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/* ----------------------------------------------------------------- */
/* The Speech Signal Processing Toolkit (SPTK) */
/* developed by SPTK Working Group */
/* http://sp-tk.sourceforge.net/ */
/* ----------------------------------------------------------------- */
/* */
/* Copyright (c) 1984-2007 Tokyo Institute of Technology */
/* Interdisciplinary Graduate School of */
/* Science and Engineering */
/* */
/* 1996-2015 Nagoya Institute of Technology */
/* Department of Computer Science */
/* */
/* All rights reserved. */
/* */
/* Redistribution and use in source and binary forms, with or */
/* without modification, are permitted provided that the following */
/* conditions are met: */
/* */
/* - Redistributions of source code must retain the above copyright */
/* notice, this list of conditions and the following disclaimer. */
/* - Redistributions in binary form must reproduce the above */
/* copyright notice, this list of conditions and the following */
/* disclaimer in the documentation and/or other materials provided */
/* with the distribution. */
/* - Neither the name of the SPTK working group nor the names of its */
/* contributors may be used to endorse or promote products derived */
/* from this software without specific prior written permission. */
/* */
/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND */
/* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, */
/* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF */
/* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE */
/* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS */
/* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, */
/* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED */
/* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, */
/* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON */
/* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, */
/* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY */
/* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE */
/* POSSIBILITY OF SUCH DAMAGE. */
/* ----------------------------------------------------------------- */
/******************************************************
$Id: _df2.c,v 1.17 2015/12/14 01:14:12 uratec Exp $
2nd order standard form digital filter
double df2(x,sf,f0p,wbp,f0z,wbz,fp,fz,buf,bufp)
double x : filter input
double sf : sampling frequency
double f0p : center frequency of pole
double wbp : band width of pole
double f0z : center frequency of zero
double wbz : band witdth of zero
int fp : if pole is exist then fp = 1
int fz : if zero is exist then fz = 1
double buf[] : buffer ( which require 3 )
int *bufp : work pointer
return : filter output
Dec.1995 Naohiro Isshiki
*******************************************************/
#include <stdio.h>
#include <math.h>
#if defined(WIN32)
#include "SPTK.h"
#else
#include <SPTK.h>
#endif
double df2(const double x, const double sf, const double f0p, const double wbp,
const double f0z, const double wbz, const int fp, const int fz,
double *buf, int *bufp)
{
double a[3], b[3];
double p, e;
p = 4 * atan(1.0) / sf;
e = exp(-p * wbz);
a[0] = 1.0;
if (fz) {
a[1] = -2 * e * cos(2 * p * f0z);
a[2] = e * e;
} else {
a[1] = 0;
a[2] = 0;
}
e = exp(-p * wbp);
b[0] = 1.0;
if (fp) {
b[1] = -2 * e * cos(2 * p * f0p);
b[2] = e * e;
} else {
b[1] = 0;
b[2] = 0;
}
return (dfs(x, b, 2, a, 2, buf, bufp));
}
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