From 3f75078174dd7cd7f696b59c3e43bd2842c6359c Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Thu, 23 Jul 2020 21:42:35 -0700
Subject: [PATCH] Util: Factor out gcd code

---
 include/mgba-util/math.h      | 13 +++++++++++++
 src/platform/qt/VideoView.cpp | 12 +++---------
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/include/mgba-util/math.h b/include/mgba-util/math.h
index eaf2087a2..9e239869c 100644
--- a/include/mgba-util/math.h
+++ b/include/mgba-util/math.h
@@ -58,6 +58,19 @@ static inline uint32_t toPow2(uint32_t bits) {
 	return 1 << (32 - lz);
 }
 
+static inline int reduceFraction(int* num, int* den) {
+	int n = *num;
+	int d = *den;
+	while (d != 0) {
+		int temp = n % d;
+		n = d;
+		d = temp;
+	}
+	*num /= n;
+	*den /= n;
+	return n;
+}
+
 CXX_GUARD_END
 
 #endif
diff --git a/src/platform/qt/VideoView.cpp b/src/platform/qt/VideoView.cpp
index 307245aa8..da09fc150 100644
--- a/src/platform/qt/VideoView.cpp
+++ b/src/platform/qt/VideoView.cpp
@@ -10,6 +10,8 @@
 #include "GBAApp.h"
 #include "LogController.h"
 
+#include <mgba-util/math.h>
+
 #include <QMap>
 
 using namespace QGBA;
@@ -396,15 +398,7 @@ void VideoView::updateAspectRatio(int width, int height, bool force) {
 	} else {
 		int w = m_width;
 		int h = m_height;
-		// Get greatest common divisor
-		while (w != 0) {
-			int temp = h % w;
-			h = w;
-			w = temp;
-		}
-		int gcd = h;
-		w = m_width / gcd;
-		h = m_height / gcd;
+		reduceFraction(&h, &w);
 		safelySet(m_ui.wratio, w);
 		safelySet(m_ui.hratio, h);
 	}