;
; unsigned char revers (unsigned char onoff);
;
- .include "atari.inc"
-
- .export _revers
- .export _revflag
+ .include "atari.inc"
+
+ .export _revers
+ .export _revflag
_revers:
- ldx #$00 ; Assume revers off
- tay ; Test onoff
- beq L1 ; Jump if off
- ldx #$80 ; Load on value
-L1: ldy #$00 ; Assume old value is zero
- lda _revflag ; Load old value
- stx _revflag ; Set new value
- beq L2 ; Jump if old value zero
- iny ; Make old value = 1
-L2: ldx #$00 ; Load high byte of result
- tya ; Load low byte, set CC
- rts
+ ldx #$00 ; Assume revers off
+ tay ; Test onoff
+ beq L1 ; Jump if off
+ ldx #$80 ; Load on value
+L1: ldy #$00 ; Assume old value is zero
+ lda _revflag ; Load old value
+ stx _revflag ; Set new value
+ beq L2 ; Jump if old value zero
+ iny ; Make old value = 1
+L2: ldx #$00 ; Load high byte of result
+ tya ; Load low byte, set CC
+ rts
- .bss
+ .bss
_revflag:
- .res 1
+ .res 1