uint32_t VP8GetValue(VP8BitReader* const br, int bits) {
uint32_t v = 0;
while (bits-- > 0) {
v |= VP8GetBit(br, 0x80) << bits;
}
return v;
}
// Paragraph 9.9
void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec) {
VP8Proba* const proba = &dec->proba_;
int t, b, c, p;
for (t = 0; t < NUM_TYPES; ++t) {
for (b = 0; b < NUM_BANDS; ++b) {
for (c = 0; c < NUM_CTX; ++c) {
for (p = 0; p < NUM_PROBAS; ++p) {
if (VP8GetBit(br, CoeffsUpdateProba[t][b][c][p])) {
proba->coeffs_[t][b][c][p] = VP8GetValue(br, 8);
}
}
}
}
}
dec->use_skip_proba_ = VP8Get(br);
if (dec->use_skip_proba_) {
dec->skip_p_ = VP8GetValue(br, 8);
}
#ifndef ONLY_KEYFRAME_CODE
if (!dec->frm_hdr_.key_frame_) {
int i;
dec->intra_p_ = VP8GetValue(br, 8);
dec->last_p_ = VP8GetValue(br, 8);
dec->golden_p_ = VP8GetValue(br, 8);
if (VP8Get(br)) { // update y-mode
for (i = 0; i < 4; ++i) {
proba->ymode_[i] = VP8GetValue(br, 8);
}
}
if (VP8Get(br)) { // update uv-mode
for (i = 0; i < 3; ++i) {
proba->uvmode_[i] = VP8GetValue(br, 8);
}
}
// update MV
for (i = 0; i < 2; ++i) {
int k;
for (k = 0; k < NUM_MV_PROBAS; ++k) {
if (VP8GetBit(br, MVUpdateProba[i][k])) {
const int v = VP8GetValue(br, 7);
proba->mv_[i][k] = v ? v << 1 : 1;
}
}
}
}
#endif
}
// Paragraph 9.9
void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec) {
VP8Proba* const proba = &dec->proba_;
int t, b, c, p;
for (t = 0; t < NUM_TYPES; ++t) {
for (b = 0; b < NUM_BANDS; ++b) {
for (c = 0; c < NUM_CTX; ++c) {
for (p = 0; p < NUM_PROBAS; ++p) {
const int v = VP8GetBit(br, CoeffsUpdateProba[t][b][c][p]) ?
VP8GetValue(br, 8) : CoeffsProba0[t][b][c][p];
proba->bands_[t][b].probas_[c][p] = v;
}
}
}
}
dec->use_skip_proba_ = VP8Get(br);
if (dec->use_skip_proba_) {
dec->skip_p_ = VP8GetValue(br, 8);
}
}
void VP8ParseIntraMode(VP8BitReader* const br, VP8Decoder* const dec) {
uint8_t* const top = dec->intra_t_ + 4 * dec->mb_x_;
uint8_t* const left = dec->intra_l_;
VP8MBData* const block = dec->mb_data_ + dec->mb_x_;
block->is_i4x4_ = !VP8GetBit(br, 145); // decide for B_PRED first
if (!block->is_i4x4_) {
// Hardcoded 16x16 intra-mode decision tree.
const int ymode =
VP8GetBit(br, 156) ? (VP8GetBit(br, 128) ? TM_PRED : H_PRED)
: (VP8GetBit(br, 163) ? V_PRED : DC_PRED);
block->imodes_[0] = ymode;
memset(top, ymode, 4 * sizeof(*top));
memset(left, ymode, 4 * sizeof(*left));
} else {
uint8_t* modes = block->imodes_;
int y;
for (y = 0; y < 4; ++y) {
int ymode = left[y];
int x;
for (x = 0; x < 4; ++x) {
const uint8_t* const prob = kBModesProba[top[x]][ymode];
#ifdef USE_GENERIC_TREE
// Generic tree-parsing
int i = kYModesIntra4[VP8GetBit(br, prob[0])];
while (i > 0) {
i = kYModesIntra4[2 * i + VP8GetBit(br, prob[i])];
}
ymode = -i;
#else
// Hardcoded tree parsing
ymode = !VP8GetBit(br, prob[0]) ? B_DC_PRED :
!VP8GetBit(br, prob[1]) ? B_TM_PRED :
!VP8GetBit(br, prob[2]) ? B_VE_PRED :
!VP8GetBit(br, prob[3]) ?
(!VP8GetBit(br, prob[4]) ? B_HE_PRED :
(!VP8GetBit(br, prob[5]) ? B_RD_PRED : B_VR_PRED)) :
(!VP8GetBit(br, prob[6]) ? B_LD_PRED :
(!VP8GetBit(br, prob[7]) ? B_VL_PRED :
(!VP8GetBit(br, prob[8]) ? B_HD_PRED : B_HU_PRED)));
#endif // USE_GENERIC_TREE
top[x] = ymode;
}
memcpy(modes, top, 4 * sizeof(*top));
modes += 4;
left[y] = ymode;
}
}
// Hardcoded UVMode decision tree
block->uvmode_ = !VP8GetBit(br, 142) ? DC_PRED
: !VP8GetBit(br, 114) ? V_PRED
: VP8GetBit(br, 183) ? TM_PRED : H_PRED;
}
static void ParseIntraMode(VP8BitReader* const br,
VP8Decoder* const dec, int mb_x) {
uint8_t* const top = dec->intra_t_ + 4 * mb_x;
uint8_t* const left = dec->intra_l_;
VP8MBData* const block = dec->mb_data_ + mb_x;
// Note: we don't save segment map (yet), as we don't expect
// to decode more than 1 keyframe.
if (dec->segment_hdr_.update_map_) {
// Hardcoded tree parsing
block->segment_ = !VP8GetBit(br, dec->proba_.segments_[0])
? VP8GetBit(br, dec->proba_.segments_[1])
: 2 + VP8GetBit(br, dec->proba_.segments_[2]);
} else {
block->segment_ = 0; // default for intra
}
if (dec->use_skip_proba_) block->skip_ = VP8GetBit(br, dec->skip_p_);
block->is_i4x4_ = !VP8GetBit(br, 145); // decide for B_PRED first
if (!block->is_i4x4_) {
// Hardcoded 16x16 intra-mode decision tree.
const int ymode =
VP8GetBit(br, 156) ? (VP8GetBit(br, 128) ? TM_PRED : H_PRED)
: (VP8GetBit(br, 163) ? V_PRED : DC_PRED);
block->imodes_[0] = ymode;
memset(top, ymode, 4 * sizeof(*top));
memset(left, ymode, 4 * sizeof(*left));
} else {
uint8_t* modes = block->imodes_;
int y;
for (y = 0; y < 4; ++y) {
int ymode = left[y];
int x;
for (x = 0; x < 4; ++x) {
const uint8_t* const prob = kBModesProba[top[x]][ymode];
#ifdef USE_GENERIC_TREE
// Generic tree-parsing
int i = kYModesIntra4[VP8GetBit(br, prob[0])];
while (i > 0) {
i = kYModesIntra4[2 * i + VP8GetBit(br, prob[i])];
}
ymode = -i;
#else
// Hardcoded tree parsing
ymode = !VP8GetBit(br, prob[0]) ? B_DC_PRED :
!VP8GetBit(br, prob[1]) ? B_TM_PRED :
!VP8GetBit(br, prob[2]) ? B_VE_PRED :
!VP8GetBit(br, prob[3]) ?
(!VP8GetBit(br, prob[4]) ? B_HE_PRED :
(!VP8GetBit(br, prob[5]) ? B_RD_PRED : B_VR_PRED)) :
(!VP8GetBit(br, prob[6]) ? B_LD_PRED :
(!VP8GetBit(br, prob[7]) ? B_VL_PRED :
(!VP8GetBit(br, prob[8]) ? B_HD_PRED : B_HU_PRED)));
#endif // USE_GENERIC_TREE
top[x] = ymode;
}
memcpy(modes, top, 4 * sizeof(*top));
modes += 4;
left[y] = ymode;
}
}
// Hardcoded UVMode decision tree
block->uvmode_ = !VP8GetBit(br, 142) ? DC_PRED
: !VP8GetBit(br, 114) ? V_PRED
: VP8GetBit(br, 183) ? TM_PRED : H_PRED;
}