FreeCalypso > hg > gsm-codec-lib

annotate libgsmefr/convolve.c @ 282:9ee8ad3d4d30

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frtest: rm gsmfr-hand-test and gsmfr-max-out utils These hack programs were never properly documented and were written only as part of a debug chase, in pursuit of a bug that ultimately turned out to be in our then-hacky patch to osmo-bts-sysmo, before beginning of proper patches in Osmocom. These hack programs need to be dropped from the present sw package because they depend on old libgsm, and we are eliminating that dependency.
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 14 Apr 2024 05:44:47 +0000
parents 8de2f0f9bd78
children
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1 /*************************************************************************
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2 *
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3 * FUNCTION: Convolve
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4 *
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5 * PURPOSE:
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6 * Perform the convolution between two vectors x[] and h[] and
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7 * write the result in the vector y[]. All vectors are of length L
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8 * and only the first L samples of the convolution are computed.
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9 *
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10 * DESCRIPTION:
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11 * The convolution is given by
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12 *
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13 * y[n] = sum_{i=0}^{n} x[i] h[n-i], n=0,...,L-1
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14 *
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15 *************************************************************************/
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16
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17 #include "gsm_efr.h"
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18 #include "typedef.h"
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19 #include "namespace.h"
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20 #include "basic_op.h"
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21 #include "no_count.h"
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22 #include "sig_proc.h"
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24 void Convolve (
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25 Word16 x[], /* (i) : input vector */
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26 Word16 h[], /* (i) : impulse response */
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27 Word16 y[], /* (o) : output vector */
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28 Word16 L /* (i) : vector size */
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29 )
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30 {
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31 Word16 i, n;
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32 Word32 s;
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33
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34 for (n = 0; n < L; n++)
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35 {
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36 s = 0; move32 ();
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37 for (i = 0; i <= n; i++)
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38 {
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39 s = L_mac (s, x[i], h[n - i]);
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40 }
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41 s = L_shl (s, 3);
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42 y[n] = extract_h (s); move16 ();
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43 }
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44
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45 return;
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46 }