[FFmpeg-cvslog] intmath: add faster clz support

[Ganesh Ajjanagadde]

ffmpeg | branch: master | Ganesh Ajjanagadde <gajjanagadde at gmail.com> | Wed Feb 22 12:53:33 2017 -0500| [7bfda7d157eb6f7a2df908addd60221a7a6f5eb0] | committer: Vittorio Giovara

intmath: add faster clz support

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7bfda7d157eb6f7a2df908addd60221a7a6f5eb0
---

 libavutil/intmath.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/libavutil/intmath.h b/libavutil/intmath.h
index a5ee6525ee..780bbab039 100644
--- a/libavutil/intmath.h
+++ b/libavutil/intmath.h
@@ -44,6 +44,10 @@
 #   endif
 #endif /* ff_log2 */
 
+#ifndef ff_clz
+#   define ff_clz(v) __builtin_clz(v)
+#endif /* ff_clz */
+
 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
 
 extern const uint8_t ff_log2_tab[256];
@@ -132,6 +136,21 @@ static av_always_inline av_const int ff_ctz_c(int v)
 }
 #endif
 
+#ifndef ff_clz
+#define ff_clz ff_clz_c
+static av_always_inline av_const unsigned ff_clz_c(unsigned x)
+{
+    unsigned i = sizeof(x) * 8;
+
+    while (x) {
+        x >>= 1;
+        i--;
+    }
+
+    return i;
+}
+#endif
+
 /**
  * Trailing zero bit count.
  *