git.sur5r.net Git - cc65/blob - libsrc/c128/readjoy.s

   1 ;
   2 ; Ullrich von Bassewitz, 23.09.1998
   3 ;
   4 ; unsigned readjoy (unsigned char joy);
   5 ;
   6
   7         .export         _readjoy
   8
   9         .include        "c128.inc"
  10
  11
  12 .proc   _readjoy
  13
  14         tax                     ; Joystick number into X
  15         bne     joy2
  16
  17 ; Read joystick 1
  18
  19 joy1:   lda     #$7F
  20         sei
  21         sta     CIA1_PRA
  22         lda     CIA1_PRB
  23         cli
  24         and     #$1F
  25         eor     #$1F
  26         rts
  27
  28 ; Read joystick 2
  29
  30 joy2:   ldx     #0
  31         lda     #$E0
  32         ldy     #$FF
  33         sta     CIA1_DDRA
  34         lda     CIA1_PRA
  35         sty     CIA1_DDRA
  36         and     #$1F
  37         eor     #$1F
  38         rts
  39
  40 .endproc
  41