--- /dev/null
+;; Jeremy English 01-December-2008
+;; Snowflakes
+
+;; Main loop Count
+lda #7
+sta $f
+
+;; pattern number
+lda #0
+sta $10
+
+;;Cells
+lda #$00
+sta $4
+lda #$10
+sta $5
+
+;;Tmp
+lda #$00
+sta $6
+lda #$11
+sta $7
+
+;;Init Cells Buffer
+;;------------------------------------------------------------
+ldy #$ff
+initCells:
+lda #0
+sta ($4),y
+sta ($6),y
+dey
+bne initCells
+
+;;Set start position
+ldy #115
+lda #1
+sta ($4),y
+
+;;Setup offset
+lda #15
+sta $d
+lda #16
+sta $e
+
+;;Start of main loop
+;;------------------------------------------------------------
+mainloop:
+
+;;init indent
+;;We want to indent every other line
+lda #0
+sta $a
+
+lda #0
+sta $9
+
+;; Display Cells
+;;------------------------------------------------------------
+;; 248 is the total number of cells
+ldy #248
+display:
+
+lda #0
+sta $8
+
+lda $a
+beq stop16
+lda #15
+sta $b
+lda #1
+sta $8
+jmp toggle
+stop16:
+lda #16
+sta $b
+toggle:
+lda $a
+eor #1
+sta $a
+
+;; Set the stop position
+ldx $b
+inner_display:
+dex
+txa
+pha
+
+dey
+tya
+pha
+lda ($4),y
+
+beq display_continue
+ldx $8
+ldy $9
+lda #1
+jsr paint
+ldx $8
+ldy $9
+inx
+jsr paint
+ldx $8
+ldy $9
+iny
+jsr paint
+ldx $8
+ldy $9
+inx
+iny
+jsr paint
+display_continue:
+inc $8
+inc $8
+
+;;Life Cycle
+;;------------------------------------------------------------
+pla
+tay
+pha ;;Store y on the stack
+
+tax
+dey
+lda ($4),y
+iny
+iny
+clc
+adc ($4),y
+sta $c
+
+txa
+sec
+sbc $d
+tay
+lda $c
+clc
+adc ($4),y
+sta $c
+
+txa
+sec
+sbc $e
+tay
+lda $c
+clc
+adc ($4),y
+sta $c
+
+txa
+clc
+adc $d
+tay
+lda $c
+clc
+adc ($4),y
+sta $c
+
+txa
+clc
+adc $e
+tay
+lda $c
+clc
+adc ($4),y
+sta $c
+
+pla
+tay ;;Pull Y off of the stack
+
+lda $c
+and #1
+beq dontset
+sta ($6),y
+dontset:
+
+pla
+tax ;;Pull x off of the stack
+beq exit_inner_display
+jmp inner_display
+exit_inner_display:
+inc $9
+inc $9
+tya
+beq display_exit
+jmp display
+display_exit:
+
+
+;;Copy Temporary Buffer
+;;------------------------------------------------------------
+ldy #248
+copybuf:
+dey
+lda ($6),y
+sta ($4),y
+tya
+bne copybuf
+
+dec $f
+lda $f
+beq reset_main
+jmp mainloop
+
+;;Reset main counter
+;;------------------------------------------------------------
+reset_main:
+lda #7
+sta $f
+
+lda #$ff ;;Delay Count
+sta $11
+delay:
+ldy #$a0
+inner_delay:
+nop
+dey
+bne inner_delay
+dec $11
+lda $11
+bne delay
+
+;; init buffer
+;; and clear screen
+clrscr:
+lda $fe
+and $f
+cmp #1
+beq clrscr ;We don't want a white background
+ldy #$00
+ldx #$0
+cs_loop:
+sta $200,x
+sta $300,x
+sta $400,x
+sta $500,x
+pha
+lda #0
+sta ($6),y
+sta ($4),y
+pla
+inx
+dey
+bne cs_loop
+
+;; Setup new pattern
+;;------------------------------------------------------------
+inc $10
+lda $10
+and #3
+sta $10
+cmp #0
+beq pattern1
+cmp #1
+beq pattern2
+cmp #2
+beq pattern3
+cmp #3
+beq pattern4
+
+pattern1:
+ldy #114
+lda #1
+sta ($4),y
+ldy #115
+lda #1
+sta ($4),y
+ldy #116
+lda #1
+sta ($4),y
+jmp mainloop
+
+pattern2:
+ldy #113
+lda #1
+sta ($4),y
+ldy #118
+lda #1
+sta ($4),y
+jmp mainloop
+
+pattern3:
+ldy #115
+lda #1
+sta ($4),y
+jmp mainloop
+
+pattern4:
+ldy #102
+lda #1
+sta ($4),y
+ldy #128
+lda #1
+sta ($4),y
+jmp mainloop
+
+;;Paint subroutine
+;;------------------------------------------------------------
+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
projects / xscreensaver / blobdiff