====== JOY ======

[vic20] [c64] [c16] [cplus4] [c128] [x16] [m65]

The ''JOY()'' function returns the status of either joysticks.

===== Function header =====

  DECLARE FUNCTION JOY AS BYTE (portnum AS BYTE) SHARED STATIC INLINE

Where //portnum// is an expression that evaluates to 1 or 2.

<adm note>
On the Commodore VIC-20, //portnum// is ignored.
</adm>

The return value is a BYTE where bits corresponding to a direction are set or unset. The direction to bit mapping if different on each target:

  * On [c64] [c128] [m65]:
    * Bit #0 is set if joystick is being pulled up
    * Bit #1 is set if joystick is being pulled down
    * Bit #2 is set if joystick is being pulled left
    * Bit #3 is set if joystick is being pulled right
    * Bit #4 is set if fire button is depressed
  * On [vic20]:
    * Bit #2 is set if joystick is being pulled up
    * Bit #3 is set if joystick is being pulled down
    * Bit #4 is set if joystick is being pulled left
    * Bit #5 is set if fire button is depressed
    * Bit #7 is set if joystick is being pulled right
  * On [c16] and [cplus4]: 
    * Bit #0 is set if joystick is being pulled up
    * Bit #1 is set if joystick is being pulled down
    * Bit #2 is set if joystick is being pulled left
    * Bit #3 is set if joystick is being pulled right
    * Bit #6 is set if fire button is depressed on joystick 1
    * Bit #7 is set if fire button is depressed on joystick 2

===== Example =====

Using the following example, you can read the joystick status on all platforms:

  ' Uncomment if target is VIC-20
  'CONST JOYUP = 4
  'CONST JOYDN = 8
  'CONST JOYLT = 16
  'CONST JOYRT = 128
  'CONST J1FIRE = 32
  
  ' Uncomment if target is C64
  'CONST JOYUP  = 1
  'CONST JOYDN  = 2
  'CONST JOYLT  = 4
  'CONST JOYRT  = 8
  'CONST J1FIRE = 16
  'CONST J2FIRE = 16
  
  ' Uncomment if target is C16 or C Plus/4
  'CONST JOYUP  = 1
  'CONST JOYDN  = 2
  'CONST JOYLT  = 4
  'CONST JOYRT  = 8
  'CONST J1FIRE = 64
  'CONST J2FIRE = 128
  
  DIM j AS BYTE
  lab:
    j = JOY(1)
    IF j = 0 THEN GOTO lab
    IF j AND JOYUP THEN PRINT " up";
    IF j AND JOYDN THEN PRINT " down";
    IF j AND JOYLT THEN PRINT " left";
    IF j AND JOYRT THEN PRINT " right";
    IF j AND J1FIRE THEN PRINT " fire";
    PRINT ""
    GOTO lab