// 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 #include #include #include "media/base/media_export.h" namespace media { class BitReader; class MEDIA_EXPORT Vp9BoolDecoder { public: Vp9BoolDecoder(); Vp9BoolDecoder(const Vp9BoolDecoder&) = delete; Vp9BoolDecoder& operator=(const Vp9BoolDecoder&) = delete; ~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 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; }; } // namespace media #endif // MEDIA_FILTERS_VP9_BOOL_DECODER_H_