Asterisk - The Open Source Telephony Project  18.5.0
ivfilt.c
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1 /*
2 
3 $Log$
4 Revision 1.16 2004/06/26 03:50:14 markster
5 Merge source cleanups (bug #1911)
6 
7 Revision 1.15 2003/09/19 01:20:22 markster
8 Code cleanups (bug #66)
9 
10 Revision 1.2 2003/09/19 01:20:22 markster
11 Code cleanups (bug #66)
12 
13 Revision 1.1.1.1 2003/02/12 13:59:15 matteo
14 mer feb 12 14:56:57 CET 2003
15 
16 Revision 1.2 2000/01/05 08:20:39 markster
17 Some OSS fixes and a few lpc changes to make it actually work
18 
19  * Revision 1.1 1996/08/19 22:31:53 jaf
20  * Initial revision
21  *
22 
23 */
24 
25 /* -- translated by f2c (version 19951025).
26  You must link the resulting object file with the libraries:
27  -lf2c -lm (in that order)
28 */
29 
30 #include "f2c.h"
31 
32 #ifdef P_R_O_T_O_T_Y_P_E_S
33 extern int ivfilt_(real *lpbuf, real *ivbuf, integer *len, integer *nsamp, real *ivrc);
34 #endif
35 
36 /* ********************************************************************* */
37 
38 /* IVFILT Version 48 */
39 
40 /* $Log$
41  * Revision 1.16 2004/06/26 03:50:14 markster
42  * Merge source cleanups (bug #1911)
43  *
44  * Revision 1.15 2003/09/19 01:20:22 markster
45  * Code cleanups (bug #66)
46  *
47  * Revision 1.2 2003/09/19 01:20:22 markster
48  * Code cleanups (bug #66)
49  *
50  * Revision 1.1.1.1 2003/02/12 13:59:15 matteo
51  * mer feb 12 14:56:57 CET 2003
52  *
53  * Revision 1.2 2000/01/05 08:20:39 markster
54  * Some OSS fixes and a few lpc changes to make it actually work
55  *
56  * Revision 1.1 1996/08/19 22:31:53 jaf
57  * Initial revision
58  * */
59 /* Revision 1.3 1996/03/15 21:36:29 jaf */
60 /* Just added a few comments about which array indices of the arguments */
61 /* are used, and mentioning that this subroutine has no local state. */
62 
63 /* Revision 1.2 1996/03/13 00:01:00 jaf */
64 /* Comments added explaining that none of the local variables of this */
65 /* subroutine need to be saved from one invocation to the next. */
66 
67 /* Revision 1.1 1996/02/07 14:47:34 jaf */
68 /* Initial revision */
69 
70 
71 /* ********************************************************************* */
72 
73 /* 2nd order inverse filter, speech is decimated 4:1 */
74 
75 /* Input: */
76 /* LEN - Length of speech buffers */
77 /* NSAMP - Number of samples to filter */
78 /* LPBUF - Low pass filtered speech buffer */
79 /* Indices LEN-NSAMP-7 through LEN read. */
80 /* Output: */
81 /* IVBUF - Inverse filtered speech buffer */
82 /* Indices LEN-NSAMP+1 through LEN written. */
83 /* IVRC - Inverse filter reflection coefficients (for voicing) */
84 /* Indices 1 and 2 both written (also read, but only after writing).
85 */
86 
87 /* This subroutine has no local state. */
88 
89 /* Subroutine */ int ivfilt_(real *lpbuf, real *ivbuf, integer *len, integer *
90  nsamp, real *ivrc)
91 {
92  /* System generated locals */
93  integer i__1;
94 
95  /* Local variables */
96  integer i__, j, k;
97  real r__[3], pc1, pc2;
98 
99 /* Arguments */
100 /* Local variables that need not be saved */
101 /* Local state */
102 /* None */
103 /* Calculate Autocorrelations */
104  /* Parameter adjustments */
105  --ivbuf;
106  --lpbuf;
107  --ivrc;
108 
109  /* Function Body */
110  for (i__ = 1; i__ <= 3; ++i__) {
111  r__[i__ - 1] = 0.f;
112  k = (i__ - 1) << 2;
113  i__1 = *len;
114  for (j = (i__ << 2) + *len - *nsamp; j <= i__1; j += 2) {
115  r__[i__ - 1] += lpbuf[j] * lpbuf[j - k];
116  }
117  }
118 /* Calculate predictor coefficients */
119  pc1 = 0.f;
120  pc2 = 0.f;
121  ivrc[1] = 0.f;
122  ivrc[2] = 0.f;
123  if (r__[0] > 1e-10f) {
124  ivrc[1] = r__[1] / r__[0];
125  ivrc[2] = (r__[2] - ivrc[1] * r__[1]) / (r__[0] - ivrc[1] * r__[1]);
126  pc1 = ivrc[1] - ivrc[1] * ivrc[2];
127  pc2 = ivrc[2];
128  }
129 /* Inverse filter LPBUF into IVBUF */
130  i__1 = *len;
131  for (i__ = *len + 1 - *nsamp; i__ <= i__1; ++i__) {
132  ivbuf[i__] = lpbuf[i__] - pc1 * lpbuf[i__ - 4] - pc2 * lpbuf[i__ - 8];
133  }
134  return 0;
135 } /* ivfilt_ */
int ivfilt_(real *lpbuf, real *ivbuf, integer *len, integer *nsamp, real *ivrc)
Definition: ivfilt.c:89
static int len(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t buflen)
float real
Definition: lpc10.h:79
INT32 integer
Definition: lpc10.h:80