300 lines
7.2 KiB
NASM
300 lines
7.2 KiB
NASM
HorzEdge:
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cpy #$ff : beq +
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jsr DetectWestEdge : ldy #$02 : bra ++
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+ jsr DetectEastEdge
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++ cmp #$ff : beq +
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sta $00 : asl : !add $00 : tax
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cpy #$ff : beq ++
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jsr LoadWestData : bra .main
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++ jsr LoadEastData
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.main
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jsr LoadEdgeRoomHorz
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sec : rts
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+ clc : rts
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VertEdge:
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cpy #$ff : beq +
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jsr DetectNorthEdge : bra ++
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+ jsr DetectSouthEdge
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++ cmp #$ff : beq +
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sta $00 : asl : !add $00 : tax
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cpy #$ff : beq ++
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jsr LoadNorthData : bra .main
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++ jsr LoadSouthData
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.main
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jsr LoadEdgeRoomVert
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sec : rts
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+ clc : rts
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LoadEdgeRoomHorz:
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lda $03 : sta $a0
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sty $06
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and.b #$0f : asl a : !sub $23 : !add $06 : sta $02
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ldy #$00 : jsr ShiftVariablesMainDir
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lda $04 : and #$80 : bne .edge
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lda $04 : sta $01 ; load up flags in $01
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jsr PrepScrollToNormal
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bra .scroll
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.edge
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lda $04 : and #$10 : beq +
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lda #$01
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+ sta $ee ; layer stuff
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jsr MathHorz
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.scroll
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jsr ScrollY
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rts
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LoadEdgeRoomVert:
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lda $03 : sta $a0
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sty $06
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and.b #$f0 : lsr #3 : !sub $21 : !add $06 : sta $02
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lda $04 : and #$80 : bne .edge
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lda $04 : sta $01 ; load up flags in $01
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and #$03 : cmp #$03 : beq .inroom
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ldy #$01 : jsr ShiftVariablesMainDir
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jsr PrepScrollToNormal
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bra .scroll
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.inroom
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jsr ScrollToInroomStairs
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rts
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.edge
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ldy #$01 : jsr ShiftVariablesMainDir
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lda $04 : and #$10 : beq +
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lda #$01
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+ sta $ee ; layer stuff
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jsr MathVert
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lda $03
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.scroll
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jsr ScrollX
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rts
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MathHorz:
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jsr MathStart : lda $20
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jsr MathMid : and #$0040
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jsr MathEnd
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rts
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MathVert:
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jsr MathStart : lda $22
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jsr MathMid : and #$0020
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jsr MathEnd
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rts
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MathStart:
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rep #$30
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lda $08 : and #$00ff : sta $00
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rts
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MathMid:
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and #$01ff : !sub $00 : and #$00ff : sta $00
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; nothing should be bigger than $a0 at this point
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lda $05 : and #$00f0 : lsr #4 : tax
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lda MultDivInfo, x : and #$00ff : tay
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lda $00 : jsr MultiplyByY : sta $02
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lda $07 : and #$00ff : jsr MultiplyByY : tax
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lda $05 : and #$000f : tay
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lda MultDivInfo, y : and #$00ff : tay
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lda $02 : jsr DivideByY : sta $00
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lda $0c : and #$00ff : sta $02
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lda $04
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rts
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MathEnd:
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beq +
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lda #$0100
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+ !add $02 : !add $00
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sta $04
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sep #$30
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rts
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; don't need midpoint of edge Link is leaving (formerly in $06 - used by dir indicator)
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; don't need width of edge Link is going to (currently in $0b)
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LoadNorthData:
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lda NorthOpenEdge, x : sta $03 : inx ; target room
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lda NorthEdgeInfo, x : sta $07 ; needed for maths - (divide by 2 anyway)
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lda NorthOpenEdge, x : sta $04 : inx ; bit field
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lda NorthEdgeInfo, x : sta $08 ; needed for maths
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lda NorthOpenEdge, x : sta $05 ; ratio
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lda $04 : jsr LoadSouthMidpoint : inx ; needed now, and for nrml transition
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lda SouthEdgeInfo, x : sta $0b : inx ; probably not needed todo: remove
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lda SouthEdgeInfo, x : sta $0c ; needed for maths
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rts
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LoadSouthMidpoint:
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and #$0f : sta $00 : asl : !add $00 : tax
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lda SouthEdgeInfo, x : sta $0a ; needed now, and for nrml transition
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rts
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LoadSouthData:
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lda SouthOpenEdge, x : sta $03 : inx
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lda SouthEdgeInfo, x : sta $07
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lda SouthOpenEdge, x : sta $04 : inx
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lda SouthEdgeInfo, x : sta $08
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lda SouthOpenEdge, x : sta $05
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lda $04 : jsr LoadNorthMidpoint : inx
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lda NorthEdgeInfo, x : sta $0b : inx
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lda NorthEdgeInfo, x : sta $0c
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rts
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LoadNorthMidpoint:
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and #$0f : sta $00 : asl : !add $00 : tax
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lda NorthEdgeInfo, x : sta $0a ; needed now, and for nrml transition
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rts
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LoadWestData:
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lda WestOpenEdge, x : sta $03 : inx
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lda WestEdgeInfo, x : sta $07
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lda WestOpenEdge, x : sta $04 : inx
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lda WestEdgeInfo, x : sta $08
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lda WestOpenEdge, x : sta $05
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lda $04 : jsr LoadEastMidpoint : inx
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lda EastEdgeInfo, x : sta $0b : inx
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lda EastEdgeInfo, x : sta $0c
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rts
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LoadEastMidpoint:
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and #$0f : sta $00 : asl : !add $00 : tax
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lda EastEdgeInfo, x : sta $0a ; needed now, and for nrml transition
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rts
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LoadEastData:
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lda EastOpenEdge, x : sta $03 : inx
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lda EastEdgeInfo, x : sta $07
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lda EastOpenEdge, x : sta $04 : inx
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lda EastEdgeInfo, x : sta $08
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lda EastOpenEdge, x : sta $05
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lda $04 : jsr LoadWestMidpoint : inx
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lda WestEdgeInfo, x : sta $0b : inx
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lda WestEdgeInfo, x : sta $0c
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LoadWestMidpoint:
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and #$0f : sta $00 : asl : !add $00 : tax
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lda WestEdgeInfo, x : sta $0a ; needed now, and for nrml transition
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rts
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DetectNorthEdge:
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ldx #$ff
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lda $a2
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cmp #$82 : bne +
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lda $22 : cmp #$50 : bcs ++
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ldx #$01 : bra .end
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++ ldx #$00 : bra .end
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+ cmp #$83 : bne +
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ldx #$02 : bra .end
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+ cmp #$84 : bne +
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lda $a9 : beq ++
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lda $22 : cmp #$78 : bcs +++
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ldx #$04 : bra .end
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+++ ldx #$05 : bra .end
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++ lda $22 : cmp #$78 : bcs ++
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ldx #$03 : bra .end
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++ ldx #$04 : bra .end
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+ cmp #$85 : bne +
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ldx #$06 : bra .end
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+ cmp #$db : bne +
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lda $a9 : beq ++
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lda $22 : beq ++
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ldx #$08 : bra .end
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++ ldx #$07 : bra .end
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+ cmp #$dc : bne .end
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lda $a9 : bne ++
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lda $22 : cmp #$b0 : bcs ++
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ldx #$09 : bra .end
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++ ldx #$0a
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.end txa : rts
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DetectSouthEdge:
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ldx #$ff
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lda $a2
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cmp #$72 : bne +
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lda $22 : cmp #$50 : bcs ++
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ldx #$01 : bra .end
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++ ldx #$00 : bra .end
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+ cmp #$73 : bne +
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ldx #$02 : bra .end
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+ cmp #$74 : bne +
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lda $a9 : beq ++
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lda $22 : cmp #$78 : bcs +++
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ldx #$04 : bra .end
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+++ ldx #$05 : bra .end
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++ lda $22 : cmp #$78 : bcs ++
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ldx #$03 : bra .end
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++ ldx #$04 : bra .end
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+ cmp #$75 : bne +
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ldx #$06 : bra .end
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+ cmp #$cb : bne +
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lda $a9 : beq ++
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lda $22 : beq ++
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ldx #$08 : bra .end
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++ ldx #$07 : bra .end
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+ cmp #$cc : bne .end
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lda $a9 : bne ++
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lda $22 : cmp #$b0 : bcs ++
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ldx #$09 : bra .end
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++ ldx #$0a
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.end txa : rts
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DetectWestEdge:
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ldx #$ff
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lda $a2
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cmp #$65 : bne +
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ldx #$00 : bra .end
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+ cmp #$74 : bne +
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ldx #$01 : bra .end
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+ cmp #$75 : bne +
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ldx #$02 : bra .end
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+ cmp #$82 : bne +
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lda $aa : beq ++
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ldx #$03 : bra .end
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++ ldx #$04 : bra .end
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+ cmp #$85 : bne +
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ldx #$05 : bra .end
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+ cmp #$cc : bne +
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lda $aa : beq ++
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ldx #$06 : bra .end
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++ ldx #$07 : bra .end
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+ cmp #$dc : bne .end
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ldx #$08
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.end txa : rts
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DetectEastEdge:
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ldx #$ff
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lda $a2
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cmp #$64 : bne +
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ldx #$00 : bra .end
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+ cmp #$73 : bne +
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ldx #$01 : bra .end
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+ cmp #$74 : bne +
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ldx #$02 : bra .end
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+ cmp #$81 : bne +
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lda $aa : beq ++
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ldx #$04 : bra .end
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++ ldx #$03 : bra .end
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+ cmp #$84 : bne +
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ldx #$05 : bra .end
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+ cmp #$cb : bne +
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lda $aa : beq ++
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ldx #$06 : bra .end
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++ ldx #$07 : bra .end
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+ cmp #$db : bne .end
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ldx #$08
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.end txa : rts
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