git.sur5r.net Git - cc65/blob - libsrc/pce/revers.s

   1
   2                 .include "pce.inc"
   3
   4                 .export _revers
   5
   6 .proc   _revers
   7
   8                 ldx     #$00                    ; Assume revers off
   9                 tay                                     ; Test onoff
  10                 beq     L1                      ; Jump if off
  11                 ldx     #$80                    ; Load on value
  12                 ldy     #$00                    ; Assume old value is zero
  13 L1:             lda     RVS                     ; Load old value
  14                 stx     RVS                     ; Set new value
  15                 beq     L2                      ; Jump if old value zero
  16                 iny                             ; Make old value = 1
  17 L2:             ldx     #$00                    ; Load high byte of result
  18                 tya                             ; Load low byte, set CC
  19                 rts
  20
  21 .endproc
  22
  23 ;-------------------------------------------------------------------------------
  24 ; force the init constructor to be imported
  25
  26                 .import initconio
  27 conio_init = initconio