Files
alttpr-baserom/entrances.asm
Kevin Cathcart d81bec6c88 Revise code for starting In Single entrance caves
No longer hardcoded to only work for link's house.
2018-08-19 10:41:17 -04:00

89 lines
3.0 KiB
NASM

;--------------------------------------------------------------------------------
; LockAgahnimDoors:
; Returns: 0=Unlocked - 1=Locked
;--------------------------------------------------------------------------------
LockAgahnimDoors:
LDA.l AgahnimDoorStyle
BNE +
;#$0 = Never Locked
LDA.w #$0000 : RTL
+ : CMP.w #$0001 : BNE +
JSR.w OldLockAgahnimDoors : RTL
+
LDA.w #$0000 ; fallback to never locked
RTL
;--------------------------------------------------------------------------------
OldLockAgahnimDoors:
LDA $7EF3C5 : AND.w #$000F : CMP.w #$0002 : !BGE + ; if we rescued zelda, skip
LDA $22 : CMP.w #1992 : !BLT + ; door too far left, skip
CMP.w #2088 : !BGE + ; door too rat right, skip
LDA $20 : CMP.w #1720 : !BGE + ; door too low, skip
LDA.w #$0001
RTS
+
LDA.w #$0000
RTS
;--------------------------------------------------------------------------------
SmithDoorCheck:
LDA.l SmithTravelsFreely : AND.w #$00FF : BEQ .orig
;If SmithTravelsFreely is set Frog/Smith can enter multi-entrance overworld doors
JML.l Overworld_Entrance_BRANCH_RHO
.orig ; The rest is equivlent to what we overwrote
CPX.w #$0076 : !BGE +
JML.l Overworld_Entrance_BRANCH_LAMBDA
+
JML.l Overworld_Entrance_BRANCH_RHO
;--------------------------------------------------------------------------------
AllowStartFromSingleEntranceCave:
; 16 Bit A, 16 bit XY
; do not need to preserve A or X or Y
LDA $7EF3C8 : AND.w #$00FF ; What we wrote over
PHA
TAX
LDA.l StartingAreaExitOffset, X
BNE +
BRL .done
+
DEC
STA $00
LSR #2 : !ADD $00 : LSR #2 ; mult by 20
TAX
LDA #$0016 : STA $7EC142 ; Cache the main screen designation
LDA.l StartingAreaExitTable+$05, X : STA $7EC144 ; Cache BG1 V scroll
LDA.l StartingAreaExitTable+$07, X : STA $7EC146 ; Cache BG1 H scroll
LDA.l StartingAreaExitTable+$09, X : !ADD.w #$0010 : STA $7EC148 ; Cache Link's Y coordinate
LDA.l StartingAreaExitTable+$0B, X : STA $7EC14A ; Cache Link's X coordinate
LDA.l StartingAreaExitTable+$0D, X : STA $7EC150 ; Cache Camera Y coord lower bound.
LDA.l StartingAreaExitTable+$0F, X : STA $7EC152 ; Cache Camera X coord lower bound.
LDA.l StartingAreaExitTable+$03, X : STA $7EC14E ; Cache Link VRAM Location
; Handle the 2 "unknown" bytes, which control what area of the backgound
; relative to the camera? gets loaded with new tile data as the player moves around
; (because some overworld areas like Kak are too big for a single VRAM tilemap)
LDA.l StartingAreaExitTable+$11, X : AND.w #$00FF
BIT.w #$0080 : BEQ + : ORA #$FF00 : + ; Sign extend
STA.l $7EC16A
LDA.l StartingAreaExitTable+$12, X : AND.w #$00FF
BIT.w #$0080 : BEQ + : ORA #$FF00 : + ; Sign extend
STA.l $7EC16E
LDA.w #$0000 : !SUB.l $7EC16A : STA $7EC16C
LDA.w #$0000 : !SUB.l $7EC16E : STA $7EC170
LDA.l StartingAreaExitTable+$02, X : AND.w #$00FF
STA $7EC14C ; Cache the overworld area number
STA $7EC140 ; Cache the aux overworld area number
.done
PLA
RTL
;--------------------------------------------------------------------------------