BitWriter.h - mozsearch

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/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef BIT_WRITER_H_

#define BIT_WRITER_H_

#include "mozilla/RefPtr.h"

namespace mozilla {

class MediaByteBuffer;

class BitWriter {

 public:

  explicit BitWriter(MediaByteBuffer* aBuffer);

  virtual ~BitWriter();

  void WriteBits(uint64_t aValue, size_t aBits);

  void WriteBit(bool aValue) { WriteBits(aValue, 1); }

  void WriteU8(uint8_t aValue) { WriteBits(aValue, 8); }

  void WriteU32(uint32_t aValue) { WriteBits(aValue, 32); }

  void WriteU64(uint64_t aValue) { WriteBits(aValue, 64); }

  // Write unsigned integer into Exp-Golomb-coded. 2^32-2 at most

  void WriteUE(uint32_t aValue);

  // Write unsigned integer Little Endian Base 128 coded.

  void WriteULEB128(uint64_t aValue);

  // Write RBSP trailing bits.

  void CloseWithRbspTrailing();

  // Advance position forward without modifying buffer, which is usually used

  // along with the case when directly appending a byte array to the

  // MediaByteBuffer for the efficiency, instead of writing bits one by one.

  // So this can only be called when the bit index is zero.

  void AdvanceBytes(uint32_t aByteOffset);

  // Return the number of bits written so far;

  size_t BitCount() const { return mPosition * 8 + mBitIndex; }

 private:

  RefPtr<MediaByteBuffer> mBuffer;

  size_t mPosition = 0;

  uint8_t mBitIndex = 0;

};

}  // namespace mozilla

#endif  // BIT_WRITER_H_