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

52 lines
1.0 KiB
ArmAsm

;
; Ullrich von Bassewitz, 05.08.1998
; Christian Krueger, 11-Mar-2017, added 65SC02 optimization
;
; CC65 runtime: long sub reversed
;
;
; EAX = EAX - TOS
;
.export tosrsub0ax, tosrsubeax
.import addysp1
.importzp sp, sreg, tmp1
.macpack cpu
tosrsub0ax:
.if (.cpu .bitand ::CPU_ISET_65SC02)
stz sreg
stz sreg+1
.else
ldy #$00
sty sreg
sty sreg+1
.endif
tosrsubeax:
sec
.if (.cpu .bitand ::CPU_ISET_65SC02)
sbc (sp)
ldy #1
.else
ldy #0
sbc (sp),y ; byte 0
iny
.endif
sta tmp1 ; use as temp storage
txa
sbc (sp),y ; byte 1
tax
iny
lda sreg
sbc (sp),y ; byte 2
sta sreg
iny
lda sreg+1
sbc (sp),y ; byte 3
sta sreg+1
lda tmp1
jmp addysp1 ; drop TOS