vp9_reader.h

/*
 *  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/vp8dx.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;
  uint8_t clear_buffer[sizeof(BD_VALUE) + 1];
  BD_VALUE value;
  int count;
  unsigned int range;
  vpx_decrypt_cb decrypt_cb;
  void *decrypt_state;
} vp9_reader;

int vp9_reader_init(vp9_reader *r,
                    const uint8_t *buffer,
                    size_t size,
                    vpx_decrypt_cb decrypt_cb,
                    void *decrypt_state);

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 INLINE 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);