Mesa (master): gallium/util: add util_last_bit64

[Marek Olšák]

Module: Mesa
Branch: master
Commit: b0a2280e45e5abc56e5301f84f33226469000d6c
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=b0a2280e45e5abc56e5301f84f33226469000d6c

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Sun May 10 20:35:15 2015 +0200

gallium/util: add util_last_bit64

This will be needed by radeonsi.

Reviewed-by: Ilia Mirkin <imirkin at alum.mit.edu>

---

 src/gallium/auxiliary/util/u_math.h |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src/gallium/auxiliary/util/u_math.h b/src/gallium/auxiliary/util/u_math.h
index 58070a9..3b4040f 100644
--- a/src/gallium/auxiliary/util/u_math.h
+++ b/src/gallium/auxiliary/util/u_math.h
@@ -425,6 +425,25 @@ util_last_bit(unsigned u)
 }
 
 /**
+ * Find last bit set in a word.  The least significant bit is 1.
+ * Return 0 if no bits are set.
+ */
+static INLINE unsigned
+util_last_bit64(uint64_t u)
+{
+#if defined(HAVE___BUILTIN_CLZLL)
+   return u == 0 ? 0 : 64 - __builtin_clzll(u);
+#else
+   unsigned r = 0;
+   while (u) {
+       r++;
+       u >>= 1;
+   }
+   return r;
+#endif
+}
+
+/**
  * Find last bit in a word that does not match the sign bit. The least
  * significant bit is 1.
  * Return 0 if no bits are set.