### From The `sfront` Reference Manual by John Lazzaro and John Wawrzynek.

# Part I/6: Change Log and License

## Sections

- Change Log. Documents each sfront release.
- Sfront License. Copyright and license for sfront source code.
- Summary.

## Change Log

The right panel documents the changes made in each sfront release.

## Change Log

`

    Version 0.89 -- 6/18/05 (download)

    [1] Source code changes to eliminate
    new warning messages from gcc 4.0.0.

    [2] Changes to sfront networking code
    to match the latest RTP MIDI changes
    (draft-ietf-avt-rtp-midi-format-09.txt).

    Version 0.88 -- 12/26/04

    [1] Networking updated to match
    draft-ietf-avt-rtp-midi-format-07.

       Chapter M fields for A-BUTTON
       and C-BUTTON use new G bit layout
       and compute count for large values
       correctly.

       Sender supports the oldest-first
       log ordering for Chapters E/A/N.

       Sender supports new Chapter Q
       coding rule Start and Continue
       commands.

       SDP sent in SIP INVITEs uses
       rtp_maxptime and rtp_ptime, and
       uses correct SDP syntax.

    [2] The -sip_ip parameter now parses
    dotted-quads correctly.

    [2] Memory management bugs fixed
    (thanks to Graydon Hoare).

    [3] Correct value for PI used in
    code examples, book (thanks to
    Tiaan Geldenhuys).

    Version 0.87 -- 10/15/04

    [1] Networking knows the
    new IP number of the
    Berkeley SIP server.

    [2] Compilation times of
    Mac OS X are improved.

    Version 0.86 -- 4/24/04

    [1] Networking now conforms
    to the RTP payload format for
    MIDI under development in the
    Audio/Video Transport group
    of the Internet Engineering
    Task Force.

    [2] The download page no longer
    offers RedHat or Debian packages,
    because I no longer have root access
    to a desktop Linux workstation to
    build and test packages.  However,
    the official Debian package for
    sfront 0.85 still exists, and will
    hopefully be updated to 0.86.

    [3] Several minor bugfixes.

    Version 0.85 -- 9/13/02

    [1] Mac OS X support for
    real-time MIDI control,
    using the -cin coremidi
    control driver. Up to four
    external MIDI sources are
    recognized. Virtual sources
    are ignored; expect virtual
    source support in a future
    release.

    [2] Mac OS X memory locking
    now works in normal user
    processes, and is no longer
    limited to root.

    Version 0.84 -- 8/29/02

    [1] CoreAudio I/O now
    works correctly under
    Mac OS X 10.2 (Jaguar).
    Thanks to Juno.

    [2] Large -latency values
    no longer hang CoreAudio;
    documentation for -latency
    option is now accurate for
    CoreAudio. Thanks to Manfred
    Brockhaus.

    [3] Sfront networking now
    works under Mac OS X,
    including PPP and DHCP.

    Version 0.83 -- 8/11/02

    [1] Low-latency audio
    output and input now
    supported for Mac OS X
    using CoreAudio.
    Developed on a TiBook
    under 10.1.5; please
    send reports for other
    platforms. Thanks to
    coreaudio-api and
    darwin mailing list
    members for extensive
    API help.

    [2] Compile-time
    warnings under
    Visual C++ fixed.
    Thanks to Kees van
    Prooijen.

    Version 0.82 -- 7/23/02

    [1] Bugfixes for large
    spline and cubicseg
    wavetables, and for
    polymorphic opcodes
    used in wavetables.
    Thanks to Michael B.

    [2] SIP server IP
    numbers updated for
    sfront networking. To
    use earlier sfront
    versions with the
    new SIP server, add

    -sip_ip 128.32.112.203

    to the sfront command
    line.

    Version 0.81 -- 5/24/02

    [1] Bugfixes for sfront
    code generation and for
    the SLib library. Thanks
    to Manfred Brockhaus and
    Michael McGonagle.

    Version 0.80 -- 5/08/02

    [1] Sfront complies with
    the MPEG 4 Structured
    Audio COR2 Corrigenda
    (March 2002). See this
    guide to COR2 changes
    for more details.

    [2] The MP4-SA book is
    now licensed under
    the GNU Free Documentation
    License, and is bundled
    with all versions of the
    sfront distribution.

    [3] Many bugfixes.

    Version 0.79 -- 11/04/01

    [1] Performance tuning for
    audio streaming under Mac
    OS X. Thanks to Richard
    Dobson and Robert.

    Version 0.78 -- 10/23/01

    [1] Sfront buffer overflow
    bugfix, caused fatal errors
    under Mac OS X. Thanks to
    Robert.

    Version 0.77 -- 10/12/01

    [1] New mac_carbon
    audio driver for Mac OS X,
    using the Carbon framework.
    Bugfixes for Windows WMME
    and DirectSound drivers.
    Thanks to portaudio.com,
    Phil Burk, Richard Dobson,
    and Dominic Mazzoni.

    Version 0.76 -- 9/23/01

    [1] Enhanced audio
    driver API to support
    soundcard APIs that
    require callback functions.

    [2] New ps_win_wmme
    and ps_win_ds audio
    drivers for Windows
    WMME and DirectSound APIs.
    Thanks to the PortAudio
    team, and testers Richard
    Dobson, Peter Maas, Kees van
    Prooijen, and Tim Thompson.

    [3] Audio drivers now control
    default time option selection.

    [4] Many bugfixes in
    SAOL audio bus system.
    Thanks to Robert Sherry.

    Version 0.75 -- 8/13/01

    [0] Sfront networking
    now works well with DHCP,
    otherwise unchanged from
    sfront 0.74. Thanks to
    Mike McGonagle.

    Version 0.74 -- 8/04/01

    [1] First release for
    sfront networking.

    [2] Audio driver for Irix
    (6.2 and above). Thanks
    to Michael Pruett (SGI).

    [3] The sfront manual is
    now under the GFDL, for
    Debian compatibility.
    Thanks to Enrique Arnuncio
    for help with the Debian
    issues. Note the MP4-SA
    book license is unchanged.

    [4] New SAOL resonant
    physical model library.
    See examples/bach and
    several examples/linux
    files for SAOL produced
    by the library, and see
    sfront/lib/reson/README
    for library details.

    [5] Many bug fixes,
    thanks to Robert Sherry,
    Michael McGonagle, and
    Kees van Prooijen.

    Version 0.72 -- 7/10/01

    [1] The -cin ascii control
    driver has been rewritten:
    it maps the ASCII keyboard
    as a two-octave pentatonic
    scale, with fixed note length.
    Special keys control MIDI
    presets and channel volume.
    Tested under Linux, should
    work on any OS that supports
    the termios API.

    [2] Sfront now fully tested
    under Mac OS X version 10.0.3.
    Work on Mac OS 9.1 under MPW
    has yet to resolve problems
    related to sample file and
    MIDI file reading, and so OS
    X is the most viable option for
    sfront Mac OS users. Thanks to
    Manfred Brockhaus.

    [3] Numerous bug fixes: variable
    length core opcodes work in
    oparrays, the && and || operators
    work for vectors, unused exports
    signal variables work correctly,
    several audio-bus errors fixed, SASL
    labelled control statements access
    multiple instrs correctly, large
    constant integer values correctly
    supported. Thanks to Robert Sherry
    and Axel Nackaerts.

    Version 0.71 -- 3/29/01

    [1] Bugfixes for user-defined
    opcodes that use slower-rate
    statements. Thanks to Robert
    Sherry and Robin Davies.

    Version 0.70 -- 2/20/01

    [0] Added MPW-related
    bugfix -- otherwise
    identical to 0.69, whose
    change-log items are
    listed below.

    [1] Sfront is compliant
    with the COR1 document,
    a new MPEG Corrigenda that
    updates the SAOL language.
    See this appendix of the
    MP4-SA Book to learn about
    the SAOL changes in COR1.

    [2] New alsaseq control driver
    written by Enrique Robledo
    Arnuncio, for MIDI control
    using the Linux ALSA sequencer.

    [3] Many bug fixes, including
    compliant global parameter
    krate determination when
    srate/krate is non-integral
    (thanks to Ross Bencina),
    Macintosh MPW compilation
    fixes (thanks to BUYO-BUYO-
    IGOR).

    Version 0.68 -- 10/28/00

    [1] C code generated for
    MIDI control now compiles
    faster.

    [2] Many contributed bug
    fixes, thanks to Kees van
    Prooijen, Richard Dobson,
    the saol.net folks, and M.
    Edward Borasky.

    Version 0.67 -- 09/09/00

    [0] Another bugfix for
    Windows sfront.dsp file
    (thanks to Kees van Prooijen).
    Rest of items unchanged
    since 0.65.

    [1] C code generated for
    SAOL and SASL wavetables
    compiles much quicker and
    runs with improved cache
    behavior. C code created
    for the "sample" wavetable
    generator no longer includes
    an WAV or AIFF parser,
    and moderately-sized constant
    tables for all generators are
    computed by sfront and placed
    into the sa.c file as constant
    float arrays. On some machine/
    compiler configurations,
    the sfront -hexdata flag
    offers additional compilation
    speedup, by encoding arrays
    as hexadecimal strings.

    [2] C code generated for
    wide oparrays compiles much
    quicker and runs with improved
    cache behavior (thanks to
    Richard Dobson).

    [3] Many sa.c memory leaks
    involving wavetables have
    been fixed, reducing the
    working memory space of
    table-intensive programs.

    [4] Bugfixes involving the
    dur standard name (thanks to
    Tobiah), empty opcode
    return() statements (thanks
    to Ross Bencina), name
    space collisions (thanks to
    Aaron Finch), oparrays, and
    wavetables.

    Version 0.64 -- 08/02/00

    [1] Optimizations for
    accessing global variables
    (via import/export) and
    opcode parameters, to
    eliminate unneeded copying.
    Programs that use these
    language features extensively
    should see significiant
    speedups (thanks to Dave
    Gillepsie).

    [2] Linux rpm and deb binary
    packages now available for
    download (thanks to Enrique
    Arnuncio and Joey Hess).

    [3] Bugfixes for fft/ifft
    shift-and-add mode (a
    startup artifact was
    eliminated, and an boxcar
    windowed fft/ifft pair
    has unity gain, thanks to
    Richard Dobson).

    [4] Bug fixes for ANSI
    constant compatibility
    (thanks for Aaron Finch)
    and name-space clashes,
    and a null -ain/-aout
    driver added was (thanks
    to Mike McGonagle).

    Version 0.63 -- 07/10/00

    [0] Several cross-platform
    bugfixes (Thanks to Michael
    McGonagle and Richard Dobson).
    Rest of change log from 0.62.

    [1] Standard name cpuload
    is now supported in -playback
    and -timesync mode, for
    all drivers. Cpuload is a
    ksig, that takes on a value
    between 0 (machine is not
    loaded at all) and 1 (any
    further loading of machine
    risks loss of real-time
    playback). Cpuload is
    computed with no temporal
    filtering or windowing,
    and shows the performance
    on the last kcycle.

    [2] The -ain/-aout linux
    and -cin linmidi drivers
    are enhanced. The drivers
    are more robust against
    lockup and MIDI data loss.
    When run as root, the driver
    uses POSIX real-time scheduling
    to reduce audio dropouts
    (while we have carefully
    tested these root features,
    bugs in programs run as root
    can cause file-system damage:
    use at your own risk). Sa.c
    start-up screen now suggests
    the best sfront flags to use
    for a given patch. FreeBSD and
    linux sources are now merged,
    with many of these features
    available for both operating
    systems. Thanks to Paul
    Barton-Davis, Bertrand Petit,
    Benno Senoner, Kai Vehmanen,
    and the folks at saol.net.

    [3] Bugfixes in: memory
    allocation, dsound driver,
    random number generators,
    polymorphic table opcode
    rate semantics, -cin fstr
    file streaming, wavetable
    generator sizing, and
    array parameters in user
    defined opcodes. Thanks
    to Richard Dobson and
    the folks at saol.net.

    Version 0.61 -- 05/28/00

    [1] Sfront is now includes
    Slib, a SAOL library that
    provides support utilities
    to simplify low-level SAOL
    programming. See this new
    chapter of the MP4-SA
    book for details.

    [2] New linux/linbuzz
    example, that shows the
    MIDI features of Slib
    in a real-time instrument.

    [3] New optimization: faster
    execution of expressions like
    tableread(t, int(x)), by
    eliminating interpolation code.

    [4] Bugfixes for the dynamic
    instr command, the outbus command,
    the buzz opcode and wavetable
    generator, specialop expressions,
    opcode table initializations that
    use opcode parameters, send
    statements that target the
    output_bus, and user-defined
    opcode rate warnings.

    Version 0.60 -- 05/07/00

    [0] Minor buzz() opcode
    bugfix -- rest of change
    log describes changes
    between 0.58 and 0.59.

    [1] Rate-semantic printf
    statement implemented,
    and a new book chapter
    on debugging SAOL
    shows how to use it.
    Like all sfront SAOL
    extensions, sfront
    drops printf statements
    as it encodes MP4 files,
    and printf is not a reserved
    word if the -isosyntax
    flag is set. New -isocheck
    flag also helps debugging,
    adding many run-time checks.

    [2] "C pre-processing" of
    SAOL and SASL is now
    integrated into sfront,
    with line-number support
    for error messages, a
    post-processor that strips
    stray semicolons. To support
    library development, sfront
    now supports multiple global
    blocks in a program. Thanks
    to Michael McGonagle.

    [3] MIDI controller,
    aftertouch, and pitch
    bend information is now
    visible to effects and
    SASL instruments. See
    this book section
    for details. Thanks to
    Robin Davies and saol.net.

    [4] Support added to
    querying audio input
    sources for sample rate
    and channel width of
    input_bus, if not
    specified in global block.

    [5] Control drivers can
    now control BIFS variables
    (including params[]) as
    accessed by SAOL code.

    [6] Bug fixes: expressions
    used in array/opcode/table
    indexing now executed just
    once (formerly done twice
    due to buggy rounding code),
    buzz opcode now works for
    large rolloff and nharm
    values, user-defined opcode
    calls in the global block
    now work correctly, recursive
    opcode calls generate an
    error message, Kaiser window
    table generator bugs fixed.
    Many bugs in MIDI File
    support fixed (thanks to
    saol.net.)

    Version 0.58 -- 04/17/00

    [1] The control driver
    API has been improved.
    It can now support
    compliant execution of
    MP4 SA_access_units,
    as well as patch editor,
    CLI, and symbolic debug
    applications. It
    includes many data
    structures that let
    the control driver
    discover information
    about the SAOL and SASL
    files used to generate
    the sa.c it lives in.

    [2] The programers
    manual for sfront has
    been reworked, and now
    includes an introductory
    section that explains
    how to use sfront from
    other programs, and a
    multi-part manual
    on the control driver
    interface.

    [3] A file streaming
    control driver has
    been written to
    demonstrate the new
    API. It opens an MP4
    file during the start
    of sa.c execution,
    seeks past the config
    section, and then
    dynamically executes
    SA_access_unit stream
    packets. It contains
    much of the codebase
    needed for true
    MP4-SA network streamer.

    [4] The spline wavetable
    generator was described
    incorrectly in the MP4-SA
    book, and implemented
    incorrectly in sfront.
    Both book and program
    are now fixed. See this
    book section for the
    correct syntax (page down
    to the spline generator).

    [5] SAOL random opcodes
    now produce a different
    random number stream on
    each sa.c run. New
    -fixedseed sfront option
    simplifies SAOL program
    testing, by making all
    random opcodes produce a
    deterministic number stream
    on every sa.c run.
    Thanks to Martin Marier and
    Michael McGonagle.

    [6] Many bugs were
    fixed. Most bugs were
    in SASL and SAOL wave
    table generator code,
    and in the control
    driver code. Bugs were
    also fixed in the
    linmidi driver.

    Version 0.57 -- 03/8/00

    [0] Windows distribution
    issues, and several bugs,
    that were found in 0.56
    are fixed -- thanks to
    Daniel Kahlin, Michael
    McGonagle, Kees van
    Prooijen, and Richard
    Dobson. Remaining change
    log entries are carried
    over from 0.56.

    [1] The -bit option now
    reads SA files that have
    streaming data (i.e.
    SA_access_units). All
    event_types are supported
    (SASL score_lines, MIDI
    midi_events, and the sample
    type for table data). SASL
    score_lines that use both
    relative and absolute
    timestamps can be read
    (i.e. has_time = 0 and 1).

    [2] The -bitout option now
    writes binary files that
    include SA_access_units.
    The new

    -sstrout filename.sasl
    -mstrout filename.mid

    options specify the SASL and
    MIDI files for encoding as
    SA_access_units. Files
    specified using the older
    options:

    -sco filename.sasl
    -midi filename.mid

    are encoded as part of the
    preamble of the binary file
    (StructuredAudioSpecificConfig)
    as before. If SASL table
    commands are used with the
    sample wavetable generator,
    the WAV or AIFF file specified
    becomes a streaming sample
    chunk.

    [3] Bug fixes: skip and size
    fields work correctly in
    sample wavetable generator
    (thanks to Bertrand Petit),
    bugs in dynamic instrs fixed
    (thanks to Michael McGonagle),
    bugs in the AIFF audio input
    driver fixed.

    [4] Default help printout
    shortened (-help prints out
    the longer option listing).

    Version 0.55 -- 02/12/00

    [1] Base frequency and loop
    points can be read by the
    sample wavetable generator,
    for both AIFF and WAV files,
    and this looping information
    is correctly captured in .mp4
    files (Thanks to Kees van
    Prooijen).

    [2] SAOL template improvements:
    the restrictions on the use
    of "<" and ">" in maplist
    expressions have been removed,
    many bugs have been fixed, and
    a new template chapter
    in the MP4-SA book is now online.

    [3] Control and audio drivers
    can now access command-line
    options of the program containing
    them, and policy has been set to
    share the command-line-option
    namespace. See the
    audio driver documentation
    and Part III of the control
    driver documentation
    for details. Thanks to Michael
    McGonagle.

    [4] Linux/FreeBSD driver
    enhancements: more soundcards
    are permitted to use -timesync
    mode, and warning messages are
    printed for ill-advised use of
    timing flags.

    [5] Bug fixes: MIDIctrl standard
    name now works as an lval, control
    driver interface bugs fixed (thanks
    to the SAOL Projekt).

    Version 0.54 -- 01/27/00

    [1] The sample wavetable
    generator can now read
    base frequency and loop
    start and end points from
    the smpl chunk of Microsoft
    WAV files (Thanks to Kees
    van Prooijen). MP4 file encoding
    and decoding correctly packs
    and unpacks this data into
    the binary MP4 encoding.
    Bugs handling 8-bit AIFF
    and WAV file data in MP4
    encoding and decoding and
    in sample wavetable generator
    fixed.

    [2] Concat wavetable generator
    bugs fixed.

    [3] Several SAOL and SASL file
    parsing errors fixed (thanks
    to Bertrand Petit and to the
    members of the SAOL Projekt).

    [4] Non-ANSI strdup() calls
    removed from sfront and
    generated code.

    Version 0.53 -- 01/12/00

    [1] Several new optimizations:

       [a] Instr and opcode tables
           generators with constant
           parameters are converted
           to imports tables.

       [b] Instr code in while and
           if-else blocks are now
           rate-optimized (i.e.
           slower subexpressions
           are moved to i-rate or
           k-rate if it is safe to
           do so).

    [2] Audio drivers for FreeBSD
    (thanks to Bertrand Petit).

    [3] New -except sfront option,
    includes a signal handler for
    gracefully shutting down audio
    drivers if generated C program
    terminates abnormally. Compiles
    as vanilla ANSI C, but may not
    work well on non-POSIX systems
    (thanks to Bertrand Petit).

    [4] Divide-by-zero bugs
    fixed in the aline, kline,
    aexpon, and kexpon core
    opcodes (thanks to Bertrand
    Petit). Bugs fixed in table
    and tablemap accesses in
    deeply nested oparrays. Bugs
    fixed in template expression
    substitution.

    [5] New binary distributions
    for Linux and DOS/Windows.
    The DOS/Windows releases
    are built using the
    dos-gcc cross-compiler that
    runs under Linux.

    Version 0.52 -- 01/03/00

    [1] Extensive optimizations
    and bug fixes for the
    filter, spectral analysis,
    gain control, sample
    conversion, delay, and
    effects core opcodes, the
    pluck and grain signal
    generator core opcodes,
    and the spatialize statement.

    [2] All a-rate core opcodes
    now function correctly when
    enclosed in if and while
    statements with a-rate guards
    (thanks to Ross Bencina).

    [3] Runtimef.c file now
    included in lib/csrc/
    directory -- thanks to
    Bertrand Petit.

    Version 0.50 -- 12/17/99

    [1] The code sfront
    generates for wavetable
    data structures has been
    improved, and many core
    opcodes and language
    elements run faster as
    a result.

    [2] Many bug fixes: nested
    oparrays of user-defined
    opcodes now work correctly,
    a specialop bug that broke
    the linux/linvoc example is
    fixed, and complex wavetable
    generates now work correctly.
    Thanks to Dan Ellis and
    Reynald Hoskinson.

    Version 0.49 -- 12/04/99

    [1] Optimizations of
    several core opcodes:
    buzz, aline, kline,
    aexpon, and kexpon.

    [2] Imports tables are
    now implemented as
    imports exports tables
    when it is safe to do so.

    Version 0.48 -- 11/22/99

    [1] Fixes optimizer bugs, and
    adds new optimizations. New
    optimizations focus on effects
    instruments, and specializes
    generated code to the unique
    properties of instruments
    launched using send().

    [2] Duration and delay
    arguments to SAOL instr
    command now correctly
    interpeted as having units
    of beats.

    Version 0.46 -- 11/16/99

    [1] Fixes optimizer bugs, and
    adds new optimizations. New
    optimizations stem from a
    reference-counting scheme that
    tracks variables in SAOL code.

    [2] Win32 DirectSound output
    driver is now works better,
    and has been tested on SB
    Live, SB16, and Creamware
    Pulsar cards. Requires 7.0
    version of DirectSound, and
    may have problems working
    under NT/Windows 2000. Thanks
    to Vincent Siliakus and Thomas
    Jongepier.

    [3] New control input driver
    alsamidi supports real-time
    MIDI input under Linux using
    the ALSA sound system (note
    OSS audio input and output
    drivers already work with ALSA).
    Thanks to Steven Pickles.

    Version 0.44 -- 11/01/99

    [1] Fixes optimizer bugs, and
    adds minor optimizations. Major
    parts of the compiler have been
    rewritten to support future
    optimization releases.

    Version 0.43 -- 09/28/99

    [1] Fixes code optimization bugs
    (0.42 produces incorrect code for
    certain arithmetic expressions).
    Running 0.42 with -O0 option
    should avoid these bugs, but
    will also avoid all optimization!

    Version 0.42 -- 09/19/99

    [1] Rate optimization added
    to sfront -- slower-rate
    subexpressions are factored
    out and executed in a slower
    pass. Default is complete
    optimization, new flags
    control turning off parts of
    the optimizer.

    [2] Fixed dsound code generation
    bugs (but not underlying sound
    generation bugs). Thanks to
    Michael Gogins.

    Version 0.41 -- 09/10/99

    [1] Fixed bugs affecting the
    special "startup" instrument
    (thanks to Michel Jullian).

    Version 0.40 -- 09/05/99

    [1] Sfront can now handle audio
    input and output drivers that
    require floating-point data
    buffers. See audio driver
    documentation for details.

    [2] New -ain and -aout options
    for .dat files, the ASCII data
    format for the curve graphing
    program view (part of the
    Chipmunk tools, a UNIX toolset
    under the GPL). This option uses
    a floating-point driver.

    Version 0.39 -- 09/03/99

    [1] Core opcodes now handle
    negative frequency arguments
    correctly (except for loscil).
    Thanks to Giorgio Zoia (ETH).

    [2] Supports Borland C++ compiler
    under Windows with very few warning
    messages (thanks to Ross Bencina).

    Version 0.38 -- 08/31/99

    [1] Supports Borland C++ compiler
    under Windows with minimal warning
    messages (thanks to Ross Bencina).

    Version 0.37 -- 08/27/99

    [1] Many minor changes to support
    compliation using Microsoft Visual
    C++.

    [2] Bundles all libraries into the
    sfront executable, so that the
    binary no longer needs to find the
    library directory.

    Version 0.36 -- 08/20/99

    [1] Adds linux audio output
    and audio and MIDI input
    support.

    [2] Core opcode rate semantics
    now match saolc.

    [3] Removes a printf option that
    was not compatible with Microsoft
    Visual C, increasing the odds sfront
    may compile under Windows w/o UWIN
    (thanks to gogins@nyc.pipeline.com).

    Version 0.35 -- 07/29/99

    Baseline version of sfront, future
    entries in this log will describe
    changes made to this release.

`

## Sfront License

The Regents of the University of California hold the copyright to sfront.

Sfront is licensed under the GNU license, which is reproduced below.

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.
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 Library 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.

GNU GENERAL PUBLIC LICENSE
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:

1. You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change.
2. 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.
3. 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:

   1. 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,
   2. 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,
   3. 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) 20yy <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) 19yy 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) 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 Library General Public License instead of this License.

## Summary

This concludes the users guide. The next section of the manual is for programmers wishing to modify `sfront` or write audio drivers for `sfront`

Next section: Part II/1: Adding Drivers to Sfront

##

Copyright 1999 John Lazzaro and John Wawrzynek.