From f7cf2757ca1839b131d153e1a50029c2ed10f8b1 Mon Sep 17 00:00:00 2001
From: jstebbins <jstebbins.hb@gmail.com>
Date: Sat, 16 Apr 2011 01:11:53 +0000
Subject: Fix int overflow that can happen when computing PAR If the source has
 large non-reduced PAR values, our computed value was overflowing an int. 
 Compute it in an int64_t then reduce it. Also, keep num and den below 65535. 
 Larger values just aren't really significant and will cause more overflow
 issues.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@3931 b64f7644-9d1e-0410-96f1-a4d463321fa5
---
 libhb/common.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

(limited to 'libhb/common.c')

diff --git a/libhb/common.c b/libhb/common.c
index 4c382e57c..a3887b680 100644
--- a/libhb/common.c
+++ b/libhb/common.c
@@ -411,6 +411,62 @@ void hb_reduce( int *x, int *y, int num, int den )
     }
 }
 
+/**********************************************************************
+ * hb_reduce64
+ **********************************************************************
+ * Given a numerator (num) and a denominator (den), reduce them to an
+ * equivalent fraction and store the result in x and y.
+ *********************************************************************/
+void hb_reduce64( int64_t *x, int64_t *y, int64_t num, int64_t den )
+{
+    // find the greatest common divisor of num & den by Euclid's algorithm
+    int64_t n = num, d = den;
+    while ( d )
+    {
+        int64_t t = d;
+        d = n % d;
+        n = t;
+    }
+
+    // at this point n is the gcd. if it's non-zero remove it from num
+    // and den. Otherwise just return the original values.
+    if ( n )
+    {
+        num /= n;
+        den /= n;
+    }
+
+    *x = num;
+    *y = den;
+
+}
+
+void hb_limit_rational64( int64_t *x, int64_t *y, int64_t num, int64_t den, int64_t limit )
+{
+    hb_reduce64( &num, &den, num, den );
+    if ( num < limit && den < limit )
+    {
+        *x = num;
+        *y = den;
+        return;
+    }
+
+    if ( num > den )
+    {
+        double div = (double)limit / num;
+        num = limit;
+        den *= div;
+    }
+    else
+    {
+        double div = (double)limit / den;
+        den = limit;
+        num *= div;
+    }
+    *x = num;
+    *y = den;
+}
+
 /**********************************************************************
  * hb_fix_aspect
  **********************************************************************
-- 
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