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Amiga Developer CD v1.2
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amidev_cd_12.iso
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reference_library
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hardware
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hard_examples
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sprite_display.asm
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Assembly Source File
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1992-08-20
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5KB
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113 lines
;
; 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