byte_reader.hpp

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// Copyright 2017-2019 the Autoware Foundation
//
// 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
//
//     http://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.
//
// Co-developed by Tier IV, Inc. and Apex.AI, Inc.
 
#ifndef HELPER_FUNCTIONS__BYTE_READER_HPP_
#define HELPER_FUNCTIONS__BYTE_READER_HPP_
 
#include <cstdint>
#include <cstring>
#include <vector>
 
namespace autoware
{
namespace common
{
namespace helper_functions
{
class ByteReader
{
private:
  const std::vector<uint8_t> & byte_vector_;
  std::size_t index_;
 
public:
  explicit ByteReader(const std::vector<uint8_t> & byte_vector)
  : byte_vector_(byte_vector),
    index_(0U)
  {
  }
 
  // brief Read bytes and store it in the argument passed in big-endian order
  template<typename T>
  void read(T & value)
  {
    constexpr std::size_t kTypeSize = sizeof(T);
    union {
      T value;
      uint8_t byte_vector[kTypeSize];
    } tmp;
 
    for (std::size_t i = 0; i < kTypeSize; ++i) {
      tmp.byte_vector[i] = byte_vector_[index_ + kTypeSize - 1 - i];
    }
 
    value = tmp.value;
 
    index_ += kTypeSize;
  }
 
  void skip(std::size_t count)
  {
    index_ += count;
  }
};
}  // namespace helper_functions
}  // namespace common
}  // namespace autoware
 
#endif  // HELPER_FUNCTIONS__BYTE_READER_HPP_