mirror of
https://github.com/cc65/cc65.git
synced 2024-11-11 01:05:25 +00:00
27 lines
518 B
ArmAsm
27 lines
518 B
ArmAsm
|
;
|
||
|
|
; Ullrich von Bassewitz, 07.08.1998
|
||
|
|
;
|
||
|
|
; unsigned char revers (unsigned char onoff);
|
||
|
|
;
|
||
|
|
|
||
|
|
.export _revers
|
||
|
|
.export revers
|
||
|
|
|
||
|
|
_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 revers ; Load old value
|
||
|
|
stx revers ; 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
|
||
|
|
|
||
|
|
revers: .res 1
|