forked from premiere/premiere-libtorrent
117 lines
3.4 KiB
C++
117 lines
3.4 KiB
C++
/*
|
|
|
|
Copyright (c) 2010-2014, Arvid Norberg
|
|
All rights reserved.
|
|
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, are permitted provided that the following conditions
|
|
are met:
|
|
|
|
* Redistributions of source code must retain the above copyright
|
|
notice, this list of conditions and the following disclaimer.
|
|
* Redistributions in binary form must reproduce the above copyright
|
|
notice, this list of conditions and the following disclaimer in
|
|
the documentation and/or other materials provided with the distribution.
|
|
* Neither the name of the author nor the names of its
|
|
contributors may be used to endorse or promote products derived
|
|
from this software without specific prior written permission.
|
|
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
*/
|
|
|
|
#ifndef TORRENT_SLIDING_AVERAGE_HPP_INCLUDED
|
|
#define TORRENT_SLIDING_AVERAGE_HPP_INCLUDED
|
|
|
|
#include <boost/cstdint.hpp>
|
|
|
|
namespace libtorrent
|
|
{
|
|
|
|
// an exponential moving average accumulator. Add samples to it and it keeps
|
|
// track of a moving mean value and an average deviation
|
|
template <int inverted_gain>
|
|
struct sliding_average
|
|
{
|
|
sliding_average(): m_mean(0), m_average_deviation(0), m_num_samples(0) {}
|
|
|
|
void add_sample(int s)
|
|
{
|
|
// fixed point
|
|
s *= 64;
|
|
int deviation;
|
|
|
|
if (m_num_samples > 0)
|
|
deviation = abs(m_mean - s);
|
|
|
|
if (m_num_samples < inverted_gain)
|
|
++m_num_samples;
|
|
|
|
m_mean += (s - m_mean) / m_num_samples;
|
|
|
|
if (m_num_samples > 1) {
|
|
// the the exact same thing for deviation off the mean except -1 on
|
|
// the samples, because the number of deviation samples always lags
|
|
// behind by 1 (you need to actual samples to have a single deviation
|
|
// sample).
|
|
m_average_deviation += (deviation - m_average_deviation) / (m_num_samples - 1);
|
|
}
|
|
}
|
|
|
|
int mean() const { return m_num_samples > 0 ? (m_mean + 32) / 64 : 0; }
|
|
int avg_deviation() const { return m_num_samples > 1 ? (m_average_deviation + 32) / 64 : 0; }
|
|
|
|
private:
|
|
// both of these are fixed point values (* 64)
|
|
int m_mean;
|
|
int m_average_deviation;
|
|
// the number of samples we have received, but no more than inverted_gain
|
|
// this is the effective inverted_gain
|
|
int m_num_samples;
|
|
};
|
|
|
|
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);
|
|
// in case we don't get any more samples, at least
|
|
// let the average roll over, but only be worth a
|
|
// single sample
|
|
m_num_samples = 1;
|
|
m_sample_sum = ret;
|
|
return ret;
|
|
}
|
|
|
|
int m_num_samples;
|
|
boost::uint64_t m_sample_sum;
|
|
};
|
|
|
|
}
|
|
|
|
#endif
|
|
|