fa7e34aaa3
This commit changes the way libraries headers are included in source files: - If the header is in the same directory the source belongs to, so the notation '#include ""' is used with the path relative to the directory containing the source. - If the header is outside the directory containing the source, then we use the notation '#include <>' with the path relative to libraries folder. Some of the advantages of such approach: - Only one search path for libraries headers. - OSs like Windows may have a better lookup time.
59 lines
2.0 KiB
C++
59 lines
2.0 KiB
C++
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
|
|
|
|
/*
|
|
This program is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
/// @file LowPassFilter.cpp
|
|
/// @brief A class to implement a second order low pass filter
|
|
/// Author: Leonard Hall <LeonardTHall@gmail.com>
|
|
|
|
#include <inttypes.h>
|
|
#include <AP_Math/AP_Math.h>
|
|
#include "LowPassFilter2p.h"
|
|
|
|
float DigitalBiquadFilter::apply(float sample, const struct biquad_params ¶ms)
|
|
{
|
|
if(is_zero(params.cutoff_freq) || is_zero(params.sample_freq)) {
|
|
return sample;
|
|
}
|
|
|
|
float delay_element_0 = sample - _delay_element_1 * params.a1 - _delay_element_2 * params.a2;
|
|
if (isnan(delay_element_0) || isinf(delay_element_0)) {
|
|
delay_element_0 = sample;
|
|
}
|
|
float output = delay_element_0 * params.b0 + _delay_element_1 * params.b1 + _delay_element_2 * params.b2;
|
|
|
|
_delay_element_2 = _delay_element_1;
|
|
_delay_element_1 = delay_element_0;
|
|
|
|
return output;
|
|
}
|
|
|
|
void DigitalBiquadFilter::compute_params(float sample_freq, float cutoff_freq, biquad_params &ret)
|
|
{
|
|
ret.cutoff_freq = cutoff_freq;
|
|
ret.sample_freq = sample_freq;
|
|
|
|
float fr = sample_freq/cutoff_freq;
|
|
float ohm = tanf(PI/fr);
|
|
float c = 1.0f+2.0f*cosf(PI/4.0f)*ohm + ohm*ohm;
|
|
|
|
ret.b0 = ohm*ohm/c;
|
|
ret.b1 = 2.0f*ret.b0;
|
|
ret.b2 = ret.b0;
|
|
ret.a1 = 2.0f*(ohm*ohm-1.0f)/c;
|
|
ret.a2 = (1.0f-2.0f*cosf(PI/4.0f)*ohm+ohm*ohm)/c;
|
|
}
|