Files
6502PC/rom/poke.s
T
2026-09-27 22:09:00 +02:00

86 lines
2.3 KiB
ArmAsm

.segment "CODE"
; ----------------------------------------------------------------------------
; EVALUATE "EXP1,EXP2"
;
; CONVERT EXP1 TO 16-BIT NUMBER IN LINNUM
; CONVERT EXP2 TO 8-BIT NUMBER IN X-REG
; ----------------------------------------------------------------------------
GTNUM:
jsr FRMNUM
jsr GETADR
; ----------------------------------------------------------------------------
; EVALUATE ",EXPRESSION"
; CONVERT EXPRESSION TO SINGLE BYTE IN X-REG
; ----------------------------------------------------------------------------
COMBYTE:
jsr CHKCOM
jmp GETBYT
; ----------------------------------------------------------------------------
; CONVERT (FAC) TO A 16-BIT VALUE IN LINNUM
; ----------------------------------------------------------------------------
GETADR:
lda FACSIGN
bmi GOIQ
lda FAC
cmp #$91
bcs GOIQ
jsr QINT
lda FAC_LAST-1
ldy FAC_LAST
sty LINNUM
sta LINNUM+1
rts
; ----------------------------------------------------------------------------
; "PEEK" FUNCTION
; ----------------------------------------------------------------------------
PEEK:
lda LINNUM+1
pha
lda LINNUM
pha
jsr GETADR
ldy #$00
lda (LINNUM),y
tay
pla
sta LINNUM
pla
sta LINNUM+1
LD6F6:
jmp SNGFLT
; ----------------------------------------------------------------------------
; "POKE" STATEMENT
; ----------------------------------------------------------------------------
POKE:
jsr GTNUM
txa
ldy #$00
sta (LINNUM),y
rts
; ----------------------------------------------------------------------------
; "WAIT" STATEMENT
; ----------------------------------------------------------------------------
WAIT:
jsr GTNUM
stx FORPNT
ldx #$00
jsr CHRGOT
beq EASTER_EGG
jsr COMBYTE
L3628:
stx FORPNT+1
ldy #$00
L362C:
lda (LINNUM),y
eor FORPNT+1
and FORPNT
beq L362C
RTS3:
rts