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joy.s
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2022-08-26
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952b
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120 lines
.org 49152
.mem
;.obj "joy driver 64.2"
sprite = 53248
joy = 56320
irqvec = 788
norirq = $ea31
nop
nop
nop
jmp install
jmp remove
install =*
sei
lda <start
sta irqvec
lda >start
sta irqvec+1
cli
rts
start =*
lda #3
sta counter
n1 lda joy
and #31
cmp #30
bne +
jsr up
jmp count
+ cmp #29
bne +
jsr down
jmp count
+ cmp #23
bne +
jsr right
jmp count
+ cmp #27
bne +
jsr left
jmp count
+ cmp #22
bne +
jsr up
jsr right
jmp count
+ cmp #21
bne +
jsr down
jsr right
jmp count
+ cmp #25
bne +
jsr down
jsr left
jmp count
+ cmp #26
bne +
jsr up
jsr left
+ jmp count
count =*
dec counter
lda counter
beq +
jmp n1
+ jmp norirq
remove =*
sei
lda <norirq
sta irqvec
lda >norirq
sta irqvec+1
cli
rts
up =*
dec sprite+1
rts
down =*
inc sprite+1
rts
right =*
inc sprite
lda sprite
cmp #0
bne +
lda sprite+16
eor #1
sta sprite+16
+ rts
left =*
dec sprite
lda sprite
cmp #255
bne +
lda sprite+16
eor #1
sta sprite+16
+ rts
counter .byte 0