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authorBrian Paul <[email protected]>2011-06-02 08:43:07 -0600
committerBrian Paul <[email protected]>2011-06-02 08:45:27 -0600
commitf62e1f41b4d6047e72222aebbb0b55a508269b0c (patch)
tree363a45b42d9bf2d70a9b8da69ada31acf73b4da7
parentbab3b4a75886acd040e81730d9d3dfb31d4f0d48 (diff)
util: faster logbase2
-rw-r--r--src/gallium/auxiliary/util/u_math.h11
1 files changed, 7 insertions, 4 deletions
diff --git a/src/gallium/auxiliary/util/u_math.h b/src/gallium/auxiliary/util/u_math.h
index 2ecade5f7e4..65a99fcb394 100644
--- a/src/gallium/auxiliary/util/u_math.h
+++ b/src/gallium/auxiliary/util/u_math.h
@@ -477,10 +477,13 @@ float_to_byte_tex(float f)
static INLINE unsigned
util_logbase2(unsigned n)
{
- unsigned log2 = 0;
- while (n >>= 1)
- ++log2;
- return log2;
+ unsigned pos = 0;
+ if (n >= 1<<16) { n >>= 16; pos += 16; }
+ if (n >= 1<< 8) { n >>= 8; pos += 8; }
+ if (n >= 1<< 4) { n >>= 4; pos += 4; }
+ if (n >= 1<< 2) { n >>= 2; pos += 2; }
+ if (n >= 1<< 1) { pos += 1; }
+ return pos;
}