git.sur5r.net Git - cc65/blob - libsrc/c64/joy/c64-stdjoy.s

   1 ;
   2 ; Standard joystick driver for the C64. May be used multiple times when linked
   3 ; to the statically application.
   4 ;
   5 ; Ullrich von Bassewitz, 2002-12-20
   6 ;
   7
   8         .include        "zeropage.inc"
   9
  10         .include        "joy-kernel.inc"
  11         .include        "joy-error.inc"
  12         .include        "c64.inc"
  13
  14         .macpack        generic
  15         .macpack        module
  16
  17
  18 ; ------------------------------------------------------------------------
  19 ; Header. Includes jump table
  20
  21         module_header   _c64_stdjoy_joy
  22
  23 ; Driver signature
  24
  25         .byte   $6A, $6F, $79           ; "joy"
  26         .byte   JOY_API_VERSION         ; Driver API version number
  27
  28 ; Library reference
  29
  30         .addr   $0000
  31
  32 ; Jump table.
  33
  34         .addr   INSTALL
  35         .addr   UNINSTALL
  36         .addr   COUNT
  37         .addr   READ
  38         .addr   0                       ; IRQ entry unused
  39
  40 ; ------------------------------------------------------------------------
  41 ; Constants
  42
  43 JOY_COUNT       = 2             ; Number of joysticks we support
  44
  45
  46 ; ------------------------------------------------------------------------
  47 ; Data.
  48
  49
  50 .code
  51
  52 ; ------------------------------------------------------------------------
  53 ; INSTALL routine. Is called after the driver is loaded into memory. If
  54 ; possible, check if the hardware is present and determine the amount of
  55 ; memory available.
  56 ; Must return an JOY_ERR_xx code in a/x.
  57 ;
  58
  59 INSTALL:
  60         lda     #<JOY_ERR_OK
  61         ldx     #>JOY_ERR_OK
  62
  63 ;       rts                     ; Run into UNINSTALL instead
  64
  65 ; ------------------------------------------------------------------------
  66 ; UNINSTALL routine. Is called before the driver is removed from memory.
  67 ; Can do cleanup or whatever. Must not return anything.
  68 ;
  69
  70 UNINSTALL:
  71         rts
  72
  73
  74 ; ------------------------------------------------------------------------
  75 ; COUNT: Return the total number of available joysticks in a/x.
  76 ;
  77
  78 COUNT:
  79         lda     #<JOY_COUNT
  80         ldx     #>JOY_COUNT
  81         rts
  82
  83 ; ------------------------------------------------------------------------
  84 ; READ: Read a particular joystick passed in A.
  85 ;
  86
  87 READ:   tax                     ; Joystick number into X
  88         bne     joy2
  89
  90 ; Read joystick 1
  91
  92 joy1:   lda     #$7F
  93         sei
  94         sta     CIA1_PRA
  95         lda     CIA1_PRB
  96         cli
  97         and     #$1F
  98         eor     #$1F
  99         rts
 100
 101 ; Read joystick 2
 102
 103 joy2:   ldx     #0
 104         lda     #$E0
 105         ldy     #$FF
 106         sei
 107         sta     CIA1_DDRA
 108         lda     CIA1_PRA
 109         sty     CIA1_DDRA
 110         cli
 111         and     #$1F
 112         eor     #$1F
 113         rts
 114
 115