let's dev 4/25/18

additional dev for inverted

entrances.asm

@@ -36,3 +36,42 @@ SmithDoorCheck:
 
 JMP.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
+    BEQ +
+      BRL .done
+    +
+        PHA
+            LDA #$0016 : STA $7EC142 ; Cache the main screen designation
+            LDA $02DCF3 : STA $7EC144 ; Cache BG1 V scroll
+            LDA $02DD91 : STA $7EC146 ; Cache BG1 H scroll
+            LDA $02DE2F : !ADD.w #$0010 : STA $7EC148 ; Cache Link's Y coordinate
+            LDA $02DECD : STA $7EC14A ; Cache Link's X coordinate
+            LDA $02DF6B : STA $7EC150 ; Cache Camera Y coord lower bound.
+            LDA $02E009 : STA $7EC152 ; Cache Camera X coord lower bound.
+            LDA $02DC55 : 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 $02E06A : AND.w #$00FF
+            BIT.w #$0080 : BEQ + : ORA #$FF00 : + ; Sign extend
+            STA.l $7EC16A
+
+            LDA.l $02E0B9 : 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 $02DBC9 : AND.w #$00FF
+            STA $7EC14C ; Cache the overworld area number
+            STA $7EC140 ; Cache the aux overworld area number
+        PLA
+    .done
+RTL
+;--------------------------------------------------------------------------------