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unroll the kBands[] indirection to remove a dereference in GetCoeffs()

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speed-up is small but visible.

Change-Id: Icff546adc3276f3c3d46b147c4a735b5eb8ff22e
This commit is contained in:
Pascal Massimino 2014-12-11 08:06:20 +01:00
parent 8ed9c00d5e
commit 1c4e3efea0
3 changed files with 16 additions and 12 deletions
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9
src/dec/tree.c
View File

@ -494,6 +494,12 @@ static const uint8_t
};
// Paragraph 9.9
static const int kBands[16 + 1] = {
0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
0 // extra entry as sentinel
};
void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec) {
VP8Proba* const proba = &dec->proba_;
int t, b, c, p;
@ -507,6 +513,9 @@ void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec) {
}
}
}
for (b = 0; b < 16 + 1; ++b) {
proba->bands_ptr_[t][b] = &proba->bands_[t][kBands[b]];
}
}
dec->use_skip_proba_ = VP8Get(br);
if (dec->use_skip_proba_) {

18
src/dec/vp8.c
View File

@ -371,11 +371,6 @@ int VP8GetHeaders(VP8Decoder* const dec, VP8Io* const io) {
//------------------------------------------------------------------------------
// Residual decoding (Paragraph 13.2 / 13.3)
static const int kBands[16 + 1] = {
0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
0 // extra entry as sentinel
};
static const uint8_t kCat3[] = { 173, 148, 140, 0 };
static const uint8_t kCat4[] = { 176, 155, 140, 135, 0 };
static const uint8_t kCat5[] = { 180, 157, 141, 134, 130, 0 };
@ -419,20 +414,19 @@ static int GetLargeValue(VP8BitReader* const br, const uint8_t* const p) {
}
// Returns the position of the last non-zero coeff plus one
static int GetCoeffs(VP8BitReader* const br, const VP8BandProbas* const prob,
static int GetCoeffs(VP8BitReader* const br, const VP8BandProbas* const prob[],
int ctx, const quant_t dq, int n, int16_t* out) {
// n is either 0 or 1 here. kBands[n] is not necessary for extracting '*p'.
const uint8_t* p = prob[n].probas_[ctx];
const uint8_t* p = prob[n]->probas_[ctx];
for (; n < 16; ++n) {
if (!VP8GetBit(br, p[0])) {
return n; // previous coeff was last non-zero coeff
}
while (!VP8GetBit(br, p[1])) { // sequence of zero coeffs
p = prob[kBands[++n]].probas_[0];
p = prob[++n]->probas_[0];
if (n == 16) return 16;
}
{ // non zero coeff
const VP8ProbaArray* const p_ctx = &prob[kBands[n + 1]].probas_[0];
const VP8ProbaArray* const p_ctx = &prob[n + 1]->probas_[0];
int v;
if (!VP8GetBit(br, p[2])) {
v = 1;
@ -455,8 +449,8 @@ static WEBP_INLINE uint32_t NzCodeBits(uint32_t nz_coeffs, int nz, int dc_nz) {
static int ParseResiduals(VP8Decoder* const dec,
VP8MB* const mb, VP8BitReader* const token_br) {
VP8BandProbas (* const bands)[NUM_BANDS] = dec->proba_.bands_;
const VP8BandProbas* ac_proba;
const VP8BandProbas* (* const bands)[16 + 1] = dec->proba_.bands_ptr_;
const VP8BandProbas* const * ac_proba;
VP8MBData* const block = dec->mb_data_ + dec->mb_x_;
const VP8QuantMatrix* const q = &dec->dqm_[block->segment_];
int16_t* dst = block->coeffs_;

1
src/dec/vp8i.h
View File

@ -141,6 +141,7 @@ typedef struct {
uint8_t segments_[MB_FEATURE_TREE_PROBS];
// Type: 0:Intra16-AC 1:Intra16-DC 2:Chroma 3:Intra4
VP8BandProbas bands_[NUM_TYPES][NUM_BANDS];
const VP8BandProbas* bands_ptr_[NUM_TYPES][16 + 1];
} VP8Proba;
// Filter parameters