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annotate libtwamr/residu.c @ 485:751f06541fbb

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doc/Codec-utils: clarify lack of DHF in gsmfr-decode-rb
author Mychaela Falconia <falcon@freecalypso.org>
date Mon, 20 May 2024 01:47:22 +0000
parents a2351f2ad4f8
children
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a2351f2ad4f8 libtwamr: integrate residu.c
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1 /*
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2 ********************************************************************************
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3 *
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4 * GSM AMR-NB speech codec R98 Version 7.6.0 December 12, 2001
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5 * R99 Version 3.3.0
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6 * REL-4 Version 4.1.0
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7 *
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8 ********************************************************************************
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9 *
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10 * File : residu.c
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11 * Purpose : Computes the LP residual.
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12 * Description : The LP residual is computed by filtering the input
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13 * : speech through the LP inverse filter A(z).
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14 *
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15 ********************************************************************************
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16 */
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17 /*
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18 ********************************************************************************
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19 * MODULE INCLUDE FILE AND VERSION ID
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20 ********************************************************************************
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21 */
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22 #include "namespace.h"
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23 #include "residu.h"
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24
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25 /*
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26 ********************************************************************************
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27 * INCLUDE FILES
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28 ********************************************************************************
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29 */
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30 #include "typedef.h"
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31 #include "basic_op.h"
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32 #include "no_count.h"
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33 #include "cnst.h"
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34
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35 /*
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36 ********************************************************************************
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37 * LOCAL VARIABLES AND TABLES
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38 ********************************************************************************
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39 */
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40 /*
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41 *--------------------------------------*
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42 * Constants (defined in cnst.h *
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43 *--------------------------------------*
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44 * M : LPC order *
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45 *--------------------------------------*
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46 */
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47
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48 /*
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49 ********************************************************************************
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50 * PUBLIC PROGRAM CODE
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51 ********************************************************************************
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52 */
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53 void Residu (
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54 Word16 a[], /* (i) : prediction coefficients */
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55 Word16 x[], /* (i) : speech signal */
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56 Word16 y[], /* (o) : residual signal */
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57 Word16 lg /* (i) : size of filtering */
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58 )
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59 {
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60 Word16 i, j;
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61 Word32 s;
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62
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63 for (i = 0; i < lg; i++)
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64 {
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65 s = L_mult (x[i], a[0]);
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66 for (j = 1; j <= M; j++)
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67 {
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68 s = L_mac (s, a[j], x[i - j]);
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69 }
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70 s = L_shl (s, 3);
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71 y[i] = round (s); move16 ();
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72 }
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73 return;
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74 }