frequency_filter.h

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/* Copyright (c) 2010 Wildfire Games
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
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 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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#ifndef INCLUDED_FREQUENCY_FILTER
#define INCLUDED_FREQUENCY_FILTER

// calculate frequency of events (tuned for 100 Hz)
struct IFrequencyFilter
{
    virtual ~IFrequencyFilter() {}

    virtual void Update(double value) = 0;

    // smoothed but rapidly tracked frequency
    virtual double SmoothedFrequency() const = 0;

    // stable, non-fluctuating value for user display
    virtual int StableFrequency() const = 0;
};

typedef shared_ptr<IFrequencyFilter> PIFrequencyFilter;

// expectedFrequency is a guess that hopefully speeds up convergence
LIB_API PIFrequencyFilter CreateFrequencyFilter(double resolution, double expectedFrequency);

#endif  // #ifndef INCLUDED_FREQUENCY_FILTER