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125 lines
2.2 KiB
C++
125 lines
2.2 KiB
C++
/*
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dsp/OnePole.h
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Copyright 2003-7 Tim Goetze <tim@quitte.de>
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http://quitte.de/dsp/
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one pole (or one zero, or one zero, one pole) hi- and lo-pass filters.
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*/
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/*
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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., 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA or point your web browser to http://www.gnu.org.
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*/
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#ifndef _ONE_POLE_H_
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#define _ONE_POLE_H_
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namespace DSP {
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class OnePoleLP
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{
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public:
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sample_t a0, b1, y1;
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OnePoleLP (double d = 1.)
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{
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set (d);
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y1 = 0.;
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}
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inline void reset()
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{
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y1 = 0.;
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}
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inline void set_f (double fc)
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{
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set (exp (-2 * M_PI * fc));
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}
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inline void set (double d)
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{
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a0 = (sample_t) d;
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b1 = (sample_t) 1. - d;
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}
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inline sample_t process (sample_t x)
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{
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return y1 = a0 * x + b1 * y1;
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}
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inline void decay (double d)
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{
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a0 *= d;
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b1 = 1. - a0;
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}
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/* clear denormal numbers in history */
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void flush_0()
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{
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if (is_denormal (y1))
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y1 = 0;
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}
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};
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class OnePoleHP
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{
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public:
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sample_t a0, a1, b1, x1, y1;
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OnePoleHP (double d = 1.)
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{
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set (d);
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x1 = y1 = 0.;
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}
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void set_f (double f)
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{
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set (exp (-2 * M_PI * f));
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}
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inline void set (double d)
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{
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a0 = (sample_t) ((1. + d) / 2.);
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a1 = (sample_t) ((1. + d) / -2.);
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b1 = d;
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}
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inline sample_t process (sample_t x)
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{
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y1 = a0 * x + a1 * x1 + b1 * y1;
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x1 = x;
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return y1;
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}
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void reset()
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{
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x1 = y1 = 0;
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}
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/* clear denormal numbers in history */
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void flush_0()
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{
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if (is_denormal (y1))
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y1 = 0;
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}
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};
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} /* namespace DSP */
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#endif /* _ONE_POLE_H_ */
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