;
; sprite_display.asm
;
; This example displays the spaceship sprite at location V = 65,
; H = 128. Remember to include the file hw_examples.i.
;
; First, we set up a single bitplane.
;
        LEA     CUSTOM,a0               ;Point a0 at custom chips
        MOVE.W  #$1200,BPLCON0(a0)      ;1 bitplane color is on
        MOVE.W  #$0000,BPL1MOD(a0)      ;Modulo = 0
        MOVE.W  #$0000,BPLCON1(a0)      ;Horizontal scroll value = 0
        MOVE.W  #$0024,BPLCON2(a0)      ;Sprites have priority over playfields
        MOVE.W  #$0038,DDFSTRT(a0)      ;Set data-fetch start
        MOVE.W  #$00D0,DDFSTOP(a0)      ;Set data-fetch stop

; Display window definitions.

        MOVE.W  #$2C81,DIWSTRT(a0)      ;Set display window start
                                        ;Vertical start in high byte.
                                        ;Horizontal start * 2 in low byte.
        MOVE.W  #$F4C1,DIWSTOP(a0)      ;Set display window stop
                                        ;Vertical stop in high byte.
                                        ;Horizontal stop * 2 in low byte.
;
; Set up color registers.
;
        MOVE.W  #$0008,COLOR00(a0)      ;Background color = dark blue
        MOVE.W  #$0000,COLOR01(a0)      ;Foreground color = black
        MOVE.W  #$0FF0,COLOR17(a0)      ;Color 17 = yellow
        MOVE.W  #$00FF,COLOR18(a0)      ;Color 18 = cyan
        MOVE.W  #$0F0F,COLOR19(a0)      ;Color 19 = magenta
;
; Move Copper list to $20000.
;
        MOVE.L  #$20000,a1              ;Point A1 at Copper list destination
        LEA     COPPERL(pc),a2          ;Point A2 at Copper list source
CLOOP:
        MOVE.L  (a2),(a1)+              ;Move a long word
        CMP.L   #$FFFFFFFE,(a2)+        ;Check for end of list
        BNE     CLOOP                   ;Loop until entire list is moved
;
; Move sprite to $25000.
;
        MOVE.L  #$25000,a1              ;Point A1 at sprite destination
        LEA     SPRITE(pc),a2           ;Point A2 at sprite source
SPRLOOP:
        MOVE.L  (a2),(a1)+              ;Move a long word
        CMP.L   #$00000000,(a2)+        ;Check for end of sprite
        BNE     SPRLOOP                 ;Loop until entire sprite is moved
;
; Now we write a dummy sprite to $30000, since all eight sprites are activated
; at the same time and we're only going to use one.  The remaining sprites
; will point to this dummy sprite data.
;
        MOVE.L  #$00000000,$30000       ;Write it
;
; Point Copper at Copper list.
;
        MOVE.L  #$20000,COP1LC(a0)
;
; Fill bitplane with $FFFFFFFF.
;
        MOVE.L  #$21000,a1              ;Point A1 at bitplane
        MOVE.W  #1999,d0                ;2000-1(for dbf) long words = 8000 bytes
FLOOP
        MOVE.L  #$FFFFFFFF,(a1)+        ;Move a long word of $FFFFFFFF
        DBF     d0,FLOOP                ;Decrement, repeat until false.
;
; Start DMA.
;
         MOVE.W  d0,COPJMP1(a0)         ;Force load into Copper
                                        ;  program counter
        MOVE.W  #$83A0,DMACON(a0)       ;Bitplane, Copper, and sprite DMA
        RTS                             ;..return to rest of program..

;
; This is a Copper list for one bitplane, and 8 sprites.
; The bitplane lives at $21000.
; Sprite 0 lives at $25000; all others live at $30000 (the dummy sprite).
;
COPPERL:
        DC.W    BPL1PTH,$0002           ;Bitplane 1 pointer = $21000
        DC.W    BPL1PTL,$1000
        DC.W    SPR0PTH,$0002           ;Sprite 0 pointer = $25000
        DC.W    SPR0PTL,$5000
        DC.W    SPR1PTH,$0003           ;Sprite 1 pointer = $30000
        DC.W    SPR1PTL,$0000
        DC.W    SPR2PTH,$0003           ;Sprite 2 pointer = $30000
        DC.W    SPR2PTL,$0000
        DC.W    SPR3PTH,$0003           ;Sprite 3 pointer = $30000
        DC.W    SPR3PTL,$0000
        DC.W    SPR4PTH,$0003           ;Sprite 4 pointer = $30000
        DC.W    SPR4PTL,$0000
        DC.W    SPR5PTH,$0003           ;Sprite 5 pointer = $30000
        DC.W    SPR5PTL,$0000
        DC.W    SPR6PTH,$0003           ;Sprite 6 pointer = $30000
        DC.W    SPR6PTL,$0000
        DC.W    SPR7PTH,$0003           ;Sprite 7 pointer = $30000
        DC.W    SPR7PTL,$0000
        DC.W    $FFFF,$FFFE             ;End of Copper list
;
; Sprite data for spaceship sprite.  It appears on the screen at V=65 and H=128.
;
SPRITE:
        DC.W    $6D60,$7200             ;VSTART, HSTART, VSTOP
        DC.W    $0990,$07E0             ;First pair of descriptor words
        DC.W    $13C8,$0FF0
        DC.W    $23C4,$1FF8
        DC.W    $13C8,$0FF0
        DC.W    $0990,$07E0
        DC.W    $0000,$0000             ;End of sprite data