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;; Jeremy English Dec 11 2007
;; Random walk
lda #16
sta $0 ; The current x pos
sta $1 ; The current y pos
lda $fe ; Get random color
sta $5 ; Store the color
lda $fe ; Amount of time to use this color
sta $6
loop:
ldx $0
ldy $1
lda $5
jsr paint
jsr walk
dec $6
bne loop
;; get a new color
lda $fe
sta $5
;; get a new duration
lda $fe
sta $6
jmp loop
walk:
lda $fe
and #3
cmp #0
beq right
cmp #1
beq left
cmp #2
beq up
jmp down
right:
inc $0
jmp done
left:
dec $0
jmp done
up:
dec $1
jmp done
down:
inc $1
jmp done
done:
lda $0
and #31
sta $0
lda $1
and #31
sta $1
rts
paint:
pha
lda yl,y
sta $2
lda yh,y
sta $3
txa
tay
pla
sta ($2),y
rts
;; Y cord MSB
yh:
dcb $02, $02, $02, $02, $02, $02, $02, $02
dcb $03, $03, $03, $03, $03, $03, $03, $03
dcb $04, $04, $04, $04, $04, $04, $04, $04
dcb $05, $05, $05, $05, $05, $05, $05, $05
;; Y cord LSB
yl:
dcb $00, $20, $40, $60, $80, $a0, $c0, $e0
dcb $00, $20, $40, $60, $80, $a0, $c0, $e0
dcb $00, $20, $40, $60, $80, $a0, $c0, $e0
dcb $00, $20, $40, $60, $80, $a0, $c0, $e0
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