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Diffstat (limited to 'hacks/images/m6502/random-walk.asm')
| -rw-r--r-- | hacks/images/m6502/random-walk.asm | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/hacks/images/m6502/random-walk.asm b/hacks/images/m6502/random-walk.asm new file mode 100644 index 0000000..4c3bd15 --- /dev/null +++ b/hacks/images/m6502/random-walk.asm @@ -0,0 +1,82 @@ + ;; 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 |