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36 lines
809 B
ArmAsm

;
; Ullrich von Bassewitz, 25.11.2002
;
; CC65 runtime: Swap 2 bytes of register variable space
;
.export regswap2
.importzp sp, regbank
.proc regswap2
; First byte
lda regbank,x ; Get old value
pha ; Save it
lda (sp),y ; Get stack loc
sta regbank,x ; Store new value
pla
sta (sp),y ; Store old value
; Second byte
iny
lda regbank+1,x ; Get old value
pha ; Save it
lda (sp),y ; Get stack loc
sta regbank+1,x ; Store new value
pla
sta (sp),y ; Store old value
rts
.endproc