fsfw/contrib/fsfw_contrib/etl-20.39.4/include/etl/mean.h

///\file

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

Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com

Copyright(c) 2021 John Wellbelove

Permission is hereby granted, free of charge, to any person obtaining a copy
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******************************************************************************/

#ifndef ETL_MEAN_INCLUDED
#define ETL_MEAN_INCLUDED

#include "platform.h"
#include "functional.h"
#include "type_traits.h"

//#include <math.h>
#include <stdint.h>

namespace etl
{
  namespace private_mean
  {
    //***************************************************************************
    /// Types for generic mean.
    //***************************************************************************
    template <typename TInput, typename TCalc>
    struct mean_traits
    {
      typedef TCalc calc_t;
    };

    //***************************************************************************
    /// Types for float mean.
    //***************************************************************************
    template <typename TCalc>
    struct mean_traits<float, TCalc>
    {
      typedef float calc_t;
    };

    //***************************************************************************
    /// Types for double mean.
    //***************************************************************************
    template <typename TCalc>
    struct mean_traits<double, TCalc>
    {
      typedef double calc_t;
    };
  }

  //***************************************************************************
  /// Mean.
  //***************************************************************************
  template <typename TInput, typename TCalc = TInput>
  class mean 
    : public private_mean::mean_traits<TInput, TCalc>
    , public etl::binary_function<TInput, TInput, void>
  {
  private:

    typedef typename private_mean::mean_traits<TInput, TCalc>::calc_t calc_t;

  public:

    //*********************************
    /// Constructor.
    //*********************************
    mean()
    {
      clear();
    }

    //*********************************
    /// Constructor.
    //*********************************
    template <typename TIterator>
    mean(TIterator first, TIterator last)
    {
      clear();
      add(first, last);
    }

    //*********************************
    /// Add a pair of values.
    //*********************************
    void add(TInput value)
    {
      sum += TCalc(value);
      ++counter;
      recalculate = true;
    }

    //*********************************
    /// Add a range.
    //*********************************
    template <typename TIterator>
    void add(TIterator first, TIterator last)
    {
      while (first != last)
      {
        add(*first);
        ++first;
      }
    }

    //*********************************
    /// operator ()
    /// Add a pair of values.
    //*********************************
    void operator ()(TInput value)
    {
      add(value);
    }

    //*********************************
    /// operator ()
    /// Add a range.
    //*********************************
    template <typename TIterator>
    void operator ()(TIterator first, TIterator last)
    {
      add(first, last);
    }

    //*********************************
    /// Get the mean.
    //*********************************
    double get_mean() const
    {
      if (recalculate)
      {
        mean_value = 0.0;

        if (counter != 0)
        {
          double n = double(counter);
          mean_value = sum / n;
        }

        recalculate = false;
      }

      return mean_value;
    }

    //*********************************
    /// Get the mean.
    //*********************************
    operator double() const
    {
      return get_mean();
    }

    //*********************************
    /// Get the total number added entries.
    //*********************************
    size_t count() const
    {
      return size_t(counter);
    }

    //*********************************
    /// Clear the correlation.
    //*********************************
    void clear()
    {
      sum         = calc_t(0);
      counter     = 0U;
      mean_value  = 0.0;
      recalculate = true;
    }

  private:
  
    calc_t   sum;
    uint32_t counter;
    mutable double mean_value;
    mutable bool   recalculate;
  };
}

#endif