types,
     variables and routines) they refer to are internally represented as
     so-called _tree nodes_ as defined in the files `../tree.h' and
     `../tree.def' from the GNU compiler back-end. (See also: *Note
     Tree nodes::.)

     The main problem when storing tree nodes is that they form a
     complicated structure in memory with a lot of circular references
     (actually, not a tree, but a directed graph in the usual
     terminology, so the name "tree nodes" is actually a misnomer), so
     the storing mechanism must make sure that nothing is stored
     multiple times.

     The functions `load_node()' and `store_node_fields()' do the main
     work of loading/storing the contents of a tree node with
     references to all its contained pointers in a GPI file. Each tree
     node has a `TREE_CODE' indicating what kind of information it
     contains. Each kind of tree nodes must be stored in a different way
     which is not described here. See the source of these functions for
     details.

     As most tree nodes contain pointers to other tree nodes,
     `load_node()' is an (indirectly) recursive function. Since this
     recursion can be circular (think of a record containing a pointer
     to a record of the same type), we must resolve references to tree
     nodes which already have been loaded. For this reason, all tree
     nodes being loaded are kept in a table (`rb.nodes'). They are
     entered there _before_ all their fields have been loaded (because
     loading them is what causes the recursion). So the table contains
     some incomplete nodes during loading, but at the end of loading a
     GPI file, they have all been completed.

     On the other hand, for `store_node_fields()' the (seeming)
     recursion must be resolved to an iterative process so that the
     single tree nodes are stored one after another in the file, and not
     mixed together. This is the job of `store_tree()'. It uses a hash
     table (see `get_node_id()') for efficiency.

     When re-exporting (directly or indirectly) a node that was imported
     from another interface, and a later compiler run imports both
     interfaces, it must merge the corresponding nodes loaded from both
     interfaces. Otherwise it would get only similar, but not identical
     items. However, we cannot simply omit the re-exported nodes from
     the new interface in case a later compiler run imports only one of
     them.  The same problem occurs when a module exports several
     interfaces. In this case, a program that imports more than one of
     them must recognize their contents as identical where they overlap.

     Therefore, each node in a GPI file is prefixed (immediately before
     its tree code) with information about the interface it was
     originally imported from or stored in first. This information is
     represented as a reference to an `INTERFACE_NAME_NODE' followed by
     the id (as an integer) of the node in that interface. If the node
     is imported again and re-re-exported, this information is copied
     unchanged, so it will always refer to the interface the node was
     originally contained it. For nodes that appear in an interface for
     the first time (the normal case), a single 0 integer is stored
     instead of interface `INTERFACE_NAME_NODE' and id (for shortness,
     since this information is implicit).

     This mechanism is not applied to `INTERFACE_NAME_NODE's since
     there would be a problem when the identifier they represent is the
     name of the interface they come from; neither to
     `IDENTIFIER_NODE's because they are handled somewhat specially by
     the backend (e.g., they contain fields like `IDENTIFIER_VALUE'
     which depend on the currently active declarations, so storing and
     loading them in GPI files would be wrong) because there is only
     one `IDENTIFIER_NODE' ever made for any particular name. But for
     the same reason, it is no problem that the mechanism can't be
     applied to them.

     `INTERFACE_NAME_NODE's are a special kind of tree nodes, only used
     for this purpose. They contain the name of the interface, the name
     of the module (to detect the unlikely case that different modules
     have interfaces of the same name which otherwise might confuse
     GPC), and the checksum of that interface. The latter may seem
     redundant with the checksum stored in the `GPI_CHUNK_IMPORT'
     chunk, but in fact it is not. On the one hand, `GPI_CHUNK_IMPORT'
     chunks occur only for interfaces imported directly, while the
     `INTERFACE_NAME_NODE' mechanism might also refer to interfaces
     imported indirectly. On the other hand, storing the checksum in
     the `GPI_CHUNK_IMPORT' chunks allows the import mechanism to
     detect discrepancies and refuse to load inconsistent interfaces,
     whereas during the handling of the `GPI_CHUNK_NODES' chunk, the
     imported modules must already have been loaded. (It would be
     possible to scan the `GPI_CHUNK_NODES' chunk while deciding
     whether to recompile, but that would be a lot of extra effort,
     compared to storing the checksum in the `GPI_CHUNK_IMPORT' chunks.)

     Finally, at the end of the `GPI_CHUNK_NODES' chunk, a checksum of
     its own contents (excluding the checksum itself, of course) is
     appended. This is to detect corrupted GPI files and is independent
     of the other uses of checksums.

`GPI_CHUNK_OFFSETS' (*)
     An offset table for the tree nodes. Each node in a GPI file is
     assigned a unique id (which is stored as an integer wherever nodes
     refer to other nodes). There are some special tree nodes (e.g.,
     `integer_type_node' or `NULL_TREE') which are used very often and
     have fixed meanings. They have been assigned predefined ids, so
     they don't have to be stored in the GPI file at all. Their number
     and values are fixed (but may change between different GPC
     versions), see `SPECIAL_NODES' in `module.c'.

     For the remaining nodes, the `GPI_CHUNK_OFFSETS' table contains
     the file offsets as integers where they are stored within the
     (only) `GPI_CHUNK_NODES' chunk. The offsets are relative to the
     start of that chunk, i.e. after the chunk header. After the table
     (but still in this chunk) the id of the main node which contains
     the list of all exported names is stored as an integer.
     (Currently, this is always the last node, but for the file format
     definition, this is not guaranteed.)

`GPI_CHUNK_IMPLEMENTATION'
     This chunk contains no data (i.e., its size must be 0). Its only
     purpose is to signal that the module implementation or the
     implementation part of the unit has been compiled. (Stored, but not
     used currently.)

   That's it. Now you should be able to "read" GPI files using GPC's
`--debug-gpi' option. There is also a utility `gpidump' (built and
installed with GPC, source code in the `utils' directory) to decode and
show the contents of GPI files. It does also some amount of integrity
checking (a little more than GPC does while loading GPI files), so if
you suspect a problem with GPI files, you might want to run `gpidump'
on them, discarding its standard output (it writes all error reports to
standard error, of course).

   If you encounter a case where the loaded information differs too
much from the stored information, you have found a bug -
congratulations! What "too much" means, depends on the object being
stored in or loaded from the GPI file. Remember that the order things
are loaded from a GPI file is the _reversed_ order things are stored
when considering _different_ recursion levels, but the _same_ order
when considering the _same_ recursion level. (This is important when
using `--debug-gpi'; with `gpidump' you can read the file in any order
you like.)


File: gpc.info,  Node: Automake,  Next: File Layout,  Prev: GPI files,  Up: Internals

12.7 GPC's Automake Mechanism - How it Works
============================================

When a program/module/unit imports (uses) an interface, GPC searches
for the GPI file (see *Note GPI files::) derived from the name of the
interface.

   Case 1: A GPI file was found.

   Each GPI file contains the name of the primary source file (normally
a `.pas' or `.p' file) of the module/unit, and the names of all
interfaces imported. GPC reads this information and invokes itself with
a command like

     gpc foo.pas -M -o foo.d

   This means: preprocess the file, and write down the name of the
object file and those of all its source files in `foo.d'. GPC reads
`foo.d' and looks if the object file exists and if the source was
modified since the creation of the object file and the gpi file. If so,
GPC calls itself again to compile the primary source file. When
everything is done, the `.d' file is removed.  If there was no need to
recompile, all interfaces imported by the module/unit are processed in
the same way as this one.

   Case 2: No GPI file was found.

   In this case, GPC derives the name of the source file from that of
the interface by trying first `interface.p', then `interface.pas'. This
will almost always work with UCSD/Borland Pascal units, but not always
with Extended Pascal modules. The programmer can override this
assumption using `uses ... in' or `import ... in'.

   All this is done by the function `gpi_open()' which uses some
auxiliary functions such as `module_must_be_recompiled()' and
`compile_module()'.

   Each time an object file is compiled or recognized as being
up-to-date, its name is stored in a temporary file with the same base
name as all the other temporary files used by GPC but the extension
`.gpc'. When the top-level `gpc' is invoked (which calls `gpc1' later
on), it passes the name of this temporary file as an additional command
line parameter to `gpc1'. After compilation has been completed, the
top-level `gpc' reads the temporary file and adds the new object files
to the arguments passed to the linker.

   The additional command `--amtmpfile' (not to be specified by the
user!) is passed to child GPC processes, so all compiles use the same
temporary file.

   The source for this is merely in `module.c', but there are also some
hacks in `gpc.c', additional command line options in `lang-options.h'
and `options.c', and `gpc.h' contains declarations for the functions
and global variables.


File: gpc.info,  Node: File Layout,  Next: Planned,  Prev: Automake,  Up: Internals

12.8 Files that make up GPC
===========================

The GNU back end (gbe) is used to convert RTL into assembler code.  It
is supposed to be language independent. Files are in the `..' directory
(i.e., the directory called `gcc'). It also uses files in the
`../config' subdirectories etc.

   Unfortunately, some of them are not completely language independent
and need patching for GPC. These patches (against all supported GCC
versions) are in the `diffs' subdirectory.

   The Pascal language implementation files are in the directory called
`p'. Some of them were written from scratch. Others are hacked from GCC
sources. Their roots, if any, are mentioned in the comment at their top.


File: gpc.info,  Node: Planned,  Prev: File Layout,  Up: Internals

12.9 Planned features
=====================

AnyStrings
----------

     GetCapacity (s):
       LongString            : s.Capacity
       UndiscriminatedString : MaxInt
       ShortString           : High (s)
       FixedString           : High (s) - Low (s) + 1
       CString (Array)       : High (s) - Low (s)
       CString (Zeiger)      : strlen (s)
       ObjectString          : s.GetCapacity

     GetLength (s):
       LongString            : s.Length
       UndiscriminatedString : s.Length
       ShortString           : Ord (s[0])
       FixedString           : c := High (s);
                               while (c >= Low (s)) and (s[c] = ' ') do
                                 Dec (c);
                               c - Low (s) + 1
       CString               : strlen (s)
       ObjectString          : s.GetLength

     SetLength (s,n):
       if n > GetCapacity (s) then
         if TruncateFlag then
           n := GetCapacity (s)
         else
           Error;
       LongString            : s.Length := n
       UndiscriminatedString : if n > s.Capacity then
                                 begin
                                   tmp := @s;
                                   { possibly round n up to m * 2^k
                                     to avoid frequent reallocations }
                                   New (@s, n);
                                   Move (tmp^[1], s[1], Length (tmp^);
                                   Dispose (tmp)
                                 end;
                               s.Length := n
       ShortString           : s[0] := Chr (n)
       FixedString           : FillChar (s[Low (s) + n],
                                 GetCapacity (s) - n, ' ')
       CString               : s[n] := #0
       ObjectString          : s.SetLength (n)

     GetFirstChar (s):
       LongString            : @s[1]
       UndiscriminatedString : @s[1]
       ShortString           : @s[1]
       FixedString           : @s[Low (s)]
       CString               : s
       ObjectString          : s.GetFirstChar

   Anything else can be reduced to these, e.g. string assignment:

     SetLength (Dest, GetLength (Src));
     Move (GetFirstChar (Src) ^, GetFirstChar (Dest) ^, GetLength (Dest));
                                                                   ^^^^
                                                    (because of truncate!)

   Note pointer CStrings because assignments to them (from long,
undiscriminated (with appending #0) or CStrings, not from short, fixed
or object strings) should set the pointer, not overwrite the memory
pointed to.

Fully automatic C header translator
-----------------------------------

   * C operators like `+=' (increment a variable and return the new
     value), or `/' (integer or real division, depending on the
     arguments). They could be emulated by special built-in functions
     in GPC which do the same ...

   * Types! C doesn't distinguish between pointers and arrays - and
     various other "jokes". E.g., a `CString' and a pointer to an array
     of bytes can both be `char *' in C. Solutions could be to
     introduce "special types" in GPC which behave like the C types
     (not so nice ...)-:, or to let the translator choose one possible
     matching GPC type (by some heuristics perhaps), and leave it up to
     the user to type-cast when necessary (also not nice)-: ...

   * Name clashes. How to map `foo', `FOO', `struct foo', `union foo'
     etc. (which can potentially be totally different things in C) to
     Pascal identifiers in a reasonable way.  Also, how to introduce
     identifiers for types when needed (e.g., typed used in parameter
     lists). Of course, that's solvable ...

   * Macros. Since GPC has a preprocessor, we can translate most of
     them, but some particularly strange ones are virtually impossible
     to translate. But there's hope that such strange macros are not
     being used in the libraries' headers ...

   * ...



File: gpc.info,  Node: Copying,  Next: Library Copying,  Prev: Internals,  Up: Top

Appendix A GNU GENERAL PUBLIC LICENSE
*************************************

                         Version 2, June 1991

     Copyright (C) 1989, 1991 Free Software Foundation, Inc.
     59 Temple Place - Suite 330, Boston, MA 02111-1307, USA

     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.

GPL Preamble
============

The licenses for most software are designed to take away your freedom
to share and change it.  By contrast, the GNU General Public License is
intended to guarantee your freedom to share and change free software -
to make sure the software is free for all its users.  This General
Public License applies to most of the Free Software Foundation's
software and to any other program whose authors commit to using it.
(Some other Free Software Foundation software is covered by the GNU
Lesser General Public License instead.)  You can apply it to your
programs, too.

   When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it in
new free programs; and that you know you can do these things.

   To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.

   For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have.  You must make sure that they, too, receive or can get the
source code.  And you must show them these terms so they know their
rights.

   We protect your rights with two steps: (1) copyright the software,
and (2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.

   Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software.  If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors' reputations.

   Finally, any free program is threatened constantly by software
patents.  We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary.  To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.

   The precise terms and conditions for copying, distribution and
modification follow.

    TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
  0. This License applies to any program or other work which contains a
     notice placed by the copyright holder saying it may be distributed
     under the terms of this General Public License.  The "Program",
     below, refers to any such program or work, and a "work based on
     the Program" means either the Program or any derivative work under
     copyright law: that is to say, a work containing the Program or a
     portion of it, either verbatim or with modifications and/or
     translated into another language.  (Hereinafter, translation is
     included without limitation in the term "modification".)  Each
     licensee is addressed as "you".

     Activities other than copying, distribution and modification are
     not covered by this License; they are outside its scope.  The act
     of running the Program is not restricted, and the output from the
     Program is covered only if its contents constitute a work based on
     the Program (independent of having been made by running the
     Program).  Whether that is true depends on what the Program does.

  1. You may copy and distribute verbatim copies of the Program's
     source code as you receive it, in any medium, provided that you
     conspicuously and appropriately publish on each copy an appropriate
     copyright notice and disclaimer of warranty; keep intact all the
     notices that refer to this License and to the absence of any
     warranty; and give any other recipients of the Program a copy of
     this License along with the Program.

     You may charge a fee for the physical act of transferring a copy,
     and you may at your option offer warranty protection in exchange
     for a fee.

  2. You may modify your copy or copies of the Program or any portion
     of it, thus forming a work based on the Program, and copy and
     distribute such modifications or work under the terms of Section 1
     above, provided that you also meet all of these conditions:

       a. You must cause the modified files to carry prominent notices
          stating that you changed the files and the date of any change.

       b. You must cause any work that you distribute or publish, that
          in whole or in part contains or is derived from the Program
          or any part thereof, to be licensed as a whole at no charge
          to all third parties under the terms of this License.

       c. If the modified program normally reads commands interactively
          when run, you must cause it, when started running for such
          interactive use in the most ordinary way, to print or display
          an announcement including an appropriate copyright notice and
          a notice that there is no warranty (or else, saying that you
          provide a warranty) and that users may redistribute the
          program under these conditions, and telling the user how to
          view a copy of this License.  (Exception: if the Program
          itself is interactive but does not normally print such an
          announcement, your work based on the Program is not required
          to print an announcement.)

     These requirements apply to the modified work as a whole.  If
     identifiable sections of that work are not derived from the
     Program, and can be reasonably considered independent and separate
     works in themselves, then this License, and its terms, do not
     apply to those sections when you distribute them as separate
     works.  But when you distribute the same sections as part of a
     whole which is a work based on the Program, the distribution of
     the whole must be on the terms of this License, whose permissions
     for other licensees extend to the entire whole, and thus to each
     and every part regardless of who wrote it.

     Thus, it is not the intent of this section to claim rights or
     contest your rights to work written entirely by you; rather, the
     intent is to exercise the right to control the distribution of
     derivative or collective works based on the Program.

     In addition, mere aggregation of another work not based on the
     Program with the Program (or with a work based on the Program) on
     a volume of a storage or distribution medium does not bring the
     other work under the scope of this License.

  3. You may copy and distribute the Program (or a work based on it,
     under Section 2) in object code or executable form under the terms
     of Sections 1 and 2 above provided that you also do one of the
     following:

       a. Accompany it with the complete corresponding machine-readable
          source code, which must be distributed under the terms of
          Sections 1 and 2 above on a medium customarily used for
          software interchange; or,

       b. Accompany it with a written offer, valid for at least three
          years, to give any third party, for a charge no more than your
          cost of physically performing source distribution, a complete
          machine-readable copy of the corresponding source code, to be
          distributed under the terms of Sections 1 and 2 above on a
          medium customarily used for software interchange; or,

       c. Accompany it with the information you received as to the offer
          to distribute corresponding source code.  (This alternative is
          allowed only for noncommercial distribution and only if you
          received the program in object code or executable form with
          such an offer, in accord with Subsection b above.)

     The source code for a work means the preferred form of the work for
     making modifications to it.  For an executable work, complete
     source code means all the source code for all modules it contains,
     plus any associated interface definition files, plus the scripts
     used to control compilation and installation of the executable.
     However, as a special exception, the source code distributed need
     not include anything that is normally distributed (in either
     source or binary form) with the major components (compiler,
     kernel, and so on) of the operating system on which the executable
     runs, unless that component itself accompanies the executable.

     If distribution of executable or object code is made by offering
     access to copy from a designated place, then offering equivalent
     access to copy the source code from the same place counts as
     distribution of the source code, even though third parties are not
     compelled to copy the source along with the object code.

  4. You may not copy, modify, sublicense, or distribute the Program
     except as expressly provided under this License.  Any attempt
     otherwise to copy, modify, sublicense or distribute the Program is
     void, and will automatically terminate your rights under this
     License.  However, parties who have received copies, or rights,
     from you under this License will not have their licenses
     terminated so long as such parties remain in full compliance.

  5. You are not required to accept this License, since you have not
     signed it.  However, nothing else grants you permission to modify
     or distribute the Program or its derivative works.  These actions
     are prohibited by law if you do not accept this License.
     Therefore, by modifying or distributing the Program (or any work
     based on the Program), you indicate your acceptance of this
     License to do so, and all its terms and conditions for copying,
     distributing or modifying the Program or works based on it.

  6. Each time you redistribute the Program (or any work based on the
     Program), the recipient automatically receives a license from the
     original licensor to copy, distribute or modify the Program
     subject to these terms and conditions.  You may not impose any
     further restrictions on the recipients' exercise of the rights
     granted herein.  You are not responsible for enforcing compliance
     by third parties to this License.

  7. If, as a consequence of a court judgment or allegation of patent
     infringement or for any other reason (not limited to patent
     issues), conditions are imposed on you (whether by court order,
     agreement or otherwise) that contradict the conditions of this
     License, they do not excuse you from the conditions of this
     License.  If you cannot distribute so as to satisfy simultaneously
     your obligations under this License and any other pertinent
     obligations, then as a consequence you may not distribute the
     Program at all.  For example, if a patent license would not permit
     royalty-free redistribution of the Program by all those who
     receive copies directly or indirectly through you, then the only
     way you could satisfy both it and this License would be to refrain
     entirely from distribution of the Program.

     If any portion of this section is held invalid or unenforceable
     under any particular circumstance, the balance of the section is
     intended to apply and the section as a whole is intended to apply
     in other circumstances.

     It is not the purpose of this section to induce you to infringe any
     patents or other property right claims or to contest validity of
     any such claims; this section has the sole purpose of protecting
     the integrity of the free software distribution system, which is
     implemented by public license practices.  Many people have made
     generous contributions to the wide range of software distributed
     through that system in reliance on consistent application of that
     system; it is up to the author/donor to decide if he or she is
     willing to distribute software through any other system and a
     licensee cannot impose that choice.

     This section is intended to make thoroughly clear what is believed
     to be a consequence of the rest of this License.

  8. If the distribution and/or use of the Program is restricted in
     certain countries either by patents or by copyrighted interfaces,
     the original copyright holder who places the Program under this
     License may add an explicit geographical distribution limitation
     excluding those countries, so that distribution is permitted only
     in or among countries not thus excluded.  In such case, this
     License incorporates the limitation as if written in the body of
     this License.

  9. The Free Software Foundation may publish revised and/or new
     versions of the General Public License from time to time.  Such
     new versions will be similar in spirit to the present version, but
     may differ in detail to address new problems or concerns.

     Each version is given a distinguishing version number.  If the
     Program specifies a version number of this License which applies
     to it and "any later version", you have the option of following
     the terms and conditions either of that version or of any later
     version published by the Free Software Foundation.  If the Program
     does not specify a version number of this License, you may choose
     any version ever published by the Free Software Foundation.

 10. If you wish to incorporate parts of the Program into other free
     programs whose distribution conditions are different, write to the
     author to ask for permission.  For software which is copyrighted
     by the Free Software Foundation, write to the Free Software
     Foundation; we sometimes make exceptions for this.  Our decision
     will be guided by the two goals of preserving the free status of
     all derivatives of our free software and of promoting the sharing
     and reuse of software generally.

                                NO WARRANTY
 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
     WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
     LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
     HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
     WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT
     NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
     FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS TO THE
     QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
     PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
     SERVICING, REPAIR OR CORRECTION.

 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
     WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
     MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
     LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
     INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
     INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
     DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
     OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
     OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
     ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

                      END OF TERMS AND CONDITIONS
How to Apply These Terms to Your New Programs
=============================================

If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.

   To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

     ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
     Copyright (C) YEAR  NAME OF AUTHOR

     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2 of the License, or
     (at your option) any later version.

     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
     GNU General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   Also add information on how to contact you by electronic and paper
mail.

   If the program is interactive, make it output a short notice like
this when it starts in an interactive mode:

     Gnomovision version 69, Copyright (C) YEAR NAME OF AUTHOR
     Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
     type `show w'.
     This is free software, and you are welcome to redistribute it
     under certain conditions; type `show c' for details.

   The hypothetical commands `show w' and `show c' should show the
appropriate parts of the General Public License.  Of course, the
commands you use may be called something other than `show w' and `show
c'; they could even be mouse-clicks or menu items - whatever suits your
program.

   You should also get your employer (if you work as a programmer) or
your school, if any, to sign a "copyright disclaimer" for the program,
if necessary.  Here is a sample; alter the names:

     Yoyodyne, Inc., hereby disclaims all copyright interest in the program
     `Gnomovision' (which makes passes at compilers) written by James Hacker.

     SIGNATURE OF TY COON, 1 April 1989
     Ty Coon, President of Vice

   This General Public License does not permit incorporating your
program into proprietary programs.  If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library.  If this is what you want to do, use the
GNU Lesser General Public License instead of this License.


File: gpc.info,  Node: Library Copying,  Next: Demo Copying,  Prev: Copying,  Up: Top

Appendix B GNU LESSER GENERAL PUBLIC LICENSE
********************************************

                      Version 2.1, February 1999

     Copyright (C) 1991, 1999 Free Software Foundation, Inc.
     59 Temple Place - Suite 330, Boston, MA 02111-1307, USA

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     [This is the first released version of the Lesser GPL.  It also counts
     as the successor of the GNU Library Public License, version 2, hence the
     version number 2.1.]

LGPL Preamble
=============

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File: gpc.info,  Node: Demo Copying,  Next: Acknowledgments,  Prev: Library Copying,  Up: Top

Appendix C DEMO COPYING
***********************

   This is the common copying notice for all files found in `demos/'
and `docdemos/' (unless stated otherwise in the file itself). They are
distributed under the GNU General Public License with a notable
exception:

   Copyright (C) 1997-2006 Free Software Foundation, Inc.

   Authors: See notice in the demo program. If not listed there, these
are the authors of the GNU Pascal Compiler.

   This demo program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.

   This demo program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.

   You should have received a copy of the GNU General Public License
along with this demo program; see the file COPYING. If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  *Note Top: Copying.

   As a special exception, if you incorporate even large parts of the
code of this demo program into another program with substantially
different functionality, this does not cause the other program to be
covered by the GNU General Public License. This exception does not
however invalidate any other reasons why it might be covered by the GNU
General Public License.


File: gpc.info,  Node: Acknowledgments,  Next: Resources,  Prev: Demo Copying,  Up: Top

Appendix D Contributors to GNU Pascal.
**************************************

Jukka Virtanen
     invented GNU Pascal in March 1988, implemented the ISO 7185 and
     most of the ISO 10206 standard, etc.

Dr. Peter Gerwinski (http://www.gerwinski.de/~peter/)
     added Borland Pascal related and other extensions to GNU Pascal in
     summer 1995, ported GPC to EMX, did most of the development of the
     compiler from 1996 to 2001, created the WWW home page, etc.

Jan-Jaap van der Heijden
     ported GPC to DJGPP and to Microsoft Windows 95/NT, added ELF
     support in spring 1996, solved a lot of configuration and
     compatibility problems, created the GPC FAQ, etc.

Frank Heckenbach (http://fjf.gnu.de)
     rewrote and maintains the Run Time System since July 1997, does
     most of the development of the compiler since July 2001, wrote
     most of the units, demo programs, scripts and utilities
     distributed with GPC, wrote many test programs, maintains the GPC
     To-Do list (*note To Do::) and the WWW home page, etc.

Waldek Hebisch
     made GPC compatible with gcc-3.1.1 and later backend versions,
     fixed backend problems on various targets and improved the
     frontend in the areas of structured initializers, qualified
     identifiers, etc.

Prof. Abimbola A. Olowofoyeku ("The African Chief") (http://www.bigfoot.com/~african_chief/)
     created the original versions of many BP compatibility units in May
     1997, contributed code to other units and the Run Time System,
     helped porting GPC and the units to Cygwin, mingw and MSYS, wrote a
     number of test programs, contributed a Borland Delphi-compatible
     `SysUtils' unit (http://www.gnu-pascal.de/contrib/chief/), etc.

Nicholas Burrett
     fixed some bugs and cleaned up GPC in May 1998, etc.

Dominik Freche
     improved and extended the GPC manual in August - September 1999 and
     wrote conversion routines for Borland compatible 6 Byte floating
     point numbers in December 1999.

Alexey Volokhov
     improved the performance of GPC's module/unit support in June 1997.

Bill Currie
     implemented more Borland extensions into GPC in July 1997.

Nicola Girardi
     wrote the GNU Pascal Coding Standards in November 2001, contributed
     a GPC unit (http://www.gnu-pascal.de/contrib/nicola/) for the
     `svgalib' graphics library for some platforms in February 2000,
     provided some portability enhancements to the RTS.

Eike Lange
     wrote an internationalization unit, translated the GNU Pascal
     Coding Standards into German and worked on the documentation.

Mirsad Todorovac
     translated the GPC documentation into Croatian and contributed code
     to the run time system.

Francisco Javier Fernandez Serrador
     translated the GPC documentation into Spanish.

Maurice Lombardi
     maintains the DJGPP port of GPC, improved the numerical routines
     for real and complex numbers and improved and extended the GMP real
     routines.

Emil Jerabek
     improved the numerical routines for real and complex numbers.

Adriaan van Os
     helped with the port of GPC to Mac OS X and set up a web site
     (http://www.microbizz.nl/gpc.html) with sources, binaries, patches
     and building instructions for this platform, and helped with Mac
     Pascal dialect support in GPC, since January 2003.

Neil Santos

James A. Morrison
     helps porting GPC to GCC-4.x backends since February 2005.

Russell Whitaker
     updated and maintained the GNU Pascal FAQ.  (*note FAQ::)

Matthias Klose
     integrated GPC into EGCS and Debian GNU/Linux in May 1998, improved
     the installation process, etc.

Peter N Lewis
     added support for Mac Pascal dialect specific features and improved
     the documentation.

Orlando Llanes
     provided some contributions to the manual in May 1998.


The development of GNU Pascal profits a lot from independent
contributions:

Anja Gerwinski
     maintains the GPC mailing list, since September 1999.

Berend de Boer
     wrote a lot of useful documentation about Extended Pascal in 1995.

Markus Gerwinski (http://www.gerwinski.de/~markus/)
     created the drawing showing a Gnu with Blaise Pascal and helped to
     design the WWW home page in October 1996.

Eike Lange
     is writing a book (http://www.gnu-pascal.org/~eike/) about GPC in
     German since March 2003.

Eike Lange
     wrote units (http://www.gnu-pascal.de/contrib/eike/) to access
     MySQL, GNU DBM and PostgreSQL databases in August 2000, and a unit
     (now part of GPC) and tools for internationalization in October -
     December 2001.

Eike Lange and Nicola Girardi
     together contributed a set of GTK units
     (http://www.gnu-pascal.de/contrib/nicola/) in February - May 2001.

Nicola Girardi
     wrote the GNU Pascal Coding Standards in English. Eike Lange
     translated them to German.

Prof. Phil Nelson
     created a bug reporting system for GPC in October 1996.

Robert Höhne
     wrote RHIDE (http://www.rhide.com), an integrated development
     environment for GNU compilers running under Dos (DJGPP) and Linux,
     and added support for GNU Pascal in autumn 1996.

Sven Hilscher
     wrote a mostly BP compatible `Graph' unit for several platforms in
     December 1996, now part of the GRX library
     (http://www.gnu.de/software/grx/).

Dario Anzani ("Predator Zeta") (http://www.geocities.com/SiliconValley/Vista/6573)
     contributed documentation about the use of assembler in GNU Pascal
     in May 1997.  (*note Assembler::)

Dieter Schmitz
     set up a German mailing list for GPC, *Note Mailing List::, in
     March 2001.

`(-:---------:-)'
     This space is reserved for _your_ name. ;-) Please contact us at
     the GPC mailing list, *Note Mailing List::, if you have something
     interesting for us.


We thank everybody who supports us by reporting bugs, providing
feedback, contributing knowledge and good ideas, donating development
tools, and giving us the opportunity to test GPC on a large variety of
systems. We are particularly indebted (in alphabetical order,
individuals first) to

Sietse Achterop, Jawaad Ahmad, Montaz Ali, Jamie Allan, Strobe Anarkhos,
John P. R. Archer, Phil Armsdon, Geoffrey Arnold, Artur Bac, Steven J.
Backus, Geoff Bagley, Andy Ball, Uwe Bauermann, Silvio a Beccara,
Michael Behm, Ariel Bendersky, Pablo Bendersky, John Blakeney, Nicolas
Bley, Philip Blundell, Preben Mikael Bohn, Ernst-Ludwig Bohnen, Nils
Bokermann, Francesco Bonomi, J. Booij, Patrice Bouchand, Jim Brander,
Frank Thomas Braun, Matthias Braun, Marcus Brinkmann, Steve Brooker,
Doug Brookmann, J. David Bryan, Kev Buckley, Jason Burgon, Ricky W.
Butler, Dr. E. Buxbaum, Andrew Cagney, Loris Caren, Theo Carr-Brion,
Fernando Carrilho, Larry Carter, Fabio Casamatta, Janet Casey, Romain
Chantereau, Emmanuel Chaput, Jean-Pierre Chevillard, Carl Eric Codere,
Jean-Philippe Combe, Paolo Cortelli, F. Couperin, Nicolas Courtel,
Miklos Cserzo, Tim Currie, Serafim Dahl, Paul Davidson, Martin G. C.
Davies, Stefan A. Deutscher, Jerry van Dijk, Thomas Dunbar, Andreas
Eckleder, Stephan Eickschen, Frank D. Engel Jr., Sven Engelhardt, Klaus
Espenlaub, Toby Ewing, Chuck B. Falconer, Joachim Falk, Irfan Fazel,
Carel Fellinger, Francisco Javier Fernandez, Christopher Ferrall, David
Fiddes, Alfredo Cesar Fontana, Kevin A. Foss, B. Gayathri, Marius
Gedminas, Philip George, Nicholas Geovanis, Jose Oliver Gil, Thorsten
Glaser, Jing Gloria, Roland Goretzki, Morten Gulbrandsen, Gerrit P.
Haase, Kocherlakota Harikrishna, Joe Hartley, Hans Hauska, Jakob
Heinemann, Boris Herman, Arvid Herzenberg, Thorsten Hindermann, Honda
Hirotaka, Stephen Hurd, Nick Ioffe, Mason Ip, Fredrik Ismyren, Richard
D. Jackson, Daniel Jacobowitz, Grant Jacobs, Andreas Jaeger, Frank
Jahnke, David James, Nathalie Jarosz, Sven Jauring, Niels Kristian Bech
Jensen, Johanna Johnston, Achim Kalwa, Christine Karow, Tim Kaulmann,
Thomas Keller, Clark Kent, Victor Khimenko, Russell King, Niels Ole
Staub Kirkeby, Prof. Donald E. Knuth, Michael Kochiashvili, Tomasz
Kowaltowski, David Kredba, Peter Ulrich Kruppa, Jochen Kuepper, Casper
ter Kuile, Oliver Kullmann, Krzysztof Kwapien, Randy Latimer, Bernard
Leak, Olivier Lecarme, Wren Lee, Martin Liddle, Kennith Linder, Stephen
Lindholm, Orlando Llanes, Miguel Lobo, Benedict Lofstedt, Steve Loft,
John Logsdon, Dominique Louis, Dmitry S. Luhtionov, Jesper Lund, Martin
Maechler, Muhammad Umer Mansoor, Claude Marinier, Ingvar Marny, Antony
Matranga, Michael McCarthy, Michael Meeks, Clyde Meli, Axel Mellinger,
Bryan Meredith, Jeff Miller, John Miller, Russell Minnich, Rudy
Moddemeijer, Jason Moore, Scott A. Moore, Jeffrey Moskot, Pierre Muller,
Adam Naumowicz, Nathanael Nerode, Andreas Neumann, Christian Neumann,
Peter Norton, Adam Oldham, Gerhard Olejniczak, Alexandre Oliva, John G.
Ollason, Marius Onica, Ole Osterby, Klaus Friis Ostergaard, Jean-Marc
Ottorini, Michael Paap, Gale Paeper, Matija Papec, Miguel A. Alonso
Pardo, Laurent Parise, Andris Pavenis, Robert R. Payne, Opie Pecheux,
Jose M. Perez, Ronald Perrella, Bjorn Persson, Per Persson, Michael
Pfeiffer, Pierre Phaneuf, Pascal Pignard, Tam Pikey, Nuno Pinhao,
Philip Plant, Larry Poorman, Stuart Pope, Yuri Prokushev, Huge
Rademaker, Shafiek Rasdien, Mike Reid, Leon Renkema, John L. Ries, Phil
Robertson, Clive Rodgers, Jim Roland, Guillaume Rousse, Daniel Rudy,
Marten Jan de Ruiter, Martin Rusko, Sven Sahle, Neil Santos, Carl-Johan
Schenstrom, Robert B. Scher, Hartmut Schmider, Thomas D. Schneider,
Dominique Schuppli, Egbert Seibertz, George Shapovalov, Richard Sharman,
Patrick Sharp, Joe da Silva, Arcadio Alivio Sincero, Ian Sinclair,
Kasper Souren, Tomas Srb, Anuradha Srinivasan, David Starner, Andrew
Stribblehill, Alan Sun, Veli Suorsa, Matthew Swift, Mark Taylor, Paul
Tedaldi, Robin S. Thompson, Ian Thurlbeck, Gerhard Tonn, Ivan Torshin,
Bernhard Tschirren, Josef Urban, Luiz Vaz, Tom Verhoeff, Kresimir
Veselic, Jean-Pierre Vial, Alejandro Villarroel, Bohdan Vlasyuk, Marco
van de Voort, Raymond Wang, Nic Webb, Peter Weber, Francisco Stefano
Wechsler, Christian Wendt, Benedikt Wildenhain, Gareth Wilson, Marc van
Woerkom, David Wood, Michael Worsley, Takashi Yamanoue, George L. Yang,
Salaam Yitbarek, Dafi Yondra, Eli Zaretskii, Artur Zaroda, Gerhard
Zintel, Mariusz Zynel, the `BIP' at the `University of Birmingham', UK,
the `Institut fuer Festkoerperforschung (IFF)' at the
`Forschungszentrum Juelich', Germany, CARNet (Croatian Academic and
Research NETwork), the Academy of Fine Arts and the Faculty of Graphic
Arts at the University of Zagreb, Croatia,

and everybody we might have forgotten to mention here.  Thanks to all
of you!

GNU Pascal is based on GNU CC by Richard Stallman. Several people have
contributed to GNU CC:

   * The idea of using RTL and some of the optimization ideas came from
     the program PO written at the University of Arizona by Jack
     Davidson and Christopher Fraser.  See "Register Allocation and
     Exhaustive Peephole Optimization", Software Practice and
     Experience 14 (9), Sept. 1984, 857-866.

   * Paul Rubin wrote most of the preprocessor.

   * Leonard Tower wrote parts of the parser, RTL generator, and RTL
     definitions, and of the Vax machine description.

   * Ted Lemon wrote parts of the RTL reader and printer.

   * Jim Wilson implemented loop strength reduction and some other loop
     optimizations.

   * Nobuyuki Hikichi of Software Research Associates, Tokyo,
     contributed the support for the Sony NEWS machine.

   * Charles LaBrec contributed the support for the Integrated Solutions
     68020 system.

   * Michael Tiemann of Cygnus Support wrote the support for inline
     functions and instruction scheduling.  Also the descriptions of the
     National Semiconductor 32000 series cpu, the SPARC cpu and part of
     the Motorola 88000 cpu.

   * Jan Stein of the Chalmers Computer Society provided support for
     Genix, as well as part of the 32000 machine description.

   * Randy Smith finished the Sun FPA support.

   * Robert Brown implemented the support for Encore 32000 systems.

   * David Kashtan of SRI adapted GNU CC to VMS.

   * Alex Crain provided changes for the 3b1.

   * Greg Satz and Chris Hanson assisted in making GNU CC work on HP-UX
     for the 9000 series 300.

   * William Schelter did most of the work on the Intel 80386 support.

   * Christopher Smith did the port for Convex machines.

   * Paul Petersen wrote the machine description for the Alliant FX/8.

   * Dario Dariol contributed the four varieties of sample programs that
     print a copy of their source.

   * Alain Lichnewsky ported GNU CC to the Mips cpu.

   * Devon Bowen, Dale Wiles and Kevin Zachmann ported GNU CC to the
     Tahoe.

   * Jonathan Stone wrote the machine description for the Pyramid
     computer.

   * Gary Miller ported GNU CC to Charles River Data Systems machines.

   * Richard Kenner of the New York University Ultracomputer Research
     Laboratory wrote the machine descriptions for the AMD 29000, the
     DEC Alpha, the IBM RT PC, and the IBM RS/6000 as well as the
     support for instruction attributes.  He also made changes to
     better support RISC processors including changes to common
     subexpression elimination, strength reduction, function calling
     sequence handling, and condition code support, in addition to
     generalizing the code for frame pointer elimination.

   * Richard Kenner and Michael Tiemann jointly developed reorg.c, the
     delay slot scheduler.

   * Mike Meissner and Tom Wood of Data General finished the port to the
     Motorola 88000.

   * Masanobu Yuhara of Fujitsu Laboratories implemented the machine
     description for the Tron architecture (specifically, the Gmicro).

   * James van Artsdalen wrote the code that makes efficient use of the
     Intel 80387 register stack.

   * Mike Meissner at the Open Software Foundation finished the port to
     the MIPS cpu, including adding ECOFF debug support, and worked on
     the Intel port for the Intel 80386 cpu.

   * Ron Guilmette implemented the `protoize' and `unprotoize' tools,
     the support for Dwarf symbolic debugging information, and much of
     the support for System V Release 4.  He has also worked heavily on
     the Intel 386 and 860 support.

   * Torbjorn Granlund implemented multiply- and divide-by-constant
     optimization, improved long long support, and improved leaf
     function register allocation.

   * Mike Stump implemented the support for Elxsi 64 bit CPU.

   * John Wehle added the machine description for the Western Electric
     32000 processor used in several 3b series machines (no relation to
     the National Semiconductor 32000 processor).



File: gpc.info,  Node: Resources,  Next: GNU,  Prev: Acknowledgments,  Up: Top

Appendix E Resources For Use With GPC.
**************************************

Many of the programs mentioned here, plus some more, can be found at
     `http://www.gnu-pascal.de/contrib/'

GNU Pascal Drawing
------------------

On the web you can find our GNU Pascal drawing as a small (1 KB)
(`images/GnuPascal-small.png' on GPC's WWW home page) and a large PNG
image (10 KB) (`images/GnuPascal.png' on GPC's WWW home page), as an
EPS file (45 KB) (`images/GnuPascal.eps' on GPC's WWW home page), and
as a PDF file (18 KB) (`images/GnuPascal.pdf' on GPC's WWW home page).

Due to patent problems (http://www.gnu.org/philosophy/gif.html) we do
not use GIF files. Fortunately the PNG format (http://www.libpng.org),
the successor of GIF, does not have this problem - and introduces
better compression and more advanced features anyway.

   By the way, the color gradient (`images/gradient.png' on GPC's WWW
home page) that makes our page background is a PNG file of only 632
bytes. It was generated by a Pascal program compiled with GPC and
`pnmtopng'.  [Example (gradient.pas)]

PENG
----

PENG is an integrated development environment (IDE) for GNU Compilers
and other purposes on any platform supported by GPC, written by Frank
Heckenbach. The home page of PENG is
     `http://fjf.gnu.de/peng/'.

RHIDE
-----

RHIDE is an integrated development environment (IDE) for GNU Compilers
on DOS (DJGPP) or Linux, written by Robert Höhne. The home page of
RHIDE is
     `http://www.rhide.com'.

DevPascal
---------

DevPascal is an integrated development environment (IDE) for GNU Pascal
on mingw32. The home page of DevPascal is
     `http://www.bloodshed.net/devpascal.html'.

GRX
---

GRX is a graphics library for C and GNU Pascal, including a mostly BP
compatible `Graph' unit. It is available from
     `http://www.gnu.de/software/grx/'

   Although GRX originated on DJGPP, a DOS programming platform, it is
portable to Linux with SVGAlib, to all Unix-like systems running the
X11 window system, and to MS-Windows 9x/NT.

Internationalization
--------------------

Units and tools for internationalization are available in
     `http://www.gnu-pascal.de/contrib/eike/'

Database units
--------------

GNU Pascal units to access MySQL, GNU DBM and PostgreSQL databases are
available in
     `http://www.gnu-pascal.de/contrib/eike/'

GTK units
---------

GNU Pascal units for the GTK+ and GTK+ GL libraries are available in
     `http://www.gnu-pascal.de/contrib/nicola/'

Documentation
-------------

A book about GPC manual in German written by Eike Lange can be found in
     `http://www.gnu-pascal.org/~eike/'

SysUtils unit
-------------

Prof. Abimbola A. Olowofoyeku ("The African Chief") wrote a
Delphi-compatible (though a few routines are still missing) `SysUtils'
unit. It has been tested under Cygwin, mingw, Linux (Mandrake 7.0), and
Solaris 7. It can be downloaded from
`http://www.gnu-pascal.de/contrib/chief/'.

Crystal, a mailing list archive program
---------------------------------------

Crystal is a web based mailing list archive, written for GNU Pascal and
used for the archives of GPC's mailing lists (*note Mailing List
Archives::). The source code can be found at
`http://fjf.gnu.de/crystal/'.

ISO standards
-------------

The Pascal standard specifications are available in PostScript format at
     `http://ftp.digital.com/pub/Digital/Pascal/'

   Alternative addresses are
     `ftp://ftp.europe.digital.com/pub/DEC/Pascal/'

     `ftp://ftp.digital.com/pub/DEC/Pascal/'

   There are also copies at
     `http://www.moorecad.com/standardpascal/iso7185.ps'
     (ISO 7185 Pascal)

     `http://www.moorecad.com/standardpascal/iso10206.ps'
     (ISO 10206 Extended Pascal)

   Note: These documents are a bit hard to navigate (e.g., in
ghostview) because they are missing the so called "document structuring
comments" (DSC). The GPC source distribution contains a little script
`ps2dsc' to add the DSC again and make the documents easier to
navigate. Note that for reasons of copyright, you are probably only
allowed to do this for your own use and not to distribute the modified
files.

   You can find an easy-to-read introduction to Extended Pascal by
Prospero Software at
     `http://www.prosperosoftware.com/epintro.html'

   Please note that Standard Pascal is *not* the same as Borland Pascal
nor a subset of it. See *Note Highlights:: for examples of Standard
Pascal features that are missing in Borland Pascal.

   Scott A. Moore's ANSI-ISO Pascal FAQ (132 KB)
(http://www.moorecad.com/standardpascal/ansiiso.faq) discusses the
differences between both dialects in detail.

   The draft standard "Object-Oriented Extensions to Pascal" can be
found at
     `http://pascal-central.com/OOE-stds.html'

Software Patents Kill Innovation
--------------------------------

Programming activities of small companies and individuals are
threatened by software patents. If you are a programmer, you are in
danger, too! Your employer or yourself might be sued by a large company
holding a patent on some _ideas_ you are using in your programs. (You
need not use foreign code in order to become vulnerable.)

   For more information look at
     `http://swpat.ffii.org' (Europe)
     `http://lpf.ai.mit.edu' (USA)


File: gpc.info,  Node: GNU,  Next: Index-GPC,  Prev: Resources,  Up: Top

Appendix F The GNU Project.
***************************

GNU Pascal is part of the GNU project which was founded by Richard
Stallman in 1984. The aim of the GNU project is to provide a complete
operating system with editors, compilers etc. as "Free Software".

   People often confuse _Free Software_ with _public domain software_
or have other wrong information about the GNU project. If you want to
know it definitely, please read the *GNU General Public License*
(http://www.gnu.org/copyleft/gpl.html).

   For even more information, please consult the official *GNU home
page* of the _Free Software Foundation (FSF)_, `http://www.gnu.org/' or
one of its mirror sites.

   Some small notes about common misunderstandings follow.

   * It is legal to compile commercial, including non-free, programs
     written in Pascal with GNU Pascal. They do _not_ automatically
     become Free Software themselves.

   * "Free" is opposed to "proprietary", but _not_ opposed to
     "commercial". Free Softare can be - and is in fact - distributed
     commercially for a real price. In contrast, most non-commercial
     software does _not_ meet the open source criteria
     (http://www.opensource.org/osd.html) and thus does _not_ qualify
     as Free Software.

   * When you modify a free program released under the *GNU General
     Public License* (http://www.gnu.org/copyleft/gpl.html), e.g. the
     GNU Pascal compiler itself:
        - You can released and license your own modifications (as a
          separate entity) any way you like.

        - If you distribute or publish the whole work with your
          modifications, including or derived from GPL licensed parts,
          the whole work (including your modifications) must be
          licensed under the terms of the GPL. (Note: This does not
          contradict the previous point since you can license your work
          in several ways.)

        - You do not have to distribute or publish the whole work at
          all. In this case the question of license of the whole work
          does not arise.
     *Please note:* These are informal explanations which should not be
     construed as legal advice. The legally binding text is only the
     text contained in the license statement.

   * When using libraries for writing proprietary programs, check the
     libraries' licenses carefully. The _GNU Lesser General Public
     License_ (http://www.gnu.org/copyleft/lesser.html) allows linking
     a library to non-free software under certain conditions, the
     ordinary _GNU General Public License_ does not.

   * It is legal to charge a fee for distributing Free Software. If
     somebody sold you a copy of GNU Pascal you could have got without
     paying for it as well, that's in agreement with the _GNU General
     Public License_.

   * However if somebody wants you to sign an agreement that you won't
     re-distribute the Free Software you have got, it would be illegal.
     That person would lose the right to use and distribute that Free
     Software.

   * The preferred form to distribute Free Software is in source code.
     This ensures that everybody has the freedom to customize the
     software or to fix bugs by themselves. When we also distribute GNU
     Pascal binaries we do it only to simplify installation and to
     encourage its use.

* Menu:

* Manifesto::  The GNU Manifesto
* Funding::    How to help assure funding for Free Software


File: gpc.info,  Node: Manifesto,  Next: Funding,  Up: GNU

F.1 The GNU Manifesto
=====================

     The GNU Manifesto which appears below was written by Richard
     Stallman at the beginning of the GNU project, to ask for
     participation and support.  For the first few years, it was
     updated in minor ways to account for developments, but now it
     seems best to leave it unchanged as most people have seen it.

     Since that time, we have learned about certain common
     misunderstandings that different wording could help avoid.
     Footnotes added in 1993 help clarify these points.

     For up-to-date information about the available GNU software,
     please see the latest issue of the GNU's Bulletin.  The list is
     much too long to include here.

* Menu:

* Gnu is Not Unix::           What's GNU?  Gnu's Not Unix!
* Why GNU::                   Why I Must Write GNU
* GNU Unix Compatibility::    Why GNU Will Be Compatible with Unix
* GNU Availability::          How GNU Will Be Available
* Why Help GNU::              Why Many Other Programmers Want to Help
* How To Contribute to GNU::  How You Can Contribute
* GNU Benefits::              Why All Computer Users Will Benefit
* Objections to GNU::         Some Easily Rebutted Objections to GNU's Goals


File: gpc.info,  Node: Gnu is Not Unix,  Next: Why GNU,  Up: Manifesto

F.1.1 What's GNU?  Gnu's Not Unix!
----------------------------------

GNU, which stands for Gnu's Not Unix, is the name for the complete
Unix-compatible software system which I am writing so that I can give it
away free to everyone who can use it.(1) Several other volunteers are
helping me.  Contributions of time, money, programs and equipment are
greatly needed.

   So far we have an Emacs text editor with Lisp for writing editor
commands, a source level debugger, a yacc-compatible parser generator,
a linker, and around 35 utilities.  A shell (command interpreter) is
nearly completed.  A new portable optimizing C compiler has compiled
itself and may be released this year.  An initial kernel exists but
many more features are needed to emulate Unix.  When the kernel and
compiler are finished, it will be possible to distribute a GNU system
suitable for program development.  We will use TeX as our text
formatter, but an nroff is being worked on.  We will use the free,
portable X window system as well.  After this we will add a portable
Common Lisp, an Empire game, a spreadsheet, and hundreds of other
things, plus on-line documentation.  We hope to supply, eventually,
everything useful that normally comes with a Unix system, and more.

   GNU will be able to run Unix programs, but will not be identical to
Unix.  We will make all improvements that are convenient, based on our
experience with other operating systems.  In particular, we plan to
have longer file names, file version numbers, a crashproof file system,
file name completion perhaps, terminal-independent display support, and
perhaps eventually a Lisp-based window system through which several
Lisp programs and ordinary Unix programs can share a screen.  Both C
and Lisp will be available as system programming languages.  We will
try to support UUCP, MIT Chaosnet, and Internet protocols for
communication.

   GNU is aimed initially at machines in the 68000/16000 class with
virtual memory, because they are the easiest machines to make it run
on.  The extra effort to make it run on smaller machines will be left
to someone who wants to use it on them.

   To avoid horrible confusion, please pronounce the `G' in the word
`GNU' when it is the name of this project.

   ---------- Footnotes ----------

   (1) The wording here was careless.  The intention was that nobody
would have to pay for _permission_ to use the GNU system.  But the
words don't make this clear, and people often interpret them as saying
that copies of GNU should always be distributed at little or no charge.
That was never the intent; later on, the manifesto mentions the
possibility of companies providing the service of distribution for a
profit.  Subsequently I have learned to distinguish carefully between
"free" in the sense of freedom and "free" in the sense of price.  Free
software is software that users have the freedom to distribute and
change.  Some users may obtain copies at no charge, while others pay to
obtain copies - and if the funds help support improving the software,
so much the better.  The important thing is that everyone who has a
copy has the freedom to cooperate with others in using it.


File: gpc.info,  Node: Why GNU,  Next: GNU Unix Compatibility,  Prev: Gnu is Not Unix,  Up: Manifesto

F.1.2 Why I Must Write GNU
--------------------------

I consider that the golden rule requires that if I like a program I must
share it with other people who like it.  Software sellers want to divide
the users and conquer them, making each user agree not to share with
others.  I refuse to break solidarity with other users in this way.  I
cannot in good conscience sign a nondisclosure agreement or a software
license agreement.  For years I worked within the Artificial
Intelligence Lab to resist such tendencies and other inhospitalities,
but eventually they had gone too far: I could not remain in an
institution where such things are done for me against my will.

   So that I can continue to use computers without dishonor, I have
decided to put together a sufficient body of free software so that I
will be able to get along without any software that is not free.  I
have resigned from the AI lab to deny MIT any legal excuse to prevent
me from giving GNU away.


File: gpc.info,  Node: GNU Unix Compatibility,  Next: GNU Availability,  Prev: Why GNU,  Up: Manifesto

F.1.3 Why GNU Will Be Compatible with Unix
------------------------------------------

Unix is not my ideal system, but it is not too bad.  The essential
features of Unix seem to be good ones, and I think I can fill in what
Unix lacks without spoiling them.  And a system compatible with Unix
would be convenient for many other people to adopt.


File: gpc.info,  Node: GNU Availability,  Next: Why Help GNU,  Prev: GNU Unix Compatibility,  Up: Manifesto

F.1.4 How GNU Will Be Available
-------------------------------

GNU is not in the public domain.  Everyone will be permitted to modify
and redistribute GNU, but no distributor will be allowed to restrict its
further redistribution.  That is to say, proprietary modifications will
not be allowed.  I want to make sure that all versions of GNU remain
free.


File: gpc.info,  Node: Why Help GNU,  Next: How To Contribute to GNU,  Prev: GNU Availability,  Up: Manifesto

F.1.5 Why Many Other Programmers Want to Help
---------------------------------------------

I have found many other programmers who are excited about GNU and want
to help.

   Many programmers are unhappy about the commercialization of system
software.  It may enable them to make more money, but it requires them
to feel in conflict with other programmers in general rather than feel
as comrades.  The fundamental act of friendship among programmers is the
sharing of programs; marketing arrangements now typically used
essentially forbid programmers to treat others as friends.  The
purchaser of software must choose between friendship and obeying the
law.  Naturally, many decide that friendship is more important.  But
those who believe in law often do not feel at ease with either choice.
They become cynical and think that programming is just a way of making
money.

   By working on and using GNU rather than proprietary programs, we can
be hospitable to everyone and obey the law.  In addition, GNU serves as
an example to inspire and a banner to rally others to join us in
sharing.  This can give us a feeling of harmony which is impossible if
we use software that is not free.  For about half the programmers I
talk to, this is an important happiness that money cannot replace.


File: gpc.info,  Node: How To Contribute to GNU,  Next: GNU Benefits,  Prev: Why Help GNU,  Up: Manifesto

F.1.6 How You Can Contribute
----------------------------

I am asking computer manufacturers for donations of machines and money.
I'm asking individuals for donations of programs and work.

   One consequence you can expect if you donate machines is that GNU
will run on them at an early date.  The machines should be complete,
ready to use systems, approved for use in a residential area, and not
in need of sophisticated cooling or power.

   I have found very many programmers eager to contribute part-time
work for GNU.  For most projects, such part-time distributed work would
be very hard to coordinate; the independently-written parts would not
work together.  But for the particular task of replacing Unix, this
problem is absent.  A complete Unix system contains hundreds of utility
programs, each of which is documented separately.  Most interface
specifications are fixed by Unix compatibility.  If each contributor
can write a compatible replacement for a single Unix utility, and make
it work properly in place of the original on a Unix system, then these
utilities will work right when put together.  Even allowing for Murphy
to create a few unexpected problems, assembling these components will
be a feasible task.  (The kernel will require closer communication and
will be worked on by a small, tight group.)

   If I get donations of money, I may be able to hire a few people full
or part time.  The salary won't be high by programmers' standards, but
I'm looking for people for whom building community spirit is as
important as making money.  I view this as a way of enabling dedicated
people to devote their full energies to working on GNU by sparing them
the need to make a living in another way.


File: gpc.info,  Node: GNU Benefits,  Next: Objections to GNU,  Prev: How To Contribute to GNU,  Up: Manifesto

F.1.7 Why All Computer Users Will Benefit
-----------------------------------------

Once GNU is written, everyone will be able to obtain good system
software free, just like air.(1)

   This means much more than just saving everyone the price of a Unix
license.  It means that much wasteful duplication of system programming
effort will be avoided.  This effort can go instead into advancing the
state of the art.

   Complete system sources will be available to everyone.  As a result,
a user who needs changes in the system will always be free to make them
himself, or hire any available programmer or company to make them for
him.  Users will no longer be at the mercy of one programmer or company
which owns the sources and is in sole position to make changes.

   Schools will be able to provide a much more educational environment
by encouraging all students to study and improve the system code.
Harvard's computer lab used to have the policy that no program could be
installed on the system if its sources were not on public display, and
upheld it by actually refusing to install certain programs.  I was very
much inspired by this.

   Finally, the overhead of considering who owns the system software
and what one is or is not entitled to do with it will be lifted.

   Arrangements to make people pay for using a program, including
licensing of copies, always incur a tremendous cost to society through
the cumbersome mechanisms necessary to figure out how much (that is,
which programs) a person must pay for.  And only a police state can
force everyone to obey them.  Consider a space station where air must
be manufactured at great cost: charging each breather per liter of air
may be fair, but wearing the metered gas mask all day and all night is
intolerable even if everyone can afford to pay the air bill.  And the
TV cameras everywhere to see if you ever take the mask off are
outrageous.  It's better to support the air plant with a head tax and
chuck the masks.

   Copying all or parts of a program is as natural to a programmer as
breathing, and as productive.  It ought to be as free.

   ---------- Footnotes ----------

   (1) This is another place I failed to distinguish carefully between
the two different meanings of "free".  The statement as it stands is
not false - you can get copies of GNU software at no charge, from your
friends or over the net.  But it does suggest the wrong idea.


File: gpc.info,  Node: Objections to GNU,  Prev: GNU Benefits,  Up: Manifesto

F.1.8 Some Easily Rebutted Objections to GNU's Goals
----------------------------------------------------

     "Nobody will use it if it is free, because that means they can't
     rely on any support."

     "You have to charge for the program to pay for providing the
     support."

   If people would rather pay for GNU plus service than get GNU free
without service, a company to provide just service to people who have
obtained GNU free ought to be profitable.(1)

   We must distinguish between support in the form of real programming
work and mere handholding.  The former is something one cannot rely on
from a software vendor.  If your problem is not shared by enough
people, the vendor will tell you to get lost.

   If your business needs to be able to rely on support, the only way
is to have all the necessary sources and tools.  Then you can hire any
available person to fix your problem; you are not at the mercy of any
individual.  With Unix, the price of sources puts this out of
consideration for most businesses.  With GNU this will be easy.  It is
still possible for there to be no available competent person, but this
problem cannot be blamed on distribution arrangements.  GNU does not
eliminate all the world's problems, only some of them.

   Meanwhile, the users who know nothing about computers need
handholding: doing things for them which they could easily do
themselves but don't know how.

   Such services could be provided by companies that sell just
hand-holding and repair service.  If it is true that users would rather
spend money and get a product with service, they will also be willing
to buy the service having got the product free.  The service companies
will compete in quality and price; users will not be tied to any
particular one.  Meanwhile, those of us who don't need the service
should be able to use the program without paying for the service.

     "You cannot reach many people without advertising, and you must
     charge for the program to support that."

     "It's no use advertising a program people can get free."

   There are various forms of free or very cheap publicity that can be
used to inform numbers of computer users about something like GNU.  But
it may be true that one can reach more microcomputer users with
advertising.  If this is really so, a business which advertises the
service of copying and mailing GNU for a fee ought to be successful
enough to pay for its advertising and more.  This way, only the users
who benefit from the advertising pay for it.

   On the other hand, if many people get GNU from their friends, and
such companies don't succeed, this will show that advertising was not
really necessary to spread GNU.  Why is it that free market advocates
don't want to let the free market decide this?(2)

     "My company needs a proprietary operating system to get a
     competitive edge."

   GNU will remove operating system software from the realm of
competition.  You will not be able to get an edge in this area, but
neither will your competitors be able to get an edge over you.  You and
they will compete in other areas, while benefiting mutually in this
one.  If your business is selling an operating system, you will not
like GNU, but that's tough on you.  If your business is something else,
GNU can save you from being pushed into the expensive business of
selling operating systems.

   I would like to see GNU development supported by gifts from many
manufacturers and users, reducing the cost to each.(3)

     "Don't programmers deserve a reward for their creativity?"

   If anything deserves a reward, it is social contribution.
Creativity can be a social contribution, but only in so far as society
is free to use the results.  If programmers deserve to be rewarded for
creating innovative programs, by the same token they deserve to be
punished if they restrict the use of these programs.

     "Shouldn't a programmer be able to ask for a reward for his
     creativity?"

   There is nothing wrong with wanting pay for work, or seeking to
maximize one's income, as long as one does not use means that are
destructive.  But the means customary in the field of software today
are based on destruction.

   Extracting money from users of a program by restricting their use of
it is destructive because the restrictions reduce the amount and the
ways that the program can be used.  This reduces the amount of wealth
that humanity derives from the program.  When there is a deliberate
choice to restrict, the harmful consequences are deliberate destruction.

   The reason a good citizen does not use such destructive means to
become wealthier is that, if everyone did so, we would all become
poorer from the mutual destructiveness.  This is Kantian ethics; or,
the Golden Rule.  Since I do not like the consequences that result if
everyone hoards information, I am required to consider it wrong for one
to do so.  Specifically, the desire to be rewarded for one's creativity
does not justify depriving the world in general of all or part of that
creativity.

     "Won't programmers starve?"

   I could answer that nobody is forced to be a programmer.  Most of us
cannot manage to get any money for standing on the street and making
faces.  But we are not, as a result, condemned to spend our lives
standing on the street making faces, and starving.  We do something
else.

   But that is the wrong answer because it accepts the questioner's
implicit assumption: that without ownership of software, programmers
cannot possibly be paid a cent.  Supposedly it is all or nothing.

   The real reason programmers will not starve is that it will still be
possible for them to get paid for programming; just not paid as much as
now.

   Restricting copying is not the only basis for business in software.
It is the most common basis because it brings in the most money.  If it
were prohibited, or rejected by the customer, software business would
move to other bases of organization which are now used less often.
There are always numerous ways to organize any kind of business.

   Probably programming will not be as lucrative on the new basis as it
is now.  But that is not an argument against the change.  It is not
considered an injustice that sales clerks make the salaries that they
now do.  If programmers made the same, that would not be an injustice
either.  (In practice they would still make considerably more than
that.)

     "Don't people have a right to control how their creativity is
     used?"

   "Control over the use of one's ideas" really constitutes control over
other people's lives; and it is usually used to make their lives more
difficult.

   People who have studied the issue of intellectual property rights
carefully (such as lawyers) say that there is no intrinsic right to
intellectual property.  The kinds of supposed intellectual property
rights that the government recognizes were created by specific acts of
legislation for specific purposes.

   For example, the patent system was established to encourage
inventors to disclose the details of their inventions.  Its purpose was
to help society rather than to help inventors.  At the time, the life
span of 17 years for a patent was short compared with the rate of
advance of the state of the art.  Since patents are an issue only among
manufacturers, for whom the cost and effort of a license agreement are
small compared with setting up production, the patents often do not do
much harm.  They do not obstruct most individuals who use patented
products.

   The idea of copyright did not exist in ancient times, when authors
frequently copied other authors at length in works of non-fiction.  This
practice was useful, and is the only way many authors' works have
survived even in part.  The copyright system was created expressly for
the purpose of encouraging authorship.  In the domain for which it was
invented - books, which could be copied economically only on a printing
press - it did little harm, and did not obstruct most of the individuals
who read the books.

   All intellectual property rights are just licenses granted by society
because it was thought, rightly or wrongly, that society as a whole
would benefit by granting them.  But in any particular situation, we
have to ask: are we really better off granting such license?  What kind
of act are we licensing a person to do?

   The case of programs today is very different from that of books a
hundred years ago.  The fact that the easiest way to copy a program is
from one neighbor to another, the fact that a program has both source
code and object code which are distinct, and the fact that a program is
used rather than read and enjoyed, combine to create a situation in
which a person who enforces a copyright is harming society as a whole
both materially and spiritually; in which a person should not do so
regardless of whether the law enables him to.

     "Competition makes things get done better."

   The paradigm of competition is a race: by rewarding the winner, we
encourage everyone to run faster.  When capitalism really works this
way, it does a good job; but its defenders are wrong in assuming it
always works this way.  If the runners forget why the reward is offered
and become intent on winning, no matter how, they may find other
strategies - such as, attacking other runners.  If the runners get into
a fist fight, they will all finish late.

   Proprietary and secret software is the moral equivalent of runners
in a fist fight.  Sad to say, the only referee we've got does not seem
to object to fights; he just regulates them ("For every ten yards you
run, you can fire one shot").  He really ought to break them up, and
penalize runners for even trying to fight.

     "Won't everyone stop programming without a monetary incentive?"

   Actually, many people will program with absolutely no monetary
incentive.  Programming has an irresistible fascination for some
people, usually the people who are best at it.  There is no shortage of
professional musicians who keep at it even though they have no hope of
making a living that way.

   But really this question, though commonly asked, is not appropriate
to the situation.  Pay for programmers will not disappear, only become
less.  So the right question is, will anyone program with a reduced
monetary incentive?  My experience shows that they will.

   For more than ten years, many of the world's best programmers worked
at the Artificial Intelligence Lab for far less money than they could
have had anywhere else.  They got many kinds of non-monetary rewards:
fame and appreciation, for example.  And creativity is also fun, a
reward in itself.

   Then most of them left when offered a chance to do the same
interesting work for a lot of money.

   What the facts show is that people will program for reasons other
than riches; but if given a chance to make a lot of money as well, they
will come to expect and demand it.  Low-paying organizations do poorly
in competition with high-paying ones, but they do not have to do badly
if the high-paying ones are banned.

     "We need the programmers desperately.  If they demand that we stop
     helping our neighbors, we have to obey."

   You're never so desperate that you have to obey this sort of demand.
Remember: millions for defense, but not a cent for tribute!

     "Programmers need to make a living somehow."

   In the short run, this is true.  However, there are plenty of ways
that programmers could make a living without selling the right to use a
program.  This way is customary now because it brings programmers and
businessmen the most money, not because it is the only way to make a
living.  It is easy to find other ways if you want to find them.  Here
are a number of examples.

   A manufacturer introducing a new computer will pay for the porting of
operating systems onto the new hardware.

   The sale of teaching, hand-holding and maintenance services could
also employ programmers.

   People with new ideas could distribute programs as freeware, asking
for donations from satisfied users, or selling hand-holding services.
I have met people who are already working this way successfully.

   Users with related needs can form users' groups, and pay dues.  A
group would contract with programming companies to write programs that
the group's members would like to use.

   All sorts of development can be funded with a Software Tax:

     Suppose everyone who buys a computer has to pay x percent of the
     price as a software tax.  The government gives this to an agency
     like the NSF to spend on software development.

     But if the computer buyer makes a donation to software development
     himself, he can take a credit against the tax.  He can donate to
     the project of his own choosing - often, chosen because he hopes to
     use the results when it is done.  He can take a credit for any
     amount of donation up to the total tax he had to pay.

     The total tax rate could be decided by a vote of the payers of the
     tax, weighted according to the amount they will be taxed on.

     The consequences:

        * The computer-using community supports software development.

        * This community decides what level of support is needed.

        * Users who care which projects their share is spent on can
          choose this for themselves.

   In the long run, making programs free is a step toward the
post-scarcity world, where nobody will have to work very hard just to
make a living.  People will be free to devote themselves to activities
that are fun, such as programming, after spending the necessary ten
hours a week on required tasks such as legislation, family counseling,
robot repair and asteroid prospecting.  There will be no need to be
able to make a living from programming.

   We have already greatly reduced the amount of work that the whole
society must do for its actual productivity, but only a little of this
has translated itself into leisure for workers because much
nonproductive activity is required to accompany productive activity.
The main causes of this are bureaucracy and isometric struggles against
competition.  Free software will greatly reduce these drains in the
area of software production.  We must do this, in order for technical
gains in productivity to translate into less work for us.

   ---------- Footnotes ----------

   (1) Several such companies now exist.

   (2) The Free Software Foundation raises most of its funds from a
distribution service, although it is a charity rather than a company.
If _no one_ chooses to obtain copies by ordering from the FSF, it will
be unable to do its work.  But this does not mean that proprietary
restrictions are justified to force every user to pay.  If a small
fraction of all the users order copies from the FSF, that is sufficient
to keep the FSF afloat.  So we ask users to choose to support us in
this way.  Have you done your part?

   (3) A group of computer companies recently pooled funds to support
maintenance of the GNU C Compiler.


File: gpc.info,  Node: Funding,  Prev: Manifesto,  Up: GNU

F.2 Funding Free Software
=========================

If you want to have more free software a few years from now, it makes
sense for you to help encourage people to contribute funds for its
development.  The most effective approach known is to encourage
commercial redistributors to donate.

   Users of free software systems can boost the pace of development by
encouraging for-a-fee distributors to donate part of their selling price
to free software developers - the Free Software Foundation, and others.

   The way to convince distributors to do this is to demand it and
expect it from them.  So when you compare distributors, judge them
partly by how much they give to free software development.  Show
distributors they must compete to be the one who gives the most.

   To make this approach work, you must insist on numbers that you can
compare, such as, "We will donate ten dollars to the Frobnitz project
for each disk sold."  Don't be satisfied with a vague promise, such as
"A portion of the profits are donated," since it doesn't give a basis
for comparison.

   Even a precise fraction "of the profits from this disk" is not very
meaningful, since creative accounting and unrelated business decisions
can greatly alter what fraction of the sales price counts as profit.
If the price you pay is $50, ten percent of the profit is probably less
than a dollar; it might be a few cents, or nothing at all.

   Some redistributors do development work themselves.  This is useful
too; but to keep everyone honest, you need to inquire how much they do,
and what kind.  Some kinds of development make much more long-term
difference than others.  For example, maintaining a separate version of
a program contributes very little; maintaining the standard version of a
program for the whole community contributes much.  Easy new ports
contribute little, since someone else would surely do them; difficult
ports such as adding a new CPU to the GNU C compiler contribute more;
major new features or packages contribute the most.

   By establishing the idea that supporting further development is "the
proper thing to do" when distributing free software for a fee, we can
assure a steady flow of resources into making more free software.

     Copyright (C) 1994 Free Software Foundation, Inc.
     Verbatim copying and redistribution of this section is permitted
     without royalty; alteration is not permitted.


File: gpc.info,  Node: Index-GPC,  Prev: GNU,  Up: Top

Index-GPC
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[index]
* Menu:

* * <1>:                                 Complex Number Operations.
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* *:                                     Set Operations.      (line   6)
* **:                                    Complex Number Operations.
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* -no-unit-path:                         GPC Command Line Options.
                                                              (line 379)
* -no-write-capital-exponent:            GPC Command Line Options.
                                                              (line 297)
* -no-write-clip-strings:                GPC Command Line Options.
                                                              (line 283)
* -no-write-real-blank:                  GPC Command Line Options.
                                                              (line 290)
* -nonlocal-exit:                        GPC Command Line Options.
                                                              (line 199)
* -nostdinc:                             GPC Command Line Options.
                                                              (line 508)
* -object-checking:                      GPC Command Line Options.
                                                              (line 225)
* -object-destination-path:              GPC Command Line Options.
                                                              (line 403)
* -object-pascal:                        GPC Command Line Options.
                                                              (line 630)
* -object-path:                          GPC Command Line Options.
                                                              (line 382)
* -objects-are-references:               GPC Command Line Options.
                                                              (line 474)
* -objects-require-override:             GPC Command Line Options.
                                                              (line 480)
* -ooe-objects:                          GPC Command Line Options.
                                                              (line 499)
* -P:                                    GPC Command Line Options.
                                                              (line 523)
* -pascal-sc:                            GPC Command Line Options.
                                                              (line 644)
* -pedantic:                             GPC Command Line Options.
                                                              (line 313)
* -pointer-arithmetic:                   GPC Command Line Options.
                                                              (line 109)
* -pointer-checking:                     GPC Command Line Options.
                                                              (line 219)
* -pointer-checking-user-defined:        GPC Command Line Options.
                                                              (line 212)
* -preprocessed:                         GPC Command Line Options.
                                                              (line 505)
* -print-needed-options:                 GPC Command Line Options.
                                                              (line 438)
* -progress-bar:                         GPC Command Line Options.
                                                              (line  39)
* -progress-messages:                    GPC Command Line Options.
                                                              (line  32)
* -propagate-units:                      GPC Command Line Options.
                                                              (line 359)
* -range-and-object-checking:            GPC Command Line Options.
                                                              (line 237)
* -range-checking:                       GPC Command Line Options.
                                                              (line 231)
* -read-base-specifier:                  GPC Command Line Options.
                                                              (line 258)
* -read-hex:                             GPC Command Line Options.
                                                              (line 265)
* -read-white-space:                     GPC Command Line Options.
                                                              (line 272)
* -remap:                                GPC Command Line Options.
                                                              (line 511)
* -setlimit:                             GPC Command Line Options.
                                                              (line 353)
* -short-circuit:                        GPC Command Line Options.
                                                              (line 129)
* -stack-checking:                       GPC Command Line Options.
                                                              (line 252)
* -standard-pascal:                      GPC Command Line Options.
                                                              (line 624)
* -standard-pascal-level-0:              GPC Command Line Options.
                                                              (line 618)
* -sun-pascal:                           GPC Command Line Options.
                                                              (line 650)
* -transparent-file-names:               GPC Command Line Options.
                                                              (line 300)
* -truncate-strings:                     GPC Command Line Options.
                                                              (line 164)
* -typed-address:                        GPC Command Line Options.
                                                              (line 320)
* -ucsd-pascal:                          GPC Command Line Options.
                                                              (line 634)
* -unit-destination-path:                GPC Command Line Options.
                                                              (line 396)
* -unit-path:                            GPC Command Line Options.
                                                              (line 376)
* -uses:                                 GPC Command Line Options.
                                                              (line 417)
* -vax-pascal:                           GPC Command Line Options.
                                                              (line 647)
* -Wabsolute:                            GPC Command Line Options.
                                                              (line 121)
* -Wdynamic-arrays:                      GPC Command Line Options.
                                                              (line 595)
* -Wfloat-equal:                         GPC Command Line Options.
                                                              (line 556)
* -Widentifier-case:                     GPC Command Line Options.
                                                              (line 454)
* -Widentifier-case-local:               GPC Command Line Options.
                                                              (line 447)
* -Wimplicit-abstract:                   GPC Command Line Options.
                                                              (line 526)
* -Wimplicit-io:                         GPC Command Line Options.
                                                              (line 550)
* -Winherited-abstract:                  GPC Command Line Options.
                                                              (line 534)
* -Winterface-file-name:                 GPC Command Line Options.
                                                              (line 461)
* -Wlocal-external:                      GPC Command Line Options.
                                                              (line 589)
* -Wmixed-comments:                      GPC Command Line Options.
                                                              (line 603)
* -Wnear-far:                            GPC Command Line Options.
                                                              (line 570)
* -Wnested-comments:                     GPC Command Line Options.
                                                              (line 609)
* -Wno-absolute:                         GPC Command Line Options.
                                                              (line 125)
* -Wno-dynamic-arrays:                   GPC Command Line Options.
                                                              (line 599)
* -Wno-float-equal:                      GPC Command Line Options.
                                                              (line 559)
* -Wno-identifier-case:                  GPC Command Line Options.
                                                              (line 457)
* -Wno-identifier-case-local:            GPC Command Line Options.
                                                              (line 451)
* -Wno-implicit-abstract:                GPC Command Line Options.
                                                              (line 530)
* -Wno-implicit-io:                      GPC Command Line Options.
                                                              (line 553)
* -Wno-inherited-abstract:               GPC Command Line Options.
                                                              (line 538)
* -Wno-interface-file-name:              GPC Command Line Options.
                                                              (line 464)
* -Wno-local-external:                   GPC Command Line Options.
                                                              (line 592)
* -Wno-mixed-comments:                   GPC Command Line Options.
                                                              (line 606)
* -Wno-near-far:                         GPC Command Line Options.
                                                              (line 573)
* -Wno-nested-comments:                  GPC Command Line Options.
                                                              (line 612)
* -Wno-object-assignment:                GPC Command Line Options.
                                                              (line 546)
* -Wno-semicolon:                        GPC Command Line Options.
                                                              (line 586)
* -Wno-typed-const:                      GPC Command Line Options.
                                                              (line 566)
* -Wno-underscore:                       GPC Command Line Options.
                                                              (line 579)
* -Wno-warnings:                         GPC Command Line Options.
                                                              (line 444)
* -Wobject-assignment:                   GPC Command Line Options.
                                                              (line 542)
* -write-capital-exponent:               GPC Command Line Options.
                                                              (line 294)
* -write-clip-strings:                   GPC Command Line Options.
                                                              (line 279)
* -write-real-blank:                     GPC Command Line Options.
                                                              (line 286)
* -Wsemicolon:                           GPC Command Line Options.
                                                              (line 583)
* -Wtyped-const:                         GPC Command Line Options.
                                                              (line 562)
* -Wunderscore:                          GPC Command Line Options.
                                                              (line 576)
* -Wwarnings:                            GPC Command Line Options.
                                                              (line 441)
* /:                                     Complex Number Operations.
                                                              (line   6)
* <:                                     Set Operations.      (line   6)
* <=:                                    Set Operations.      (line   6)
* <>:                                    Set Operations.      (line   6)
* =:                                     Set Operations.      (line   6)
* >:                                     Set Operations.      (line   6)
* ><:                                    Set Operations.      (line   6)
* >=:                                    Set Operations.      (line   6)
* Abs:                                   Abs.                 (line   6)
* absolute <1>:                          Keywords.            (line  59)
* absolute:                              absolute.            (line   6)
* abstract <1>:                          Keywords.            (line  62)
* abstract:                              abstract.            (line   6)
* Acknowledgments:                       Acknowledgments.     (line   6)
* Addr:                                  Addr.                (line   6)
* alignment:                             AlignOf.             (line   6)
* Alignment, Type Implementation:        Alignment.           (line   6)
* AlignOf:                               AlignOf.             (line   6)
* all <1>:                               Keywords.            (line  65)
* all <2>:                               export.              (line   6)
* all:                                   all.                 (line   6)
* and <1>:                               Operations for Integer and Ordinal Types.
                                                              (line   6)
* and <2>:                               and.                 (line   6)
* and:                                   Keywords.            (line  68)
* and then:                              and then.            (line   6)
* and_then <1>:                          Keywords.            (line  72)
* and_then:                              and_then.            (line   6)
* ANSI:                                  Resources.           (line 107)
* AnsiChar:                              AnsiChar.            (line   6)
* AnyFile:                               AnyFile.             (line   6)
* Append:                                Append.              (line   6)
* ArcCos <1>:                            Complex Number Operations.
                                                              (line   6)
* ArcCos:                                ArcCos.              (line   6)
* Archives, mailing list:                Mailing List Archives.
                                                              (line   6)
* ArcSin <1>:                            Complex Number Operations.
                                                              (line   6)
* ArcSin:                                ArcSin.              (line   6)
* ArcTan <1>:                            Complex Number Operations.
                                                              (line   6)
* ArcTan:                                ArcTan.              (line   6)
* Arg <1>:                               Complex Number Operations.
                                                              (line   6)
* Arg:                                   Arg.                 (line   6)
* arguments, command line:               Accessing Command Line Arguments.
                                                              (line   6)
* array <1>:                             Keywords.            (line  75)
* array:                                 array.               (line   6)
* Array Types, Data Types:               Array Types.         (line   6)
* array, conformant:                     Conformant Arrays.   (line   6)
* array, open:                           Open Arrays.         (line   6)
* array, slice access:                   String Slice Access. (line   6)
* as <1>:                                Keywords.            (line  78)
* as:                                    as.                  (line   6)
* asm <1>:                               Keywords.            (line  81)
* asm:                                   asm.                 (line   6)
* asm, Statements, Source Structure:     asm Inline.          (line   6)
* asmname <1>:                           Keywords.            (line  84)
* asmname:                               asmname.             (line   6)
* Assert:                                Assert.              (line   6)
* Assign:                                Assign.              (line   6)
* Assigned:                              Assigned.            (line   6)
* Assignment, Statements, Source Structure: Assignment.       (line   6)
* attribute <1>:                         attribute.           (line   6)
* attribute:                             Keywords.            (line  87)
* authors:                               Acknowledgments.     (line   6)
* Automake, internals:                   Automake.            (line   6)
* begin <1>:                             begin.               (line   6)
* begin:                                 Keywords.            (line  90)
* begin end, Statements, Source Structure: begin end Compound Statement.
                                                              (line   6)
* binary distributions, installing:      Binary Distributions.
                                                              (line   6)
* Bind <1>:                              Bind.                (line   6)
* Bind:                                  File Routines.       (line   6)
* bindable <1>:                          Keywords.            (line  94)
* bindable:                              bindable.            (line   6)
* Binding <1>:                           Binding.             (line   6)
* Binding:                               File Routines.       (line   6)
* BindingType:                           BindingType.         (line   6)
* bits:                                  BitSizeOf.           (line   6)
* BitSizeOf:                             BitSizeOf.           (line   6)
* Blaise Pascal:                         Resources.           (line  12)
* BlockRead:                             BlockRead.           (line   6)
* BlockWrite:                            BlockWrite.          (line   6)
* book:                                  Resources.           (line  84)
* Boolean:                               Boolean.             (line   6)
* Boolean, Intrinsic, Data Types:        Boolean (Intrinsic). (line   6)
* BP character constants, internals <1>: BP character constants.
                                                              (line   6)
* BP character constants, internals:     Compiler directives internally.
                                                              (line   6)
* Break:                                 Break.               (line   6)
* bugs:                                  Support.             (line   6)
* Bugs, reporting:                       Reporting Bugs.      (line   6)
* Built-in:                              Library Routines.    (line   6)
* Byte:                                  Byte.                (line   6)
* ByteBool:                              ByteBool.            (line   6)
* ByteCard:                              ByteCard.            (line   6)
* ByteInt:                               ByteInt.             (line   6)
* c <1>:                                 c.                   (line   6)
* c:                                     Keywords.            (line  97)
* C:                                     Other Languages.     (line   6)
* c_language <1>:                        Keywords.            (line 100)
* c_language:                            c_language.          (line   6)
* Card <1>:                              Card.                (line   6)
* Card:                                  Set Operations.      (line   6)
* Cardinal:                              Cardinal.            (line   6)
* case <1>:                              Keywords.            (line 103)
* case:                                  case.                (line   6)
* case, Statements, Source Structure:    case Statement.      (line   6)
* CBoolean:                              CBoolean.            (line   6)
* CCardinal:                             CCardinal.           (line   6)
* Char:                                  Char.                (line   6)
* Char, Intrinsic, Data Types:           Character Types.     (line   6)
* character constants, internals <1>:    Compiler directives internally.
                                                              (line   6)
* character constants, internals:        BP character constants.
                                                              (line   6)
* ChDir:                                 ChDir.               (line   6)
* Chr:                                   Chr.                 (line   6)
* CInteger:                              CInteger.            (line   6)
* class <1>:                             class.               (line   6)
* class:                                 Keywords.            (line 107)
* Classic Pascal:                        Resources.           (line 107)
* Close:                                 Close.               (line   6)
* Cmplx <1>:                             Complex Number Operations.
                                                              (line   6)
* Cmplx:                                 Cmplx.               (line   6)
* command line arguments:                Accessing Command Line Arguments.
                                                              (line   6)
* command line options:                  Invoking GPC.        (line   6)
* Commercial Support:                    Professional Support.
                                                              (line   6)
* Comp:                                  Comp.                (line   6)
* Compilation notes for specific platforms: Compilation Notes.
                                                              (line   6)
* Compiler Crashes:                      Compiler Crashes.    (line   6)
* compiler directives:                   Compiler Directives. (line   6)
* Compiler directives, internals:        Compiler directives internally.
                                                              (line   6)
* CompilerAssert:                        CompilerAssert.      (line   6)
* Complex:                               Complex.             (line   6)
* complex numbers, operations:           Complex Number Operations.
                                                              (line   6)
* Concat <1>:                            Concat.              (line   6)
* Concat:                                String Operations.   (line   6)
* conformant arrays, internals:          Parameter passing.   (line  16)
* Conjugate:                             Conjugate.           (line   6)
* const <1>:                             Keywords.            (line 110)
* const:                                 const.               (line   6)
* const parameters, internals:           Parameter passing.   (line  43)
* Constant Declaration, Source Structures: Constant Declaration.
                                                              (line   6)
* constructor <1>:                       Keywords.            (line 113)
* constructor:                           constructor.         (line   6)
* Continue:                              Continue.            (line   6)
* contributed units:                     Contributed units.   (line   6)
* Contributions:                         Resources.           (line   6)
* contributors:                          Acknowledgments.     (line   6)
* Copy:                                  Copy.                (line   6)
* Copying <1>:                           Copying.             (line   6)
* Copying:                               Library Copying.     (line   6)
* Cos <1>:                               Complex Number Operations.
                                                              (line   6)
* Cos:                                   Cos.                 (line   6)
* Crash, of the compiler:                Compiler Crashes.    (line   6)
* cross-compilers:                       Cross-Compilers.     (line   6)
* crossbuilding:                         Crossbuilding.       (line   6)
* CRT:                                   CRT.                 (line   6)
* Crystal:                               Resources.           (line  99)
* CString:                               CString.             (line   6)
* CString2String:                        CString2String.      (line   6)
* CStringCopyString:                     CStringCopyString.   (line   6)
* CurrentRoutineName:                    CurrentRoutineName.  (line   6)
* curses:                                CRT.                 (line   6)
* CWord:                                 CWord.               (line   6)
* Cycle:                                 Cycle.               (line   6)
* Data Types:                            Enumerated Types.    (line   6)
* Data Types, Definition:                Type Definition.     (line   6)
* Database:                              Resources.           (line  71)
* Date <1>:                              Date And Time Routines.
                                                              (line   6)
* Date:                                  Date.                (line   6)
* DBM:                                   Resources.           (line  71)
* debugging:                             Notes for Debugging. (line   6)
* Dec <1>:                               Operations for Integer and Ordinal Types.
                                                              (line   6)
* Dec:                                   Dec.                 (line   6)
* DefineSize:                            DefineSize.          (line   6)
* Delete:                                Delete.              (line   6)
* destructor <1>:                        destructor.          (line   6)
* destructor:                            Keywords.            (line 116)
* DevPascal <1>:                         IDE.                 (line  23)
* DevPascal:                             Resources.           (line  47)
* Discard:                               Discard.             (line   6)
* Dispose <1>:                           Dispose.             (line   6)
* Dispose:                               Memory Management Routines.
                                                              (line   6)
* distribution, minimal:                 Compiling GPC.       (line  51)
* div <1>:                               div.                 (line   6)
* div:                                   Keywords.            (line 119)
* djgpp:                                 MS-DOS with DJGPP.   (line   6)
* do <1>:                                Keywords.            (line 122)
* do:                                    do.                  (line   6)
* documentation:                         Resources.           (line  84)
* Dos:                                   Dos.                 (line   6)
* DOS, MS- <1>:                          MS-DOS or OS/2 with EMX.
                                                              (line   6)
* DOS, MS-:                              MS-DOS with DJGPP.   (line   6)
* DosUnix:                               DosUnix.             (line   6)
* Double <1>:                            Double.              (line   6)
* Double:                                Real Types.          (line   6)
* download:                              Download.            (line   6)
* downto <1>:                            downto.              (line   6)
* downto:                                Keywords.            (line 128)
* Drawing:                               Resources.           (line  12)
* Editor:                                Resources.           (line  47)
* efence:                                Libraries.           (line   6)
* ElectricFence:                         Libraries.           (line   6)
* else <1>:                              Keywords.            (line 131)
* else:                                  else.                (line   6)
* emacs:                                 IDE.                 (line   9)
* Empty:                                 Empty.               (line   6)
* EMX:                                   MS-DOS or OS/2 with EMX.
                                                              (line   6)
* end <1>:                               end.                 (line   6)
* end:                                   Keywords.            (line 136)
* endianness:                            Endianness.          (line   6)
* EOF:                                   EOF.                 (line   6)
* EOLn:                                  EOLn.                (line   6)
* EpsReal:                               EpsReal.             (line   6)
* EQ:                                    EQ.                  (line   6)
* EQPad:                                 EQPad.               (line   6)
* Erase:                                 Erase.               (line   6)
* except <1>:                            Keywords.            (line 142)
* except:                                except.              (line   6)
* Exclude:                               Exclude.             (line   6)
* Exit:                                  Exit.                (line   6)
* Exp <1>:                               Complex Number Operations.
                                                              (line   6)
* Exp:                                   Exp.                 (line   6)
* export <1>:                            Keywords.            (line 145)
* export:                                export.              (line   6)
* exports <1>:                           exports.             (line   6)
* exports:                               Keywords.            (line 148)
* Extend:                                Extend.              (line   6)
* Extended <1>:                          Real Types.          (line   6)
* Extended:                              Extended.            (line   6)
* Extended Pascal:                       Resources.           (line 107)
* external <1>:                          Keywords.            (line 151)
* external <2>:                          Importing Libraries from Other Languages.
                                                              (line   6)
* external:                              external.            (line   6)
* Fail:                                  Fail.                (line   6)
* False:                                 False.               (line   6)
* FAQ:                                   FAQ.                 (line   6)
* far <1>:                               far.                 (line   6)
* far:                                   Keywords.            (line 154)
* far, internals:                        forward near far.    (line   6)
* file <1>:                              file.                (line   6)
* file:                                  Keywords.            (line 157)
* File layout, internals:                File Layout.         (line   6)
* File Types, Intrinsic, Data Types:     File Types.          (line   6)
* FilePos:                               FilePos.             (line   6)
* files, operations:                     File Routines.       (line   6)
* FileSize:                              FileSize.            (line   6)
* FileUtils:                             FileUtils.           (line   6)
* FillChar:                              FillChar.            (line   6)
* finalization <1>:                      finalization.        (line   6)
* finalization:                          Keywords.            (line 160)
* Finalize:                              Finalize.            (line   6)
* finally <1>:                           finally.             (line   6)
* finally:                               Keywords.            (line 163)
* Flush:                                 Flush.               (line   6)
* for <1>:                               for.                 (line   6)
* for:                                   Keywords.            (line 166)
* for, Statements, Source Structure:     for Statement.       (line   6)
* FormatString <1>:                      I18N.                (line   6)
* FormatString:                          FormatString.        (line   6)
* forward <1>:                           Keywords.            (line 169)
* forward:                               forward.             (line   6)
* forward, internals:                    forward near far.    (line   6)
* Frac:                                  Frac.                (line   6)
* FrameAddress:                          FrameAddress.        (line   6)
* Free Software:                         GNU.                 (line   6)
* Freedom <1>:                           Copying.             (line   6)
* Freedom <2>:                           Library Copying.     (line   6)
* Freedom:                               Resources.           (line 149)
* FreeMem <1>:                           Memory Management Routines.
                                                              (line   6)
* FreeMem:                               FreeMem.             (line   6)
* Frequently Asked Questions:            FAQ.                 (line   6)
* front-end, internals <1>:              Syntax parsing.      (line   6)
* front-end, internals:                  Tree nodes.          (line   6)
* function <1>:                          Keywords.            (line 172)
* function:                              function.            (line   6)
* function, Subroutine Declaration, Source Structure: The Function.
                                                              (line   6)
* functional type:                       Procedural Types.    (line   6)
* functions as parameters, internals:    Parameter passing.   (line  20)
* functions, predefined:                 Library Routines.    (line   6)
* GDBM:                                  Resources.           (line  71)
* GE:                                    GE.                  (line   6)
* General Public License:                Copying.             (line   6)
* GEPad:                                 GEPad.               (line   6)
* German:                                Resources.           (line  84)
* Get <1>:                               File Routines.       (line   6)
* Get:                                   Get.                 (line   6)
* GetMem <1>:                            Memory Management Routines.
                                                              (line   6)
* GetMem:                                GetMem.              (line   6)
* GetText:                               I18N.                (line   6)
* gettext:                               Resources.           (line  65)
* GetTimeStamp <1>:                      Date And Time Routines.
                                                              (line   6)
* GetTimeStamp:                          GetTimeStamp.        (line   6)
* gmp:                                   Libraries.           (line   6)
* GMP:                                   GMP.                 (line   6)
* GNU DBM:                               Resources.           (line  71)
* GNU General Public License:            Copying.             (line   6)
* GNU Lesser General Public License:     Library Copying.     (line   6)
* GNU Library General Public License:    Library Copying.     (line   6)
* GNU Pascal command line options:       Invoking GPC.        (line   6)
* GNU, project:                          GNU.                 (line   6)
* goto <1>:                              Keywords.            (line 175)
* goto:                                  goto.                (line   6)
* goto, Statements, Source Structure:    goto Statement.      (line   6)
* GPC and other languages:               Other Languages.     (line   6)
* GPC source, internals:                 Internals.           (line   6)
* GPC, internals:                        Internals.           (line   6)
* GPCUtil:                               GPCUtil.             (line   6)
* GPI files, internals:                  GPI files.           (line   6)
* GPL:                                   Copying.             (line   6)
* grammar, internals:                    Syntax parsing.      (line   6)
* Graphics:                              Resources.           (line  54)
* GRX:                                   Resources.           (line  54)
* GT:                                    GT.                  (line   6)
* GTK:                                   Resources.           (line  78)
* GTPad:                                 GTPad.               (line   6)
* GUI:                                   Resources.           (line  78)
* Halt:                                  Halt.                (line   6)
* HeapMon:                               HeapMon.             (line   6)
* help:                                  Support.             (line   6)
* High:                                  High.                (line   6)
* highlights:                            Highlights.          (line   6)
* HTTP:                                  Download.            (line   6)
* I18N:                                  I18N.                (line   6)
* IDE <1>:                               IDE.                 (line   6)
* IDE:                                   Resources.           (line  47)
* if <1>:                                Keywords.            (line 178)
* if:                                    if.                  (line   6)
* if, Statements, Source Structure:      if Statement.        (line   6)
* Im <1>:                                Complex Number Operations.
                                                              (line   6)
* Im:                                    Im.                  (line   6)
* implementation <1>:                    Keywords.            (line 181)
* implementation:                        implementation.      (line   6)
* import <1>:                            Keywords.            (line 184)
* import:                                import.              (line   6)
* import part <1>:                       Modules.             (line   6)
* import part:                           Units.               (line   6)
* Import Part, Source Structures:        Modules and Units.   (line   6)
* in <1>:                                Keywords.            (line 187)
* in <2>:                                in.                  (line   6)
* in:                                    Set Operations.      (line   6)
* Inc <1>:                               Operations for Integer and Ordinal Types.
                                                              (line   6)
* Inc:                                   Inc.                 (line   6)
* Include:                               Include.             (line   6)
* Index:                                 Index.               (line   6)
* inherited <1>:                         inherited.           (line   6)
* inherited <2>:                         OOP.                 (line 142)
* inherited:                             Keywords.            (line 191)
* initialization <1>:                    initialization.      (line   6)
* initialization:                        Keywords.            (line 194)
* Initialize:                            Initialize.          (line   6)
* InOutRes:                              InOutRes.            (line   6)
* Input:                                 Input.               (line   6)
* Insert:                                Insert.              (line   6)
* installing binary distributions:       Binary Distributions.
                                                              (line   6)
* installing GNU Pascal:                 Installation.        (line   6)
* installing source distributions:       Compiling GPC.       (line   6)
* Int:                                   Int.                 (line   6)
* Integer:                               Integer.             (line   6)
* Integer types:                         Integer Types.       (line   6)
* integer types, compatibility:          Integer Types and Compatibility.
                                                              (line   6)
* integer types, main branch:            Main Branch Integer Types.
                                                              (line   6)
* integer types, natural:                Natural Integer Types.
                                                              (line   6)
* integer types, specified size:         Integer Types with Specified Size.
                                                              (line   6)
* integer types, summary:                Summary of Integer Types.
                                                              (line   6)
* integer, operations:                   Operations for Integer and Ordinal Types.
                                                              (line   6)
* interface <1>:                         Keywords.            (line 197)
* interface:                             interface.           (line   6)
* interfaces, internals:                 GPI files.           (line   6)
* intermediate code, internals:          Tree nodes.          (line   6)
* Internals:                             Internals.           (line   6)
* Internationalization <1>:              Resources.           (line  65)
* Internationalization:                  I18N.                (line   6)
* interrupt <1>:                         interrupt.           (line   6)
* interrupt:                             Keywords.            (line 200)
* Intl:                                  Intl.                (line   6)
* IOResult:                              IOResult.            (line   6)
* is <1>:                                Keywords.            (line 203)
* is:                                    is.                  (line   6)
* ISO 10206:                             Resources.           (line 107)
* ISO 7185:                              Resources.           (line 107)
* keywords, internals:                   Parsing keywords.    (line   6)
* label <1>:                             label.               (line   6)
* label:                                 Keywords.            (line 206)
* Label Declaration, Source Structures:  Label Declaration.   (line   6)
* language definition, internals:        Syntax parsing.      (line   6)
* LastPosition <1>:                      File Routines.       (line   6)
* LastPosition:                          LastPosition.        (line   6)
* LE:                                    LE.                  (line   6)
* Leave:                                 Leave.               (line   6)
* Length:                                Length.              (line   6)
* LEPad:                                 LEPad.               (line   6)
* Lesser General Public License:         Library Copying.     (line   6)
* Lexer problems, internals:             Lexer problems.      (line   6)
* lexical analyzer, internals:           Lexical analyzer.    (line   6)
* LGPL:                                  Library Copying.     (line   6)
* libraries:                             Libraries.           (line   6)
* Libraries:                             GPC Options.         (line  87)
* library <1>:                           Keywords.            (line 209)
* library:                               library.             (line   6)
* Library General Public License:        Library Copying.     (line   6)
* linking:                               Importing Libraries from Other Languages.
                                                              (line  75)
* Ln <1>:                                Ln.                  (line   6)
* Ln:                                    Complex Number Operations.
                                                              (line   6)
* LoCase:                                LoCase.              (line   6)
* LongBool:                              LongBool.            (line   6)
* LongCard:                              LongCard.            (line   6)
* LongestBool:                           LongestBool.         (line   6)
* LongestCard:                           LongestCard.         (line   6)
* LongestInt:                            LongestInt.          (line   6)
* LongestReal:                           LongestReal.         (line   6)
* LongestWord:                           LongestWord.         (line   6)
* LongInt:                               LongInt.             (line   6)
* LongReal <1>:                          Real Types.          (line   6)
* LongReal:                              LongReal.            (line   6)
* LongWord:                              LongWord.            (line   6)
* Loops, Loop Control Statements:        Loop Control Statements.
                                                              (line   6)
* Low:                                   Low.                 (line   6)
* LT:                                    LT.                  (line   6)
* LTPad:                                 LTPad.               (line   6)
* Machine-dependencies in Types:         Machine-dependencies in Types.
                                                              (line   6)
* magic, internals:                      Tree nodes.          (line 106)
* Mailing List:                          Mailing List.        (line   6)
* Mailing List Archives <1>:             Resources.           (line  99)
* Mailing List Archives:                 Mailing List Archives.
                                                              (line   6)
* main program:                          Importing Libraries from Other Languages.
                                                              (line 103)
* Mark:                                  Mark.                (line   6)
* Max <1>:                               Operations for Integer and Ordinal Types.
                                                              (line   6)
* Max:                                   Max.                 (line   6)
* MaxChar:                               MaxChar.             (line   6)
* MaxInt:                                MaxInt.              (line   6)
* MaxReal:                               MaxReal.             (line   6)
* MD5:                                   MD5.                 (line   6)
* MedBool:                               MedBool.             (line   6)
* MedCard:                               MedCard.             (line   6)
* MedInt:                                MedInt.              (line   6)
* MedReal:                               MedReal.             (line   6)
* MedWord:                               MedWord.             (line   6)
* memory management:                     Memory Management Routines.
                                                              (line   6)
* Min <1>:                               Operations for Integer and Ordinal Types.
                                                              (line   6)
* Min:                                   Min.                 (line   6)
* MinReal:                               MinReal.             (line   6)
* MkDir:                                 MkDir.               (line   6)
* mod <1>:                               mod.                 (line   6)
* mod:                                   Keywords.            (line 212)
* module <1>:                            module.              (line   6)
* module:                                Keywords.            (line 215)
* modules, internals:                    GPI files.           (line   6)
* Modules, source structure:             Modules.             (line   6)
* Move:                                  Move.                (line   6)
* MoveLeft:                              MoveLeft.            (line   6)
* MoveRight:                             MoveRight.           (line   6)
* MS Windows 95/98/NT <1>:               MS Windows 95/98/NT. (line   6)
* MS Windows 95/98/NT:                   Download.            (line 153)
* MS-DOS <1>:                            MS-DOS with DJGPP.   (line   6)
* MS-DOS:                                MS-DOS or OS/2 with EMX.
                                                              (line   6)
* MySQL:                                 Resources.           (line  71)
* name <1>:                              Keywords.            (line 218)
* name <2>:                              name.                (line   6)
* name:                                  Importing Libraries from Other Languages.
                                                              (line   6)
* ncurses <1>:                           Libraries.           (line   6)
* ncurses:                               CRT.                 (line   6)
* NE:                                    NE.                  (line   6)
* near <1>:                              near.                (line   6)
* near:                                  Keywords.            (line 221)
* near, internals:                       forward near far.    (line   6)
* NEPad:                                 NEPad.               (line   6)
* New <1>:                               Memory Management Routines.
                                                              (line   6)
* New <2>:                               OOP.                 (line 148)
* New:                                   New.                 (line   6)
* NewCString:                            NewCString.          (line   6)
* news:                                  News.                (line   6)
* Newsgroups:                            Newsgroups.          (line   6)
* nil <1>:                               nil.                 (line   6)
* nil:                                   Keywords.            (line 224)
* not <1>:                               Operations for Integer and Ordinal Types.
                                                              (line   6)
* not <2>:                               not.                 (line   6)
* not:                                   Keywords.            (line 227)
* Null:                                  Null.                (line   6)
* object <1>:                            Keywords.            (line 230)
* object:                                object.              (line   6)
* Object Types, Data Types:              Object Types.        (line   6)
* object-oriented programming:           OOP.                 (line   6)
* Objects:                               Exporting GPC Libraries to Other Languages.
                                                              (line  26)
* Odd:                                   Odd.                 (line   6)
* of <1>:                                of.                  (line   6)
* of:                                    Keywords.            (line 233)
* on <1>:                                Keywords.            (line 239)
* on:                                    on.                  (line   6)
* only <1>:                              Keywords.            (line 242)
* only:                                  only.                (line   6)
* OOP:                                   OOP.                 (line   6)
* operations, complex numbers:           Complex Number Operations.
                                                              (line   6)
* operations, files:                     File Routines.       (line   6)
* operations, integer and ordinal:       Operations for Integer and Ordinal Types.
                                                              (line   6)
* operations, sets:                      Set Operations.      (line   6)
* operations, string:                    String Operations.   (line   6)
* operator <1>:                          operator.            (line   6)
* operator:                              Keywords.            (line 245)
* operator, Subroutine Declaration, Source Structure: The Operator.
                                                              (line   6)
* Operators:                             Operators.           (line   6)
* operators, built-in:                   Built-in Operators.  (line   6)
* operators, user-defined:               User-defined Operators.
                                                              (line   6)
* options, command line:                 Invoking GPC.        (line   6)
* or <1>:                                or.                  (line   6)
* or <2>:                                Operations for Integer and Ordinal Types.
                                                              (line   6)
* or:                                    Keywords.            (line 248)
* or else:                               or else.             (line   6)
* or_else <1>:                           or_else.             (line   6)
* or_else:                               Keywords.            (line 252)
* Ord:                                   Ord.                 (line   6)
* Ordinal Types, Intrinsic, Data Types:  Ordinal Types.       (line   6)
* ordinal, operations:                   Operations for Integer and Ordinal Types.
                                                              (line   6)
* OS/2:                                  MS-DOS or OS/2 with EMX.
                                                              (line   6)
* otherwise <1>:                         Keywords.            (line 255)
* otherwise:                             otherwise.           (line   6)
* Output:                                Output.              (line   6)
* output file option:                    GPC Options.         (line  62)
* Overlay:                               Overlay.             (line   6)
* overload <1>:                          Keywords.            (line 259)
* overload:                              overload.            (line   6)
* override <1>:                          override.            (line   6)
* override:                              Keywords.            (line 262)
* Pack:                                  Pack.                (line   6)
* packed <1>:                            packed.              (line   6)
* packed:                                Keywords.            (line 265)
* Page:                                  Page.                (line   6)
* PAnsiChar:                             PAnsiChar.           (line   6)
* ParamCount <1>:                        ParamCount.          (line   6)
* ParamCount:                            Accessing Command Line Arguments.
                                                              (line   6)
* Parameter List, Subroutine Declaration, Source Structure: Subroutine Parameter List Declaration.
                                                              (line   6)
* parameter passing, internals:          Parameter passing.   (line   6)
* parameter, protected:                  Protected Parameters.
                                                              (line   6)
* ParamStr <1>:                          ParamStr.            (line   6)
* ParamStr:                              Accessing Command Line Arguments.
                                                              (line   6)
* parser, internals:                     Syntax parsing.      (line   6)
* parsing, internals:                    Parsing keywords.    (line   6)
* Pascal standards:                      Resources.           (line 107)
* Pascal, Blaise:                        Resources.           (line  12)
* Patents:                               Resources.           (line 149)
* PChar:                                 PChar.               (line   6)
* PDCurses <1>:                          CRT.                 (line   6)
* PDCurses:                              Libraries.           (line   6)
* PENG <1>:                              IDE.                 (line  13)
* PENG:                                  Resources.           (line  31)
* Pi:                                    Pi.                  (line   6)
* Pipes:                                 Pipes.               (line   6)
* Planned features, internals:           Planned.             (line   6)
* PObjectType:                           PObjectType.         (line   6)
* Pointer:                               Pointer.             (line   6)
* pointer arithmetics:                   Pointer Arithmetics. (line   6)
* pointer types:                         Pointer Types.       (line   6)
* Pointer, Intrinsic, Data Types:        Pointer (Intrinsic). (line   6)
* Polar <1>:                             Complex Number Operations.
                                                              (line   6)
* Polar:                                 Polar.               (line   6)
* Ports:                                 Ports.               (line   6)
* Pos:                                   Pos.                 (line   6)
* Position <1>:                          File Routines.       (line   6)
* Position:                              Position.            (line   6)
* PostgreSQL:                            Resources.           (line  71)
* pow <1>:                               Keywords.            (line 270)
* pow <2>:                               Complex Number Operations.
                                                              (line   6)
* pow:                                   pow.                 (line   6)
* Pred <1>:                              Operations for Integer and Ordinal Types.
                                                              (line   6)
* Pred:                                  Pred.                (line   6)
* preprocessor:                          Compiler Directives. (line   6)
* preprocessor, internals:               Preprocessor.        (line   6)
* Printer:                               Printer.             (line   6)
* private <1>:                           Keywords.            (line 273)
* private:                               private.             (line   6)
* procedural parameters, internals:      Parameter passing.   (line  20)
* procedural type:                       Procedural Types.    (line   6)
* procedure <1>:                         procedure.           (line   6)
* procedure:                             Keywords.            (line 276)
* Procedure Call, Statements, Source Structure: Procedure Call.
                                                              (line   6)
* procedure, Subroutine Declaration, Source Structure: The Procedure.
                                                              (line   6)
* procedures, predefined:                Library Routines.    (line   6)
* Professional Support:                  Professional Support.
                                                              (line   6)
* program <1>:                           program.             (line   6)
* program:                               Keywords.            (line 279)
* programming in GPC:                    Programming.         (line   6)
* Programs, source structure:            The Program.         (line   6)
* property <1>:                          property.            (line   6)
* property:                              Keywords.            (line 282)
* protected <1>:                         protected.           (line   6)
* protected <2>:                         Importing Libraries from Other Languages.
                                                              (line  96)
* protected:                             Keywords.            (line 285)
* protected, parameter:                  Protected Parameters.
                                                              (line   6)
* PtrCard:                               PtrCard.             (line   6)
* PtrDiffType:                           PtrDiffType.         (line   6)
* PtrInt:                                PtrInt.              (line   6)
* PtrWord:                               PtrWord.             (line   6)
* public <1>:                            public.              (line   6)
* public:                                Keywords.            (line 289)
* published <1>:                         Keywords.            (line 292)
* published:                             published.           (line   6)
* Put <1>:                               Put.                 (line   6)
* Put:                                   File Routines.       (line   6)
* qualified <1>:                         Keywords.            (line 295)
* qualified:                             qualified.           (line   6)
* Questions, Frequently Asked:           FAQ.                 (line   6)
* raise <1>:                             raise.               (line   6)
* raise:                                 Keywords.            (line 298)
* Random:                                Random.              (line   6)
* Randomize:                             Randomize.           (line   6)
* Re <1>:                                Complex Number Operations.
                                                              (line   6)
* Re:                                    Re.                  (line   6)
* Read:                                  Read.                (line   6)
* ReadLn:                                ReadLn.              (line   6)
* ReadStr:                               ReadStr.             (line   6)
* Real <1>:                              Real.                (line   6)
* Real:                                  Real Types.          (line   6)
* record <1>:                            record.              (line   6)
* record:                                Keywords.            (line 301)
* Record Types, Data Types:              Record Types.        (line   6)
* record, variant:                       Variant Records.     (line   6)
* Redistribution <1>:                    Library Copying.     (line   6)
* Redistribution:                        Copying.             (line   6)
* RegEx:                                 RegEx.               (line   6)
* Release:                               Release.             (line   6)
* Rename:                                Rename.              (line   6)
* repeat <1>:                            repeat.              (line   6)
* repeat:                                Keywords.            (line 304)
* repeat, Statements, Source Structure:  repeat Statement.    (line   6)
* Reporting Bugs:                        Reporting Bugs.      (line   6)
* Reset:                                 Reset.               (line   6)
* resident <1>:                          resident.            (line   6)
* resident:                              Keywords.            (line 307)
* Resources:                             Resources.           (line   6)
* restricted <1>:                        restricted.          (line   6)
* restricted:                            Keywords.            (line 310)
* Result:                                Result.              (line   6)
* Return:                                Return.              (line   6)
* ReturnAddress:                         ReturnAddress.       (line   6)
* Rewrite:                               Rewrite.             (line   6)
* RHIDE <1>:                             IDE.                 (line  18)
* RHIDE:                                 Resources.           (line  39)
* RmDir:                                 RmDir.               (line   6)
* Round:                                 Round.               (line   6)
* routines, predefined:                  Library Routines.    (line   6)
* Run Time Library <1>:                  Run Time System.     (line   6)
* Run Time Library:                      Library Routines.    (line   6)
* Run Time System <1>:                   Run Time System.     (line   6)
* Run Time System:                       Library Routines.    (line   6)
* RunError:                              RunError.            (line   6)
* rx <1>:                                Libraries.           (line   6)
* rx:                                    RegEx.               (line   6)
* schema parameters, internals:          Parameter passing.   (line  32)
* schemata:                              Schema Types.        (line   6)
* Seek:                                  Seek.                (line   6)
* SeekEOF:                               SeekEOF.             (line   6)
* SeekEOLn:                              SeekEOLn.            (line   6)
* SeekRead <1>:                          File Routines.       (line   6)
* SeekRead:                              SeekRead.            (line   6)
* SeekUpdate <1>:                        SeekUpdate.          (line   6)
* SeekUpdate:                            File Routines.       (line   6)
* SeekWrite <1>:                         File Routines.       (line   6)
* SeekWrite:                             SeekWrite.           (line   6)
* segment <1>:                           segment.             (line   6)
* segment:                               Keywords.            (line 313)
* Self:                                  Self.                (line   6)
* set <1>:                               Keywords.            (line 316)
* set:                                   set.                 (line   6)
* Set Types, Data Types:                 Set Types.           (line   6)
* SetFileTime:                           SetFileTime.         (line   6)
* SetLength:                             SetLength.           (line   6)
* sets, operations:                      Set Operations.      (line   6)
* SetType:                               SetType.             (line   6)
* shl <1>:                               Operations for Integer and Ordinal Types.
                                                              (line   6)
* shl <2>:                               Keywords.            (line 319)
* shl:                                   shl.                 (line   6)
* ShortBool:                             ShortBool.           (line   6)
* ShortCard:                             ShortCard.           (line   6)
* ShortInt:                              ShortInt.            (line   6)
* ShortReal <1>:                         ShortReal.           (line   6)
* ShortReal:                             Real Types.          (line   6)
* ShortWord:                             ShortWord.           (line   6)
* shr <1>:                               Keywords.            (line 322)
* shr <2>:                               shr.                 (line   6)
* shr:                                   Operations for Integer and Ordinal Types.
                                                              (line   6)
* Sin <1>:                               Complex Number Operations.
                                                              (line   6)
* Sin:                                   Sin.                 (line   6)
* Single <1>:                            Real Types.          (line   6)
* Single:                                Single.              (line   6)
* SizeOf:                                SizeOf.              (line   6)
* SizeType:                              SizeType.            (line   6)
* Slice access:                          String Slice Access. (line   6)
* SmallInt:                              SmallInt.            (line   6)
* Software patents:                      Resources.           (line 149)
* source distributions, installing:      Compiling GPC.       (line   6)
* source structures:                     Source Structures.   (line   6)
* source, internals:                     Internals.           (line   6)
* Sqr <1>:                               Sqr.                 (line   6)
* Sqr:                                   Complex Number Operations.
                                                              (line   6)
* SqRt <1>:                              Complex Number Operations.
                                                              (line   6)
* SqRt:                                  SqRt.                (line   6)
* Standard Pascal:                       Resources.           (line 107)
* standard units:                        GPC Units.           (line   6)
* StandardError:                         StandardError.       (line   6)
* StandardInput:                         StandardInput.       (line   6)
* StandardOutput:                        StandardOutput.      (line   6)
* Standards:                             Resources.           (line 107)
* Statements, Source Structures:         Statements.          (line   6)
* StdErr:                                StdErr.              (line   6)
* Str:                                   Str.                 (line   6)
* String:                                String.              (line   6)
* string parameters, internals:          Parameter passing.   (line  32)
* String, Intrinsic, Data Types:         String Types.        (line   6)
* string, slice access:                  String Slice Access. (line   6)
* String2CString:                        String2CString.      (line   6)
* Strings:                               Strings.             (line   6)
* strings, operations:                   String Operations.   (line   6)
* StringUtils:                           StringUtils.         (line   6)
* subrange types:                        Subrange Types.      (line   6)
* Subroutine Declaration, Source Structures: Subroutine Declaration.
                                                              (line   6)
* SubStr:                                SubStr.              (line   6)
* Succ <1>:                              Succ.                (line   6)
* Succ:                                  Operations for Integer and Ordinal Types.
                                                              (line   6)
* support:                               Support.             (line   6)
* Support, professional:                 Professional Support.
                                                              (line   6)
* syntax conflicts, internals:           Parsing conflicts.   (line   6)
* Syntax parsing, internals:             Syntax parsing.      (line   6)
* System:                                System.              (line   6)
* SysUtils:                              Resources.           (line  90)
* team:                                  Acknowledgments.     (line   6)
* Test Suite, Running:                   Testing.             (line   6)
* Test Suite, writing tests:             Reporting Bugs.      (line   6)
* Text <1>:                              Text.                (line   6)
* Text:                                  File Types.          (line   6)
* Text editor:                           Resources.           (line  31)
* TFDD <1>:                              TFDDs.               (line   6)
* TFDD:                                  TFDD.                (line   6)
* then <1>:                              then.                (line   6)
* then:                                  Keywords.            (line 325)
* Time <1>:                              Time.                (line   6)
* Time:                                  Date And Time Routines.
                                                              (line   6)
* TimeStamp:                             TimeStamp.           (line   6)
* to <1>:                                Keywords.            (line 329)
* to:                                    to.                  (line   6)
* to begin do:                           to begin do.         (line   6)
* to end do:                             to end do.           (line   6)
* Trap:                                  Trap.                (line   6)
* tree nodes, internals:                 Tree nodes.          (line   6)
* Trim:                                  Trim.                (line   6)
* True:                                  True.                (line   6)
* Trunc:                                 Trunc.               (line   6)
* Truncate:                              Truncate.            (line   6)
* try <1>:                               try.                 (line   6)
* try:                                   Keywords.            (line 334)
* Turbo3:                                Turbo3.              (line   6)
* type <1>:                              Keywords.            (line 337)
* type:                                  type.                (line   6)
* type casts:                            Type Casts.          (line   6)
* Type Declaration, Source Structures:   Type Declaration.    (line   6)
* Type Definition Possibilities:         Type Definition Possibilities.
                                                              (line   6)
* type of:                               type of.             (line   6)
* typeless parameters, internals:        Parameter passing.   (line  50)
* TypeOf:                                TypeOf.              (line   6)
* types, functional:                     Procedural Types.    (line   6)
* types, initializers:                   Type Initializers.   (line   6)
* types, Integer:                        Integer Types.       (line   6)
* types, pointer:                        Pointer Types.       (line   6)
* types, procedural:                     Procedural Types.    (line   6)
* types, real:                           Real Types.          (line   6)
* types, restricted:                     Restricted Types.    (line   6)
* types, schema:                         Schema Types.        (line   6)
* types, schemata:                       Schema Types.        (line   6)
* types, subrange:                       Subrange Types.      (line   6)
* types, variant records:                Variant Records.     (line   6)
* Unbind <1>:                            File Routines.       (line   6)
* Unbind:                                Unbind.              (line   6)
* unit <1>:                              unit.                (line   6)
* unit:                                  Keywords.            (line 341)
* units, contributed:                    Contributed units.   (line   6)
* units, included with GPC:              GPC Units.           (line   6)
* units, internals:                      GPI files.           (line   6)
* Units, source structure:               Units.               (line   6)
* Unpack:                                Unpack.              (line   6)
* until <1>:                             Keywords.            (line 344)
* until:                                 until.               (line   6)
* untyped files:                         File Types.          (line   6)
* untyped parameters, internals:         Parameter passing.   (line  50)
* UpCase:                                UpCase.              (line   6)
* Update <1>:                            Update.              (line   6)
* Update:                                File Routines.       (line   6)
* uses <1>:                              Keywords.            (line 347)
* uses:                                  uses.                (line   6)
* Val:                                   Val.                 (line   6)
* value <1>:                             Keywords.            (line 350)
* value:                                 value.               (line   6)
* var <1>:                               var.                 (line   6)
* var:                                   Keywords.            (line 353)
* var, Statements, Source Structure:     The Declaring Statement.
                                                              (line   6)
* Variable Declaration, Source Structures: Variable Declaration.
                                                              (line   6)
* view <1>:                              view.                (line   6)
* view:                                  Keywords.            (line 356)
* virtual <1>:                           Keywords.            (line 359)
* virtual:                               virtual.             (line   6)
* VMT:                                   Exporting GPC Libraries to Other Languages.
                                                              (line  26)
* Void:                                  Void.                (line   6)
* web site:                              Download.            (line   6)
* while <1>:                             while.               (line   6)
* while:                                 Keywords.            (line 362)
* while, Statements, Source Structure:   while Statement.     (line   6)
* WinDos:                                WinDos.              (line   6)
* Windows 95/98/NT, MS <1>:              Download.            (line 144)
* Windows 95/98/NT, MS:                  MS Windows 95/98/NT. (line   6)
* with <1>:                              with.                (line   6)
* with:                                  Keywords.            (line 365)
* with, Statements, Source Structure:    with Statement.      (line   6)
* Word:                                  Word.                (line   6)
* WordBool:                              WordBool.            (line   6)
* Write:                                 Write.               (line   6)
* WriteLn:                               WriteLn.             (line   6)
* WriteStr:                              WriteStr.            (line   6)
* WWW:                                   Download.            (line   6)
* xemacs:                                IDE.                 (line   9)
* xor <1>:                               Keywords.            (line 368)
* xor <2>:                               xor.                 (line   6)
* xor:                                   Operations for Integer and Ordinal Types.
                                                              (line   6)
* xwpe:                                  IDE.                 (line  27)



Tag Table:
Node: Top1485
Node: Welcome3345
Node: Highlights8543
Node: News20566
Node: FAQ35923
Node: GNU Pascal36614
Node: What and why36981
Node: Current version38901
Node: Turbo Pascal compatibility39788
Node: Supported platforms40663
Node: Installing GPC42182
Node: Documentation files42927
Node: Components43485
Node: Debugger44123
Node: Libraries46107
Node: Contributed units50106
Node: IDE50434
Node: GPC on DJGPP51688
Node: What is DJGPP52607
Node: DJGPP FAQ53149
Node: DJGPP download53640
Node: Installing GPC on DJGPP54361
Node: DJGPP Info reader56334
Node: DJGPP DPMI server56654
Node: Assembler syntax57089
Node: DJGPP specific code58593
Node: Stack size60981
Node: Strings in GPC62649
Node: String schema63195
Node: Strings in variant records64153
Node: Length byte66120
Node: Strings as value parameters66906
Node: Short strings67694
Node: C strings68614
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Node: Miscellaneous FAQ70820
Node: Contributing71088
Node: GPC web site71349
Node: About the FAQ71720
Node: Installation72521
Node: Download73062
Node: Binary Distributions78575
Node: Compiling GPC81203
Node: Compilation Notes91704
Node: MS-DOS with DJGPP92137
Node: MS-DOS or OS/2 with EMX93124
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Node: Cross-Compilers94452
Node: Crossbuilding95862
Node: Invoking GPC96704
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Node: -w - disable all warnings587319
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Node: -D__BP_RANDOM__ - BP compatible pseudo random number generator589745
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Node: Typed Constants607477
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Node: BP Procedural Types616349
Node: Files618296
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End Tag Table
