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Fixed bugs; and, improved the efficiency of some pce library functions.

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This commit is contained in:
Greg King
2015-11-26 15:06:20 -05:00
committed by Oliver Schmidt
parent 959eff34a3
commit 39694d0aaa
16 changed files with 158 additions and 229 deletions
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27
libsrc/pce/revers.s
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@@ -1,24 +1,23 @@
;
; Ullrich von Bassewitz, 07.08.1998
; 1998-08-07, Ullrich von Bassewitz
; 2015-11-23, Greg King
;
; unsigned char revers (unsigned char onoff);
; unsigned char __fastcall__ revers (unsigned char onoff);
;
.export _revers
.include "extzp.inc"
.importzp RVS
.proc _revers
ldx #$00 ; Assume revers off
tay ; Test onoff
beq L1 ; Jump if off
ldx #$80 ; Load on value
ldy #$00 ; Assume old value is zero
L1: lda RVS ; Load old value
stx RVS ; 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
cmp #$01 ; False or true?
cla
ror a ; Either $00 or $80
ldy RVS ; Load old value
sta RVS ; Set new value
tya
asl a
rol a ; Either $00 or $01
clx
rts
.endproc