==============================================================================
 jzIntv Joystick Support
==============================================================================


----------------
 Identification
----------------

jzIntv scans for joysticks when it starts.  It will look for and configure
up to 4 joysticks.  It prints out information on each joystick it finds,
as well as what name it has assigned to the joystick.  For example:

    joy:  Found 1 joystick(s)
    joy:  Joystick JS0 "Logitech Inc. WingMan Extreme Digital 3D"
    joy:     4 axes, 0 trackball(s), 1 hat(s), 7 button(s)

This indicates that jzIntv found one joystick, and assigned it the name
"JS0".  All events associated wit this joystick will have the prefix
"JS0_".  If additional joysticks were detected, they would be assigned
the names JS1 through JS3.

----------------------
 Analog Configuration
----------------------

jzIntv offers several configuration options for adapting analog inputs
to the 16-direction Intellivision controller input.  If you're using a
digital joystick, please see the next section, "Digital Joysticks."

You can configure joysticks with command line flags.  For each joystick,
jzIntv accepts a configuration string such as this one:

--js0="xaxis=0,yaxis=1,noac,push=17,rels=10,xrng=-49:50,yrng=-49:50,16dir"

If you provide an empty configuration string (i.e. --js0=""), jzIntv
will print out a configuration string for you that corresponds to the
current defaults.  You can then edit that string as needed.  If you
only wish to change one item, you need not provide the entire string.
Rather just supply the portion you wish to change.  For example, if
to change "push=17" to "push=33", supply the following configuration
string:

    --js0="push=33"

Most of jzIntv's joystick configuration operations focus on calibrating
the analog input axes.  The following paragraphs describe these options.
Here's a short summary of the various options:

    xaxis=#     Axis for horizontal input.  Default: 0
    yaxis=#     Axis for vertical input.    Default: 1
    ac / noac   Turn auto-centering on or off.
    push=#      Joystick "pushed" threshold.    0-100
    rels=#      Joystick "released" threshold.  0-100
    xrng=#:#    Initial estimate of joystick horizontal range.  
    yrng=#:#    Initial estimate of joystick vertical range.  
    4dir        Quantize input to 4 directions:  N, S, E, W
    4diag       Quantize input to 4 directions:  NE, NW, SE, SW
    8dir        Quantize input to 8 directions
    16dir       Quantize input to 16 directions (default)

Typically, the defaults should be suitable for most joysticks.  These
options are provided "just in case."  


xaxis, yaxis
------------

Joysticks offer multiple "axes" for various inputs.  The most basic
joystick offers two axes, one for horizontal (X axis) motion, and one
for vertical (Y axis) motion.  By default, jzIntv assumes the joystick's
axis 0 is the X axis, and axis 1 is the Y axis.  This works for most
joysticks, although you can change the mapping using the "xaxis=#" and
"yaxis=#" configuration inputs.  Other axes offered by the joystick may
correspond to other analog inputs such as throttles and force-sensitive
feedback.  Typically, jzIntv does not need and is not able to use these
additional inputs.


ac, noac
--------

The ac and noac parameters determine whether jzIntv tries to autocenter
the joystick.  The default depends on the operating system.  Linux, for
instance, offers highly filtered joystick input.  Therefore, jzIntv on
Linux disables autocentering.

Autocentering works by dynamically estimating where the "center" of
the joystick travel range is.  All push/release deflection estimates
are based off this dynamic-center position.  If you experience drift,
you might consider enabling autocentering if it's disabled.  If the
joystick seems unresponsive, try disabling autocentering if it's enabled.


push, rels
----------

Most analog joysticks have some hysteresis or slop.  That is, when you
push the joystick off-center and release it, it comes back to a position
near center that depends on the direction you pushed it.  It never quite
gets to center.  It may stop short of center, or it may over-shoot.

jzIntv compensates for this by creating a dead-zone around the center.
If the joystick position is inside the dead-zone, then the joystick
is not considered "pushed".

The "push=#" configuration option sets the percent deflection (distance
from center towards edge) required before jzIntv considers the joystick
"pushed."  The push threshold is the percentage of travel distance from
center to the maximum travel range.  (See the notes on xrng/yrng below
for more information on travel range.)

The "rels=#" option sets the percent deflection that the joystick must
drop below before jzIntv considers the joystick released.  This number
must be less than or equal to the "push" threshold.  The idea hear is
that joystick inputs are often noisy.  Thus, once "pushed," the joystick
has to move noticeably towards center before it's "released."  


xrng, yrng
----------

jzIntv tracks the maximum range of travel for the joystick.
It starts with an initial, conservative estimate that it expands as
it sees controller input.  The initial estimate assumes 50% of full
scale travel from center.  You can see this in the default settings:
"xrng=-49:50,yrng=-49:50".  Negative numbers specify positions to the
left or top.  Positive numbers specify positions to the right or bottom.

jzIntv uses maximum travel range to scale the inputs it sees to a
full "normalized" range.  This compensates for joysticks that do
not provide full-range input, or which have a center position that's
considerably off center.  jzIntv uses the normalized joystick input
for all its compensation.  

Typically the initial min/max ranges do not need adjustment.  If jzIntv
does not respond reliably to joystick inputs, try reducing these ranges.

You can also use the xrng/yrng inputs to invert one or both axes.  To do
this, specify the min and max values in reverse order.   For example,
"yrng=50:-49" will invert the Y axis.



4dir, 4diag, 8dir, 16dir
------------------------

Analog joysticks offer an "infinite" number of directions.  The
Intellivision, in contrast, has a 16-direction joystick.  So, by default,
jzIntv quantizes the joystick input to 16 directions.

Many games do not use the Intellivision's 16-direction input capability.
These games reduce the input down to 8 or 4 directions.  Usually,
the default joystick operation works well in these conditions--jzIntv
quantizes the input to 16 directions and the game quantizes it further.

Occasionally, though, the results are quirky.  In these situations,
you can tell jzIntv to quantize to 8 or 4 directions based on the
raw analog inputs.  This potentially gives a higher quality result.
For games requiring diagonal input (e.g. Checkers), jzIntv even offers a
"4 direction diagonal" mode.


-----------------------
 Digital Configuration
-----------------------

jzIntv supports both analog and digital joysticks through a common code
set.  jzIntv expects digital joysticks to return their controller pad
inputs similarly to analog joysticks.  Thus, for most digital joysticks,
no special configuration is necessary.

Some devices, such as the Retrobox, return their inputs redundantly,
both as X/Y inputs and as button inputs.  These redundant inputs arrive
as button inputs, and are intended for less capable emulators that don't
wish to decode analog inputs.  These extra inputs will confuse jzIntv,
since they look like action button inputs.

To use these types of joysticks with jzIntv, you will need to create a
"kbdhackfile" which tells jzIntv to ignore these button presses.  You may
also need to explicitly bind any actual buttons on the joystick for them
to become functional, as described in the next section.

For the Retrobox specifically, you can use the included file
"retrobox.kbd" to get started.  This file was provided by David Harley.


------------------------------
 Button and Hat Configuration
------------------------------


Joysticks also offer multiple buttons and hats for input.  By default,
jzIntv maps the first 9 buttons to the 3 action buttons on the first
joystick like so:

Buttons 0, 3, 6:  Top action buttons, left controller
Buttons 1, 4, 7:  Lower left action button, left controller
Buttons 2, 5, 8:  Lower left action button, left controller

jzIntv maps the first joystick's first hat's 8 directions to the numeric
keypad on the right controller, making the hat usable in games such as
Night Stalker and TRON Deadly Discs.

To change these bindings, you must use a "kbdhackfile".  See 
kbdhackfile.txt for information on setting one up.

Button events are named "JSx_BTN_yy", where 'x' is the joystick number,
and 'yy' is the button number.  Button numbers start at 0.  Under some
operating systems, the OS may report button numbers starting at 1.
You will need to subtract 1 from its reported number when working out
the button numbers for jzIntv.

Hat events are named "JSx_HATy_d" where 'x' is the joystick number, 'y'
is the hat number, and 'd' is one of the following 8 compass directions:
N, NW, W, SW, S, SE, E, NE.

jzIntv itself can tell you what names it assigns to each button.  Run the
included ROM file "event_diag.rom", found in the directory jzintv/rom/.
Press the buttons of interest and jzIntv will print the names associated
with the buttons.


--------------------
 Disc Configuration
--------------------

By default, jzIntv maps the first joystick's stick input to the left
controller's disc input with the following bindings:

    JS0_E      PD0L_J_E
    JS0_ENE    PD0L_J_ENE
    JS0_NE     PD0L_J_NE
    JS0_NNE    PD0L_J_NNE
    JS0_N      PD0L_J_N
    JS0_NNW    PD0L_J_NNW
    JS0_NW     PD0L_J_NW
    JS0_WNW    PD0L_J_WNW
    JS0_W      PD0L_J_W
    JS0_WSW    PD0L_J_WSW
    JS0_SW     PD0L_J_SW
    JS0_SSW    PD0L_J_SSW
    JS0_S      PD0L_J_S
    JS0_SSE    PD0L_J_SSE
    JS0_SE     PD0L_J_SE
    JS0_ESE    PD0L_J_ESE

To bind JS0 to another input controller, or to create bindings for a
second, third or fourth joystick, you will need to write a kbdhackfile
to generate these bindings.

Note, for proper joystick operation, bind the stick input events to
the PDxx_J events, not the PDxx_D inputs.

