vp8_bool_decoder.cc | Explore in Territory

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40285824): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

/*
 * Copyright (c) 2010, The WebM Project authors. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *
 *   * Neither the name of Google, nor the WebM Project, nor the names
 *     of its contributors may be used to endorse or promote products
 *     derived from this software without specific prior written
 *     permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

// This file is modified from the dboolhuff.{c,h} from the WebM's libvpx
// project. (http://www.webmproject.org/code)
// It is used to decode bits from a vp8 stream.

#include "media/parsers/vp8_bool_decoder.h"

#include <limits.h>

#include <algorithm>

#include "base/check_op.h"
#include "base/numerics/safe_conversions.h"

namespace media {

#define VP8_BD_VALUE_BIT …

static const int kDefaultProbability = …;  // 0x80 / 256 = 0.5

// This is meant to be a large, positive constant that can still be efficiently
// loaded as an immediate (on platforms like ARM, for example). Even relatively
// modest values like 100 would work fine.
#define VP8_LOTS_OF_BITS …

// The number of leading zeros.
static const unsigned char kVp8Norm[256] = …;

Vp8BoolDecoder::Vp8BoolDecoder()
    : … { … }

bool Vp8BoolDecoder::Initialize(const uint8_t* data, size_t size) { … }

void Vp8BoolDecoder::FillDecoder() { … }

int Vp8BoolDecoder::ReadBit(int probability) { … }

bool Vp8BoolDecoder::ReadLiteral(size_t num_bits, int* out) { … }

bool Vp8BoolDecoder::ReadBool(bool* out, uint8_t probability) { … }

bool Vp8BoolDecoder::ReadBool(bool* out) { … }

bool Vp8BoolDecoder::ReadLiteralWithSign(size_t num_bits, int* out) { … }

size_t Vp8BoolDecoder::BitOffset() { … }

uint8_t Vp8BoolDecoder::GetRange() { … }

uint8_t Vp8BoolDecoder::GetBottom() { … }

inline bool Vp8BoolDecoder::OutOfBuffer() { … }

}  // namespace media
chromium/media/parsers/vp8_bool_decoder.cc
