/* $Log: deemp.c,v $ Revision 1.1 2000/06/05 04:45:12 robertj Added LPC-10 2400bps 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 2000/06/05 04:45:12 robertj /* Added LPC-10 2400bps 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 The coefficients above may be out of date with the code */ /* below.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_ */
