nni.hpp

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#ifndef NDNPH_TLV_NNI_HPP
#define NDNPH_TLV_NNI_HPP
 
#include "decoder.hpp"
#include "encoder.hpp"
 
namespace ndnph {
namespace tlv {
namespace detail {
 
template<typename T>
class NNIValue {
public:
  static bool decode(const Decoder::Tlv& d, T& value) {
    if (d.length != sizeof(T)) {
      return false;
    }
    value = readValue(d.value);
    return true;
  }
 
  explicit NNIValue(T number)
    : m_number(number) {}
 
  void encodeTo(Encoder& encoder) const {
    uint8_t* room = encoder.prependRoom(sizeof(m_number));
    if (room != nullptr) {
      writeValue(room, m_number);
    }
  }
 
  static T readValue(const uint8_t* input);
 
  static void writeValue(uint8_t* room, T n);
 
private:
  T m_number = 0;
};
 
template<>
inline uint8_t
NNIValue<uint8_t>::readValue(const uint8_t* input) {
  return input[0];
}
 
template<>
inline void
NNIValue<uint8_t>::writeValue(uint8_t* room, uint8_t n) {
  room[0] = n;
}
 
template<>
inline uint16_t
NNIValue<uint16_t>::readValue(const uint8_t* input) {
  return (static_cast<uint16_t>(input[0]) << 8) | static_cast<uint16_t>(input[1]);
}
 
template<>
inline void
NNIValue<uint16_t>::writeValue(uint8_t* room, uint16_t n) {
  room[0] = n >> 8;
  room[1] = n;
}
 
template<>
inline uint32_t
NNIValue<uint32_t>::readValue(const uint8_t* input) {
  return (static_cast<uint32_t>(input[0]) << 24) | (static_cast<uint32_t>(input[1]) << 16) |
         (static_cast<uint32_t>(input[2]) << 8) | static_cast<uint32_t>(input[3]);
}
 
template<>
inline void
NNIValue<uint32_t>::writeValue(uint8_t* room, uint32_t n) {
  room[0] = n >> 24;
  room[1] = n >> 16;
  room[2] = n >> 8;
  room[3] = n;
}
 
template<>
inline uint64_t
NNIValue<uint64_t>::readValue(const uint8_t* input) {
  return (static_cast<uint64_t>(input[0]) << 56) | (static_cast<uint64_t>(input[1]) << 48) |
         (static_cast<uint64_t>(input[2]) << 40) | (static_cast<uint64_t>(input[3]) << 32) |
         (static_cast<uint64_t>(input[4]) << 24) | (static_cast<uint64_t>(input[5]) << 16) |
         (static_cast<uint64_t>(input[6]) << 8) | static_cast<uint64_t>(input[7]);
}
 
template<>
inline void
NNIValue<uint64_t>::writeValue(uint8_t* room, uint64_t n) {
  room[0] = n >> 56;
  room[1] = n >> 48;
  room[2] = n >> 40;
  room[3] = n >> 32;
  room[4] = n >> 24;
  room[5] = n >> 16;
  room[6] = n >> 8;
  room[7] = n;
}
 
} // namespace detail
 
using NNI1 = detail::NNIValue<uint8_t>;
 
using NNI2 = detail::NNIValue<uint16_t>;
 
using NNI4 = detail::NNIValue<uint32_t>;
 
using NNI8 = detail::NNIValue<uint64_t>;
 
class NNI {
public:
  template<typename I, typename Limit = typename std::enable_if<std::is_integral<I>::value,
                                                                std::numeric_limits<I>>::type>
  static bool decode(const Decoder::Tlv& d, I& value, uint64_t max = Limit::max()) {
    uint64_t n = 0;
    switch (d.length) {
      case 1:
        n = NNI1::readValue(d.value);
        break;
      case 2:
        n = NNI2::readValue(d.value);
        break;
      case 4:
        n = NNI4::readValue(d.value);
        break;
      case 8:
        n = NNI8::readValue(d.value);
        break;
      default:
        return false;
    }
    value = n;
    return n <= max;
  }
 
  explicit NNI(uint64_t number)
    : m_number(number) {}
 
  void encodeTo(Encoder& encoder) const {
    if (m_number <= std::numeric_limits<uint8_t>::max()) {
      NNI1(m_number).encodeTo(encoder);
    } else if (m_number <= std::numeric_limits<uint16_t>::max()) {
      NNI2(m_number).encodeTo(encoder);
    } else if (m_number <= std::numeric_limits<uint32_t>::max()) {
      NNI4(m_number).encodeTo(encoder);
    } else {
      NNI8(m_number).encodeTo(encoder);
    }
  }
 
private:
  uint64_t m_number = 0;
};
 
template<typename N = NNI>
class NniElement {
public:
  template<typename I>
  explicit NniElement(uint32_t type, I value)
    : m_type(type)
    , m_nni(value) {}
 
  void encodeTo(Encoder& encoder) const {
    encoder.prependTlv(m_type, m_nni);
  }
 
private:
  uint32_t m_type;
  N m_nni;
};
 
} // namespace tlv
} // namespace ndnph
 
#endif // NDNPH_TLV_NNI_HPP