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annotate libgsmefr/agc.c @ 494:aaf4dec8bee0

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libgsmhr1: implement perfect SID detection
author Mychaela Falconia <falcon@freecalypso.org>
date Mon, 17 Jun 2024 23:14:19 +0000
parents 7b11cbe99a0e
children
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1 /*************************************************************************
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2 *
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3 * FUNCTION: agc
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4 *
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5 * PURPOSE: Scales the postfilter output on a subframe basis by automatic
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6 * control of the subframe gain.
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7 *
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8 * DESCRIPTION:
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9 * sig_out[n] = sig_out[n] * gain[n];
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10 * where gain[n] is the gain at the nth sample given by
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11 * gain[n] = agc_fac * gain[n-1] + (1 - agc_fac) g_in/g_out
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12 * g_in/g_out is the square root of the ratio of energy at the input
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13 * and output of the postfilter.
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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 "cnst.h"
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23 #include "dec_state.h"
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24 #include "sig_proc.h"
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25
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26 void agc (
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27 struct EFR_decoder_state *st,
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28 Word16 *sig_in, /* (i) : postfilter input signal */
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29 Word16 *sig_out, /* (i/o) : postfilter output signal */
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30 Word16 agc_fac, /* (i) : AGC factor */
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31 Word16 l_trm /* (i) : subframe size */
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32 )
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33 {
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34 Word16 i, exp;
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35 Word16 gain_in, gain_out, g0, gain;
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36 Word32 s;
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37
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38 Word16 temp;
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39
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40 /* calculate gain_out with exponent */
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41
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42 temp = shr (sig_out[0], 2);
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43 s = L_mult (temp, temp);
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44
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45 for (i = 1; i < l_trm; i++)
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46 {
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47 temp = shr (sig_out[i], 2);
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48 s = L_mac (s, temp, temp);
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49 }
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50
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51 if (s == 0)
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52 {
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53 st->past_gain = 0;
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54 return;
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55 }
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56 exp = sub (norm_l (s), 1);
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57 gain_out = round (L_shl (s, exp));
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58
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59 /* calculate gain_in with exponent */
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61 temp = shr (sig_in[0], 2);
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62 s = L_mult (temp, temp);
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63
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64 for (i = 1; i < l_trm; i++)
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65 {
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66 temp = shr (sig_in[i], 2);
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67 s = L_mac (s, temp, temp);
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68 }
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69
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70 if (s == 0)
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71 {
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72 g0 = 0;
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73 }
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74 else
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75 {
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76 i = norm_l (s);
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77 gain_in = round (L_shl (s, i));
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78 exp = sub (exp, i);
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79
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80 /*---------------------------------------------------*
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81 * g0 = (1-agc_fac) * sqrt(gain_in/gain_out); *
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82 *---------------------------------------------------*/
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83
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84 s = L_deposit_l (div_s (gain_out, gain_in));
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85 s = L_shl (s, 7); /* s = gain_out / gain_in */
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86 s = L_shr (s, exp); /* add exponent */
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87
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88 s = Inv_sqrt (s);
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89 i = round (L_shl (s, 9));
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90
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91 /* g0 = i * (1-agc_fac) */
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92 g0 = mult (i, sub (32767, agc_fac));
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93 }
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94
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95 /* compute gain[n] = agc_fac * gain[n-1]
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96 + (1-agc_fac) * sqrt(gain_in/gain_out) */
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97 /* sig_out[n] = gain[n] * sig_out[n] */
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98
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99 gain = st->past_gain;
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100
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101 for (i = 0; i < l_trm; i++)
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102 {
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103 gain = mult (gain, agc_fac);
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104 gain = add (gain, g0);
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105 sig_out[i] = extract_h (L_shl (L_mult (sig_out[i], gain), 3));
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106 }
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107
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108 st->past_gain = gain;
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109
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110 return;
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111 }
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112
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113 void agc2 (
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114 Word16 *sig_in, /* (i) : postfilter input signal */
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115 Word16 *sig_out, /* (i/o) : postfilter output signal */
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116 Word16 l_trm /* (i) : subframe size */
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117 )
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118 {
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119 Word16 i, exp;
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120 Word16 gain_in, gain_out, g0;
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121 Word32 s;
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122
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123 Word16 temp;
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124
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125 /* calculate gain_out with exponent */
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126
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127 temp = shr (sig_out[0], 2);
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128 s = L_mult (temp, temp);
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129 for (i = 1; i < l_trm; i++)
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130 {
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131 temp = shr (sig_out[i], 2);
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132 s = L_mac (s, temp, temp);
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133 }
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134
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135 test ();
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
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136 if (s == 0)
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137 {
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
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138 return;
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Mychaela Falconia <falcon@freecalypso.org>
parents:
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139 }
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Mychaela Falconia <falcon@freecalypso.org>
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140 exp = sub (norm_l (s), 1);
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Mychaela Falconia <falcon@freecalypso.org>
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141 gain_out = round (L_shl (s, exp));
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142
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Mychaela Falconia <falcon@freecalypso.org>
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143 /* calculate gain_in with exponent */
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Mychaela Falconia <falcon@freecalypso.org>
parents:
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144
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Mychaela Falconia <falcon@freecalypso.org>
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145 temp = shr (sig_in[0], 2);
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146 s = L_mult (temp, temp);
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147 for (i = 1; i < l_trm; i++)
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148 {
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149 temp = shr (sig_in[i], 2);
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parents:
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150 s = L_mac (s, temp, temp);
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parents:
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151 }
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Mychaela Falconia <falcon@freecalypso.org>
parents:
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152
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Mychaela Falconia <falcon@freecalypso.org>
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153 test ();
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Mychaela Falconia <falcon@freecalypso.org>
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154 if (s == 0)
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Mychaela Falconia <falcon@freecalypso.org>
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155 {
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
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156 g0 = 0; move16 ();
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parents:
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157 }
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158 else
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159 {
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Mychaela Falconia <falcon@freecalypso.org>
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160 i = norm_l (s);
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Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
161 gain_in = round (L_shl (s, i));
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
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parents:
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162 exp = sub (exp, i);
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
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163
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
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164 /*---------------------------------------------------*
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Mychaela Falconia <falcon@freecalypso.org>
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165 * g0 = sqrt(gain_in/gain_out); *
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166 *---------------------------------------------------*/
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parents:
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167
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Mychaela Falconia <falcon@freecalypso.org>
parents:
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168 s = L_deposit_l (div_s (gain_out, gain_in));
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parents:
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169 s = L_shl (s, 7); /* s = gain_out / gain_in */
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Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
170 s = L_shr (s, exp); /* add exponent */
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Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
171
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
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172 s = Inv_sqrt (s);
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
173 g0 = round (L_shl (s, 9));
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
174 }
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
175
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
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176 /* sig_out(n) = gain(n) sig_out(n) */
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
177
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
178 for (i = 0; i < l_trm; i++)
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
179 {
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
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180 sig_out[i] = extract_h (L_shl (L_mult (sig_out[i], g0), 3));
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
181 move16 ();
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
182 }
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
183
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
184 return;
49dd1ac8e75b libgsmefr: import most *.c files from ETSI source
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
185 }