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136 lines
3.6 KiB
C
136 lines
3.6 KiB
C
/*
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$Log$
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Revision 1.16 2004/06/26 03:50:14 markster
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Merge source cleanups (bug #1911)
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Revision 1.15 2003/09/19 01:20:22 markster
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Code cleanups (bug #66)
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Revision 1.2 2003/09/19 01:20:22 markster
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Code cleanups (bug #66)
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Revision 1.1.1.1 2003/02/12 13:59:15 matteo
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mer feb 12 14:56:57 CET 2003
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Revision 1.2 2000/01/05 08:20:39 markster
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Some OSS fixes and a few lpc changes to make it actually work
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* Revision 1.1 1996/08/19 22:31:53 jaf
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* Initial revision
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*
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*/
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/* -- translated by f2c (version 19951025).
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You must link the resulting object file with the libraries:
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-lf2c -lm (in that order)
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*/
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#include "f2c.h"
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#ifdef P_R_O_T_O_T_Y_P_E_S
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extern int ivfilt_(real *lpbuf, real *ivbuf, integer *len, integer *nsamp, real *ivrc);
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#endif
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/* ********************************************************************* */
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/* IVFILT Version 48 */
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/* $Log$
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* Revision 1.16 2004/06/26 03:50:14 markster
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* Merge source cleanups (bug #1911)
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*
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* Revision 1.15 2003/09/19 01:20:22 markster
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* Code cleanups (bug #66)
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*
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* Revision 1.2 2003/09/19 01:20:22 markster
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* Code cleanups (bug #66)
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*
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* Revision 1.1.1.1 2003/02/12 13:59:15 matteo
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* mer feb 12 14:56:57 CET 2003
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*
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* Revision 1.2 2000/01/05 08:20:39 markster
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* Some OSS fixes and a few lpc changes to make it actually work
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*
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* Revision 1.1 1996/08/19 22:31:53 jaf
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* Initial revision
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* */
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/* Revision 1.3 1996/03/15 21:36:29 jaf */
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/* Just added a few comments about which array indices of the arguments */
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/* are used, and mentioning that this subroutine has no local state. */
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/* Revision 1.2 1996/03/13 00:01:00 jaf */
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/* Comments added explaining that none of the local variables of this */
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/* subroutine need to be saved from one invocation to the next. */
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/* Revision 1.1 1996/02/07 14:47:34 jaf */
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/* Initial revision */
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/* ********************************************************************* */
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/* 2nd order inverse filter, speech is decimated 4:1 */
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/* Input: */
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/* LEN - Length of speech buffers */
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/* NSAMP - Number of samples to filter */
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/* LPBUF - Low pass filtered speech buffer */
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/* Indices LEN-NSAMP-7 through LEN read. */
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/* Output: */
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/* IVBUF - Inverse filtered speech buffer */
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/* Indices LEN-NSAMP+1 through LEN written. */
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/* IVRC - Inverse filter reflection coefficients (for voicing) */
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/* Indices 1 and 2 both written (also read, but only after writing).
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*/
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/* This subroutine has no local state. */
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/* Subroutine */ int ivfilt_(real *lpbuf, real *ivbuf, integer *len, integer *
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nsamp, real *ivrc)
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{
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/* System generated locals */
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integer i__1;
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/* Local variables */
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integer i__, j, k;
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real r__[3], pc1, pc2;
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/* Arguments */
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/* Local variables that need not be saved */
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/* Local state */
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/* None */
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/* Calculate Autocorrelations */
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/* Parameter adjustments */
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--ivbuf;
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--lpbuf;
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--ivrc;
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/* Function Body */
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for (i__ = 1; i__ <= 3; ++i__) {
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r__[i__ - 1] = 0.f;
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k = (i__ - 1) << 2;
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i__1 = *len;
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for (j = (i__ << 2) + *len - *nsamp; j <= i__1; j += 2) {
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r__[i__ - 1] += lpbuf[j] * lpbuf[j - k];
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}
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}
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/* Calculate predictor coefficients */
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pc1 = 0.f;
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pc2 = 0.f;
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ivrc[1] = 0.f;
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ivrc[2] = 0.f;
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if (r__[0] > 1e-10f) {
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ivrc[1] = r__[1] / r__[0];
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ivrc[2] = (r__[2] - ivrc[1] * r__[1]) / (r__[0] - ivrc[1] * r__[1]);
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pc1 = ivrc[1] - ivrc[1] * ivrc[2];
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pc2 = ivrc[2];
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}
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/* Inverse filter LPBUF into IVBUF */
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i__1 = *len;
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for (i__ = *len + 1 - *nsamp; i__ <= i__1; ++i__) {
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ivbuf[i__] = lpbuf[i__] - pc1 * lpbuf[i__ - 4] - pc2 * lpbuf[i__ - 8];
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}
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return 0;
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} /* ivfilt_ */
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