From ee610db141499fb7d8ebae3901838a7e893adcd2 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Tue, 28 Dec 2021 17:12:22 -0800
Subject: [PATCH] GBA BIOS: Work around IRQ handling hiccup in Mario & Luigi
 (fixes #1059)

---
 CHANGES            |  1 +
 src/gba/hle-bios.c | 12 ++++++------
 src/gba/hle-bios.s | 14 +++++++-------
 3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/CHANGES b/CHANGES
index 398df1445..62f6daa64 100644
--- a/CHANGES
+++ b/CHANGES
@@ -15,6 +15,7 @@ Emulation fixes:
  - ARM7: Fix unsigned multiply timing
  - GB Memory: Add cursory cartridge open bus emulation (fixes mgba.io/i/2032)
  - GBA: Improve timing when not booting from BIOS
+ - GBA BIOS: Work around IRQ handling hiccup in Mario & Luigi (fixes mgba.io/i/1059)
  - GBA I/O: Redo internal key input, enabling edge-based key IRQs
  - GBA Memory: Fix misaligned 32-bit I/O loads (fixes mgba.io/i/2307)
 Other fixes:
diff --git a/src/gba/hle-bios.c b/src/gba/hle-bios.c
index 05223b937..9ee6dd5b1 100644
--- a/src/gba/hle-bios.c
+++ b/src/gba/hle-bios.c
@@ -9,17 +9,17 @@ const uint8_t hleBios[SIZE_BIOS] = {
 	0x03, 0x10, 0xd0, 0xe5, 0xea, 0x00, 0x51, 0xe3, 0x4c, 0x01, 0x9f, 0x15,
 	0x10, 0xff, 0x2f, 0xe1, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x29, 0xe1,
 	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x5d, 0xe3, 0x01, 0xd3, 0xa0, 0x03,
-	0x20, 0xd0, 0x4d, 0x02, 0x00, 0x58, 0x2d, 0xe9, 0x02, 0xb0, 0x5e, 0xe5,
-	0xd4, 0xc0, 0xa0, 0xe3, 0x0b, 0xb1, 0x9c, 0xe7, 0xd2, 0xcf, 0xa0, 0xe3,
-	0x0b, 0x00, 0x5c, 0xe1, 0x00, 0xc0, 0x4f, 0xe1, 0x00, 0x10, 0x2d, 0xe9,
+	0x20, 0xd0, 0x4d, 0x02, 0x10, 0x50, 0x2d, 0xe9, 0x02, 0x40, 0x5e, 0xe5,
+	0xd4, 0xc0, 0xa0, 0xe3, 0x04, 0x41, 0x9c, 0xe7, 0xd2, 0xcf, 0xa0, 0xe3,
+	0x04, 0x00, 0x5c, 0xe1, 0x00, 0xc0, 0x4f, 0xe1, 0x00, 0x10, 0x2d, 0xe9,
 	0x80, 0xc0, 0x0c, 0xe2, 0x1f, 0xc0, 0x8c, 0xe3, 0x0c, 0xf0, 0x21, 0xe1,
-	0x00, 0x00, 0xf0, 0x0f, 0x04, 0x40, 0x2d, 0xe9, 0x00, 0x00, 0x5b, 0xe3,
+	0x00, 0x00, 0xf0, 0x0f, 0x04, 0x40, 0x2d, 0xe9, 0x00, 0x00, 0x54, 0xe3,
 	0x00, 0x00, 0xa0, 0xe1, 0x00, 0x00, 0xa0, 0xe1, 0x00, 0x00, 0xa0, 0xe1,
 	0x00, 0x00, 0xa0, 0xe1, 0x00, 0x00, 0xa0, 0xe1, 0x00, 0x00, 0xa0, 0xe1,
-	0x0f, 0xe0, 0xa0, 0xe1, 0x1b, 0xff, 0x2f, 0x11, 0x00, 0x00, 0xa0, 0xe1,
+	0x0f, 0xe0, 0xa0, 0xe1, 0x14, 0xff, 0x2f, 0x11, 0x00, 0x00, 0xa0, 0xe1,
 	0x00, 0x00, 0xa0, 0xe1, 0x00, 0x00, 0xa0, 0xe1, 0x04, 0x40, 0xbd, 0xe8,
 	0x93, 0xf0, 0x29, 0xe3, 0x00, 0x10, 0xbd, 0xe8, 0x0c, 0xf0, 0x69, 0xe1,
-	0x00, 0x58, 0xbd, 0xe8, 0x0e, 0xf0, 0xb0, 0xe1, 0x00, 0x00, 0x00, 0x00,
+	0x10, 0x50, 0xbd, 0xe8, 0x0e, 0xf0, 0xb0, 0xe1, 0x00, 0x00, 0x00, 0x00,
 	0x04, 0x20, 0xa0, 0xe3, 0x00, 0x00, 0x00, 0x00, 0xb0, 0x01, 0x00, 0x00,
 	0xb0, 0x01, 0x00, 0x00, 0xb4, 0x01, 0x00, 0x00, 0xb0, 0x01, 0x00, 0x00,
 	0xcc, 0x01, 0x00, 0x00, 0xc4, 0x01, 0x00, 0x00, 0x48, 0x03, 0x00, 0x00,
diff --git a/src/gba/hle-bios.s b/src/gba/hle-bios.s
index 8234b9e45..be0d81703 100644
--- a/src/gba/hle-bios.s
+++ b/src/gba/hle-bios.s
@@ -31,12 +31,12 @@ swiBase:
 cmp    sp, #0
 moveq  sp, #0x04000000
 subeq  sp, #0x20
-stmfd  sp!, {r11-r12, lr}
-ldrb   r11, [lr, #-2]
+stmfd  sp!, {r4, r12, lr}
+ldrb   r4, [lr, #-2]
 mov    r12, #swiTable
-ldr    r11, [r12, r11, lsl #2]
+ldr    r4, [r12, r4, lsl #2]
 mov    r12, #StallCall
-cmp    r12, r11
+cmp    r12, r4
 mrs    r12, spsr
 stmfd  sp!, {r12}
 and    r12, #0x80
@@ -44,7 +44,7 @@ orr    r12, #0x1F
 msr    cpsr_c, r12
 swieq  0xF00000  @ Special mGBA-internal call to load the stall count into r12
 stmfd  sp!, {r2, lr}
-cmp    r11, #0
+cmp    r4, #0
 nop
 nop
 nop
@@ -52,7 +52,7 @@ nop
 nop
 nop
 mov    lr, pc
-bxne   r11
+bxne   r4
 nop
 nop
 nop
@@ -60,7 +60,7 @@ ldmfd  sp!, {r2, lr}
 msr    cpsr, #0x93
 ldmfd  sp!, {r12}
 msr    spsr, r12
-ldmfd  sp!, {r11-r12, lr}
+ldmfd  sp!, {r4, r12, lr}
 movs   pc, lr
 .word 0
 .word 0xE3A02004