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48 lines
935 B
ArmAsm
48 lines
935 B
ArmAsm
include "includes.i"
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xdef SwitchBuffers
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SwitchBuffers:
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;; offscreen - bitplane address
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move.l foregroundScrollX,d0
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lsr.l #4,d0 ; convert to pixels
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lsr.l #3,d0 ; bytes to scroll
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move.l foregroundOffscreen,a0
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move.l foregroundOnscreen,foregroundOffscreen
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move.l a0,foregroundOnscreen
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move.l a0,a1
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lea copperListBpl1Ptr,a0
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jsr PokeBitplanePointers
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;; background is not double buffered
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move.l backgroundScrollX,d0
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lsr.l #3,d0 ; bytes to scroll
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move.l backgroundOnscreen,a1
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lea copperListBpl2Ptr,a0
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jsr PokeBitplanePointers
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rts
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PokeBitplanePointers:
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; d0 = frame offset in bytes
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; a0 = BPLP copper list address
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; a1 = bitplanes pointer
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;; movem.l d0-a6,-(sp)
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add.l d0,a1 ; bitplane offset
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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 BITPLANE_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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