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/*
dsp/BiQuad.h
Copyright 2003-4 Tim Goetze <tim@quitte.de>
http://quitte.de/dsp/
bi-quad implementation.
*/
/*
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 _DSP_BI_QUAD_H_
#define _DSP_BI_QUAD_H_
namespace DSP {
class BiQuad
{
public:
/* coefficients */
d_sample a[3], b[3];
/* history */
int h;
d_sample x[2], y[2];
BiQuad()
{
a[0] = 1;
a[1] = a[2] = b[0] = b[1] = b[2] = 0;
reset();
}
BiQuad (d_sample * _a, d_sample * _b)
{
for (int i = 0; i < 3; ++i)
a[i] = _a[i],
b[i] = _b[i];
reset();
}
void reset()
{
h = 0;
x[0] = x[1] =
y[0] = y[1] = 0.;
}
inline d_sample process (d_sample s)
{
register int z = h;
register d_sample r = s * a[0];
r += a[1] * x[z];
r += b[1] * y[z];
z ^= 1;
r += a[2] * x[z];
r += b[2] * y[z];
y[z] = r;
x[z] = s;
h = z;
return r;
}
/* additional methods for using the biquad to upsample */
inline d_sample process_0_1()
{
register int z = h;
register d_sample r = 0;
r += a[1] * x[z];
r += b[1] * y[z];
z ^= 1;
r += a[2] * x[z];
r += b[2] * y[z];
y[z] = r;
x[z] = 0;
h = z;
return r;
}
inline d_sample process_0_2()
{
register int z = h;
register d_sample r = 0;
r += b[1] * y[z];
z ^= 1;
r += a[2] * x[z];
r += b[2] * y[z];
y[z] = r;
x[z] = 0;
h = z;
return r;
}
inline d_sample process_0_3()
{
register int z = h;
register d_sample r = 0;
r += b[1] * y[z];
z ^= 1;
r += b[2] * y[z];
y[z] = r;
x[z] = 0;
h = z;
return r;
}
};
} /* namespace DSP */
#endif /* _DSP_BI_QUAD_H_ */
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