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https://github.com/f4exb/sdrangel.git
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152 lines
4.0 KiB
C++
152 lines
4.0 KiB
C++
/* iir.c
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This file is part of a program that implements a Software-Defined Radio.
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Copyright (C) 2014, 2022, 2023 Warren Pratt, NR0V
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Copyright (C) 2024 Edouard Griffiths, F4EXB Adapted to SDRangel
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (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, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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The author can be reached by email at
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warren@wpratt.com
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*/
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#include "comm.hpp"
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#include "bqlp.hpp"
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namespace WDSP {
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/********************************************************************************************************
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* *
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* Complex Bi-Quad Low-Pass *
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* *
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********************************************************************************************************/
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void BQLP::calc()
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{
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double w0;
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double cs;
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double c;
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double den;
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w0 = TWOPI * fc / rate;
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cs = cos(w0);
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c = sin(w0) / (2.0 * Q);
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den = 1.0 + c;
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a0 = 0.5 * (1.0 - cs) / den;
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a1 = (1.0 - cs) / den;
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a2 = 0.5 * (1.0 - cs) / den;
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b1 = 2.0 * cs / den;
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b2 = (c - 1.0) / den;
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flush();
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}
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BQLP::BQLP(
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int _run,
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int _size,
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float* _in,
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float* _out,
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double _rate,
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double _fc,
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double _Q,
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double _gain,
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int _nstages
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) :
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run(_run),
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size(_size),
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in(_in),
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out(_out),
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rate(_rate),
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fc(_fc),
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Q(_Q),
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gain(_gain),
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nstages(_nstages)
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{
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x0.resize(nstages * 2); // (float*)malloc0(nstages * sizeof(complex));
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x1.resize(nstages * 2); // (float*)malloc0(nstages * sizeof(complex));
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x2.resize(nstages * 2); // (float*)malloc0(nstages * sizeof(complex));
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y0.resize(nstages * 2); // (float*)malloc0(nstages * sizeof(complex));
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y1.resize(nstages * 2); // (float*)malloc0(nstages * sizeof(complex));
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y2.resize(nstages * 2); // (float*)malloc0(nstages * sizeof(complex));
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calc();
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}
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void BQLP::flush()
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{
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for (int i = 0; i < nstages; i++)
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{
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x1[2 * i + 0] = x2[2 * i + 0] = y1[2 * i + 0] = y2[2 * i + 0] = 0.0;
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x1[2 * i + 1] = x2[2 * i + 1] = y1[2 * i + 1] = y2[2 * i + 1] = 0.0;
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}
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}
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void BQLP::execute()
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{
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if (run)
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{
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for (int i = 0; i < size; i++)
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{
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for (int j = 0; j < 2; j++)
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{
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x0[j] = gain * in[2 * i + j];
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for (int n = 0; n < nstages; n++)
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{
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if (n > 0)
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x0[2 * n + j] = y0[2 * (n - 1) + j];
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y0[2 * n + j] = a0 * x0[2 * n + j]
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+ a1 * x1[2 * n + j]
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+ a2 * x2[2 * n + j]
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+ b1 * y1[2 * n + j]
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+ b2 * y2[2 * n + j];
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y2[2 * n + j] = y1[2 * n + j];
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y1[2 * n + j] = y0[2 * n + j];
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x2[2 * n + j] = x1[2 * n + j];
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x1[2 * n + j] = x0[2 * n + j];
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}
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out[2 * i + j] = (float) y0[2 * (nstages - 1) + j];
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}
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}
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}
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else if (out != in)
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{
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std::copy(in, in + size * 2, out);
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}
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}
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void BQLP::setBuffers(float* _in, float* _out)
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{
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in = _in;
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out = _out;
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}
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void BQLP::setSamplerate(int _rate)
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{
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rate = _rate;
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calc();
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}
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void BQLP::setSize(int _size)
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{
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size = _size;
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flush();
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}
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} // namespace WDSP
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