mirror of
https://frontier.innolan.net/github/AmigaExamples.git
synced 2026-09-12 09:22:02 +00:00
164 lines
2.6 KiB
ArmAsm
164 lines
2.6 KiB
ArmAsm
include "../include/registers.i"
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include "hardware/dmabits.i"
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include "hardware/intbits.i"
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include "constants.i"
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Entry:
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lea CUSTOM,a6
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bsr Init
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.mainLoop:
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bsr WaitVerticalBlank
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move.l #0,bitplaneAddress
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bsr HoriScrollPlayfield
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bsr VertScrollPlayfield
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lea copper(pc),a0
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move.l bitplaneAddress,d0
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bsr PokeBitplanePointers
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bsr UpdateHoriScrollPos
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bsr UpdateVertScrollPos
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bra .mainLoop
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SetupHoriScrollBitDelay:
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;; d0 = number of bits to scroll
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movem.l d0/d1,-(sp)
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move.w d0,d1
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lsl.w #4,d1
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or.w d1,d0
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move.w d0,BPLCON1(a6)
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movem.l (sp)+,d0/d1
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rts
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HoriScrollPlayfield:
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movem.l d0-a6,-(sp)
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move.l hpos,d0
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lsr.l #3,d0 ;bytes to scroll
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add.l d0,bitplaneAddress
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move.l hpos,d1
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and.l #$F,d1
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move.l #$F,d0
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sub.l d1,d0 ;bits to delay
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bsr SetupHoriScrollBitDelay
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.done:
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movem.l (sp)+,d0-a6
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rts
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UpdateHoriScrollPos:
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movem.l d0-a6,-(sp)
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cmp.l #1,directionLeft
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beq .left
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add.l #1,hpos
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cmp.l #SCREEN_WIDTH,hpos
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bge .switchToLeft
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bra .done
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.switchToLeft:
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move.l #1,directionLeft
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move.l #SCREEN_WIDTH-1,hpos
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bra .done
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.left:
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sub.l #1,hpos
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cmp.l #0,hpos
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ble .switchToRight
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bra .done
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.switchToRight:
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move.l #0,directionLeft
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move.l #0,hpos
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bra .done
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.done:
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movem.l (sp)+,d0-a6
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rts
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UpdateVertScrollPos:
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movem.l d0-a6,-(sp)
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cmp.l #1,directionUp
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beq .up
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add.l #SCROLL_SPEED*SCREEN_WIDTH_BYTES*SCREEN_BIT_DEPTH,vpos
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cmp.l #SCREEN_WIDTH_BYTES*SCREEN_BIT_DEPTH*256,vpos
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bge .switchToUp
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bra .done
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.switchToUp:
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move.l #1,directionUp
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move.l #SCREEN_WIDTH_BYTES*SCREEN_BIT_DEPTH*256,vpos
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bra .done
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.up:
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sub.l #SCROLL_SPEED*SCREEN_WIDTH_BYTES*SCREEN_BIT_DEPTH,vpos
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cmp.l #0,vpos
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ble .switchToDown
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bra .done
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.switchToDown:
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move.l #0,directionUp
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move.l #0,vpos
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bra .done
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.done:
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movem.l (sp)+,d0-a6
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rts
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VertScrollPlayfield:
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movem.l d0-a6,-(sp)
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move.l vpos,d0
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add.l d0,bitplaneAddress
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movem.l (sp)+,d0-a6
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rts
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PokeBitplanePointers:
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;; d0 = scroll offset
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;; a0 = BPLP copper list address
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movem.l d0-a6,-(sp)
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lea bitplanes(pc),a1
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add.l d0, a1
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moveq #SCREEN_BIT_DEPTH-1,d0
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.bitplaneloop:
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move.l a1,d1
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move.w d1,2(a0)
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swap d1
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move.w d1,6(a0)
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lea SCREEN_WIDTH_BYTES(a1),a1
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addq #8,a0
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dbra d0,.bitplaneloop
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movem.l (sp)+,d0-a6
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rts
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InstallColorPalette:
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include "out/image-palette.s"
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rts
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include "init.s"
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include "utils.s"
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bitplaneAddress:
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dc.l 0
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vpos:
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dc.l 0
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hpos:
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dc.l 0
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directionUp:
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dc.l 0
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directionLeft:
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dc.l 0
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copper:
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;; bitplane pointers must be first else poking addresses will be incorrect
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dc.w BPL1PTL,0
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dc.w BPL1PTH,0
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dc.w BPL2PTL,0
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dc.w BPL2PTH,0
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dc.w BPL3PTL,0
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dc.w BPL3PTH,0
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dc.w BPL4PTL,0
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dc.w BPL4PTH,0
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dc.w BPL5PTL,0
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dc.w BPL5PTH,0
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dc.l $fffffffe
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bitplanes:
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incbin "out/image.bin" |