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53 lines
1.6 KiB
53 lines
1.6 KiB
// -*- 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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// update - Add a new raw value to the filter, but don't recalculate |
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virtual void update(T sample, uint32_t timestamp); |
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// return the derivative value |
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virtual float slope(void); |
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// reset - clear the filter |
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virtual void reset(); |
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private: |
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bool _new_data; |
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float _last_slope; |
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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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