svf.h

/*
 * Copyright © 2015-2023 Synthstrom Audible Limited
 *
 * This file is part of The Synthstrom Audible Deluge Firmware.
 *
 * The Synthstrom Audible Deluge Firmware 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 <https://www.gnu.org/licenses/>.
 */
 
#pragma once
 
#include "dsp/filter/filter.h"
#include "util/fixedpoint.h"
 
namespace deluge::dsp::filter {
 
class SVFilter : public Filter<SVFilter> {
public:
    SVFilter() = default;
    // returns a compensatory gain value
    q31_t setConfig(q31_t hpfFrequency, q31_t hpfResonance, FilterMode lpfMode, q31_t lpfMorph, q31_t filterGain);
    void doFilter(q31_t* startSample, q31_t* endSample, int32_t sampleIncrememt);
    void doFilterStereo(q31_t* startSample, q31_t* endSample);
    void resetFilter() {
        l = (SVFState){0, 0};
        r = (SVFState){0, 0};
    }
 
private:
    struct SVFState {
        q31_t low;
        q31_t band;
    };
    [[gnu::always_inline]] inline q31_t doSVF(q31_t input, SVFState& state);
    SVFState l;
    SVFState r;
 
    q31_t q;
    q31_t in;
    q31_t c_low;
    q31_t c_band;
    q31_t c_notch;
    q31_t c_high;
    bool band_mode;
};
} // namespace deluge::dsp::filter