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Move the HuffmanCost() function to dsp lib

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This is to help further optimizations.
(like in https://gerrit.chromium.org/gerrit/#/c/69787/)

There's a small slowdown (~0.5% at -z 9 quality) due to
function pointer usage. Note that, for speed, it's important
to return VP8LStreaks by value, and not pass a pointer.

Change-Id: Id4167366765fb7fc5dff89c1fd75dee456737000
This commit is contained in:
skal
2014-04-18 08:14:46 -07:00
parent 6653b601ef
commit 75b12006e3
4 changed files with 82 additions and 64 deletions
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63
src/enc/histogram.c
View File

@ -180,7 +180,7 @@ static double BitsEntropyCombined(const int* const X, const int* const Y,
return BitsEntropyRefine(nonzeros, sum, max_val, retval);
}
static WEBP_INLINE double InitialHuffmanCost(void) {
static double InitialHuffmanCost(void) {
// Small bias because Huffman code length is typically not stored in
// full length.
static const int kHuffmanCodeOfHuffmanCodeSize = CODE_LENGTH_CODES * 3;
@ -188,66 +188,29 @@ static WEBP_INLINE double InitialHuffmanCost(void) {
return kHuffmanCodeOfHuffmanCodeSize - kSmallBias;
}
double VP8FinalHuffmanCost(int cnt_z, int streak_z_le3, int streak_z_gt3,
int cnt_nz, int streak_nz_le3, int streak_nz_gt3) {
// Finalize the Huffman cost based on streak numbers and length type (<3 or >=3)
static double FinalHuffmanCost(const VP8LStreaks* const stats) {
double retval = InitialHuffmanCost();
retval += cnt_z * 1.5625 + 0.234375 * streak_z_gt3;
retval += cnt_nz * 2.578125 + 0.703125 * streak_nz_gt3;
retval += 1.796875 * streak_z_le3;
retval += 3.28125 * streak_nz_le3;
retval += stats->counts[0] * 1.5625 + 0.234375 * stats->streaks[0][1];
retval += stats->counts[1] * 2.578125 + 0.703125 * stats->streaks[1][1];
retval += 1.796875 * stats->streaks[0][0];
retval += 3.28125 * stats->streaks[1][0];
return retval;
}
// Returns the cost encode the rle-encoded entropy code.
// The constants in this function are experimental.
// Trampolines
static double HuffmanCost(const int* const population, int length) {
int cnts[2] = { 0, 0 };
int streaks[2][2] = { { 0, 0 }, { 0, 0 } };
int streak = 0;
int i;
for (i = 0; i < length - 1; ++i) {
++streak;
if (population[i] == population[i + 1]) {
continue;
}
cnts[population[i] != 0] += (streak > 3);
streaks[population[i] != 0][(streak > 3)] += streak;
streak = 0;
}
++streak;
cnts[population[i] != 0] += (streak > 3);
streaks[population[i] != 0][(streak > 3)] += streak;
return VP8FinalHuffmanCost(cnts[0], streaks[0][0], streaks[0][1],
cnts[1], streaks[1][0], streaks[1][1]);
const VP8LStreaks stats = VP8LHuffmanCostCount(population, length);
return FinalHuffmanCost(&stats);
}
static double HuffmanCostCombined(const int* const X, const int* const Y,
int length) {
int cnts[2] = { 0, 0 };
int streaks[2][2] = { { 0, 0 }, { 0, 0 } };
int streak = 0;
int i;
for (i = 0; i < length - 1; ++i) {
const int xy = X[i] + Y[i];
const int xy_next = X[i + 1] + Y[i + 1];
++streak;
if (xy == xy_next) {
continue;
}
cnts[xy != 0] += (streak > 3);
streaks[xy != 0][streak > 3] += streak;
streak = 0;
}
{
const int xy = X[i] + Y[i];
++streak;
cnts[xy != 0] += (streak > 3);
streaks[xy != 0][streak > 3] += streak;
}
return VP8FinalHuffmanCost(cnts[0], streaks[0][0], streaks[0][1],
cnts[1], streaks[1][0], streaks[1][1]);
const VP8LStreaks stats = VP8LHuffmanCostCombinedCount(X, Y, length);
return FinalHuffmanCost(&stats);
}
// Aggregated costs
static double PopulationCost(const int* const population, int length) {
return BitsEntropy(population, length) + HuffmanCost(population, length);
}

7
src/enc/histogram.h
View File

@ -90,13 +90,6 @@ static WEBP_INLINE int VP8LHistogramNumCodes(int palette_code_bits) {
((palette_code_bits > 0) ? (1 << palette_code_bits) : 0);
}
// Used to finalized the Huffman cost:
// cnt_z / cnt_nz: counts the number of 0's and non-0's
// streak_{z,nz}_le3 / streak_{z,nz}_gt3: number of streaks larger than 3
// or less-or-equal than 3.
double VP8FinalHuffmanCost(int cnt_z, int streak_z_le3, int streak_z_gt3,
int cnt_nz, int streak_nz_le3, int streak_nz_gt3);
// Builds the histogram image.
int VP8LGetHistoImageSymbols(int xsize, int ysize,
const VP8LBackwardRefs* const refs,