portapack-mayhem/firmware/baseband/dsp_hilbert.cpp

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/*
* Copyright (C) 2020 Belousov Oleg
*
* This file is part of PortaPack.
*
* 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 2, 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; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "dsp_hilbert.hpp"
#include "dsp_sos_config.hpp"
namespace dsp {
HilbertTransform::HilbertTransform() {
n = 0;
sos_i.configure(half_band_lpf_config);
sos_q.configure(half_band_lpf_config);
}
void HilbertTransform::execute(float in, float &out_i, float &out_q) {
float a = 0, b = 0;
switch (n) {
case 0: a = in; b = 0; break;
case 1: a = 0; b = -in; break;
case 2: a = -in; b = 0; break;
case 3: a = 0; b = in; break;
}
float i = sos_i.execute(a) * 2.0f;
float q = sos_q.execute(b) * 2.0f;
switch (n) {
case 0: out_i = i; out_q = q; break;
case 1: out_i = -q; out_q = i; break;
case 2: out_i = -i; out_q = -q; break;
case 3: out_i = q; out_q = -i; break;
}
n = (n + 1) % 4;
}
} /* namespace dsp */