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Provide an SSE2 implementation of CombinedShannonEntropy.

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CombinedShannonEntropy takes 30% for lossless compression.
This implementation speeds up the overall process by 2 to 3 %.

Change-Id: I04a71743284c38814fd0726034d51a02b1b6ba8f
This commit is contained in:
Vincent Rabaud
2015-12-11 15:12:19 +01:00
parent 04507dc91f
commit 2835089d6a
3 changed files with 86 additions and 6 deletions
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3
src/dsp/lossless.h
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@ -199,9 +199,12 @@ static WEBP_INLINE float VP8LFastSLog2(uint32_t v) {
typedef double (*VP8LCostFunc)(const uint32_t* population, int length);
typedef double (*VP8LCostCombinedFunc)(const uint32_t* X, const uint32_t* Y,
int length);
typedef float (*VP8LCombinedShannonEntropyFunc)(const int X[256],
const int Y[256]);
extern VP8LCostFunc VP8LExtraCost;
extern VP8LCostCombinedFunc VP8LExtraCostCombined;
extern VP8LCombinedShannonEntropyFunc VP8LCombinedShannonEntropy;
typedef struct { // small struct to hold counters
int counts[2]; // index: 0=zero steak, 1=non-zero streak