50 lines
1.5 KiB
C++
50 lines
1.5 KiB
C++
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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//
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// This is free software; you can redistribute it and/or modify it under
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// the terms of the GNU Lesser General Public License as published by the
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// Free Software Foundation; either version 2.1 of the License, or (at
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// your option) any later version.
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//
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/// @file Derivative.h
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/// @brief A class to implement a derivative (slope) filter
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/// See http://www.holoborodko.com/pavel/numerical-methods/numerical-derivative/smooth-low-noise-differentiators/
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#ifndef Derivative_h
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#define Derivative_h
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#include <inttypes.h>
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#include <Filter.h>
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#include <FilterWithBuffer.h>
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// 1st parameter <T> is the type of data being filtered.
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// 2nd parameter <FILTER_SIZE> is the number of elements in the filter
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template <class T, uint8_t FILTER_SIZE>
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class DerivativeFilter : public FilterWithBuffer<T,FILTER_SIZE>
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{
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public:
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// constructor
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DerivativeFilter() : FilterWithBuffer<T,FILTER_SIZE>() {};
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// apply - Add a new raw value to the filter, retrieve the filtered result
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virtual float apply(T sample, uint32_t timestamp);
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// reset - clear the filter
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virtual void reset();
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private:
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uint32_t _last_time;
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// microsecond timestamps for samples. This is needed
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// to cope with non-uniform time spacing of the data
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uint32_t _timestamps[FILTER_SIZE];
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};
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typedef DerivativeFilter<float,5> DerivativeFilterFloat_Size5;
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typedef DerivativeFilter<float,7> DerivativeFilterFloat_Size7;
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typedef DerivativeFilter<float,9> DerivativeFilterFloat_Size9;
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#endif // Derivative_h
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