From 6f9dbbc20d155b09aef456de2a7db45286ac56dd Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Mon, 10 Feb 2020 18:03:48 -0800
Subject: [PATCH] GBA BIOS: Fix undefined instruction HLE behavior

---
 CHANGES            | 1 +
 src/gba/hle-bios.c | 7 ++++---
 src/gba/hle-bios.s | 5 +++++
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/CHANGES b/CHANGES
index 1f0f3be33..63260cd1f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,7 @@
 0.8.1: (Future)
 Emulation fixes:
  - GB Serialize: Fix timing bug loading channel 4 timing
+ - GBA BIOS: Fix undefined instruction HLE behavior
  - GBA Memory: Misaligned SRAM writes are ignored
  - GBA Serialize: Fix serializing DMA transfer register
  - GBA Serialize: Fix audio DMA timing deserialization
diff --git a/src/gba/hle-bios.c b/src/gba/hle-bios.c
index 776c3d550..8903ca0ac 100644
--- a/src/gba/hle-bios.c
+++ b/src/gba/hle-bios.c
@@ -3,10 +3,10 @@
 #include <mgba/internal/gba/memory.h>
 
 const uint8_t hleBios[SIZE_BIOS] = {
-	0x06, 0x00, 0x00, 0xea, 0xfe, 0xff, 0xff, 0xea, 0x0b, 0x00, 0x00, 0xea,
+	0x06, 0x00, 0x00, 0xea, 0x88, 0x00, 0x00, 0xea, 0x0b, 0x00, 0x00, 0xea,
 	0xfe, 0xff, 0xff, 0xea, 0xfe, 0xff, 0xff, 0xea, 0x00, 0x00, 0xa0, 0xe1,
 	0x2c, 0x00, 0x00, 0xea, 0xfe, 0xff, 0xff, 0xea, 0x02, 0x03, 0xa0, 0xe3,
-	0x03, 0x10, 0xd0, 0xe5, 0xea, 0x00, 0x51, 0xe3, 0xf8, 0x01, 0x9f, 0x15,
+	0x03, 0x10, 0xd0, 0xe5, 0xea, 0x00, 0x51, 0xe3, 0x04, 0x02, 0x9f, 0x15,
 	0x10, 0xff, 0x2f, 0xe1, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x29, 0xe1,
 	0x00, 0x00, 0x5d, 0xe3, 0x01, 0xd3, 0xa0, 0x03, 0x20, 0xd0, 0x4d, 0x02,
 	0x00, 0x58, 0x2d, 0xe9, 0x02, 0xb0, 0x5e, 0xe5, 0x9c, 0xc0, 0xa0, 0xe3,
@@ -49,5 +49,6 @@ const uint8_t hleBios[SIZE_BIOS] = {
 	0x03, 0xa0, 0xa0, 0xe1, 0x02, 0x00, 0x51, 0xe1, 0xf8, 0x07, 0xa1, 0xb8,
 	0xfc, 0xff, 0xff, 0xba, 0x03, 0x00, 0x00, 0xea, 0x02, 0x00, 0x51, 0xe1,
 	0xf8, 0x07, 0xb0, 0xb8, 0xf8, 0x07, 0xa1, 0xb8, 0xfb, 0xff, 0xff, 0xba,
-	0xf0, 0x87, 0xbd, 0xe8, 0xc0, 0x00, 0x00, 0x02
+	0xf0, 0x87, 0xbd, 0xe8, 0x04, 0xf0, 0x5e, 0xe2, 0x00, 0x00, 0x00, 0x00,
+	0x04, 0xe0, 0xa0, 0x03, 0xc0, 0x00, 0x00, 0x02
 };
diff --git a/src/gba/hle-bios.s b/src/gba/hle-bios.s
index 96de3ad61..bb7eb0c43 100644
--- a/src/gba/hle-bios.s
+++ b/src/gba/hle-bios.s
@@ -187,4 +187,9 @@ blt    0b
 2:
 ldmfd  sp!, {r4-r10, pc}
 
+undefBase:
+subs   pc, lr, #4
+.word 0
+.word 0x03A0E004
+
 .ltorg