FreeCalypso > hg > gsm-codec-lib
annotate libgsmefr/oper_32b.c @ 183:452c1d5a6268
libgsmefr BFI w/o data: emit zero output after decoder reset
In real-life usage, each EFR decoder session will most likely begin
with lots of BFI frames before the first real frame arrives. However,
because the spec-defined home state of the decoder is speech rather
than CN, our regular logic for BFI w/o data would have to feed
pseudorandom noise to the decoder (in the "fixed codebook excitation
pulses" part), which is silly to do at the beginning of the decoder
session right out of reset. Therefore, let's check reset_flag_old,
and if we are still in the reset state, simply emit zero output.
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Tue, 03 Jan 2023 00:12:18 +0000 |
parents | 92479d9a8e38 |
children | 3da7ab45910d |
rev | line source |
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1 /***************************************************************************** |
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2 * * |
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3 * This file contains operations in double precision. * |
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4 * These operations are not standard double precision operations. * |
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5 * They are used where single precision is not enough but the full 32 bits * |
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6 * precision is not necessary. For example, the function Div_32() has a * |
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7 * 24 bits precision which is enough for our purposes. * |
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8 * * |
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9 * The double precision numbers use a special representation: * |
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10 * * |
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11 * L_32 = hi<<16 + lo<<1 * |
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12 * * |
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13 * L_32 is a 32 bit integer. * |
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14 * hi and lo are 16 bit signed integers. * |
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15 * As the low part also contains the sign, this allows fast multiplication. * |
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16 * * |
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17 * 0x8000 0000 <= L_32 <= 0x7fff fffe. * |
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18 * * |
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19 * We will use DPF (Double Precision Format )in this file to specify * |
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20 * this special format. * |
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21 ***************************************************************************** |
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22 */ |
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23 |
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24 #include "gsm_efr.h" |
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25 #include "typedef.h" |
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26 #include "namespace.h" |
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27 #include "basic_op.h" |
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28 #include "oper_32b.h" |
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29 #include "no_count.h" |
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30 |
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31 /***************************************************************************** |
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32 * * |
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33 * Function L_Extract() * |
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34 * * |
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35 * Extract from a 32 bit integer two 16 bit DPF. * |
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36 * * |
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37 * Arguments: * |
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38 * * |
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39 * L_32 : 32 bit integer. * |
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40 * 0x8000 0000 <= L_32 <= 0x7fff ffff. * |
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41 * hi : b16 to b31 of L_32 * |
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42 * lo : (L_32 - hi<<16)>>1 * |
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43 ***************************************************************************** |
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44 */ |
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45 |
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46 void L_Extract (Word32 L_32, Word16 *hi, Word16 *lo) |
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47 { |
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48 *hi = extract_h (L_32); |
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49 *lo = extract_l (L_msu (L_shr (L_32, 1), *hi, 16384)); |
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50 return; |
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51 } |
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52 |
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53 /***************************************************************************** |
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54 * * |
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55 * Function L_Comp() * |
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56 * * |
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57 * Compose from two 16 bit DPF a 32 bit integer. * |
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58 * * |
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59 * L_32 = hi<<16 + lo<<1 * |
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60 * * |
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61 * Arguments: * |
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62 * * |
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63 * hi msb * |
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64 * lo lsf (with sign) * |
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65 * * |
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66 * Return Value : * |
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67 * * |
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68 * 32 bit long signed integer (Word32) whose value falls in the * |
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69 * range : 0x8000 0000 <= L_32 <= 0x7fff fff0. * |
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70 * * |
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71 ***************************************************************************** |
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72 */ |
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73 |
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74 Word32 L_Comp (Word16 hi, Word16 lo) |
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75 { |
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76 Word32 L_32; |
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77 |
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78 L_32 = L_deposit_h (hi); |
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79 return (L_mac (L_32, lo, 1)); /* = hi<<16 + lo<<1 */ |
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80 } |
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81 |
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82 /***************************************************************************** |
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83 * Function Mpy_32() * |
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84 * * |
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85 * Multiply two 32 bit integers (DPF). The result is divided by 2**31 * |
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86 * * |
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87 * L_32 = (hi1*hi2)<<1 + ( (hi1*lo2)>>15 + (lo1*hi2)>>15 )<<1 * |
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88 * * |
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89 * This operation can also be viewed as the multiplication of two Q31 * |
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90 * number and the result is also in Q31. * |
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91 * * |
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92 * Arguments: * |
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93 * * |
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94 * hi1 hi part of first number * |
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95 * lo1 lo part of first number * |
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96 * hi2 hi part of second number * |
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97 * lo2 lo part of second number * |
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98 * * |
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99 ***************************************************************************** |
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100 */ |
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101 |
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102 Word32 Mpy_32 (Word16 hi1, Word16 lo1, Word16 hi2, Word16 lo2) |
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103 { |
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104 Word32 L_32; |
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105 |
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106 L_32 = L_mult (hi1, hi2); |
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107 L_32 = L_mac (L_32, mult (hi1, lo2), 1); |
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108 L_32 = L_mac (L_32, mult (lo1, hi2), 1); |
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109 |
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110 return (L_32); |
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111 } |
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112 |
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113 /***************************************************************************** |
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114 * Function Mpy_32_16() * |
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115 * * |
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116 * Multiply a 16 bit integer by a 32 bit (DPF). The result is divided * |
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117 * by 2**15 * |
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118 * * |
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119 * * |
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120 * L_32 = (hi1*lo2)<<1 + ((lo1*lo2)>>15)<<1 * |
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121 * * |
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122 * Arguments: * |
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123 * * |
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124 * hi hi part of 32 bit number. * |
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125 * lo lo part of 32 bit number. * |
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126 * n 16 bit number. * |
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127 * * |
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128 ***************************************************************************** |
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129 */ |
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130 |
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131 Word32 Mpy_32_16 (Word16 hi, Word16 lo, Word16 n) |
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132 { |
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133 Word32 L_32; |
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134 |
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135 L_32 = L_mult (hi, n); |
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136 L_32 = L_mac (L_32, mult (lo, n), 1); |
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137 |
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138 return (L_32); |
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139 } |
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140 |
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141 /***************************************************************************** |
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142 * * |
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143 * Function Name : Div_32 * |
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144 * * |
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145 * Purpose : * |
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146 * Fractional integer division of two 32 bit numbers. * |
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147 * L_num / L_denom. * |
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148 * L_num and L_denom must be positive and L_num < L_denom. * |
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149 * L_denom = denom_hi<<16 + denom_lo<<1 * |
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150 * denom_hi is a normalize number. * |
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151 * * |
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152 * Inputs : * |
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153 * * |
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154 * L_num * |
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155 * 32 bit long signed integer (Word32) whose value falls in the * |
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156 * range : 0x0000 0000 < L_num < L_denom * |
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157 * * |
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158 * L_denom = denom_hi<<16 + denom_lo<<1 (DPF) * |
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159 * * |
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160 * denom_hi * |
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161 * 16 bit positive normalized integer whose value falls in the * |
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162 * range : 0x4000 < hi < 0x7fff * |
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163 * denom_lo * |
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164 * 16 bit positive integer whose value falls in the * |
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165 * range : 0 < lo < 0x7fff * |
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166 * * |
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167 * Return Value : * |
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168 * * |
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169 * L_div * |
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170 * 32 bit long signed integer (Word32) whose value falls in the * |
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171 * range : 0x0000 0000 <= L_div <= 0x7fff ffff. * |
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172 * * |
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173 * Algorithm: * |
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174 * * |
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175 * - find = 1/L_denom. * |
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176 * First approximation: approx = 1 / denom_hi * |
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177 * 1/L_denom = approx * (2.0 - L_denom * approx ) * |
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178 * * |
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179 * - result = L_num * (1/L_denom) * |
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180 ***************************************************************************** |
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181 */ |
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182 |
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183 Word32 Div_32 (Word32 L_num, Word16 denom_hi, Word16 denom_lo) |
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184 { |
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185 Word16 approx, hi, lo, n_hi, n_lo; |
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186 Word32 L_32; |
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187 |
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188 /* First approximation: 1 / L_denom = 1/denom_hi */ |
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189 |
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190 approx = div_s ((Word16) 0x3fff, denom_hi); |
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191 |
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192 /* 1/L_denom = approx * (2.0 - L_denom * approx) */ |
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193 |
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194 L_32 = Mpy_32_16 (denom_hi, denom_lo, approx); |
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195 |
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196 L_32 = L_sub ((Word32) 0x7fffffffL, L_32); |
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197 |
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198 L_Extract (L_32, &hi, &lo); |
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199 |
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200 L_32 = Mpy_32_16 (hi, lo, approx); |
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201 |
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202 /* L_num * (1/L_denom) */ |
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203 |
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204 L_Extract (L_32, &hi, &lo); |
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205 L_Extract (L_num, &n_hi, &n_lo); |
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206 L_32 = Mpy_32 (n_hi, n_lo, hi, lo); |
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207 L_32 = L_shl (L_32, 2); |
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208 |
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209 return (L_32); |
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210 } |