mirror of
https://github.com/blondie7575/GSCats.git
synced 2024-10-31 15:05:46 +00:00
305 lines
5.9 KiB
ArmAsm
305 lines
5.9 KiB
ArmAsm
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; terrain (in E1 bank)
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;
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; Fill-mode terrain rendering code snippets
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; that live in bank E1 for maximum speed.
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;
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; Created by Quinn Dunki on 7/29/17
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;
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.include "equates.s"
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.include "macros.s"
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UNRENDERCACHESTACK = $7ff
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OP16
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.org $800
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; renderTerrainSpans:
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;
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;
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renderTerrainSpans:
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SAVE_AXY
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SAVE_DBR
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FASTGRAPHICS
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lda #UNRENDERCACHESTACK ; Prepare unrender cache
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tcs
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lda #MAXTERRAINHEIGHT-1
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renderTerrainSpansLoop:
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sta PARAML1
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; Find row data
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lda PARAML1
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asl ; Shifts must match SPANROWBYTES
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asl
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asl
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asl
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asl
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tay
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lda terrainSpanData,y
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sta SCRATCHL ; Track span color
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; Find VRAM row
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lda PARAML1
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asl
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tax
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lda vramRowInvertedSpanLookup,x
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tax
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adc #160
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sta PARAML0 ; Watch for end of VRAM row
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; Find span that intersects left logical edge
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lda #0
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clc
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renderTerrainRowSpansFindLeftLoop:
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adc terrainSpanData+2,y
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cmp leftScreenEdge
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bpl renderTerrainRowSpansFoundLeft
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iny
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iny
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sta CACHEDATA
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lda SCRATCHL
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eor #%110000 ; Toggle span color cache
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sta SCRATCHL
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lda CACHEDATA
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bra renderTerrainRowSpansFindLeftLoop
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renderTerrainRowSpansFoundLeft:
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sec
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sbc leftScreenEdge ; A now holds remainder of leftmost span
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; and Y points to leftmost span
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renderTerrainRowSpansLoop:
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sta SCRATCHL2
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; Set fill mode byte for this span
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lda SCRATCHL
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sta VRAMBANK,x
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; Cache the index we wrote to so we can erase later
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phx
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; Advance to end of span
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clc
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txa
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adc SCRATCHL2
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cmp PARAML0
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bpl renderTerrainRowSpansDone
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tax
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; Prepare for next span
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iny
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iny
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lda SCRATCHL
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eor #%110000 ; Toggle span color cache
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sta SCRATCHL
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lda terrainSpanData+2,y
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bra renderTerrainRowSpansLoop
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renderTerrainRowSpansDone:
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lda PARAML1
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dec
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bne renderTerrainSpansLoop
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pea 0 ; Null-terminate the unrender cache
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SLOWGRAPHICS
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RESTORE_DBR
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RESTORE_AXY
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rtl
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; unrenderTerrainSpans:
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;
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;
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unrenderTerrainSpans:
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SAVE_AXY
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SAVE_DBR
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phb
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pea $e1e1 ; Work entirely in bank E1 for all local read/writes
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plb
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plb
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ldy #UNRENDERCACHESTACK-1
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unrenderTerrainSpansLoop:
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lda 0,y
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beq unrenderTerrainSpansDone
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tax
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lda #0
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sta a:0,x
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dey
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dey
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bra unrenderTerrainSpansLoop
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unrenderTerrainSpansDone:
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plb
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RESTORE_DBR
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RESTORE_AXY
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rtl
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; compileTerrainSpans:
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;
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;
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compileTerrainSpans:
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pha
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SAVE_DBR
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lda #0
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compileTerrainSpansLoop:
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sta PARAML1
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jsr compileTerrainSpansRow
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lda PARAML1
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inc
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cmp #MAXTERRAINHEIGHT
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bne compileTerrainSpansLoop
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RESTORE_DBR
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pla
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rtl
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; compileTerrainSpansRow:
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;
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; PARAML1 = Row index (bottom relative)
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;
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; Trashes SCRATCHL
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;
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compileTerrainSpansRow:
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SAVE_AXY
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lda PARAML1
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asl ; Shifts must match SPANROWBYTES
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asl
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asl
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asl
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asl
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clc
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adc #terrainSpanData
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sta SCRATCHL
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ldy #0
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ldx #TERRAINWIDTH-2
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lda terrainDataFar,x ; Figure out start value for row
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cmp PARAML1
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bcs compileTerrainSpansRowInitGreen
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compileTerrainSpansRowInitBlack:
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lda #$0020 ; First span is black
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sta (SCRATCHL) ; Initialize the row
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inc SCRATCHL
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inc SCRATCHL
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ldy #-1
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compileTerrainSpansRowBlackStart:
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iny
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compileTerrainSpansRowBlackLoop:
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lda terrainDataFar,x
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cmp PARAML1
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bcs compileTerrainSpansBlackEnd
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dex
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dex
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iny
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cpx #-2
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bne compileTerrainSpansRowBlackLoop
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compileTerrainSpansBlackEnd:
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tya ; Store this span's length
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sta (SCRATCHL)
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inc SCRATCHL
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inc SCRATCHL
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dex ; Begin searching for next span
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dex
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cpx #0
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bmi compileTerrainSpansRowDone
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ldy #0
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bra compileTerrainSpansRowGreenStart
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compileTerrainSpansRowDone:
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RESTORE_AXY
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rts
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compileTerrainSpansRowInitGreen:
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lda #$0010 ; First span is green
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sta (SCRATCHL) ; Initialize the row
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inc SCRATCHL
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inc SCRATCHL
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ldy #-1
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compileTerrainSpansRowGreenStart:
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iny
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compileTerrainSpansRowGreenLoop:
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lda terrainDataFar,x
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cmp PARAML1
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bcc compileTerrainSpansGreenEnd
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dex
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dex
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iny
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cpx #-2
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bne compileTerrainSpansRowGreenLoop
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compileTerrainSpansGreenEnd:
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tya ; Store this span's length
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sta (SCRATCHL)
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inc SCRATCHL
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inc SCRATCHL
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dex ; Begin searching for next span
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dex
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cpx #0
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bmi compileTerrainSpansRowDone
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ldy #0
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bra compileTerrainSpansRowBlackStart
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terrainSpanData:
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.repeat MAXTERRAINHEIGHT
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.word 0 ; Start value (0=BG)
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.repeat MAXSPANSPERROW
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.word 0 ; Length (in bytes)
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.endrepeat
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.endrepeat
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vramRowInvertedSpanLookup:
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.word $9d00,$9c60,$9bc0,$9b20,$9a80,$99e0,$9940,$98a0,$9800,$9760,$96c0,$9620,$9580,$94e0,$9440,$93a0,$9300,$9260,$91c0,$9120
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.word $9080,$8fe0,$8f40,$8ea0,$8e00,$8d60,$8cc0,$8c20,$8b80,$8ae0,$8a40,$89a0,$8900,$8860,$87c0,$8720,$8680,$85e0,$8540,$84a0
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.word $8400,$8360,$82c0,$8220,$8180,$80e0,$8040,$7fa0,$7f00,$7e60,$7dc0,$7d20,$7c80,$7be0,$7b40,$7aa0,$7a00,$7960,$78c0,$7820
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.word $7780,$76e0,$7640,$75a0,$7500,$7460,$73c0,$7320,$7280,$71e0,$7140,$70a0,$7000,$6f60,$6ec0,$6e20,$6d80,$6ce0,$6c40,$6ba0
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.word $6b00,$6a60,$69c0,$6920,$6880,$67e0,$6740,$66a0,$6600,$6560,$64c0,$6420,$6380,$62e0,$6240,$61a0,$6100,$6060,$5fc0,$5f20
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.word $5e80,$5de0,$5d40,$5ca0,$5c00,$5b60,$5ac0,$5a20,$5980,$58e0,$5840,$57a0,$5700,$5660,$55c0,$5520,$5480,$53e0,$5340,$52a0
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.word $5200,$5160,$50c0,$5020,$4f80,$4ee0,$4e40,$4da0,$4d00,$4c60,$4bc0,$4b20,$4a80,$49e0,$4940,$48a0,$4800,$4760,$46c0,$4620
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.word $4580,$44e0,$4440,$43a0,$4300,$4260,$41c0,$4120,$4080,$3fe0,$3f40,$3ea0,$3e00,$3d60,$3cc0,$3c20,$3b80,$3ae0,$3a40,$39a0
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.word $3900,$3860,$37c0,$3720,$3680,$35e0,$3540,$34a0,$3400,$3360,$32c0,$3220,$3180,$30e0,$3040,$2fa0,$2f00,$2e60,$2dc0,$2d20
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.word $2c80,$2be0,$2b40,$2aa0,$2a00,$2960,$28c0,$2820,$2780,$26e0,$2640,$25a0,$2500,$2460,$23c0,$2320,$2280,$21e0,$2140,$20a0
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.export renderTerrainSpans
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.export unrenderTerrainSpans
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.export compileTerrainSpans
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; Suppress some linker warnings - Must be the last thing in the file
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.SEGMENT "ZPSAVE"
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.SEGMENT "EXEHDR"
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.SEGMENT "STARTUP"
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.SEGMENT "INIT"
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.SEGMENT "LOWCODE"
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