gstutils: add a 64 bit version of GCD calculation

https://bugzilla.gnome.org/show_bug.cgi?id=665294

gst/gstutils.c

@@ -3521,6 +3521,32 @@ gst_util_greatest_common_divisor (gint a, gint b)
   return ABS (a);
 }
 
+/**
+ * gst_util_greatest_common_divisor_int64:
+ * @a: First value as #gint64
+ * @b: Second value as #gint64
+ *
+ * Calculates the greatest common divisor of @a
+ * and @b.
+ *
+ * Returns: Greatest common divisor of @a and @b
+ *
+ * Since: 0.11.0
+ */
+gint64
+gst_util_greatest_common_divisor_int64 (gint64 a, gint64 b)
+{
+  while (b != 0) {
+    gint64 temp = a;
+
+    a = b;
+    b = temp % b;
+  }
+
+  return ABS (a);
+}
+
+
 /**
  * gst_util_fraction_to_double:
  * @src_n: Fraction numerator as #gint

gst/gstutils.h

@@ -957,6 +957,7 @@ gpointer      gst_util_array_binary_search      (gpointer array, guint num_eleme
 
 /* fraction operations */
 gint          gst_util_greatest_common_divisor  (gint a, gint b);
+gint64        gst_util_greatest_common_divisor_int64 (gint64 a, gint64 b);
 
 void          gst_util_fraction_to_double       (gint src_n, gint src_d, gdouble *dest);
 void          gst_util_double_to_fraction       (gdouble src, gint *dest_n, gint *dest_d);