FreeCalypso > hg > gsm-codec-lib

comparison libgsmefr/convolve.c @ 53:49dd1ac8e75b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
libgsmefr: import most *.c files from ETSI source
author Mychaela Falconia <falcon@freecalypso.org>
date Fri, 25 Nov 2022 16:18:21 +0000
parents
children 8de2f0f9bd78
comparison
equal deleted inserted replaced
52:988fd7ff514f 53:49dd1ac8e75b
1 /*************************************************************************
2 *
3 * FUNCTION: Convolve
4 *
5 * PURPOSE:
6 * Perform the convolution between two vectors x[] and h[] and
7 * write the result in the vector y[]. All vectors are of length L
8 * and only the first L samples of the convolution are computed.
9 *
10 * DESCRIPTION:
11 * The convolution is given by
12 *
13 * y[n] = sum_{i=0}^{n} x[i] h[n-i], n=0,...,L-1
14 *
15 *************************************************************************/
16
17 #include "typedef.h"
18 #include "basic_op.h"
19 #include "count.h"
20
21 void Convolve (
22 Word16 x[], /* (i) : input vector */
23 Word16 h[], /* (i) : impulse response */
24 Word16 y[], /* (o) : output vector */
25 Word16 L /* (i) : vector size */
26 )
27 {
28 Word16 i, n;
29 Word32 s;
30
31 for (n = 0; n < L; n++)
32 {
33 s = 0; move32 ();
34 for (i = 0; i <= n; i++)
35 {
36 s = L_mac (s, x[i], h[n - i]);
37 }
38 s = L_shl (s, 3);
39 y[n] = extract_h (s); move16 ();
40 }
41
42 return;
43 }