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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() = default;
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();
// Advance bits and return the actual number of bits forwarded. Unlike
// ReadBits, which can only read up to 32 bits, this function does not limit
// how many bits it can advance. If fewer bits are available than requested,
// it will only advance the available bits.
size_t AdvanceBits(size_t aNum);
// 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_
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