buffer_reader.h

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// Copyright 2017 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef SHAKA_EMBEDDED_UTIL_BUFFER_READER_H_
#define SHAKA_EMBEDDED_UTIL_BUFFER_READER_H_

#include <stddef.h>
#include <stdint.h>

namespace shaka {
namespace util {

enum Endianness {
  kBigEndian,
  kLittleEndian,

#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
  kHostOrder = kLittleEndian,
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
  kHostOrder = kBigEndian,
#else
#  error "Invalid byte order"
#endif
};

class BufferReader {
 public:
  BufferReader();
  BufferReader(const uint8_t* data, size_t data_size);

  const uint8_t* data() const {
    return data_;
  }

  bool empty() const {
    return size_ == 0;
  }

  size_t BytesRemaining() const {
    return size_;
  }

  void SetBuffer(const uint8_t* data, size_t data_size);

  size_t Read(uint8_t* dest, size_t dest_size);

  size_t Skip(size_t count) {
    return SkipBits(count * 8) / 8;
  }

  size_t SkipBits(size_t count);

  uint8_t ReadUint8() {
    return static_cast<uint8_t>(ReadBits(8, kBigEndian));
  }

  uint32_t ReadUint32(Endianness endianness = kBigEndian) {
    return static_cast<uint32_t>(ReadBits(32, endianness));
  }

  uint64_t ReadBits(size_t count, Endianness endianness = kBigEndian);

  uint64_t ReadExpGolomb();

 private:
  const uint8_t* data_;
  size_t size_;
  size_t bit_offset_;
};

}  // namespace util
}  // namespace shaka

#endif  // SHAKA_EMBEDDED_UTIL_BUFFER_READER_H_