From c9d411a762ec6ef13c3108d0479408f8326df442 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Thu, 20 Apr 2017 17:53:01 -0700
Subject: [PATCH] GBA BIOS: Fix ArcTan sign in HLE BIOS

---
 CHANGES        | 1 +
 src/gba/bios.c | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/CHANGES b/CHANGES
index 4b31d0426..e86548eeb 100644
--- a/CHANGES
+++ b/CHANGES
@@ -38,6 +38,7 @@ Bugfixes:
  - GB: Fix flickering when screen is strobed quickly
  - FFmpeg: Fix overflow and general issues with audio encoding
  - Qt: Fix crash when changing audio settings after a game is closed
+ - GBA BIOS: Fix ArcTan sign in HLE BIOS
 Misc:
  - SDL: Remove scancode key input
  - GBA Video: Clean up unused timers
diff --git a/src/gba/bios.c b/src/gba/bios.c
index 9d8b6ccdc..2bc853a3c 100644
--- a/src/gba/bios.c
+++ b/src/gba/bios.c
@@ -271,7 +271,7 @@ static void _Div(struct GBA* gba, int32_t num, int32_t denom) {
 	}
 }
 
-static int16_t _ArcTan(int16_t i) {
+static int16_t _ArcTan(int32_t i) {
 	int32_t a = -((i * i) >> 14);
 	int32_t b = ((0xA9 * a) >> 14) + 0x390;
 	b = ((b * a) >> 14) + 0x91C;
@@ -356,7 +356,7 @@ void GBASwi16(struct ARMCore* cpu, int immediate) {
 		cpu->gprs[0] = sqrt((uint32_t) cpu->gprs[0]);
 		break;
 	case 0x9:
-		cpu->gprs[0] = (uint16_t) _ArcTan(cpu->gprs[0]);
+		cpu->gprs[0] = _ArcTan(cpu->gprs[0]);
 		break;
 	case 0xA:
 		cpu->gprs[0] = (uint16_t) _ArcTan2(cpu->gprs[0], cpu->gprs[1]);