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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: /tmp_amd/presto/export/kbs/jutta/src/gsm/RCS/code.c,v 1.3 1996/07/02 09:59:05 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 #include <string.h> |
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12 |
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13 #ifdef HAS_STDLIB_H |
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14 #include <stdlib.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 /* |
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26 * 4.2 FIXED POINT IMPLEMENTATION OF THE RPE-LTP CODER |
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27 */ |
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28 |
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29 void Gsm_Coder P8((S,s,LARc,Nc,bc,Mc,xmaxc,xMc), |
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30 |
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31 struct gsm_state * S, |
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32 |
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33 word * s, /* [0..159] samples IN */ |
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34 |
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35 /* |
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36 * The RPE-LTD coder works on a frame by frame basis. The length of |
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37 * the frame is equal to 160 samples. Some computations are done |
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38 * once per frame to produce at the output of the coder the |
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39 * LARc[1..8] parameters which are the coded LAR coefficients and |
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40 * also to realize the inverse filtering operation for the entire |
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41 * frame (160 samples of signal d[0..159]). These parts produce at |
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42 * the output of the coder: |
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43 */ |
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44 |
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45 word * LARc, /* [0..7] LAR coefficients OUT */ |
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46 |
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47 /* |
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48 * Procedure 4.2.11 to 4.2.18 are to be executed four times per |
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49 * frame. That means once for each sub-segment RPE-LTP analysis of |
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50 * 40 samples. These parts produce at the output of the coder: |
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51 */ |
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52 |
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53 word * Nc, /* [0..3] LTP lag OUT */ |
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54 word * bc, /* [0..3] coded LTP gain OUT */ |
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55 word * Mc, /* [0..3] RPE grid selection OUT */ |
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56 word * xmaxc,/* [0..3] Coded maximum amplitude OUT */ |
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57 word * xMc /* [13*4] normalized RPE samples OUT */ |
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58 ) |
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59 { |
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60 int k; |
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61 word * dp = S->dp0 + 120; /* [ -120...-1 ] */ |
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62 word * dpp = dp; /* [ 0...39 ] */ |
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63 |
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64 static word e[50]; |
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65 |
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66 word so[160]; |
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67 |
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68 Gsm_Preprocess (S, s, so); |
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69 Gsm_LPC_Analysis (S, so, LARc); |
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70 Gsm_Short_Term_Analysis_Filter (S, LARc, so); |
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71 |
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72 for (k = 0; k <= 3; k++, xMc += 13) { |
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73 |
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74 Gsm_Long_Term_Predictor ( S, |
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75 so+k*40, /* d [0..39] IN */ |
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76 dp, /* dp [-120..-1] IN */ |
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77 e + 5, /* e [0..39] OUT */ |
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78 dpp, /* dpp [0..39] OUT */ |
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79 Nc++, |
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80 bc++); |
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81 |
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82 Gsm_RPE_Encoding ( S, |
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83 e + 5, /* e ][0..39][ IN/OUT */ |
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84 xmaxc++, Mc++, xMc ); |
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85 /* |
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86 * Gsm_Update_of_reconstructed_short_time_residual_signal |
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87 * ( dpp, e + 5, dp ); |
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88 */ |
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89 |
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90 { register int i; |
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91 register longword ltmp; |
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92 for (i = 0; i <= 39; i++) |
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93 dp[ i ] = GSM_ADD( e[5 + i], dpp[i] ); |
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94 } |
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95 dp += 40; |
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96 dpp += 40; |
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97 |
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98 } |
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99 |
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100 (void)memcpy( (char *)S->dp0, (char *)(S->dp0 + 160), |
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101 120 * sizeof(*S->dp0) ); |
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102 |
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103 |
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104 } |