utils: factor out the leading zero count code

diff --git a/gst/gstutils.c b/gst/gstutils.c
index 505b7f5..fddf871 100644 (file)
--- a/gst/gstutils.c
+++ b/gst/gstutils.c
@@ -247,19 +247,13 @@ gst_util_uint64_mul_uint64 (GstUInt64 * c1, GstUInt64 * c0, guint64 arg1,
   c1->ll = (guint64) v.l.high * n.l.high + c1->l.high + a1.l.high + b0.l.high;
 }
 
-/* based on Hacker's Delight p152 */
-static guint64
-gst_util_div128_64 (GstUInt64 c1, GstUInt64 c0, guint64 denom)
+/* count leading zeros */
+static guint
+gst_util_clz (guint32 val)
 {
-  GstUInt64 q1, q0, rhat;
-  GstUInt64 v, cmp1, cmp2;
   guint s;
 
-  v.ll = denom;
-
-  /* count number of leading zeroes, we know they must be in the high
-   * part of denom since denom > G_MAXUINT32. */
-  s = v.l.high | (v.l.high >> 1);
+  s = val | (val >> 1);
   s |= (s >> 2);
   s |= (s >> 4);
   s |= (s >> 8);
@@ -270,6 +264,23 @@ gst_util_div128_64 (GstUInt64 c1, GstUInt64 c0, guint64 denom)
   s += (s >> 8);
   s = (s + (s >> 16)) & 0x3f;
 
+  return s;
+}
+
+/* based on Hacker's Delight p152 */
+static guint64
+gst_util_div128_64 (GstUInt64 c1, GstUInt64 c0, guint64 denom)
+{
+  GstUInt64 q1, q0, rhat;
+  GstUInt64 v, cmp1, cmp2;
+  guint s;
+
+  v.ll = denom;
+
+  /* count number of leading zeroes, we know they must be in the high
+   * part of denom since denom > G_MAXUINT32. */
+  s = gst_util_clz (v.l.high);
+
   if (s > 0) {
     /* normalize divisor and dividend */
     v.ll <<= s;