BitWriter.h (1554B)
1 /* This Source Code Form is subject to the terms of the Mozilla Public 2 * License, v. 2.0. If a copy of the MPL was not distributed with this 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 4 5 #ifndef BIT_WRITER_H_ 6 #define BIT_WRITER_H_ 7 8 #include "mozilla/RefPtr.h" 9 10 namespace mozilla { 11 12 class MediaByteBuffer; 13 14 class BitWriter { 15 public: 16 explicit BitWriter(MediaByteBuffer* aBuffer); 17 virtual ~BitWriter(); 18 void WriteBits(uint64_t aValue, size_t aBits); 19 void WriteBit(bool aValue) { WriteBits(aValue, 1); } 20 void WriteU8(uint8_t aValue) { WriteBits(aValue, 8); } 21 void WriteU32(uint32_t aValue) { WriteBits(aValue, 32); } 22 void WriteU64(uint64_t aValue) { WriteBits(aValue, 64); } 23 24 // Write unsigned integer into Exp-Golomb-coded. 2^32-2 at most 25 void WriteUE(uint32_t aValue); 26 // Write unsigned integer Little Endian Base 128 coded. 27 void WriteULEB128(uint64_t aValue); 28 29 // Write RBSP trailing bits. 30 void CloseWithRbspTrailing(); 31 32 // Advance position forward without modifying buffer, which is usually used 33 // along with the case when directly appending a byte array to the 34 // MediaByteBuffer for the efficiency, instead of writing bits one by one. 35 // So this can only be called when the bit index is zero. 36 void AdvanceBytes(uint32_t aByteOffset); 37 38 // Return the number of bits written so far; 39 size_t BitCount() const { return mPosition * 8 + mBitIndex; } 40 41 private: 42 RefPtr<MediaByteBuffer> mBuffer; 43 size_t mPosition = 0; 44 uint8_t mBitIndex = 0; 45 }; 46 47 } // namespace mozilla 48 49 #endif // BIT_WRITER_H_