84 lines
2.2 KiB
C++
84 lines
2.2 KiB
C++
/*
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* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
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*
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* This file is part of PortaPack.
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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 2, or (at your option)
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* any later version.
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*
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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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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "dsp_iir.hpp"
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#include <hal.h>
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void IIRBiquadFilter::configure(const iir_biquad_config_t& new_config) {
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config = new_config;
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}
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void IIRBiquadFilter::execute(const buffer_f32_t& buffer_in, const buffer_f32_t& buffer_out) {
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const auto a_ = config.a;
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const auto b_ = config.b;
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auto x_ = x;
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auto y_ = y;
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// TODO: Assert that buffer_out.count == buffer_in.count.
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for(size_t i=0; i<buffer_out.count; i++) {
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x_[0] = x_[1];
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x_[1] = x_[2];
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x_[2] = buffer_in.p[i];
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y_[0] = y_[1];
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y_[1] = y_[2];
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y_[2] = b_[0] * x_[2] + b_[1] * x_[1] + b_[2] * x_[0]
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- a_[1] * y_[1] - a_[2] * y_[0];
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buffer_out.p[i] = y_[2];
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}
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x = x_;
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y = y_;
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}
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void IIRBiquadFilter::execute_in_place(const buffer_f32_t& buffer) {
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execute(buffer, buffer);
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}
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void IIRBiquadDF2Filter::configure(const iir_biquad_df2_config_t& config) {
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b0 = config[0] / config[3];
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b1 = config[1] / config[3];
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b2 = config[2] / config[3];
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a1 = config[4] / config[3];
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a2 = config[5] / config[3];
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}
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// scipy.signal.sosfilt
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//
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// x_n = x[i, n] # make a temporary copy
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// # Use direct II transposed structure:
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// x[i, n] = b[s, 0] * x_n + zi[i, s, 0]
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// zi[i, s, 0] = (b[s, 1] * x_n - a[s, 0] * x[i, n] + zi[i, s, 1])
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// zi[i, s, 1] = (b[s, 2] * x_n - a[s, 1] * x[i, n])
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float IIRBiquadDF2Filter::execute(float x) {
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float y;
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y = b0 * x + z0;
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z0 = b1 * x - a1 * y + z1;
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z1 = b2 * x - a2 * y;
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return y;
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}
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