Optimization
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blondie7575
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fa19888d4d
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af525a26fe
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gscats.2mg
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gscats.2mg
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3
gscats.s
3
gscats.s
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@ -30,6 +30,7 @@ mainBank2:
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jsr colorFill
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jsr generateTerrain
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jsr computeScrollClipBoundaries
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mainGameLoop:
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ldy mapScrollPos
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@ -107,7 +108,7 @@ kbdScanSpace:
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basePalette:
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.word $0800,$0080,$0000,$000F,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000
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mapScrollPos: ; 4-pixel columns distance from right terrain edge
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.word 80
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.word 0
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quitRequested:
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.word $0000
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105
terrain.s
105
terrain.s
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@ -13,6 +13,9 @@ MAXTERRAINHEIGHT = 100 ; In pixels
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;
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; No stack operations permitted here!
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;
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; Initial implementation: 535 cycles per row
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; Current implementation: 443 cycles per row
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;
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renderTerrain:
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lda #199*2
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sta <ROWINDEX
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@ -62,15 +65,14 @@ renderClippedSpanChain:
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lda #renderClippedSpanChainRenderNext ; 2
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sta renderSpanComplete+1 ; 4
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; Find right edge of screen within span chains
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; = 27 cycles per skipped span
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; Look up right edge clipping data from precalculated table
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; = 15 cycles per row
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renderClippedSpanChainLoop:
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lda spanChain,y ; 4
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sec ; 2
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sbc <RIGHTEDGE ; 3
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bmi renderClippedSpanChainNextSpan ; 2/3
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beq renderClippedSpanChainNextSpan ; 2/3
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lda <MAPSCROLLPOS ; 3
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asl ; 2
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tax ; 2
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ldy scrollClipIndices,x ; 4
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lda scrollClipIndices+2,x ; 4
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renderClippedSpanChainLoop2:
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; Now render spans until left edge of screen
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@ -91,7 +93,6 @@ renderSpanComplete:
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; unrolled span rendering blocks
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jmp renderClippedSpanChainRenderNext ; 3
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renderClippedSpanChainRenderNext:
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; Track remaining words until left edge
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; = 26 cycles per span rendered
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@ -108,16 +109,6 @@ renderClippedSpanChainRenderNext:
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lda spanChain,y ; 5
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bra renderClippedSpanChainLoop2 ; 3
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renderClippedSpanChainNextSpan:
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; Track remaining distance from right edge and
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; continue searching for visible right edge
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eor #$ffff ; 2
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inc ; 2
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sta <RIGHTEDGE ; 3
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dey ; 2
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dey ; 2
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bra renderClippedSpanChainLoop ; 3
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renderClippedSpanChainLastSpan:
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; Render visible portion of last visible span
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; = 26 cycles per row
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@ -151,6 +142,75 @@ spanColors:
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spanChainIndex:
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.word 0
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; computeScrollClipBoundaries
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;
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; Generates a table of the clipped span indices for the right edge
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; at every possible scroll position
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;
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computeScrollClipBoundaries:
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SAVE_AXY
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lda #0
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sta <MAPSCROLLPOS
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computeScrollClipBoundariesOuterLoop:
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; Prepare our state
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lda #80 ; 2
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sta <XLEFT ; 3
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ldy #spanChainEnd-spanChain-2 ; 2
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lda <MAPSCROLLPOS ; 3
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sta <RIGHTEDGE ; 3
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; Find right edge of screen within span chains
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computeScrollClipBoundariesInnerLoop:
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lda spanChain,y ; 4
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sec ; 2
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sbc <RIGHTEDGE ; 3
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bmi computeScrollClipBoundariesNextSpan ; 2/3
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beq computeScrollClipBoundariesNextSpan ; 2/3
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; Y now contains the pointer to span that will be clipped at this scroll position
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; A now contains remaining words of clipped span to render
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; Write these values into our tuple data structure
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pha
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ldx <MAPSCROLLPOS
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txa
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asl
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tax
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tya
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sta scrollClipIndices,x
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inx
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inx
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pla
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sta scrollClipIndices,x
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; On to the next scroll position
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lda <MAPSCROLLPOS
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inc
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inc
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cmp #(TERRAINWIDTH-320)/4+2
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beq computeScrollClipBoundariesDone
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sta <MAPSCROLLPOS
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bra computeScrollClipBoundariesOuterLoop
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computeScrollClipBoundariesNextSpan:
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; Track remaining distance from right edge and
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; continue searching for visible right edge
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eor #$ffff ; 2
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inc ; 2
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sta <RIGHTEDGE ; 3
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dey ; 2
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dey ; 2
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bra computeScrollClipBoundariesInnerLoop ; 3
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computeScrollClipBoundariesDone:
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RESTORE_AXY
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; generateTerrain
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;
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@ -186,9 +246,14 @@ generateTerrainLoop:
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terrainData:
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.repeat TERRAINWIDTH/2
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.byte 0
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.word 0
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.endrepeat
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scrollClipIndices:
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; Tuples: (Clipped span, Words to Render)
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.repeat (TERRAINWIDTH-320)/4+2 ; Always scroll by two words
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.word 0
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.endrepeat
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.if 0
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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