63 lines
2.0 KiB
C++
63 lines
2.0 KiB
C++
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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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_FILTER_H__
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#define __DERIVATIVE_FILTER_H__
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#include "FilterClass.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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};
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// update - Add a new raw value to the filter, but don't recalculate
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void update(T sample, uint32_t timestamp);
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// return the derivative value
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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_FILTER_H__
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