From 03ed8bc47a11a676e029a288e61e2da09ce8f13b Mon Sep 17 00:00:00 2001
From: Justin Scofield <justin.scofield@outlook.com>
Date: Mon, 30 May 2022 23:13:21 -0400
Subject: [PATCH] links awakening dungeon keyblocks

---
 KeyBlock/keyblock.asm | 52 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 KeyBlock/keyblock.asm

diff --git a/KeyBlock/keyblock.asm b/KeyBlock/keyblock.asm
new file mode 100644
index 0000000..82669fe
--- /dev/null
+++ b/KeyBlock/keyblock.asm
@@ -0,0 +1,52 @@
+;===========================================================
+; Key Block Object like Link's Awakening
+; Overwrites the Prison Door
+;
+;
+; WRITTEN: 	by XaserLE
+; THANKS TO: -PuzzleDude for finding a drawing bug and get rid of it
+;			-MathOnNapkins' Zelda Doc's
+;			-wiiqwertyuiop for his Zelda Disassembly
+;
+; The blocks can be opened from up- or downside only, left and right will not work (will try to fix this in the future).
+; The patch is "in place" so it doesn't overwrite other data or patches you added.  
+;
+; PuzzleDudes Note:
+; The key block must always be placed on EVEN x and y.
+; The even x or y is: 00, 02, 04, 06, 08, 0A, 0C, 0E, 10, 12 etc.
+; HM x and y value of the position of the key block must end with: 0, 2, 4, 6, 8, A, C, E.
+;===========================================================
+
+namespace KeyBlock
+{
+  Main: {
+    lorom
+
+    ORG $01EB8C			; go to the code that loads the big key holding variable
+    LDA $7EF36F			; load the small key counter
+    AND #$00FF			; check if we have at least one small key (AND will not be zero)
+    BEQ $4C				  ; if not (AND is zero), don't do anything and especially don't give this "Eh? It's locked..." - message
+                    ; otherwise we will decrement the small key counter and branch to the code that opens the prison door
+    LDA $7EF36F			; reload small key counter
+    DEC A				    ; remove one key
+    STA $7EF36F			; save the new value at small key counter position
+    BRA $05				  ; branch to the code that opens the prison door
+
+    ; now correct a drawing bug in the original game that causes the floor tile under the door drawed odd
+    ORG $01EBC8
+    LDA.w $9B5A,y
+    ORG $01EBD1
+    LDA.w $9B54,y
+    ORG $01EBDA
+    LDA.w $9B5C,y
+    ; draw values representation
+    ; 50- /
+    ; 52- normal
+    ; 54- x mirror
+    ; 56- normal
+    ; 58- x mirror
+    ; 5A- y mirror
+    ; 5C- xy mirror
+    ; 5E- y mirror
+  }  ; label Main
+}  ; namespace KeyBlock
\ No newline at end of file