crc16_kermit.h

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/******************************************************************************
The MIT License(MIT)

Embedded Template Library.

Copyright(c) 2014 jwellbelove

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#ifndef __etl_crc16_kermit__
#define __etl_crc16_kermit__

#include <stdint.h>

#include "static_assert.h"
#include "type_traits.h"
#include "endian.h"


namespace etl
{
  //***************************************************************************
  //***************************************************************************
  extern const uint16_t CRC_KERMIT[];
  
  //***************************************************************************
  //***************************************************************************
  template <const int ENDIANNESS = endian::little>
  class crc16_kermit
  {
  public:

    typedef uint16_t value_type;

    //*************************************************************************
    //*************************************************************************
    crc16_kermit()
    {
      reset();
    }

    //*************************************************************************
    //*************************************************************************
    template<typename TIterator>
    crc16_kermit(TIterator begin, const TIterator end)
    {
      reset();
      add(begin, end);
    }

    //*************************************************************************
    //*************************************************************************
    void reset()
    {
      crc = 0;
    }

    //*************************************************************************
    //*************************************************************************
    template<typename TValue>
    void add(TValue value)
    {
      STATIC_ASSERT(is_integral<TValue>::value, "Non-integral parameter");

      if (ENDIANNESS == endian::little)
      {
        for (int i = 0; i < sizeof(TValue); ++i)
        {
          add(uint8_t((value >> (i * 8)) & 0xFF));
        }
      }
      else
      {
        for (int i = sizeof(TValue) - 1; i >= 0; --i)
        {
          add(uint8_t((value >> (i * 8)) & 0xFF));
        }
      }
    }

    //*************************************************************************
    //*************************************************************************
    void add(uint8_t value)
    {
      crc = (crc >> 8) ^ CRC_KERMIT[(crc ^ value) & 0xFF];
    }

    //*************************************************************************
    //*************************************************************************
    template<typename TIterator>
    void add(TIterator begin, const TIterator end)
    {
      while (begin != end)
      {
        add(*begin);
        ++begin;
      }
    }

    //*************************************************************************
    //*************************************************************************
    value_type value() const
    {
      return crc;
    }

    //*************************************************************************
    //*************************************************************************
    template<typename TValue>
    crc16_kermit<ENDIANNESS>& operator +=(TValue value)
    {
      add(value);

      return *this;
    }

    //*************************************************************************
    //*************************************************************************
    operator value_type () const
    {
      return crc;
    }

  private:

    value_type crc;
  };
}

#endif