premiere-libtorrent/include/libtorrent/sliding_average.hpp

/*

Copyright (c) 2010-2013, Arvid Norberg
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    * Redistributions in binary form must reproduce the above copyright
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      the documentation and/or other materials provided with the distribution.
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      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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*/

#ifndef TORRENT_SLIDING_AVERAGE_HPP_INCLUDED
#define TORRENT_SLIDING_AVERAGE_HPP_INCLUDED

namespace libtorrent
{
// a sliding average accumulator. Add samples to it and it
// keeps track of a sliding mean value and an average deviation
// from that average.
template <int history_size>
struct sliding_average
{
	sliding_average(): m_mean(-1), m_average_deviation(-1) {}

	void add_sample(int s)
	{
		if (m_mean == -1)
		{
			m_mean = s;
			return;
		}
		int deviation = abs(m_mean - s);

		m_mean = m_mean - m_mean / history_size + s / history_size;

		if (m_average_deviation == -1)
		{
			m_average_deviation = deviation;
			return;
		}
		m_average_deviation = m_average_deviation - m_average_deviation
			/ history_size + deviation / history_size;
	}

	int mean() const { return m_mean != -1 ? m_mean : 0; }
	int avg_deviation() const { return m_average_deviation != -1 ? m_average_deviation : 0; }

private:
	int m_mean;
	int m_average_deviation;
};

struct average_accumulator
{
	average_accumulator()
		: m_num_samples(0)
		, m_sample_sum(0)
	{}

	void add_sample(int s)
	{
		++m_num_samples;
		m_sample_sum += s;
	}

	int mean()
	{
		int ret;
		if (m_num_samples == 0) ret = 0;
		else ret = int(m_sample_sum / m_num_samples);
		m_num_samples = 0;
		m_sample_sum = 0;
		return ret;
	}

	int m_num_samples;
	size_type m_sample_sum;
};

}

#endif