checksum.h

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

Embedded Template Library.

Copyright(c) 2014 jwellbelove

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of this software and associated documentation files(the "Software"), to deal
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******************************************************************************/

#ifndef __ETL_CHECKSUM__
#define __ETL_CHECKSUM__

#include <stdint.h>

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


namespace etl
{
  //***************************************************************************
  //***************************************************************************
  template <typename TSum, const int ENDIANNESS = endian::little>
  class checksum
  {
  public:

    STATIC_ASSERT(is_unsigned<TSum>::value, "Signed TSum template parameter");

    typedef TSum value_type;

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

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

    //*************************************************************************
    //*************************************************************************
    void reset()
    {
      sum = 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)
    {
      sum += value;
    }

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

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

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

      return *this;
    }

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

  private:

    value_type sum;
  };
}

#endif