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remove use of log2(). Use VP8LFastLog2() instead.

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Order-by-cost mostly unchanged (up to a scaling constant 1/log(2))
(except for few minor diff in < 2% of cases)

+ remove unused field cost_mode->cache_bits_

Change-Id: I714f8ab12f49a23f5d499a64c741382c9b489a3e
This commit is contained in:
Pascal Massimino
2012-08-01 18:22:06 -07:00
parent 8c515d54ea
commit 323dc4d9b9
5 changed files with 214 additions and 192 deletions
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6
src/dsp/lossless.h
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@ -59,8 +59,10 @@ static WEBP_INLINE uint32_t VP8LSubSampleSize(uint32_t size,
return (size + (1 << sampling_bits) - 1) >> sampling_bits;
}
// Faster logarithm for small integers, with the property of log(0) == 0.
float VP8LFastLog(int v);
// Faster logarithm for integers, with the property of log2(0) == 0.
float VP8LFastLog2(int v);
// Fast calculation of v * log2(v) for integer input.
static WEBP_INLINE float VP8LFastSLog2(int v) { return VP8LFastLog2(v) * v; }
// In-place difference of each component with mod 256.
static WEBP_INLINE uint32_t VP8LSubPixels(uint32_t a, uint32_t b) {