BitReader.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_READER_H_

#define BIT_READER_H_

#include "MediaData.h"

namespace mozilla {

class BitReader {

 public:

  explicit BitReader(const MediaByteBuffer* aBuffer);

  BitReader(const MediaByteBuffer* aBuffer, size_t aBits);

  BitReader(const uint8_t* aBuffer, size_t aBits);

  ~BitReader();

  uint32_t ReadBits(size_t aNum);

  bool ReadBit() { return ReadBits(1) != 0; }

  uint32_t ReadU32() { return ReadBits(32); }

  uint64_t ReadU64();

  // Read the UTF-8 sequence and convert it to its 64-bit UCS-4 encoded form.

  // Return 0xfffffffffffffff if sequence was invalid.

  uint64_t ReadUTF8();

  // Read unsigned integer Exp-Golomb-coded.

  uint32_t ReadUE();

  // Read signed integer Exp-Golomb-coded.

  int32_t ReadSE();

  // Read unsigned integer Little Endian Base 128 coded.

  // Limited to unsigned 64 bits.

  CheckedUint64 ReadULEB128();

  // Return the number of bits parsed so far;

  size_t BitCount() const;

  // Return the number of bits left.

  size_t BitsLeft() const;

  // Return RBSP bit length.

  static uint32_t GetBitLength(const MediaByteBuffer* aNAL);

 private:

  void FillReservoir();

  const uint8_t* mData;

  const size_t mOriginalBitSize;

  size_t mTotalBitsLeft;

  size_t mSize;         // Size left in bytes

  uint32_t mReservoir;  // Left-aligned bits

  size_t mNumBitsLeft;  // Number of bits left in reservoir.

};

}  // namespace mozilla

#endif  // BIT_READER_H_