codecs/lpc10/hp100.c

   1 /*
   2
   3 $Log$
   4 Revision 1.15  2004/06/26 03:50:14  markster
   5 Merge source cleanups (bug #1911)
   6
   7 Revision 1.14  2003/02/12 13:59:15  matteo
   8 mer feb 12 14:56:57 CET 2003
   9
  10 Revision 1.1.1.1  2003/02/12 13:59:15  matteo
  11 mer feb 12 14:56:57 CET 2003
  12
  13 Revision 1.2  2000/01/05 08:20:39  markster
  14 Some OSS fixes and a few lpc changes to make it actually work
  15
  16  * Revision 1.2  1996/08/20  20:28:05  jaf
  17  * Removed all static local variables that were SAVE'd in the Fortran
  18  * code, and put them in struct lpc10_encoder_state that is passed as an
  19  * argument.
  20  *
  21  * Removed init function, since all initialization is now done in
  22  * init_lpc10_encoder_state().
  23  *
  24  * Revision 1.1  1996/08/19  22:32:04  jaf
  25  * Initial revision
  26  *
  27
  28 */
  29
  30 /*  -- translated by f2c (version 19951025).
  31    You must link the resulting object file with the libraries:
  32         -lf2c -lm   (in that order)
  33 */
  34
  35 #include "f2c.h"
  36
  37 #ifdef P_R_O_T_O_T_Y_P_E_S
  38 extern int hp100_(real *speech, integer *start, integer *end,
  39                   struct lpc10_encoder_state *st);
  40 extern int inithp100_(void);
  41 #endif
  42
  43 /* ********************************************************************* */
  44
  45 /*      HP100 Version 55 */
  46
  47 /* $Log$
  48  * Revision 1.15  2004/06/26 03:50:14  markster
  49  * Merge source cleanups (bug #1911)
  50  *
  51  * Revision 1.14  2003/02/12 13:59:15  matteo
  52  * mer feb 12 14:56:57 CET 2003
  53  *
  54  * Revision 1.1.1.1  2003/02/12 13:59:15  matteo
  55  * mer feb 12 14:56:57 CET 2003
  56  *
  57  * Revision 1.2  2000/01/05 08:20:39  markster
  58  * Some OSS fixes and a few lpc changes to make it actually work
  59  *
  60  * Revision 1.2  1996/08/20  20:28:05  jaf
  61  * Removed all static local variables that were SAVE'd in the Fortran
  62  * code, and put them in struct lpc10_encoder_state that is passed as an
  63  * argument.
  64  *
  65  * Removed init function, since all initialization is now done in
  66  * init_lpc10_encoder_state().
  67  *
  68  * Revision 1.1  1996/08/19  22:32:04  jaf
  69  * Initial revision
  70  * */
  71 /* Revision 1.6  1996/03/15  16:45:25  jaf */
  72 /* Rearranged a few comments. */
  73
  74 /* Revision 1.5  1996/03/14  23:20:54  jaf */
  75 /* Added comments about when INITHP100 should be used. */
  76
  77 /* Revision 1.4  1996/03/14  23:08:08  jaf */
  78 /* Added an entry named INITHP100 that initializes the local state of */
  79 /* subroutine HP100. */
  80
  81 /* Revision 1.3  1996/03/14  22:09:20  jaf */
  82 /* Comments added explaining which of the local variables of this */
  83 /* subroutine need to be saved from one invocation to the next, and which */
  84 /* do not. */
  85
  86 /* Revision 1.2  1996/02/12  15:05:54  jaf */
  87 /* Added lots of comments explaining why I changed one line, which was a */
  88 /* declaration with initializations. */
  89
  90 /* Revision 1.1  1996/02/07 14:47:12  jaf */
  91 /* Initial revision */
  92
  93
  94 /* ********************************************************************* */
  95
  96 /*    100 Hz High Pass Filter */
  97
  98 /* Jan 92 - corrected typo (1.937148 to 1.935715), */
  99 /*          rounded coefficients to 7 places, */
 100 /*          corrected and merged gain (.97466**4), */
 101 /*          merged numerator into first two sections. */
 102
 103 /* Input: */
 104 /*  start, end - Range of samples to filter */
 105 /* Input/Output: */
 106 /*  speech(end) - Speech data. */
 107 /*                Indices start through end are read and modified. */
 108
 109 /* This subroutine maintains local state from one call to the next.  If */
 110 /* you want to switch to using a new audio stream for this filter, or */
 111 /* reinitialize its state for any other reason, call the ENTRY */
 112 /* INITHP100. */
 113 /* Subroutine */ int hp100_(real *speech, integer *start, integer *end,
 114         struct lpc10_encoder_state *st)
 115 {
 116     /* Temporary local copies of variables in lpc10_encoder_state.
 117        I've only created these because it might cause the loop below
 118        to execute a bit faster to access local variables, rather than
 119        variables in the lpc10_encoder_state structure.  It is just a
 120        guess that it will be faster. */
 121
 122     real z11;
 123     real z21;
 124     real z12;
 125     real z22;
 126
 127     /* System generated locals */
 128     integer i__1;
 129
 130     /* Local variables */
 131     integer i__;
 132     real si, err;
 133
 134 /*       Arguments */
 135 /*       Local variables that need not be saved */
 136 /*       Local state */
 137     /* Parameter adjustments */
 138     if (speech) {
 139         --speech;
 140         }
 141
 142     /* Function Body */
 143
 144     z11 = st->z11;
 145     z21 = st->z21;
 146     z12 = st->z12;
 147     z22 = st->z22;
 148
 149     i__1 = *end;
 150     for (i__ = *start; i__ <= i__1; ++i__) {
 151         si = speech[i__];
 152         err = si + z11 * 1.859076f - z21 * .8648249f;
 153         si = err - z11 * 2.f + z21;
 154         z21 = z11;
 155         z11 = err;
 156         err = si + z12 * 1.935715f - z22 * .9417004f;
 157         si = err - z12 * 2.f + z22;
 158         z22 = z12;
 159         z12 = err;
 160         speech[i__] = si * .902428f;
 161     }
 162
 163     st->z11 = z11;
 164     st->z21 = z21;
 165     st->z12 = z12;
 166     st->z22 = z22;
 167
 168     return 0;
 169 } /* hp100_ */