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cc65/libsrc/runtime/rsub.s
2017-03-12 23:21:43 +01:00

38 lines
712 B
ArmAsm

;
; Ullrich von Bassewitz, 05.08.1998
; Christian Krueger, 11-Mar-2017, added 65SC02 optimization
;
; CC65 runtime: sub ints reversed
;
.export tosrsuba0, tosrsubax
.import addysp1
.importzp sp, tmp1
.macpack cpu
;
; AX = AX - TOS
;
tosrsuba0:
ldx #0
tosrsubax:
sec
.if (.cpu .bitand CPU_ISET_65SC02)
sbc (sp)
ldy #1
.else
ldy #0
sbc (sp),y ; lo byte
iny
.endif
sta tmp1 ; save lo byte
txa
sbc (sp),y ; hi byte
tax
lda tmp1
jmp addysp1 ; drop TOS, set condition codes