1 files changed, 56 insertions, 0 deletions
diff --git a/rate-lavc/gcd.h b/rate-lavc/gcd.h
new file mode 100644
index 0000000..672084c
--- /dev/null
+++ b/rate-lavc/gcd.h
@@ -0,0 +1,56 @@
+/*
+ * Fast implementation of greatest common divisor using the binary algorithm.
+ * Copyright (c) 2007 Nicholas Kain
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/* computes gcd using binary algorithm */
+static int gcd(int a, int b)
+{
+	int s,d;
+
+	if (!a || !b)
+		return a | b;
+
+	for (s=0; ((a|b)&1) == 0; ++s) {
+		a >>= 1;
+		b >>= 1;
+	}
+
+	while ((a&1) == 0)
+		a >>= 1;
+	
+	do {
+		while ((b&1) == 0) {
+			b >>= 1;
+		}
+		if (a<b) {
+			b -= a;
+		} else {
+			d = a-b;
+			a = b;
+			b = d;
+		}
+		b >>= 1;
+	} while (b);
+
+	return a << s;
+}
+