mirror of
https://github.com/cc65/cc65.git
synced 2024-06-09 06:29:38 +00:00
29 lines
820 B
ArmAsm
29 lines
820 B
ArmAsm
;
|
|
; Ullrich von Bassewitz, 07.08.1998
|
|
;
|
|
; unsigned char revers (unsigned char onoff);
|
|
;
|
|
.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
|
|
|
|
.bss
|
|
|
|
_revflag:
|
|
.res 1
|