diff options
author | Brian Paul <[email protected]> | 2011-06-02 08:43:07 -0600 |
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committer | Brian Paul <[email protected]> | 2011-06-02 08:45:27 -0600 |
commit | f62e1f41b4d6047e72222aebbb0b55a508269b0c (patch) | |
tree | 363a45b42d9bf2d70a9b8da69ada31acf73b4da7 | |
parent | bab3b4a75886acd040e81730d9d3dfb31d4f0d48 (diff) |
util: faster logbase2
-rw-r--r-- | src/gallium/auxiliary/util/u_math.h | 11 |
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; } |