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annotate libgsmfr2/lpc.c @ 288:e0b46ac2c326

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gsmfr-encode-r: convert to libgsmfr2
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 14 Apr 2024 06:20:04 +0000
parents 0cfb7c95cce2
children
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0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
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1 /*
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2 * This C source file has been adapted from TU-Berlin libgsm source,
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3 * original notice follows:
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4 *
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5 * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
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6 * Universitaet Berlin. See the accompanying file "COPYRIGHT" for
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7 * details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
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8 */
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9
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10 #include <stdint.h>
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11 #include <assert.h>
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12 #include "tw_gsmfr.h"
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13 #include "typedef.h"
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14 #include "ed_state.h"
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15 #include "ed_internal.h"
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16
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17 /*
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18 * 4.2.4 .. 4.2.7 LPC ANALYSIS SECTION
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19 */
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20
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21 /* 4.2.4 */
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22
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23 static void Autocorrelation (
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24 word * s, /* [0..159] IN/OUT */
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25 longword * L_ACF) /* [0..8] OUT */
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26 /*
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27 * The goal is to compute the array L_ACF[k]. The signal s[i] must
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28 * be scaled in order to avoid an overflow situation.
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29 */
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30 {
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31 register int k, i;
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32
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33 word temp, smax, scalauto;
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34
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35 /* Dynamic scaling of the array s[0..159]
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36 */
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37
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38 /* Search for the maximum.
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39 */
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40 smax = 0;
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41 for (k = 0; k <= 159; k++) {
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42 temp = GSM_ABS( s[k] );
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43 if (temp > smax) smax = temp;
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44 }
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45
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46 /* Computation of the scaling factor.
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47 */
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48 if (smax == 0) scalauto = 0;
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49 else {
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50 assert(smax > 0);
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51 scalauto = 4 - gsm_norm( (longword)smax << 16 );/* sub(4,..) */
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52 }
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53
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54 /* Scaling of the array s[0...159]
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55 */
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56
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57 if (scalauto > 0) {
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58
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59 # define SCALE(n) \
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60 case n: for (k = 0; k <= 159; k++) \
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61 s[k] = GSM_MULT_R( s[k], 16384 >> (n-1) );\
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62 break;
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63
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64 switch (scalauto) {
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65 SCALE(1)
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66 SCALE(2)
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67 SCALE(3)
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68 SCALE(4)
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69 }
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70 # undef SCALE
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71 }
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72
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73 /* Compute the L_ACF[..].
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74 */
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75 {
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76 word * sp = s;
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77 word sl = *sp;
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78
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79 # define STEP(k) L_ACF[k] += ((longword)sl * sp[ -(k) ]);
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80
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81 # define NEXTI sl = *++sp
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82
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83
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84 for (k = 9; k--; L_ACF[k] = 0) ;
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85
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86 STEP (0);
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87 NEXTI;
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88 STEP(0); STEP(1);
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89 NEXTI;
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90 STEP(0); STEP(1); STEP(2);
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91 NEXTI;
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92 STEP(0); STEP(1); STEP(2); STEP(3);
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93 NEXTI;
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94 STEP(0); STEP(1); STEP(2); STEP(3); STEP(4);
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95 NEXTI;
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96 STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5);
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97 NEXTI;
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98 STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5); STEP(6);
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99 NEXTI;
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100 STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5); STEP(6); STEP(7);
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101
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102 for (i = 8; i <= 159; i++) {
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103
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104 NEXTI;
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105
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106 STEP(0);
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107 STEP(1); STEP(2); STEP(3); STEP(4);
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108 STEP(5); STEP(6); STEP(7); STEP(8);
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109 }
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110
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111 for (k = 9; k--; L_ACF[k] <<= 1) ;
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112
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113 }
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114 /* Rescaling of the array s[0..159]
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115 */
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116 if (scalauto > 0) {
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117 assert(scalauto <= 4);
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118 for (k = 160; k--; *s++ <<= scalauto) ;
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119 }
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120 }
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121
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122 /* 4.2.5 */
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123
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124 static void Reflection_coefficients (
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diff changeset
125 longword * L_ACF, /* 0...8 IN */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
126 register word * r /* 0...7 OUT */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
127 )
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
128 {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
129 register int i, m, n;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
130 register word temp;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
131 register longword ltmp;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
132 word ACF[9]; /* 0..8 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
133 word P[ 9]; /* 0..8 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
134 word K[ 9]; /* 2..8 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
135
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
136 /* Schur recursion with 16 bits arithmetic.
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
137 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
138
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
139 if (L_ACF[0] == 0) {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
140 for (i = 8; i--; *r++ = 0) ;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
141 return;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
142 }
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
143
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
144 assert( L_ACF[0] != 0 );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
145 temp = gsm_norm( L_ACF[0] );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
146
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
147 assert(temp >= 0 && temp < 32);
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
148
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Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
149 /* ? overflow ? */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
150 for (i = 0; i <= 8; i++) ACF[i] = SASR( L_ACF[i] << temp, 16 );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
151
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
152 /* Initialize array P[..] and K[..] for the recursion.
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
153 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
154
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
155 for (i = 1; i <= 7; i++) K[ i ] = ACF[ i ];
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
156 for (i = 0; i <= 8; i++) P[ i ] = ACF[ i ];
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
157
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
158 /* Compute reflection coefficients
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
159 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
160 for (n = 1; n <= 8; n++, r++) {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
161
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
162 temp = P[1];
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
163 temp = GSM_ABS(temp);
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
164 if (P[0] < temp) {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
165 for (i = n; i <= 8; i++) *r++ = 0;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
166 return;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
167 }
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
168
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
169 *r = gsm_div( temp, P[0] );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
170
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
171 assert(*r >= 0);
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
172 if (P[1] > 0) *r = -*r; /* r[n] = sub(0, r[n]) */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
173 assert (*r != MIN_WORD);
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
174 if (n == 8) return;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
175
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
176 /* Schur recursion
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
177 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
178 temp = GSM_MULT_R( P[1], *r );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
179 P[0] = GSM_ADD( P[0], temp );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
180
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
181 for (m = 1; m <= 8 - n; m++) {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
182 temp = GSM_MULT_R( K[ m ], *r );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
183 P[m] = GSM_ADD( P[ m+1 ], temp );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
184
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
185 temp = GSM_MULT_R( P[ m+1 ], *r );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
186 K[m] = GSM_ADD( K[ m ], temp );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
187 }
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
188 }
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
189 }
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
190
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
191 /* 4.2.6 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
192
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
193 static void Transformation_to_Log_Area_Ratios (
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
194 register word * r /* 0..7 IN/OUT */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
195 )
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
196 /*
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
197 * The following scaling for r[..] and LAR[..] has been used:
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
198 *
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
199 * r[..] = integer( real_r[..]*32768. ); -1 <= real_r < 1.
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
200 * LAR[..] = integer( real_LAR[..] * 16384 );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
201 * with -1.625 <= real_LAR <= 1.625
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
202 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
203 {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
204 register word temp;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
205 register int i;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
206
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
207 /* Computation of the LAR[0..7] from the r[0..7]
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
208 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
209 for (i = 1; i <= 8; i++, r++) {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
210
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
211 temp = *r;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
212 temp = GSM_ABS(temp);
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
213 assert(temp >= 0);
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
214
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
215 if (temp < 22118) {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
216 temp >>= 1;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
217 } else if (temp < 31130) {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
218 assert( temp >= 11059 );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
219 temp -= 11059;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
220 } else {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
221 assert( temp >= 26112 );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
222 temp -= 26112;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
223 temp <<= 2;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
224 }
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
225
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
226 *r = *r < 0 ? -temp : temp;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
227 assert( *r != MIN_WORD );
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
228 }
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
229 }
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
230
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
231 /* 4.2.7 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
232
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
233 static void Quantization_and_coding (
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
234 register word * LAR /* [0..7] IN/OUT */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
235 )
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
236 {
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
237 register word temp;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
238 longword ltmp;
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
239
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
240 /* This procedure needs four tables; the following equations
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
241 * give the optimum scaling for the constants:
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
242 *
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
243 * A[0..7] = integer( real_A[0..7] * 1024 )
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
244 * B[0..7] = integer( real_B[0..7] * 512 )
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
245 * MAC[0..7] = maximum of the LARc[0..7]
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
246 * MIC[0..7] = minimum of the LARc[0..7]
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
247 */
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
248
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
249 # undef STEP
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
250 # define STEP( A, B, MAC, MIC ) \
0cfb7c95cce2 libgsmfr2: integrate lpc.c from libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
251 temp = GSM_MULT( A, *LAR ); \
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252 temp = GSM_ADD( temp, B ); \
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253 temp = GSM_ADD( temp, 256 ); \
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254 temp = SASR( temp, 9 ); \
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255 *LAR = temp>MAC ? MAC - MIC : (temp<MIC ? 0 : temp - MIC); \
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256 LAR++;
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257
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258 STEP( 20480, 0, 31, -32 );
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259 STEP( 20480, 0, 31, -32 );
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260 STEP( 20480, 2048, 15, -16 );
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261 STEP( 20480, -2560, 15, -16 );
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262
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263 STEP( 13964, 94, 7, -8 );
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264 STEP( 15360, -1792, 7, -8 );
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265 STEP( 8534, -341, 3, -4 );
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266 STEP( 9036, -1144, 3, -4 );
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267
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268 # undef STEP
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269 }
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270
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271 void Gsm_LPC_Analysis (
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272 struct gsmfr_0610_state *S,
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273 word * s, /* 0..159 signals IN/OUT */
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274 word * LARc) /* 0..7 LARc's OUT */
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275 {
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276 longword L_ACF[9];
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277
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278 Autocorrelation (s, L_ACF );
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279 Reflection_coefficients (L_ACF, LARc );
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280 Transformation_to_Log_Area_Ratios (LARc);
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281 Quantization_and_coding (LARc);
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282 }