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/*
dsp/OnePole.h
Copyright 2003-4 Tim Goetze <tim@quitte.de>
http://quitte.de/dsp/
one pole (or one zero, or one zero, one pole) hi- and lo-pass filters.
*/
/*
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., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA or point your web browser to http://www.gnu.org.
*/
#ifndef _ONE_POLE_H_
#define _ONE_POLE_H_
namespace DSP {
class OnePoleLP
{
public:
d_sample a0, b1, y1;
OnePoleLP (double d = 1.)
{
set (d);
y1 = 0.;
}
inline void reset()
{
y1 = 0.;
}
inline void set_f (double fc)
{
set (exp (-2 * M_PI * fc));
}
inline void set (double d)
{
a0 = (d_sample) d;
b1 = (d_sample) 1. - d;
}
inline d_sample process (d_sample x)
{
return y1 = a0 * x + b1 * y1;
}
inline void decay (double d)
{
a0 *= d;
b1 = 1. - a0;
}
};
class OnePoleHP
{
public:
d_sample a0, a1, b1, x1, y1;
double fc;
OnePoleHP (double d = 1.)
{
fc = 0;
set (d);
x1 = y1 = 0.;
}
void set_f (double f)
{
fc = f;
set (exp (-2 * M_PI * fc));
}
inline void set (double d)
{
a0 = (d_sample) ((1. + d) / 2.);
a1 = (d_sample) ((1. + d) / -2.);
b1 = d;
}
inline d_sample process (d_sample x)
{
y1 = a0 * x + a1 * x1 + b1 * y1;
x1 = x;
return y1;
}
void reset()
{
x1 = y1 = 0;
}
};
} /* namespace DSP */
#endif /* _ONE_POLE_H_ */
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