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cc65/libsrc/cbm510/pokesys.s

50 lines
1.1 KiB
ArmAsm

;
; Ullrich von Bassewitz, 13.09.2001
;
; void pokebsys (unsigned Addr, unsigned char Val);
; void pokewsys (unsigned Addr, unsigned Val);
.export _pokebsys, _pokewsys
.import popsreg
.importzp sreg, tmp1
.include "cbm510.inc"
; ------------------------------------------------------------------------
;
.proc _pokebsys
jsr popsreg ; Get the address
ldx IndReg
ldy #$0F
sty IndReg ; Switch to the system bank
ldy #$00
sta (sreg),y
stx IndReg
rts
.endproc
; ------------------------------------------------------------------------
;
.proc _pokewsys
stx tmp1 ; Save high byte
jsr popsreg ; Get the address
ldx IndReg
ldy #$0F
sty IndReg ; Switch to the system bank
ldy #$00
sta (sreg),y
iny
lda tmp1
sta (sreg),y
stx IndReg
rts
.endproc