144 lines
3.8 KiB
NASM
144 lines
3.8 KiB
NASM
SpiralWarp: {
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pha : lda $040c : cmp.b #$ff : beq .abort ; abort if not in dungeon
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cmp #$06 : bcs .abort ; abort if not supported yet -- todo: this needs to be altered/removed as more dungeons are implemented
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lda $0e : cmp #$5e : beq .gtg ; abort if not spiral - intended room is in A!
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cmp #$5f : beq .gtg
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.abort pla : sta $a0 : bra .end
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.gtg
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pla
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phb : phk : plb : phx : phy ; push stuff
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jsr LookupSpiralOffset
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rep #$30 : and #$00FF : asl #2 : tax
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lda SpiralTable, x : sta $00
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lda SpiralTable+2, x : sta $02
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sep #$30
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lda $00 : sta $a0
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; shift quadrant if necessary
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lda $01 : and #$01 : !sub $a9
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beq .skipXQuad
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sta $06 : !add $a9 : sta $a9
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ldy #$00 : jsr ShiftQuadSimple
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.skipXQuad
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lda $01 : and #$02 : lsr : sta $06 : lda $aa : lsr : !sub $06
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beq .skipYQuad
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sta $06 : asl : !add $aa : sta $aa
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ldy #$01 : jsr ShiftQuadSimple
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.skipYQuad
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lda $01 : and #$04 : lsr : sta $048a ;fix layer calc 0->0 2->1
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; shift lower coordinates
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lda $02 : sta $22
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lda $03 : sta $20
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lda $01 : and #$10 : sta $07 ; zeroHzCam check
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ldy #$00 : jsr SetCamera
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lda $01 : and #$20 : sta $07 ; zeroVtCam check
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ldy #$01 : jsr SetCamera
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ply : plx : plb ; pull the stuff we pushed
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.end rtl
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; this is the code we are hijacking
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; lda $a0 - we overwrote all this behavior
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; lda $063d, x
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; sta $048a
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}
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;Sets the offset in A
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LookupSpiralOffset: {
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;where link currently is in $a2: quad in a8 & #$03
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;count doors
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stz $00 : ldx #$00 : stz $01
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.loop
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lda $047e, x : cmp $00 : bcc .continue
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sta $00
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.continue inx #2
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cpx #$08 : bcc .loop
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lda $00 : lsr
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cmp #$01 : beq .done
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; look up the quad
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lda $a8 : and #$03 : beq .quad0
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cmp #$01 : beq .quad1
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cmp #$02 : beq .quad2
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cmp #$03 : beq .quad3
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.quad0
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inc $01 : lda $22 : cmp #$98 : bcc .done ;gt ent and hc stairwell
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inc $01 : bra .done
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.quad1
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lda $22 : cmp #$78 : bcc .done ;swamp/pod dual stairs
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inc $01 : bra .done
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.quad2 ;ice room
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lda #$03 : sta $01
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lda $22 : cmp #$78 : bcc .done
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inc $01 : bra .done
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.quad3 lda #$02 : sta $01 ; always 2
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.done
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lda $a2 : tax : lda SpiralOffset,x
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!add $01 ;add a thing (0 in .easy)
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rts
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}
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ShiftQuadSimple: {
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lda CoordIndex,y : tax
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lda $21,x : !add $06 : sta $21,x ; coordinate update
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lda CamQuadIndex,y : tax
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lda $0601,x : !add $06 : sta $0601,x
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lda $0605,x : !add $06 : sta $0605,x ; high bytes of these guys
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rts
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}
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SetCamera: {
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stz $04 : sty $05
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tyx : lda $a9,x : bne .nonZeroHalf
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lda CamQuadIndex,y : tax : lda $607,x : pha
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lda CameraIndex,y : tax : pla : cmp $e3, x : bne .noQuadAdj
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dec $e3,x
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.noQuadAdj
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lda $07 : bne .adj0
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lda CoordIndex,y : tax
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lda $20,x : cmp #$79 : bcc .adj0
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!sub #$78 : sta $04
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tya : asl : !add #$04 : tax : jsr AdjCamBounds : bra .done
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.adj0
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tya : asl : tax : jsr AdjCamBounds : bra .done
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.nonZeroHalf ;meaning either right half or bottom half
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lda CoordIndex,y : tax
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lda $20,x : cmp #$78 : bcs .setQuad
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lda $07 : bne .adj1
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!add #$78 : sta $04
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tya : asl : !add #$08 : tax : jsr AdjCamBounds : bra .done
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.setQuad
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lda CamQuadIndex,y : tax : lda $0607, x : pha
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lda CameraIndex,y : tax : pla : sta $e3, x
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.adj1
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tya : asl : !add #$0c : tax : jsr AdjCamBounds : bra .done
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.done
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lda CameraIndex,y : tax : lda $e2, x
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lda $04 : sta $e2, x
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rts
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}
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; input, expects X to be an appropriate offset into the CamBoundBaseLine table
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; when $04 is 0 no coordinate are added
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AdjCamBounds: {
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rep #$20 : lda CamBoundBaseLine, x : sta $05
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lda $04 : and #$00ff : beq .common
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lda CoordIndex,y : tax
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lda $20, x : and #$00ff : !add $05 : sta $05
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.common
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lda OppCamBoundIndex,y : tax
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lda $05 : sta $0618, x
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inc #2 : sta $061A, x : sep #$20
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rts
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} |