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/*
Copyright (C) 2008 Fons Adriaensen <fons@kokkinizita.net>
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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <math.h>
#include "stcorrdsp.h"
float Stcorrdsp::_w1;
float Stcorrdsp::_w2;
Stcorrdsp::Stcorrdsp (void) :
_zl (0),
_zr (0),
_zlr (0),
_zll (0),
_zrr (0)
{
}
Stcorrdsp::~Stcorrdsp (void)
{
}
void Stcorrdsp::process (float *pl, float *pr, int n)
{
// Called by JACK's process callback.
//
// pl : pointer to left channel sample buffer
// pr : pointer to right channel sample buffer
// n : number of samples to process
float zl, zr, zlr, zll, zrr;
zl = _zl;
zr = _zr;
zlr = _zlr;
zll = _zll;
zrr = _zrr;
while (n--)
{
zl += _w1 * (*pl++ - zl) + 1e-20f;
zr += _w1 * (*pr++ - zr) + 1e-20f;
zlr += _w2 * (zl * zr - zlr);
zll += _w2 * (zl * zl - zll);
zrr += _w2 * (zr * zr - zrr);
}
_zl = zl;
_zr = zr;
_zlr = zlr;
_zll = zll;
_zrr = zrr;
}
float Stcorrdsp::read (void)
{
// Called by display process approx. 30 times per second.
return _zlr / sqrtf (_zll * _zrr + 1e-12f);
}
void Stcorrdsp::init (int fsamp, float flp, float tcf)
{
// Called by initialisation code.
//
// fsamp = sample frequency
// flp = lowpass frequency
// tcf = correlation filter time constant
_w1 = 6.28f * flp / fsamp;
_w2 = 1 / (tcf * fsamp);
}
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