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// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_FILTERS_VP9_BOOL_DECODER_H_
#define MEDIA_FILTERS_VP9_BOOL_DECODER_H_
#include <stddef.h>
#include <stdint.h>
#include <memory>
#include "base/macros.h"
#include "media/base/media_export.h"
namespace media {
class BitReader;
class MEDIA_EXPORT Vp9BoolDecoder {
public:
Vp9BoolDecoder();
~Vp9BoolDecoder();
// |data| is the input buffer with |size| bytes.
// Returns true if read first marker bit successfully.
bool Initialize(const uint8_t* data, size_t size);
// Returns true if none of the reads since the last Initialize() call has
// gone beyond the end of available data.
bool IsValid() const { return valid_; }
// Reads one bit. B(p).
// If the read goes beyond the end of buffer, the return value is undefined.
bool ReadBool(int prob);
// Reads a literal. L(n).
// If the read goes beyond the end of buffer, the return value is undefined.
uint8_t ReadLiteral(int bits);
// Consumes padding bits up to end of data. Returns true if no
// padding bits or they are all zero.
bool ConsumePaddingBits();
private:
// The highest 8 bits of BigBool is actual "bool value". The remain bits
// are optimization of prefill buffer.
using BigBool = size_t;
// The size of "bool value" used for boolean decoding defined in spec.
const int kBoolSize = 8;
const int kBigBoolBitSize = sizeof(BigBool) * 8;
bool Fill();
std::unique_ptr<BitReader> reader_;
// Indicates if none of the reads since the last Initialize() call has gone
// beyond the end of available data.
bool valid_ = true;
BigBool bool_value_ = 0;
// Need to fill at least |count_to_fill_| bits. Negative value means extra
// bits pre-filled.
int count_to_fill_ = 0;
unsigned int bool_range_ = 0;
DISALLOW_COPY_AND_ASSIGN(Vp9BoolDecoder);
};
} // namespace media
#endif // MEDIA_FILTERS_VP9_BOOL_DECODER_H_