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1 /* Copyright (C) 2007, 2009 Free Software Foundation, Inc.
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2
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3 This file is part of GCC.
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4
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5 GCC is free software; you can redistribute it and/or modify it under
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6 the terms of the GNU General Public License as published by the Free
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7 Software Foundation; either version 3, or (at your option) any later
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8 version.
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9
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10 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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11 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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12 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 for more details.
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14
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15 Under Section 7 of GPL version 3, you are granted additional
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16 permissions described in the GCC Runtime Library Exception, version
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17 3.1, as published by the Free Software Foundation.
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18
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19 You should have received a copy of the GNU General Public License and
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20 a copy of the GCC Runtime Library Exception along with this program;
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21 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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22 <http://www.gnu.org/licenses/>. */
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23
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24 #define BID_128RES
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25 #include "bid_internal.h"
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26
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27 BID128_FUNCTION_ARG2 (bid128_quantize, x, y)
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28
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29 UINT256 CT;
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30 UINT128 CX, CY, T, CX2, CR, Stemp, res, REM_H, C2N;
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31 UINT64 sign_x, sign_y, remainder_h, carry, CY64, valid_x;
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32 int_float tempx;
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33 int exponent_x, exponent_y, digits_x, extra_digits, amount;
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34 int expon_diff, total_digits, bin_expon_cx, rmode, status;
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35
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36 valid_x = unpack_BID128_value (&sign_x, &exponent_x, &CX, x);
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37
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38 // unpack arguments, check for NaN or Infinity
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39 if (!unpack_BID128_value (&sign_y, &exponent_y, &CY, y)) {
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40 // y is Inf. or NaN
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41 #ifdef SET_STATUS_FLAGS
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42 if ((x.w[1] & SNAN_MASK64) == SNAN_MASK64) // y is sNaN
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43 __set_status_flags (pfpsf, INVALID_EXCEPTION);
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44 #endif
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45
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46 // test if y is NaN
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47 if ((y.w[1] & 0x7c00000000000000ull) == 0x7c00000000000000ull) {
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48 #ifdef SET_STATUS_FLAGS
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49 if ((y.w[1] & 0x7e00000000000000ull) == 0x7e00000000000000ull) {
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50 // set status flags
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51 __set_status_flags (pfpsf, INVALID_EXCEPTION);
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52 }
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53 #endif
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54 if ((x.w[1] & 0x7c00000000000000ull) != 0x7c00000000000000ull) {
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55 res.w[1] = CY.w[1] & QUIET_MASK64;
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56 res.w[0] = CY.w[0];
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57 } else {
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58 res.w[1] = CX.w[1] & QUIET_MASK64;
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59 res.w[0] = CX.w[0];
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60 }
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61 BID_RETURN (res);
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62 }
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63 // y is Infinity?
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64 if ((y.w[1] & 0x7800000000000000ull) == 0x7800000000000000ull) {
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65 // check if x is not Inf.
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66 if (((x.w[1] & 0x7c00000000000000ull) < 0x7800000000000000ull)) {
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67 // return NaN
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68 #ifdef SET_STATUS_FLAGS
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69 // set status flags
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70 __set_status_flags (pfpsf, INVALID_EXCEPTION);
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71 #endif
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72 res.w[1] = 0x7c00000000000000ull;
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73 res.w[0] = 0;
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74 BID_RETURN (res);
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75 } else
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76 if (((x.w[1] & 0x7c00000000000000ull) <= 0x7800000000000000ull)) {
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77 res.w[1] = CX.w[1] & QUIET_MASK64;
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78 res.w[0] = CX.w[0];
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79 BID_RETURN (res);
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80 }
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81 }
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82
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83 }
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84
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85 if (!valid_x) {
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86 // test if x is NaN or Inf
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87 if ((x.w[1] & 0x7c00000000000000ull) == 0x7800000000000000ull) {
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88 #ifdef SET_STATUS_FLAGS
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89 // set status flags
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90 __set_status_flags (pfpsf, INVALID_EXCEPTION);
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91 #endif
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92 res.w[1] = 0x7c00000000000000ull;
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93 res.w[0] = 0;
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94 BID_RETURN (res);
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95 } else if ((x.w[1] & 0x7c00000000000000ull) == 0x7c00000000000000ull) {
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96 if ((x.w[1] & 0x7e00000000000000ull) == 0x7e00000000000000ull) {
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97 #ifdef SET_STATUS_FLAGS
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98 // set status flags
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99 __set_status_flags (pfpsf, INVALID_EXCEPTION);
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100 #endif
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101 }
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102 res.w[1] = CX.w[1] & QUIET_MASK64;
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103 res.w[0] = CX.w[0];
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104 BID_RETURN (res);
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105 }
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106 if (!CX.w[1] && !CX.w[0]) {
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107 get_BID128_very_fast (&res, sign_x, exponent_y, CX);
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108 BID_RETURN (res);
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109 }
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110 }
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111 // get number of decimal digits in coefficient_x
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112 if (CX.w[1]) {
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113 tempx.d = (float) CX.w[1];
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114 bin_expon_cx = ((tempx.i >> 23) & 0xff) - 0x7f + 64;
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115 } else {
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116 tempx.d = (float) CX.w[0];
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117 bin_expon_cx = ((tempx.i >> 23) & 0xff) - 0x7f;
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118 }
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119
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120 digits_x = estimate_decimal_digits[bin_expon_cx];
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121 if (CX.w[1] > power10_table_128[digits_x].w[1]
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122 || (CX.w[1] == power10_table_128[digits_x].w[1]
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123 && CX.w[0] >= power10_table_128[digits_x].w[0]))
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124 digits_x++;
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125
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126 expon_diff = exponent_x - exponent_y;
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127 total_digits = digits_x + expon_diff;
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128
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129 if ((UINT32) total_digits <= 34) {
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130 if (expon_diff >= 0) {
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131 T = power10_table_128[expon_diff];
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132 __mul_128x128_low (CX2, T, CX);
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133 get_BID128_very_fast (&res, sign_x, exponent_y, CX2);
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134 BID_RETURN (res);
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135 }
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136 #ifndef IEEE_ROUND_NEAREST_TIES_AWAY
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137 #ifndef IEEE_ROUND_NEAREST
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138 rmode = rnd_mode;
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139 if (sign_x && (unsigned) (rmode - 1) < 2)
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140 rmode = 3 - rmode;
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141 #else
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142 rmode = 0;
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143 #endif
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144 #else
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145 rmode = 0;
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146 #endif
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147 // must round off -expon_diff digits
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148 extra_digits = -expon_diff;
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149 __add_128_128 (CX, CX, round_const_table_128[rmode][extra_digits]);
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150
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151 // get P*(2^M[extra_digits])/10^extra_digits
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152 __mul_128x128_to_256 (CT, CX, reciprocals10_128[extra_digits]);
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153
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154 // now get P/10^extra_digits: shift C64 right by M[extra_digits]-128
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155 amount = recip_scale[extra_digits];
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156 CX2.w[0] = CT.w[2];
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157 CX2.w[1] = CT.w[3];
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158 if (amount >= 64) {
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159 CR.w[1] = 0;
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160 CR.w[0] = CX2.w[1] >> (amount - 64);
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161 } else {
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162 __shr_128 (CR, CX2, amount);
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163 }
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164
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165 #ifndef IEEE_ROUND_NEAREST_TIES_AWAY
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166 #ifndef IEEE_ROUND_NEAREST
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167 if (rnd_mode == 0)
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168 #endif
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169 if (CR.w[0] & 1) {
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170 // check whether fractional part of initial_P/10^extra_digits is
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171 // exactly .5 this is the same as fractional part of
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172 // (initial_P + 0.5*10^extra_digits)/10^extra_digits is exactly zero
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173
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174 // get remainder
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175 if (amount >= 64) {
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176 remainder_h = CX2.w[0] | (CX2.w[1] << (128 - amount));
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177 } else
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178 remainder_h = CX2.w[0] << (64 - amount);
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179
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180 // test whether fractional part is 0
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181 if (!remainder_h
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182 && (CT.w[1] < reciprocals10_128[extra_digits].w[1]
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183 || (CT.w[1] == reciprocals10_128[extra_digits].w[1]
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184 && CT.w[0] < reciprocals10_128[extra_digits].w[0]))) {
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185 CR.w[0]--;
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186 }
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187 }
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188 #endif
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189
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190 #ifdef SET_STATUS_FLAGS
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191 status = INEXACT_EXCEPTION;
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192
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193 // get remainder
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194 if (amount >= 64) {
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195 REM_H.w[1] = (CX2.w[1] << (128 - amount));
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196 REM_H.w[0] = CX2.w[0];
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197 } else {
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198 REM_H.w[1] = CX2.w[0] << (64 - amount);
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199 REM_H.w[0] = 0;
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200 }
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201
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202 switch (rmode) {
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203 case ROUNDING_TO_NEAREST:
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204 case ROUNDING_TIES_AWAY:
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205 // test whether fractional part is 0
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206 if (REM_H.w[1] == 0x8000000000000000ull && !REM_H.w[0]
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207 && (CT.w[1] < reciprocals10_128[extra_digits].w[1]
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208 || (CT.w[1] == reciprocals10_128[extra_digits].w[1]
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209 && CT.w[0] < reciprocals10_128[extra_digits].w[0])))
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210 status = EXACT_STATUS;
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211 break;
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212 case ROUNDING_DOWN:
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213 case ROUNDING_TO_ZERO:
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214 if (!(REM_H.w[1] | REM_H.w[0])
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215 && (CT.w[1] < reciprocals10_128[extra_digits].w[1]
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216 || (CT.w[1] == reciprocals10_128[extra_digits].w[1]
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217 && CT.w[0] < reciprocals10_128[extra_digits].w[0])))
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218 status = EXACT_STATUS;
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219 break;
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220 default:
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221 // round up
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222 __add_carry_out (Stemp.w[0], CY64, CT.w[0],
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223 reciprocals10_128[extra_digits].w[0]);
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224 __add_carry_in_out (Stemp.w[1], carry, CT.w[1],
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225 reciprocals10_128[extra_digits].w[1], CY64);
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226 if (amount < 64) {
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227 C2N.w[1] = 0;
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228 C2N.w[0] = ((UINT64) 1) << amount;
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229 REM_H.w[0] = REM_H.w[1] >> (64 - amount);
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230 REM_H.w[1] = 0;
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231 } else {
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232 C2N.w[1] = ((UINT64) 1) << (amount - 64);
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233 C2N.w[0] = 0;
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234 REM_H.w[1] >>= (128 - amount);
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235 }
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236 REM_H.w[0] += carry;
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237 if (REM_H.w[0] < carry)
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238 REM_H.w[1]++;
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239 if (__unsigned_compare_ge_128 (REM_H, C2N))
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240 status = EXACT_STATUS;
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241 }
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242
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243 __set_status_flags (pfpsf, status);
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244
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245 #endif
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246 get_BID128_very_fast (&res, sign_x, exponent_y, CR);
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247 BID_RETURN (res);
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248 }
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249 if (total_digits < 0) {
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250 CR.w[1] = CR.w[0] = 0;
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251 #ifndef IEEE_ROUND_NEAREST_TIES_AWAY
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252 #ifndef IEEE_ROUND_NEAREST
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253 rmode = rnd_mode;
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254 if (sign_x && (unsigned) (rmode - 1) < 2)
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255 rmode = 3 - rmode;
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256 if (rmode == ROUNDING_UP)
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257 CR.w[0] = 1;
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258 #endif
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259 #endif
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260 #ifdef SET_STATUS_FLAGS
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261 __set_status_flags (pfpsf, INEXACT_EXCEPTION);
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262 #endif
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263 get_BID128_very_fast (&res, sign_x, exponent_y, CR);
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264 BID_RETURN (res);
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265 }
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266 // else more than 34 digits in coefficient
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267 #ifdef SET_STATUS_FLAGS
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268 __set_status_flags (pfpsf, INVALID_EXCEPTION);
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269 #endif
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270 res.w[1] = 0x7c00000000000000ull;
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271 res.w[0] = 0;
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272 BID_RETURN (res);
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273
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274 }
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