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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_BASE_MOVING_AVERAGE_H_
#define MEDIA_BASE_MOVING_AVERAGE_H_
#include <stddef.h>
#include <stdint.h>
#include <utility>
#include <vector>
#include "base/macros.h"
#include "base/time/time.h"
#include "media/base/media_export.h"
#include "media/base/timestamp_constants.h"
namespace media {
// Simple class for calculating a moving average of fixed size.
class MEDIA_EXPORT MovingAverage {
public:
// Creates a MovingAverage instance with space for |depth| samples.
explicit MovingAverage(size_t depth);
~MovingAverage();
// Adds a new sample to the average; replaces the oldest sample if |depth_|
// has been exceeded. Updates |total_| to the new sum of values.
void AddSample(base::TimeDelta sample);
// Returns the current average of all held samples.
base::TimeDelta Average() const;
// Returns the population standard deviation of all held samples.
base::TimeDelta Deviation() const;
// Resets the state of the class to its initial post-construction state.
void Reset();
uint64_t count() const { return count_; }
base::TimeDelta max() const { return max_; }
size_t depth() const { return depth_; }
// |first| is min, |second| is max of all samples in the window.
std::pair<base::TimeDelta, base::TimeDelta> GetMinAndMax();
private:
// Maximum number of elements allowed in the average.
const size_t depth_;
std::vector<base::TimeDelta> samples_;
// Number of elements seen thus far.
uint64_t count_ = 0;
base::TimeDelta total_;
// Maximum value ever seen.
base::TimeDelta max_ = kNoTimestamp;
DISALLOW_COPY_AND_ASSIGN(MovingAverage);
};
} // namespace media
#endif // MEDIA_BASE_MOVING_AVERAGE_H_
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