/* $Log: hp100.c,v $ Revision 1.1 2000/06/05 04:45:12 robertj Added LPC-10 2400bps codec * 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 * */ #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 /* -- translated by f2c (version 19951025). You must link the resulting object file with the libraries: -lf2c -lm (in that order) */ #include "f2c.h" /* ********************************************************************* */ /* HP100 Version 55 */ /* $Log: hp100.c,v $ /* Revision 1.1 2000/06/05 04:45:12 robertj /* Added LPC-10 2400bps codec /* * 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__ 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_ */
