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sdrangel/wdsp/bqlp.cpp
2024-08-05 20:05:59 +02:00

152 lines
4.0 KiB
C++

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