diff options
Diffstat (limited to 'conio/revers.s')
| -rw-r--r-- | conio/revers.s | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/conio/revers.s b/conio/revers.s new file mode 100644 index 0000000..7195039 --- /dev/null +++ b/conio/revers.s @@ -0,0 +1,28 @@ +; +; 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 |