From 4e83a497dfddeff730607989b3c377d07636d5a6 Mon Sep 17 00:00:00 2001
From: Snesrev <snesrev@protonmail.com>
Date: Mon, 6 Mar 2023 18:55:05 +0100
Subject: [PATCH] Orig game reads uninitialized memory in xray

---
 src/sm_91.c        | 3 +++
 src/sm_cpu_infra.c | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/src/sm_91.c b/src/sm_91.c
index 2528bf7..c6cb450 100644
--- a/src/sm_91.c
+++ b/src/sm_91.c
@@ -1985,6 +1985,9 @@ void Xray_SetupStage4_Func1(void) {  // 0x91CCF1
 }
 
 void Xray_SetupStage4_Func2(void) {  // 0x91CD42
+  // bug: passing 0xffff to this function is invalid and will read invalid memory.
+  if (R34 == 0)
+    return;
   unsigned int v2;
   int16 v3;
   unsigned int v7;
diff --git a/src/sm_cpu_infra.c b/src/sm_cpu_infra.c
index b2496a4..fbefe7a 100644
--- a/src/sm_cpu_infra.c
+++ b/src/sm_cpu_infra.c
@@ -282,6 +282,10 @@ void PatchBugs(uint32 mode, uint32 addr) {
   } else if (FixBugHook(0xA7CEB2)) {
     // Phantoon_Main forgots to reload x
     g_cpu->x = cur_enemy_index;
+  } else if (FixBugHook(0x91CD44)) {
+    // Xray_SetupStage4_Func2 passes a bad value to Xray_HandleXrayedBlock
+    if (g_cpu->x == 0)
+      g_cpu->pc = 0xCD52;
   }
 }