70 lines
757 B
ArmAsm
70 lines
757 B
ArmAsm
.MACPACK generic
|
|
|
|
.export _init, _nmi_int, _irq_int
|
|
|
|
.import tmp1
|
|
|
|
CMD = $effc
|
|
DAT = $effd
|
|
|
|
.zeropage
|
|
finish: .res 1
|
|
curr_irq: .res 1
|
|
|
|
.code
|
|
|
|
_nmi_int:
|
|
_irq_int:
|
|
; We should have triggered interrupt 1
|
|
stz CMD
|
|
lda DAT
|
|
cmp curr_irq
|
|
bne @bad
|
|
|
|
lda #$ff
|
|
sta CMD
|
|
lda #$1
|
|
sta DAT
|
|
|
|
inc curr_irq
|
|
beq @good
|
|
cli
|
|
rti
|
|
|
|
@good:
|
|
lda #$6d
|
|
sta finish
|
|
|
|
@bad:
|
|
lda #$bd
|
|
sta finish
|
|
|
|
_init:
|
|
ldx #$ff
|
|
txs
|
|
ldx #$20 ; enable
|
|
ldy #$ff
|
|
jsr cmd_all
|
|
ldx #$40 ; edge type
|
|
ldy #$00
|
|
jsr cmd_all
|
|
stz curr_irq
|
|
cli
|
|
jmp wait
|
|
|
|
cmd_all:
|
|
txa
|
|
add #$20
|
|
sta tmp1
|
|
loop:
|
|
txa
|
|
sta CMD
|
|
tya
|
|
sta DAT
|
|
inx
|
|
cpx tmp1
|
|
blt loop
|
|
rts
|
|
|
|
wait:
|
|
bra wait |