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/*
* 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.
*/
#ifndef VP9_DECODER_VP9_READER_H_
#define VP9_DECODER_VP9_READER_H_
#include <stddef.h>
#include <limits.h>
#include "./vpx_config.h"
#include "vpx_ports/mem.h"
#include "vpx/vpx_integer.h"
#include "vp9/common/vp9_prob.h"
#ifdef __cplusplus
extern "C" {
#endif
typedef size_t BD_VALUE;
#define BD_VALUE_SIZE ((int)sizeof(BD_VALUE) * CHAR_BIT)
typedef struct {
const uint8_t *buffer_end;
const uint8_t *buffer;
BD_VALUE value;
int count;
unsigned int range;
} vp9_reader;
int vp9_reader_init(vp9_reader *r, const uint8_t *buffer, size_t size);
void vp9_reader_fill(vp9_reader *r);
int vp9_reader_has_error(vp9_reader *r);
const uint8_t *vp9_reader_find_end(vp9_reader *r);
static int vp9_read(vp9_reader *r, int prob) {
unsigned int bit = 0;
BD_VALUE value;
BD_VALUE bigsplit;
int count;
unsigned int range;
unsigned int split = (r->range * prob + (256 - prob)) >> CHAR_BIT;
if (r->count < 0)
vp9_reader_fill(r);
value = r->value;
count = r->count;
bigsplit = (BD_VALUE)split << (BD_VALUE_SIZE - CHAR_BIT);
range = split;
if (value >= bigsplit) {
range = r->range - split;
value = value - bigsplit;
bit = 1;
}
{
register unsigned int shift = vp9_norm[range];
range <<= shift;
value <<= shift;
count -= shift;
}
r->value = value;
r->count = count;
r->range = range;
return bit;
}
static int vp9_read_bit(vp9_reader *r) {
return vp9_read(r, 128); // vp9_prob_half
}
static int vp9_read_literal(vp9_reader *r, int bits) {
int literal = 0, bit;
for (bit = bits - 1; bit >= 0; bit--)
literal |= vp9_read_bit(r) << bit;
return literal;
}
static int vp9_read_tree(vp9_reader *r, const vp9_tree_index *tree,
const vp9_prob *probs) {
vp9_tree_index i = 0;
while ((i = tree[i + vp9_read(r, probs[i >> 1])]) > 0)
continue;
return -i;
}
#ifdef __cplusplus
} // extern "C"
#endif
#endif // VP9_DECODER_VP9_READER_H_
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