hp100.c

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/*

$Log$
Revision 1.15 2004/06/26 03:50:14 markster
Merge source cleanups (bug #1911)

Revision 1.14 2003/02/12 13:59:15 matteo
mer feb 12 14:56:57 CET 2003

Revision 1.1.1.1 2003/02/12 13:59:15 matteo
mer feb 12 14:56:57 CET 2003

Revision 1.2 2000/01/05 08:20:39 markster
Some OSS fixes and a few lpc changes to make it actually work

 * Revision 1.2 1996/08/20 20:28:05 jaf
 * Removed all static local variables that were SAVE'd in the Fortran
 * code, and put them in struct lpc10_encoder_state that is passed as an
 * argument.
 *
 * Removed init function, since all initialization is now done in
 * init_lpc10_encoder_state().
 *
 * Revision 1.1 1996/08/19 22:32:04 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"

#ifdef P_R_O_T_O_T_Y_P_E_S
extern int hp100_(real *speech, integer *start, integer *end,
 struct lpc10_encoder_state *st);
extern int inithp100_(void);
#endif

/* ********************************************************************* */

/* HP100 Version 55 */

/* $Log$
 * Revision 1.15 2004/06/26 03:50:14 markster
 * Merge source cleanups (bug #1911)
 *
 * Revision 1.14 2003/02/12 13:59:15 matteo
 * mer feb 12 14:56:57 CET 2003
 *
 * Revision 1.1.1.1 2003/02/12 13:59:15 matteo
 * mer feb 12 14:56:57 CET 2003
 *
 * Revision 1.2 2000/01/05 08:20:39 markster
 * Some OSS fixes and a few lpc changes to make it actually work
 *
 * Revision 1.2 1996/08/20 20:28:05 jaf
 * Removed all static local variables that were SAVE'd in the Fortran
 * code, and put them in struct lpc10_encoder_state that is passed as an
 * argument.
 *
 * Removed init function, since all initialization is now done in
 * init_lpc10_encoder_state().
 *
 * Revision 1.1 1996/08/19 22:32:04 jaf
 * Initial revision
 * */
/* Revision 1.6 1996/03/15 16:45:25 jaf */
/* Rearranged a few comments. */

/* Revision 1.5 1996/03/14 23:20:54 jaf */
/* Added comments about when INITHP100 should be used. */

/* Revision 1.4 1996/03/14 23:08:08 jaf */
/* Added an entry named INITHP100 that initializes the local state of */
/* subroutine HP100. */

/* Revision 1.3 1996/03/14 22:09:20 jaf */
/* Comments added explaining which of the local variables of this */
/* subroutine need to be saved from one invocation to the next, and which */
/* do not. */

/* Revision 1.2 1996/02/12 15:05:54 jaf */
/* Added lots of comments explaining why I changed one line, which was a */
/* declaration with initializations. */

/* Revision 1.1 1996/02/07 14:47:12 jaf */
/* Initial revision */


/* ********************************************************************* */

/* 100 Hz High Pass Filter */

/* Jan 92 - corrected typo (1.937148 to 1.935715), */
/* rounded coefficients to 7 places, */
/* corrected and merged gain (.97466**4), */
/* merged numerator into first two sections. */

/* Input: */
/* start, end - Range of samples to filter */
/* Input/Output: */
/* speech(end) - Speech data. */
/* Indices start through end are read and modified. */

/* This subroutine maintains local state from one call to the next. If */
/* you want to switch to using a new audio stream for this filter, or */
/* reinitialize its state for any other reason, call the ENTRY */
/* INITHP100. */
/* Subroutine */ int hp100_(real *speech, integer *start, integer *end,
 struct lpc10_encoder_state *st)
{
 /* Temporary local copies of variables in lpc10_encoder_state.
 I've only created these because it might cause the loop below
 to execute a bit faster to access local variables, rather than
 variables in the lpc10_encoder_state structure. It is just a
 guess that it will be faster. */

 real z11;
 real z21;
 real z12;
 real z22;

 /* System generated locals */
 integer i__1;

 /* Local variables */
 integer i__;
 real si, err;

/* Arguments */
/* Local variables that need not be saved */
/* Local state */
 /* Parameter adjustments */
 if (speech) {
 --speech;
 }

 /* Function Body */

 z11 = st->z11;
 z21 = st->z21;
 z12 = st->z12;
 z22 = st->z22;

 i__1 = *end;
 for (i__ = *start; i__ <= i__1; ++i__) {
 si = speech[i__];
 err = si + z11 * 1.859076f - z21 * .8648249f;
 si = err - z11 * 2.f + z21;
 z21 = z11;
 z11 = err;
 err = si + z12 * 1.935715f - z22 * .9417004f;
 si = err - z12 * 2.f + z22;
 z22 = z12;
 z12 = err;
 speech[i__] = si * .902428f;
 }

 st->z11 = z11;
 st->z21 = z21;
 st->z12 = z12;
 st->z22 = z22;

 return 0;
} /* hp100_ */