ref: 1571c87c9519923b30d16c92f17515228c983924
dir: /lpc10/lpfilt.c/
/*
* Revision 1.1 1996/08/19 22:31:35 jaf
* Initial revision
*
*/
/* -- translated by f2c (version 19951025).
You must link the resulting object file with the libraries:
-lf2c -lm (in that order)
*/
#include "f2c.h"
extern int lpfilt_(real *inbuf, real *lpbuf, integer *len, integer *nsamp);
/* *********************************************************************** */
/* LPFILT Version 55 */
/*
* Revision 1.1 1996/08/19 22:31:35 jaf
* Initial revision
* */
/* Revision 1.3 1996/03/15 16:53:49 jaf */
/* Just put comment header in standard form. */
/* Revision 1.2 1996/03/12 23:58:06 jaf */
/* Comments added explaining that none of the local variables of this */
/* subroutine need to be saved from one invocation to the next. */
/* Revision 1.1 1996/02/07 14:47:44 jaf */
/* Initial revision */
/* *********************************************************************** */
/* 31 Point Equiripple FIR Low-Pass Filter */
/* Linear phase, delay = 15 samples */
/* Passband: ripple = 0.25 dB, cutoff = 800 Hz */
/* Stopband: atten. = 40. dB, cutoff = 1240 Hz */
/* Inputs: */
/* LEN - Length of speech buffers */
/* NSAMP - Number of samples to filter */
/* INBUF - Input speech buffer */
/* Indices len-nsamp-29 through len are read. */
/* Output: */
/* LPBUF - Low passed speech buffer (must be different array than INBUF) */
/* Indices len+1-nsamp through len are written. */
/* This subroutine has no local state. */
/* Subroutine */ int lpfilt_(real *inbuf, real *lpbuf, integer *len, integer *
nsamp)
{
/* System generated locals */
integer i__1;
/* Local variables */
integer j;
real t;
/* Arguments */
/* Parameters/constants */
/* Local variables that need not be saved */
/* Local state */
/* None */
/* Parameter adjustments */
--lpbuf;
--inbuf;
/* Function Body */
i__1 = *len;
for (j = *len + 1 - *nsamp; j <= i__1; ++j) {
t = (inbuf[j] + inbuf[j - 30]) * -.0097201988f;
t += (inbuf[j - 1] + inbuf[j - 29]) * -.0105179986f;
t += (inbuf[j - 2] + inbuf[j - 28]) * -.0083479648f;
t += (inbuf[j - 3] + inbuf[j - 27]) * 5.860774e-4f;
t += (inbuf[j - 4] + inbuf[j - 26]) * .0130892089f;
t += (inbuf[j - 5] + inbuf[j - 25]) * .0217052232f;
t += (inbuf[j - 6] + inbuf[j - 24]) * .0184161253f;
t += (inbuf[j - 7] + inbuf[j - 23]) * 3.39723e-4f;
t += (inbuf[j - 8] + inbuf[j - 22]) * -.0260797087f;
t += (inbuf[j - 9] + inbuf[j - 21]) * -.0455563702f;
t += (inbuf[j - 10] + inbuf[j - 20]) * -.040306855f;
t += (inbuf[j - 11] + inbuf[j - 19]) * 5.029835e-4f;
t += (inbuf[j - 12] + inbuf[j - 18]) * .0729262903f;
t += (inbuf[j - 13] + inbuf[j - 17]) * .1572008878f;
t += (inbuf[j - 14] + inbuf[j - 16]) * .2247288674f;
t += inbuf[j - 15] * .250535965f;
lpbuf[j] = t;
}
return 0;
} /* lpfilt_ */