122 lines
3.2 KiB
C++
122 lines
3.2 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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#ifndef LOWPASSFILTER2P_H
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#define LOWPASSFILTER2P_H
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/// @file LowPassFilter2p.h
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/// @brief A class to implement a second order low pass filter
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/// Author: Leonard Hall <LeonardTHall@gmail.com>
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class DigitalBiquadFilter
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{
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public:
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DigitalBiquadFilter() :
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_delay_element_1(0.0f),
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_delay_element_2(0.0f){}
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struct biquad_params {
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float cutoff_freq;
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float sample_freq;
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float a1;
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float a2;
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float b0;
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float b1;
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float b2;
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};
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float apply(float sample, const struct biquad_params ¶ms);
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void reset() { _delay_element_1 = _delay_element_2 = 0.0f; }
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static void compute_params(float sample_freq, float cutoff_freq, biquad_params &ret);
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private:
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float _delay_element_1;
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float _delay_element_2;
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};
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class LowPassFilter2p
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{
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public:
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LowPassFilter2p() { memset(&_params, 0, sizeof(_params)); }
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// constructor
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LowPassFilter2p(float sample_freq, float cutoff_freq) {
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// set initial parameters
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set_cutoff_frequency(sample_freq, cutoff_freq);
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}
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// change parameters
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void set_cutoff_frequency(float sample_freq, float cutoff_freq) {
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DigitalBiquadFilter::compute_params(sample_freq, cutoff_freq, _params);
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}
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// return the cutoff frequency
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float get_cutoff_freq(void) const {
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return _params.cutoff_freq;
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}
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float get_sample_freq(void) const {
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return _params.sample_freq;
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}
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protected:
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struct DigitalBiquadFilter::biquad_params _params;
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};
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class LowPassFilter2pfloat : public LowPassFilter2p
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{
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public:
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LowPassFilter2pfloat() :
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LowPassFilter2p() {}
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LowPassFilter2pfloat(float sample_freq, float cutoff_freq):
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LowPassFilter2p(sample_freq,cutoff_freq) {}
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float apply(float sample) {
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return _filter.apply(sample, _params);
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}
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private:
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DigitalBiquadFilter _filter;
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};
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class LowPassFilter2pVector3f : public LowPassFilter2p
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{
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public:
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LowPassFilter2pVector3f() :
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LowPassFilter2p() {}
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LowPassFilter2pVector3f(float sample_freq, float cutoff_freq) :
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LowPassFilter2p(sample_freq,cutoff_freq) {}
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Vector3f apply(const Vector3f &sample) {
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Vector3f ret;
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ret.x = _filter_x.apply(sample.x, _params);
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ret.y = _filter_y.apply(sample.y, _params);
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ret.z = _filter_z.apply(sample.z, _params);
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return ret;
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}
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private:
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DigitalBiquadFilter _filter_x;
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DigitalBiquadFilter _filter_y;
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DigitalBiquadFilter _filter_z;
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};
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#endif // LOWPASSFILTER2P_H
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