ref: 3f18b08397674e4fe5b327c735f4945cb1892c41
dir: /vp8/decoder/detokenize.c/
/*
* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "vp8/common/blockd.h"
#include "onyxd_int.h"
#include "vpx_mem/vpx_mem.h"
#include "vpx_ports/compiler_attributes.h"
#include "vpx_ports/mem.h"
#include "detokenize.h"
void vp8_reset_mb_tokens_context(MACROBLOCKD *x) {
ENTROPY_CONTEXT *a_ctx = ((ENTROPY_CONTEXT *)x->above_context);
ENTROPY_CONTEXT *l_ctx = ((ENTROPY_CONTEXT *)x->left_context);
memset(a_ctx, 0, sizeof(ENTROPY_CONTEXT_PLANES) - 1);
memset(l_ctx, 0, sizeof(ENTROPY_CONTEXT_PLANES) - 1);
/* Clear entropy contexts for Y2 blocks */
if (!x->mode_info_context->mbmi.is_4x4) {
a_ctx[8] = l_ctx[8] = 0;
}
}
/*
------------------------------------------------------------------------------
Residual decoding (Paragraph 13.2 / 13.3)
*/
static const uint8_t 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 };
static const uint8_t kCat6[] = { 254, 254, 243, 230, 196, 177,
153, 140, 133, 130, 129, 0 };
static const uint8_t *const kCat3456[] = { kCat3, kCat4, kCat5, kCat6 };
static const uint8_t kZigzag[16] = { 0, 1, 4, 8, 5, 2, 3, 6,
9, 12, 13, 10, 7, 11, 14, 15 };
#define VP8GetBit vp8dx_decode_bool
#define NUM_PROBAS 11
#define NUM_CTX 3
/* for const-casting */
typedef const uint8_t (*ProbaArray)[NUM_CTX][NUM_PROBAS];
// With corrupt / fuzzed streams the calculation of br->value may overflow. See
// b/148271109.
static VPX_NO_UNSIGNED_OVERFLOW_CHECK int GetSigned(BOOL_DECODER *br,
int value_to_sign) {
int split = (br->range + 1) >> 1;
VP8_BD_VALUE bigsplit = (VP8_BD_VALUE)split << (VP8_BD_VALUE_SIZE - 8);
int v;
if (br->count < 0) vp8dx_bool_decoder_fill(br);
if (br->value < bigsplit) {
br->range = split;
v = value_to_sign;
} else {
br->range = br->range - split;
br->value = br->value - bigsplit;
v = -value_to_sign;
}
br->range += br->range;
br->value += br->value;
br->count--;
return v;
}
/*
Returns the position of the last non-zero coeff plus one
(and 0 if there's no coeff at all)
*/
static int GetCoeffs(BOOL_DECODER *br, ProbaArray prob, int ctx, int n,
int16_t *out) {
const uint8_t *p = prob[n][ctx];
if (!VP8GetBit(br, p[0])) { /* first EOB is more a 'CBP' bit. */
return 0;
}
while (1) {
++n;
if (!VP8GetBit(br, p[1])) {
p = prob[kBands[n]][0];
} else { /* non zero coeff */
int v, j;
if (!VP8GetBit(br, p[2])) {
p = prob[kBands[n]][1];
v = 1;
} else {
if (!VP8GetBit(br, p[3])) {
if (!VP8GetBit(br, p[4])) {
v = 2;
} else {
v = 3 + VP8GetBit(br, p[5]);
}
} else {
if (!VP8GetBit(br, p[6])) {
if (!VP8GetBit(br, p[7])) {
v = 5 + VP8GetBit(br, 159);
} else {
v = 7 + 2 * VP8GetBit(br, 165);
v += VP8GetBit(br, 145);
}
} else {
const uint8_t *tab;
const int bit1 = VP8GetBit(br, p[8]);
const int bit0 = VP8GetBit(br, p[9 + bit1]);
const int cat = 2 * bit1 + bit0;
v = 0;
for (tab = kCat3456[cat]; *tab; ++tab) {
v += v + VP8GetBit(br, *tab);
}
v += 3 + (8 << cat);
}
}
p = prob[kBands[n]][2];
}
j = kZigzag[n - 1];
out[j] = GetSigned(br, v);
if (n == 16 || !VP8GetBit(br, p[0])) { /* EOB */
return n;
}
}
if (n == 16) {
return 16;
}
}
}
int vp8_decode_mb_tokens(VP8D_COMP *dx, MACROBLOCKD *x) {
BOOL_DECODER *bc = x->current_bc;
const FRAME_CONTEXT *const fc = &dx->common.fc;
char *eobs = x->eobs;
int i;
int nonzeros;
int eobtotal = 0;
short *qcoeff_ptr;
ProbaArray coef_probs;
ENTROPY_CONTEXT *a_ctx = ((ENTROPY_CONTEXT *)x->above_context);
ENTROPY_CONTEXT *l_ctx = ((ENTROPY_CONTEXT *)x->left_context);
ENTROPY_CONTEXT *a;
ENTROPY_CONTEXT *l;
int skip_dc = 0;
qcoeff_ptr = &x->qcoeff[0];
if (!x->mode_info_context->mbmi.is_4x4) {
a = a_ctx + 8;
l = l_ctx + 8;
coef_probs = fc->coef_probs[1];
nonzeros = GetCoeffs(bc, coef_probs, (*a + *l), 0, qcoeff_ptr + 24 * 16);
*a = *l = (nonzeros > 0);
eobs[24] = nonzeros;
eobtotal += nonzeros - 16;
coef_probs = fc->coef_probs[0];
skip_dc = 1;
} else {
coef_probs = fc->coef_probs[3];
skip_dc = 0;
}
for (i = 0; i < 16; ++i) {
a = a_ctx + (i & 3);
l = l_ctx + ((i & 0xc) >> 2);
nonzeros = GetCoeffs(bc, coef_probs, (*a + *l), skip_dc, qcoeff_ptr);
*a = *l = (nonzeros > 0);
nonzeros += skip_dc;
eobs[i] = nonzeros;
eobtotal += nonzeros;
qcoeff_ptr += 16;
}
coef_probs = fc->coef_probs[2];
a_ctx += 4;
l_ctx += 4;
for (i = 16; i < 24; ++i) {
a = a_ctx + ((i > 19) << 1) + (i & 1);
l = l_ctx + ((i > 19) << 1) + ((i & 3) > 1);
nonzeros = GetCoeffs(bc, coef_probs, (*a + *l), 0, qcoeff_ptr);
*a = *l = (nonzeros > 0);
eobs[i] = nonzeros;
eobtotal += nonzeros;
qcoeff_ptr += 16;
}
return eobtotal;
}