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Unify some entropy functions.

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The code and logic is unified when computing bit entropy + Huffman cost.

Speed-wise, we gain 8% for lossless encoding.
Logic-wise, the beginning/end of the distributions are handled properly
and the compression ratio does not change much.

Change-Id: Ifa91d7d3e667c9a9a421faec4e845ecb6479a633
This commit is contained in:
Vincent Rabaud
2015-12-17 16:25:34 +01:00
parent ba7f4b68c9
commit ca509a3362
4 changed files with 107 additions and 142 deletions
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69
src/dsp/lossless_enc_mips32.c
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@ -217,51 +217,31 @@ static double ExtraCostCombined(const uint32_t* const X,
);
// Returns the various RLE counts
static VP8LStreaks HuffmanCostCount(const uint32_t* population, int length) {
int i;
int streak = 0;
VP8LStreaks stats;
int* const pstreaks = &stats.streaks[0][0];
int* const pcnts = &stats.counts[0];
static WEBP_INLINE void GetEntropyUnrefinedHelper(
uint32_t val, int i, uint32_t* const val_prev, int* const i_prev,
VP8LBitEntropy* const bit_entropy, VP8LStreaks* const stats) {
int* const pstreaks = &stats->streaks[0][0];
int* const pcnts = &stats->counts[0];
int temp0, temp1, temp2, temp3;
memset(&stats, 0, sizeof(stats));
for (i = 0; i < length - 1; ++i) {
++streak;
if (population[i] == population[i + 1]) {
continue;
const int streak = i - *i_prev;
// Gather info for the bit entropy.
if (*val_prev != 0) {
bit_entropy->sum += (*val_prev) * streak;
bit_entropy->nonzeros += streak;
bit_entropy->nonzero_code = *i_prev;
bit_entropy->entropy -= VP8LFastSLog2(*val_prev) * streak;
if (bit_entropy->max_val < *val_prev) {
bit_entropy->max_val = *val_prev;
}
temp0 = (population[i] != 0);
HUFFMAN_COST_PASS
streak = 0;
}
++streak;
temp0 = (population[i] != 0);
// Gather info for the Huffman cost.
temp0 = (*val_prev != 0);
HUFFMAN_COST_PASS
return stats;
}
static VP8LStreaks HuffmanCostCombinedCount(const uint32_t* X,
const uint32_t* Y, int length) {
int i;
int streak = 0;
uint32_t xy_prev = 0xffffffff;
VP8LStreaks stats;
int* const pstreaks = &stats.streaks[0][0];
int* const pcnts = &stats.counts[0];
int temp0, temp1, temp2, temp3;
memset(&stats, 0, sizeof(stats));
for (i = 0; i < length; ++i) {
const uint32_t xy = X[i] + Y[i];
++streak;
if (xy != xy_prev) {
temp0 = (xy != 0);
HUFFMAN_COST_PASS
streak = 0;
xy_prev = xy;
}
}
return stats;
*val_prev = val;
*i_prev = i;
}
#define ASM_START \
@ -399,14 +379,7 @@ WEBP_TSAN_IGNORE_FUNCTION void VP8LEncDspInitMIPS32(void) {
VP8LFastLog2Slow = FastLog2Slow;
VP8LExtraCost = ExtraCost;
VP8LExtraCostCombined = ExtraCostCombined;
VP8LHuffmanCostCount = HuffmanCostCount;
// TODO(mips team): rewrite VP8LGetCombinedEntropy (which used to use
// HuffmanCostCombinedCount) with MIPS optimizations
#if 0
VP8LHuffmanCostCombinedCount = HuffmanCostCombinedCount;
#else
(void)HuffmanCostCombinedCount;
#endif
VP8LGetEntropyUnrefinedHelper = GetEntropyUnrefinedHelper;
VP8LHistogramAdd = HistogramAdd;
}