1 // Copyright 2015 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 // Note: ported from Chromium commit head: e5a9a62 5 6 #ifndef VP9_RAW_BITS_READER_H_ 7 #define VP9_RAW_BITS_READER_H_ 8 9 #include <stddef.h> 10 #include <stdint.h> 11 12 #include <memory> 13 14 #include "base/macros.h" 15 16 namespace media { 17 18 class BitReader; 19 20 // A class to read raw bits stream. See VP9 spec, "RAW-BITS DECODING" section 21 // for detail. 22 class Vp9RawBitsReader { 23 public: 24 Vp9RawBitsReader(); 25 ~Vp9RawBitsReader(); 26 27 // |data| is the input buffer with |size| bytes. 28 void Initialize(const uint8_t* data, size_t size); 29 30 // Returns true if none of the reads since the last Initialize() call has 31 // gone beyond the end of available data. 32 bool IsValid() const { return valid_; } 33 34 // Returns how many bytes were read since the last Initialize() call. 35 // Partial bytes will be counted as one byte. For example, it will return 1 36 // if 3 bits were read. 37 size_t GetBytesRead() const; 38 39 // Reads one bit. 40 // If the read goes beyond the end of buffer, the return value is undefined. 41 bool ReadBool(); 42 43 // Reads a literal with |bits| bits. 44 // If the read goes beyond the end of buffer, the return value is undefined. 45 int ReadLiteral(int bits); 46 47 // Reads a signed literal with |bits| bits (not including the sign bit). 48 // If the read goes beyond the end of buffer, the return value is undefined. 49 int ReadSignedLiteral(int bits); 50 51 // Consumes trailing bits up to next byte boundary. Returns true if no 52 // trailing bits or they are all zero. 53 bool ConsumeTrailingBits(); 54 55 private: 56 std::unique_ptr<BitReader> reader_; 57 58 // Indicates if none of the reads since the last Initialize() call has gone 59 // beyond the end of available data. 60 bool valid_; 61 62 DISALLOW_COPY_AND_ASSIGN(Vp9RawBitsReader); 63 }; 64 65 } // namespace media 66 67 #endif // VP9_RAW_BITS_READER_H_ 68
