/*
$Log: deemp.c,v $
Revision 1.1.1.1 2002/07/28 05:23:23 freeman_yong
lpc10 codec
* Revision 1.2 1996/08/20 20:23:46 jaf
* Removed all static local variables that were SAVE'd in the Fortran
* code, and put them in struct lpc10_decoder_state that is passed as an
* argument.
*
* Removed init function, since all initialization is now done in
* init_lpc10_decoder_state().
*
* Revision 1.1 1996/08/19 22:32:34 jaf
* Initial revision
*
*/
#ifdef P_R_O_T_O_T_Y_P_E_S
extern int deemp_(real *x, integer *n, struct lpc10_decoder_state *st);
#endif
/* -- translated by f2c (version 19951025).
You must link the resulting object file with the libraries:
-lf2c -lm (in that order)
*/
#include "f2c.h"
/* ***************************************************************** */
/* DEEMP Version 48 */
/* $Log: deemp.c,v $
/* Revision 1.1.1.1 2002/07/28 05:23:23 freeman_yong
/* lpc10 codec
/*
* Revision 1.2 1996/08/20 20:23:46 jaf
* Removed all static local variables that were SAVE'd in the Fortran
* code, and put them in struct lpc10_decoder_state that is passed as an
* argument.
*
* Removed init function, since all initialization is now done in
* init_lpc10_decoder_state().
*
* Revision 1.1 1996/08/19 22:32:34 jaf
* Initial revision
* */
/* Revision 1.3 1996/03/20 15:54:37 jaf */
/* Added comments about which indices of array arguments are read or */
/* written. */
/* Added entry INITDEEMP to reinitialize the local state variables, if */
/* desired. */
/* Revision 1.2 1996/03/14 22:11:13 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 1.1 1996/02/07 14:44:53 jaf */
/* Initial revision */
/* ***************************************************************** */
/* De-Emphasize output speech with 1 / ( 1 - .75z**-1 ) */
/* cascaded with 200 Hz high pass filter */
/* ( 1 - 1.9998z**-1 + z**-2 ) / ( 1 - 1.75z**-1 + .78z**-2 ) */
/* WARNING! The coefficients above may be out of date with the code */
/* below. Either that, or some kind of transformation was performed */
/* on the coefficients above to create the code below. */
/* Input: */
/* N - Number of samples */
/* Input/Output: */
/* X - Speech */
/* Indices 1 through N are read before being written. */
/* 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 */
/* INITDEEMP. */
/* Subroutine */ int deemp_(real *x, integer *n, struct lpc10_decoder_state *st)
{
/* Initialized data */
real *dei1;
real *dei2;
real *deo1;
real *deo2;
real *deo3;
/* System generated locals */
integer i__1;
real r__1;
/* Local variables */
integer k;
real dei0;
/* Arguments */
/* Local variables that need not be saved */
/* Local state */
/* All of the locals saved below were not given explicit initial */
/* values in the original code. I think 0 is a safe choice. */
/* Parameter adjustments */
if (x) {
--x;
}
/* Function Body */
dei1 = &(st->dei1);
dei2 = &(st->dei2);
deo1 = &(st->deo1);
deo2 = &(st->deo2);
deo3 = &(st->deo3);
i__1 = *n;
for (k = 1; k dei0 = x[k];
r__1 = x[k] - *dei1 * 1.9998f + *dei2;
x[k] = r__1 + *deo1 * 2.5f - *deo2 * 2.0925f + *deo3 * .585f;
*dei2 = *dei1;
*dei1 = dei0;
*deo3 = *deo2;
*deo2 = *deo1;
*deo1 = x[k];
}
return 0;
} /* deemp_ */
