73 lines
1008 B
NASM
73 lines
1008 B
NASM
; head position
|
|
ldx #$00
|
|
stx $00 ; head position low
|
|
ldx #$e0
|
|
stx $01 ; head position high
|
|
|
|
; old head position
|
|
ldx #$ff ; start one behind head
|
|
stx $02 ; old head position low
|
|
ldx #$e0
|
|
stx $03 ; old head position high
|
|
|
|
; colours
|
|
ldx #$f0
|
|
stx $04 ; paint colour
|
|
ldx #$00
|
|
stx $05 ; rubber colour
|
|
|
|
move_head_right
|
|
inc $00
|
|
|
|
lda $04
|
|
ldx #$00
|
|
sta ($00, x)
|
|
|
|
clv
|
|
bvc move_rubber_right
|
|
|
|
after_rubbed
|
|
ldx $00
|
|
cpx #$ff
|
|
beq move_head_down
|
|
bne move_head_right
|
|
|
|
move_rubber_right
|
|
inc $02
|
|
|
|
lda $05
|
|
ldx #$02
|
|
sta ($00, x)
|
|
|
|
; ldx $02
|
|
; cpx #$40
|
|
; bne continue_rubbing
|
|
; dec $02
|
|
clv
|
|
; bvc continue_rubbing
|
|
|
|
;continue_rubbing
|
|
ldx $02
|
|
cpx #$ff
|
|
beq move_rubber_down
|
|
clv
|
|
bvc after_rubbed
|
|
|
|
move_head_down
|
|
inc $01
|
|
|
|
ldx $00
|
|
stx $00
|
|
|
|
clv
|
|
bvc move_head_right
|
|
|
|
move_rubber_down
|
|
inc $03
|
|
ldx $00
|
|
stx $02
|
|
bvc after_rubbed
|
|
|
|
|
|
|