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1 /*
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2 * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
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3 * Universitaet Berlin. See the accompanying file "COPYRIGHT" for
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4 * details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
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5 */
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6
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7 /* $Header: /home/kbs/jutta/src/gsm/gsm-1.0/src/RCS/code.c,v 1.1 1992/10/28 00:15:50 jutta Exp $ */
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8
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9 #include "config.h"
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10
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11
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12 #ifdef HAS_STDLIB_H
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13 #include <stdlib.h>
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14 #include <string.h>
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15 #else
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16 # include "proto.h"
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17 extern char *memcpy P((char *, char *, int));
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18 #endif
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19
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20 #include "private.h"
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21 #include "gsm.h"
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22 #include "proto.h"
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23
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24 /*
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25 * 4.2 FIXED POINT IMPLEMENTATION OF THE RPE-LTP CODER
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26 */
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27
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28 void Gsm_Coder P8((S, s, LARc, Nc, bc, Mc, xmaxc, xMc), struct gsm_state *S, word * s, /* [0..159] samples IN */
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29 /*
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30 * The RPE-LTD coder works on a frame by frame basis. The length of
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31 * the frame is equal to 160 samples. Some computations are done
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32 * once per frame to produce at the output of the coder the
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33 * LARc[1..8] parameters which are the coded LAR coefficients and
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34 * also to realize the inverse filtering operation for the entire
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35 * frame (160 samples of signal d[0..159]). These parts produce at
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36 * the output of the coder:
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37 */
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38 word * LARc, /* [0..7] LAR coefficients OUT */
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39 /*
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40 * Procedure 4.2.11 to 4.2.18 are to be executed four times per
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41 * frame. That means once for each sub-segment RPE-LTP analysis of
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42 * 40 samples. These parts produce at the output of the coder:
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43 */
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44 word * Nc, /* [0..3] LTP lag OUT */
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45 word * bc, /* [0..3] coded LTP gain OUT */
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46 word * Mc, /* [0..3] RPE grid selection OUT */
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47 word * xmaxc, /* [0..3] Coded maximum amplitude OUT */
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48 word * xMc /* [13*4] normalized RPE samples OUT */
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49 )
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50 {
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51 int k;
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52 word *dp = S->dp0 + 120; /* [ -120...-1 ] */
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53 word *dpp = dp; /* [ 0...39 ] */
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54
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55 static word e[50] = { 0 };
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56
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57 word so[160];
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58
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59 Gsm_Preprocess(S, s, so);
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60 Gsm_LPC_Analysis(S, so, LARc);
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61 Gsm_Short_Term_Analysis_Filter(S, LARc, so);
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62
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63 for (k = 0; k <= 3; k++, xMc += 13) {
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64
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65 Gsm_Long_Term_Predictor(S, so + k * 40, /* d [0..39] IN */
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66 dp, /* dp [-120..-1] IN */
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67 e + 5, /* e [0..39] OUT */
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68 dpp, /* dpp [0..39] OUT */
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69 Nc++, bc++);
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70
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71 Gsm_RPE_Encoding(S, e + 5, /* e ][0..39][ IN/OUT */
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72 xmaxc++, Mc++, xMc);
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73 /*
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74 * Gsm_Update_of_reconstructed_short_time_residual_signal
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75 * ( dpp, e + 5, dp );
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76 */
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77
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78 {
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79 register int i;
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80 register longword ltmp;
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81 for (i = 0; i <= 39; i++)
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82 dp[i] = GSM_ADD(e[5 + i], dpp[i]);
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83 }
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84 dp += 40;
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85 dpp += 40;
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86
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87 }
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88 (void) memcpy((char *) S->dp0, (char *) (S->dp0 + 160),
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89 120 * sizeof(*S->dp0));
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90 }
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