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4349 | Serge | 1 | /**************************************************************** |
2 | * |
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3 | * The author of this software is David M. Gay. |
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4 | * |
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5 | * Copyright (c) 1991 by AT&T. |
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6 | * |
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7 | * Permission to use, copy, modify, and distribute this software for any |
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8 | * purpose without fee is hereby granted, provided that this entire notice |
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9 | * is included in all copies of any software which is or includes a copy |
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10 | * or modification of this software and in all copies of the supporting |
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11 | * documentation for such software. |
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12 | * |
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13 | * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED |
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14 | * WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY |
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15 | * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY |
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16 | * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. |
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17 | * |
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18 | ***************************************************************/ |
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19 | |||
20 | /* Please send bug reports to |
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21 | David M. Gay |
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22 | AT&T Bell Laboratories, Room 2C-463 |
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23 | 600 Mountain Avenue |
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24 | Murray Hill, NJ 07974-2070 |
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25 | U.S.A. |
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26 | dmg@research.att.com or research!dmg |
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27 | */ |
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28 | |||
29 | #include <_ansi.h> |
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30 | #include |
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31 | #include |
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32 | #include |
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33 | #include "mprec.h" |
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34 | |||
35 | static int |
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36 | _DEFUN (quorem, |
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37 | (b, S), |
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38 | _Bigint * b _AND _Bigint * S) |
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39 | { |
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40 | int n; |
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41 | __Long borrow, y; |
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42 | __ULong carry, q, ys; |
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43 | __ULong *bx, *bxe, *sx, *sxe; |
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44 | #ifdef Pack_32 |
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45 | __Long z; |
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46 | __ULong si, zs; |
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47 | #endif |
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48 | |||
49 | n = S->_wds; |
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50 | #ifdef DEBUG |
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51 | /*debug*/ if (b->_wds > n) |
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52 | /*debug*/ Bug ("oversize b in quorem"); |
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53 | #endif |
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54 | if (b->_wds < n) |
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55 | return 0; |
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56 | sx = S->_x; |
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57 | sxe = sx + --n; |
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58 | bx = b->_x; |
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59 | bxe = bx + n; |
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60 | q = *bxe / (*sxe + 1); /* ensure q <= true quotient */ |
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61 | #ifdef DEBUG |
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62 | /*debug*/ if (q > 9) |
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63 | /*debug*/ Bug ("oversized quotient in quorem"); |
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64 | #endif |
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65 | if (q) |
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66 | { |
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67 | borrow = 0; |
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68 | carry = 0; |
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69 | do |
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70 | { |
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71 | #ifdef Pack_32 |
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72 | si = *sx++; |
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73 | ys = (si & 0xffff) * q + carry; |
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74 | zs = (si >> 16) * q + (ys >> 16); |
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75 | carry = zs >> 16; |
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76 | y = (*bx & 0xffff) - (ys & 0xffff) + borrow; |
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77 | borrow = y >> 16; |
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78 | Sign_Extend (borrow, y); |
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79 | z = (*bx >> 16) - (zs & 0xffff) + borrow; |
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80 | borrow = z >> 16; |
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81 | Sign_Extend (borrow, z); |
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82 | Storeinc (bx, z, y); |
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83 | #else |
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84 | ys = *sx++ * q + carry; |
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85 | carry = ys >> 16; |
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86 | y = *bx - (ys & 0xffff) + borrow; |
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87 | borrow = y >> 16; |
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88 | Sign_Extend (borrow, y); |
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89 | *bx++ = y & 0xffff; |
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90 | #endif |
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91 | } |
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92 | while (sx <= sxe); |
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93 | if (!*bxe) |
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94 | { |
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95 | bx = b->_x; |
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96 | while (--bxe > bx && !*bxe) |
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97 | --n; |
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98 | b->_wds = n; |
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99 | } |
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100 | } |
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101 | if (cmp (b, S) >= 0) |
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102 | { |
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103 | q++; |
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104 | borrow = 0; |
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105 | carry = 0; |
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106 | bx = b->_x; |
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107 | sx = S->_x; |
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108 | do |
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109 | { |
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110 | #ifdef Pack_32 |
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111 | si = *sx++; |
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112 | ys = (si & 0xffff) + carry; |
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113 | zs = (si >> 16) + (ys >> 16); |
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114 | carry = zs >> 16; |
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115 | y = (*bx & 0xffff) - (ys & 0xffff) + borrow; |
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116 | borrow = y >> 16; |
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117 | Sign_Extend (borrow, y); |
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118 | z = (*bx >> 16) - (zs & 0xffff) + borrow; |
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119 | borrow = z >> 16; |
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120 | Sign_Extend (borrow, z); |
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121 | Storeinc (bx, z, y); |
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122 | #else |
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123 | ys = *sx++ + carry; |
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124 | carry = ys >> 16; |
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125 | y = *bx - (ys & 0xffff) + borrow; |
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126 | borrow = y >> 16; |
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127 | Sign_Extend (borrow, y); |
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128 | *bx++ = y & 0xffff; |
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129 | #endif |
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130 | } |
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131 | while (sx <= sxe); |
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132 | bx = b->_x; |
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133 | bxe = bx + n; |
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134 | if (!*bxe) |
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135 | { |
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136 | while (--bxe > bx && !*bxe) |
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137 | --n; |
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138 | b->_wds = n; |
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139 | } |
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140 | } |
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141 | return q; |
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142 | } |
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143 | |||
144 | /* dtoa for IEEE arithmetic (dmg): convert double to ASCII string. |
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145 | * |
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146 | * Inspired by "How to Print Floating-Point Numbers Accurately" by |
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147 | * Guy L. Steele, Jr. and Jon L. White [Proc. ACM SIGPLAN '90, pp. 92-101]. |
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148 | * |
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149 | * Modifications: |
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150 | * 1. Rather than iterating, we use a simple numeric overestimate |
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151 | * to determine k = floor(log10(d)). We scale relevant |
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152 | * quantities using O(log2(k)) rather than O(k) multiplications. |
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153 | * 2. For some modes > 2 (corresponding to ecvt and fcvt), we don't |
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154 | * try to generate digits strictly left to right. Instead, we |
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155 | * compute with fewer bits and propagate the carry if necessary |
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156 | * when rounding the final digit up. This is often faster. |
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157 | * 3. Under the assumption that input will be rounded nearest, |
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158 | * mode 0 renders 1e23 as 1e23 rather than 9.999999999999999e22. |
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159 | * That is, we allow equality in stopping tests when the |
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160 | * round-nearest rule will give the same floating-point value |
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161 | * as would satisfaction of the stopping test with strict |
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162 | * inequality. |
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163 | * 4. We remove common factors of powers of 2 from relevant |
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164 | * quantities. |
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165 | * 5. When converting floating-point integers less than 1e16, |
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166 | * we use floating-point arithmetic rather than resorting |
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167 | * to multiple-precision integers. |
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168 | * 6. When asked to produce fewer than 15 digits, we first try |
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169 | * to get by with floating-point arithmetic; we resort to |
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170 | * multiple-precision integer arithmetic only if we cannot |
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171 | * guarantee that the floating-point calculation has given |
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172 | * the correctly rounded result. For k requested digits and |
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173 | * "uniformly" distributed input, the probability is |
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174 | * something like 10^(k-15) that we must resort to the long |
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175 | * calculation. |
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176 | */ |
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177 | |||
178 | |||
179 | char * |
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180 | _DEFUN (_dtoa_r, |
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181 | (ptr, _d, mode, ndigits, decpt, sign, rve), |
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182 | struct _reent *ptr _AND |
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183 | double _d _AND |
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184 | int mode _AND |
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185 | int ndigits _AND |
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186 | int *decpt _AND |
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187 | int *sign _AND |
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188 | char **rve) |
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189 | { |
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190 | /* Arguments ndigits, decpt, sign are similar to those |
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191 | of ecvt and fcvt; trailing zeros are suppressed from |
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192 | the returned string. If not null, *rve is set to point |
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193 | to the end of the return value. If d is +-Infinity or NaN, |
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194 | then *decpt is set to 9999. |
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195 | |||
196 | mode: |
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197 | |||
198 | and rounded to nearest. |
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199 | 1 ==> like 0, but with Steele & White stopping rule; |
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200 | e.g. with IEEE P754 arithmetic , mode 0 gives |
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201 | 1e23 whereas mode 1 gives 9.999999999999999e22. |
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202 | 2 ==> max(1,ndigits) significant digits. This gives a |
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203 | return value similar to that of ecvt, except |
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204 | that trailing zeros are suppressed. |
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205 | 3 ==> through ndigits past the decimal point. This |
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206 | gives a return value similar to that from fcvt, |
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207 | except that trailing zeros are suppressed, and |
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208 | ndigits can be negative. |
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209 | 4-9 should give the same return values as 2-3, i.e., |
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210 | 4 <= mode <= 9 ==> same return as mode |
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211 | 2 + (mode & 1). These modes are mainly for |
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212 | debugging; often they run slower but sometimes |
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213 | faster than modes 2-3. |
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214 | 4,5,8,9 ==> left-to-right digit generation. |
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215 | 6-9 ==> don't try fast floating-point estimate |
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216 | (if applicable). |
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217 | |||
218 | Values of mode other than 0-9 are treated as mode 0. |
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219 | |||
220 | Sufficient space is allocated to the return value |
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221 | to hold the suppressed trailing zeros. |
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222 | */ |
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223 | |||
224 | int bbits, b2, b5, be, dig, i, ieps, ilim, ilim0, ilim1, j, j1, k, k0, |
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225 | k_check, leftright, m2, m5, s2, s5, spec_case, try_quick; |
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226 | union double_union d, d2, eps; |
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227 | __Long L; |
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228 | #ifndef Sudden_Underflow |
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229 | int denorm; |
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230 | __ULong x; |
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231 | #endif |
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232 | _Bigint *b, *b1, *delta, *mlo = NULL, *mhi, *S; |
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233 | double ds; |
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234 | char *s, *s0; |
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235 | |||
236 | d.d = _d; |
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237 | |||
238 | _REENT_CHECK_MP(ptr); |
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239 | if (_REENT_MP_RESULT(ptr)) |
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240 | { |
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241 | _REENT_MP_RESULT(ptr)->_k = _REENT_MP_RESULT_K(ptr); |
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242 | _REENT_MP_RESULT(ptr)->_maxwds = 1 << _REENT_MP_RESULT_K(ptr); |
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243 | Bfree (ptr, _REENT_MP_RESULT(ptr)); |
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244 | _REENT_MP_RESULT(ptr) = 0; |
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245 | } |
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246 | |||
247 | if (word0 (d) & Sign_bit) |
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248 | { |
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249 | /* set sign for everything, including 0's and NaNs */ |
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250 | *sign = 1; |
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251 | word0 (d) &= ~Sign_bit; /* clear sign bit */ |
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252 | } |
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253 | else |
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254 | *sign = 0; |
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255 | |||
256 | #if defined(IEEE_Arith) + defined(VAX) |
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257 | #ifdef IEEE_Arith |
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258 | if ((word0 (d) & Exp_mask) == Exp_mask) |
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259 | #else |
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260 | if (word0 (d) == 0x8000) |
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261 | #endif |
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262 | { |
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263 | /* Infinity or NaN */ |
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264 | *decpt = 9999; |
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265 | s = |
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266 | #ifdef IEEE_Arith |
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267 | !word1 (d) && !(word0 (d) & 0xfffff) ? "Infinity" : |
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268 | #endif |
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269 | "NaN"; |
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270 | if (rve) |
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271 | *rve = |
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272 | #ifdef IEEE_Arith |
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273 | s[3] ? s + 8 : |
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274 | #endif |
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275 | s + 3; |
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276 | return s; |
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277 | } |
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278 | #endif |
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279 | #ifdef IBM |
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280 | d.d += 0; /* normalize */ |
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281 | #endif |
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282 | if (!d.d) |
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283 | { |
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284 | *decpt = 1; |
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285 | s = "0"; |
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286 | if (rve) |
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287 | *rve = s + 1; |
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288 | return s; |
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289 | } |
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290 | |||
291 | b = d2b (ptr, d.d, &be, &bbits); |
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292 | #ifdef Sudden_Underflow |
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293 | i = (int) (word0 (d) >> Exp_shift1 & (Exp_mask >> Exp_shift1)); |
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294 | #else |
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295 | if ((i = (int) (word0 (d) >> Exp_shift1 & (Exp_mask >> Exp_shift1))) != 0) |
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296 | { |
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297 | #endif |
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298 | d2.d = d.d; |
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299 | word0 (d2) &= Frac_mask1; |
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300 | word0 (d2) |= Exp_11; |
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301 | #ifdef IBM |
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302 | if (j = 11 - hi0bits (word0 (d2) & Frac_mask)) |
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303 | d2.d /= 1 << j; |
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304 | #endif |
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305 | |||
306 | /* log(x) ~=~ log(1.5) + (x-1.5)/1.5 |
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307 | * log10(x) = log(x) / log(10) |
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308 | * ~=~ log(1.5)/log(10) + (x-1.5)/(1.5*log(10)) |
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309 | * log10(d) = (i-Bias)*log(2)/log(10) + log10(d2) |
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310 | * |
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311 | * This suggests computing an approximation k to log10(d) by |
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312 | * |
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313 | * k = (i - Bias)*0.301029995663981 |
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314 | * + ( (d2-1.5)*0.289529654602168 + 0.176091259055681 ); |
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315 | * |
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316 | * We want k to be too large rather than too small. |
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317 | * The error in the first-order Taylor series approximation |
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318 | * is in our favor, so we just round up the constant enough |
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319 | * to compensate for any error in the multiplication of |
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320 | * (i - Bias) by 0.301029995663981; since |i - Bias| <= 1077, |
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321 | * and 1077 * 0.30103 * 2^-52 ~=~ 7.2e-14, |
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322 | * adding 1e-13 to the constant term more than suffices. |
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323 | * Hence we adjust the constant term to 0.1760912590558. |
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324 | * (We could get a more accurate k by invoking log10, |
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325 | * but this is probably not worthwhile.) |
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326 | */ |
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327 | |||
328 | i -= Bias; |
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329 | #ifdef IBM |
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330 | i <<= 2; |
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331 | i += j; |
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332 | #endif |
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333 | #ifndef Sudden_Underflow |
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334 | denorm = 0; |
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335 | } |
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336 | else |
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337 | { |
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338 | /* d is denormalized */ |
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339 | |||
340 | i = bbits + be + (Bias + (P - 1) - 1); |
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341 | #if defined (_DOUBLE_IS_32BITS) |
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342 | x = word0 (d) << (32 - i); |
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343 | #else |
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344 | x = (i > 32) ? (word0 (d) << (64 - i)) | (word1 (d) >> (i - 32)) |
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345 | : (word1 (d) << (32 - i)); |
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346 | #endif |
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347 | d2.d = x; |
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348 | word0 (d2) -= 31 * Exp_msk1; /* adjust exponent */ |
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349 | i -= (Bias + (P - 1) - 1) + 1; |
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350 | denorm = 1; |
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351 | } |
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352 | #endif |
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353 | #if defined (_DOUBLE_IS_32BITS) |
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354 | ds = (d2.d - 1.5) * 0.289529651 + 0.176091269 + i * 0.30103001; |
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355 | #else |
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356 | ds = (d2.d - 1.5) * 0.289529654602168 + 0.1760912590558 + i * 0.301029995663981; |
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357 | #endif |
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358 | k = (int) ds; |
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359 | if (ds < 0. && ds != k) |
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360 | k--; /* want k = floor(ds) */ |
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361 | k_check = 1; |
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362 | if (k >= 0 && k <= Ten_pmax) |
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363 | { |
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364 | if (d.d < tens[k]) |
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365 | k--; |
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366 | k_check = 0; |
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367 | } |
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368 | j = bbits - i - 1; |
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369 | if (j >= 0) |
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370 | { |
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371 | b2 = 0; |
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372 | s2 = j; |
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373 | } |
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374 | else |
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375 | { |
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376 | b2 = -j; |
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377 | s2 = 0; |
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378 | } |
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379 | if (k >= 0) |
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380 | { |
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381 | b5 = 0; |
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382 | s5 = k; |
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383 | s2 += k; |
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384 | } |
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385 | else |
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386 | { |
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387 | b2 -= k; |
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388 | b5 = -k; |
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389 | s5 = 0; |
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390 | } |
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391 | if (mode < 0 || mode > 9) |
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392 | mode = 0; |
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393 | try_quick = 1; |
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394 | if (mode > 5) |
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395 | { |
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396 | mode -= 4; |
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397 | try_quick = 0; |
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398 | } |
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399 | leftright = 1; |
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400 | ilim = ilim1 = -1; |
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401 | switch (mode) |
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402 | { |
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403 | case 0: |
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404 | case 1: |
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405 | i = 18; |
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406 | ndigits = 0; |
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407 | break; |
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408 | case 2: |
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409 | leftright = 0; |
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410 | /* no break */ |
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411 | case 4: |
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412 | if (ndigits <= 0) |
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413 | ndigits = 1; |
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414 | ilim = ilim1 = i = ndigits; |
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415 | break; |
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416 | case 3: |
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417 | leftright = 0; |
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418 | /* no break */ |
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419 | case 5: |
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420 | i = ndigits + k + 1; |
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421 | ilim = i; |
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422 | ilim1 = i - 1; |
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423 | if (i <= 0) |
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424 | i = 1; |
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425 | } |
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426 | j = sizeof (__ULong); |
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427 | for (_REENT_MP_RESULT_K(ptr) = 0; sizeof (_Bigint) - sizeof (__ULong) + j <= i; |
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428 | j <<= 1) |
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429 | _REENT_MP_RESULT_K(ptr)++; |
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430 | _REENT_MP_RESULT(ptr) = Balloc (ptr, _REENT_MP_RESULT_K(ptr)); |
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431 | s = s0 = (char *) _REENT_MP_RESULT(ptr); |
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432 | |||
433 | if (ilim >= 0 && ilim <= Quick_max && try_quick) |
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434 | { |
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435 | /* Try to get by with floating-point arithmetic. */ |
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436 | |||
437 | i = 0; |
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438 | d2.d = d.d; |
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439 | k0 = k; |
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440 | ilim0 = ilim; |
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441 | ieps = 2; /* conservative */ |
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442 | if (k > 0) |
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443 | { |
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444 | ds = tens[k & 0xf]; |
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445 | j = k >> 4; |
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446 | if (j & Bletch) |
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447 | { |
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448 | /* prevent overflows */ |
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449 | j &= Bletch - 1; |
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450 | d.d /= bigtens[n_bigtens - 1]; |
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451 | ieps++; |
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452 | } |
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453 | for (; j; j >>= 1, i++) |
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454 | if (j & 1) |
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455 | { |
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456 | ieps++; |
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457 | ds *= bigtens[i]; |
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458 | } |
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459 | d.d /= ds; |
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460 | } |
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461 | else if ((j1 = -k) != 0) |
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462 | { |
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463 | d.d *= tens[j1 & 0xf]; |
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464 | for (j = j1 >> 4; j; j >>= 1, i++) |
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465 | if (j & 1) |
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466 | { |
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467 | ieps++; |
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468 | d.d *= bigtens[i]; |
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469 | } |
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470 | } |
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471 | if (k_check && d.d < 1. && ilim > 0) |
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472 | { |
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473 | if (ilim1 <= 0) |
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474 | goto fast_failed; |
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475 | ilim = ilim1; |
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476 | k--; |
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477 | d.d *= 10.; |
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478 | ieps++; |
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479 | } |
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480 | eps.d = ieps * d.d + 7.; |
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481 | word0 (eps) -= (P - 1) * Exp_msk1; |
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482 | if (ilim == 0) |
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483 | { |
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484 | S = mhi = 0; |
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485 | d.d -= 5.; |
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486 | if (d.d > eps.d) |
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487 | goto one_digit; |
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488 | if (d.d < -eps.d) |
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489 | goto no_digits; |
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490 | goto fast_failed; |
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491 | } |
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492 | #ifndef No_leftright |
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493 | if (leftright) |
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494 | { |
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495 | /* Use Steele & White method of only |
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496 | * generating digits needed. |
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497 | */ |
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498 | eps.d = 0.5 / tens[ilim - 1] - eps.d; |
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499 | for (i = 0;;) |
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500 | { |
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501 | L = d.d; |
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502 | d.d -= L; |
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503 | *s++ = '0' + (int) L; |
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504 | if (d.d < eps.d) |
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505 | goto ret1; |
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506 | if (1. - d.d < eps.d) |
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507 | goto bump_up; |
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508 | if (++i >= ilim) |
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509 | break; |
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510 | eps.d *= 10.; |
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511 | d.d *= 10.; |
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512 | } |
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513 | } |
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514 | else |
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515 | { |
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516 | #endif |
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517 | /* Generate ilim digits, then fix them up. */ |
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518 | eps.d *= tens[ilim - 1]; |
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519 | for (i = 1;; i++, d.d *= 10.) |
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520 | { |
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521 | L = d.d; |
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522 | d.d -= L; |
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523 | *s++ = '0' + (int) L; |
||
524 | if (i == ilim) |
||
525 | { |
||
526 | if (d.d > 0.5 + eps.d) |
||
527 | goto bump_up; |
||
528 | else if (d.d < 0.5 - eps.d) |
||
529 | { |
||
530 | while (*--s == '0'); |
||
531 | s++; |
||
532 | goto ret1; |
||
533 | } |
||
534 | break; |
||
535 | } |
||
536 | } |
||
537 | #ifndef No_leftright |
||
538 | } |
||
539 | #endif |
||
540 | fast_failed: |
||
541 | s = s0; |
||
542 | d.d = d2.d; |
||
543 | k = k0; |
||
544 | ilim = ilim0; |
||
545 | } |
||
546 | |||
547 | /* Do we have a "small" integer? */ |
||
548 | |||
549 | if (be >= 0 && k <= Int_max) |
||
550 | { |
||
551 | /* Yes. */ |
||
552 | ds = tens[k]; |
||
553 | if (ndigits < 0 && ilim <= 0) |
||
554 | { |
||
555 | S = mhi = 0; |
||
556 | if (ilim < 0 || d.d <= 5 * ds) |
||
557 | goto no_digits; |
||
558 | goto one_digit; |
||
559 | } |
||
560 | for (i = 1;; i++) |
||
561 | { |
||
562 | L = d.d / ds; |
||
563 | d.d -= L * ds; |
||
564 | #ifdef Check_FLT_ROUNDS |
||
565 | /* If FLT_ROUNDS == 2, L will usually be high by 1 */ |
||
566 | if (d.d < 0) |
||
567 | { |
||
568 | L--; |
||
569 | d.d += ds; |
||
570 | } |
||
571 | #endif |
||
572 | *s++ = '0' + (int) L; |
||
573 | if (i == ilim) |
||
574 | { |
||
575 | d.d += d.d; |
||
576 | if ((d.d > ds) || ((d.d == ds) && (L & 1))) |
||
577 | { |
||
578 | bump_up: |
||
579 | while (*--s == '9') |
||
580 | if (s == s0) |
||
581 | { |
||
582 | k++; |
||
583 | *s = '0'; |
||
584 | break; |
||
585 | } |
||
586 | ++*s++; |
||
587 | } |
||
588 | break; |
||
589 | } |
||
590 | if (!(d.d *= 10.)) |
||
591 | break; |
||
592 | } |
||
593 | goto ret1; |
||
594 | } |
||
595 | |||
596 | m2 = b2; |
||
597 | m5 = b5; |
||
598 | mhi = mlo = 0; |
||
599 | if (leftright) |
||
600 | { |
||
601 | if (mode < 2) |
||
602 | { |
||
603 | i = |
||
604 | #ifndef Sudden_Underflow |
||
605 | denorm ? be + (Bias + (P - 1) - 1 + 1) : |
||
606 | #endif |
||
607 | #ifdef IBM |
||
608 | 1 + 4 * P - 3 - bbits + ((bbits + be - 1) & 3); |
||
609 | #else |
||
610 | 1 + P - bbits; |
||
611 | #endif |
||
612 | } |
||
613 | else |
||
614 | { |
||
615 | j = ilim - 1; |
||
616 | if (m5 >= j) |
||
617 | m5 -= j; |
||
618 | else |
||
619 | { |
||
620 | s5 += j -= m5; |
||
621 | b5 += j; |
||
622 | m5 = 0; |
||
623 | } |
||
624 | if ((i = ilim) < 0) |
||
625 | { |
||
626 | m2 -= i; |
||
627 | i = 0; |
||
628 | } |
||
629 | } |
||
630 | b2 += i; |
||
631 | s2 += i; |
||
632 | mhi = i2b (ptr, 1); |
||
633 | } |
||
634 | if (m2 > 0 && s2 > 0) |
||
635 | { |
||
636 | i = m2 < s2 ? m2 : s2; |
||
637 | b2 -= i; |
||
638 | m2 -= i; |
||
639 | s2 -= i; |
||
640 | } |
||
641 | if (b5 > 0) |
||
642 | { |
||
643 | if (leftright) |
||
644 | { |
||
645 | if (m5 > 0) |
||
646 | { |
||
647 | mhi = pow5mult (ptr, mhi, m5); |
||
648 | b1 = mult (ptr, mhi, b); |
||
649 | Bfree (ptr, b); |
||
650 | b = b1; |
||
651 | } |
||
652 | if ((j = b5 - m5) != 0) |
||
653 | b = pow5mult (ptr, b, j); |
||
654 | } |
||
655 | else |
||
656 | b = pow5mult (ptr, b, b5); |
||
657 | } |
||
658 | S = i2b (ptr, 1); |
||
659 | if (s5 > 0) |
||
660 | S = pow5mult (ptr, S, s5); |
||
661 | |||
662 | /* Check for special case that d is a normalized power of 2. */ |
||
663 | |||
664 | spec_case = 0; |
||
665 | if (mode < 2) |
||
666 | { |
||
667 | if (!word1 (d) && !(word0 (d) & Bndry_mask) |
||
668 | #ifndef Sudden_Underflow |
||
669 | && word0 (d) & Exp_mask |
||
670 | #endif |
||
671 | ) |
||
672 | { |
||
673 | /* The special case */ |
||
674 | b2 += Log2P; |
||
675 | s2 += Log2P; |
||
676 | spec_case = 1; |
||
677 | } |
||
678 | } |
||
679 | |||
680 | /* Arrange for convenient computation of quotients: |
||
681 | * shift left if necessary so divisor has 4 leading 0 bits. |
||
682 | * |
||
683 | * Perhaps we should just compute leading 28 bits of S once |
||
684 | * and for all and pass them and a shift to quorem, so it |
||
685 | * can do shifts and ors to compute the numerator for q. |
||
686 | */ |
||
687 | |||
688 | #ifdef Pack_32 |
||
689 | if ((i = ((s5 ? 32 - hi0bits (S->_x[S->_wds - 1]) : 1) + s2) & 0x1f) != 0) |
||
690 | i = 32 - i; |
||
691 | #else |
||
692 | if ((i = ((s5 ? 32 - hi0bits (S->_x[S->_wds - 1]) : 1) + s2) & 0xf) != 0) |
||
693 | i = 16 - i; |
||
694 | #endif |
||
695 | if (i > 4) |
||
696 | { |
||
697 | i -= 4; |
||
698 | b2 += i; |
||
699 | m2 += i; |
||
700 | s2 += i; |
||
701 | } |
||
702 | else if (i < 4) |
||
703 | { |
||
704 | i += 28; |
||
705 | b2 += i; |
||
706 | m2 += i; |
||
707 | s2 += i; |
||
708 | } |
||
709 | if (b2 > 0) |
||
710 | b = lshift (ptr, b, b2); |
||
711 | if (s2 > 0) |
||
712 | S = lshift (ptr, S, s2); |
||
713 | if (k_check) |
||
714 | { |
||
715 | if (cmp (b, S) < 0) |
||
716 | { |
||
717 | k--; |
||
718 | b = multadd (ptr, b, 10, 0); /* we botched the k estimate */ |
||
719 | if (leftright) |
||
720 | mhi = multadd (ptr, mhi, 10, 0); |
||
721 | ilim = ilim1; |
||
722 | } |
||
723 | } |
||
724 | if (ilim <= 0 && mode > 2) |
||
725 | { |
||
726 | if (ilim < 0 || cmp (b, S = multadd (ptr, S, 5, 0)) <= 0) |
||
727 | { |
||
728 | /* no digits, fcvt style */ |
||
729 | no_digits: |
||
730 | k = -1 - ndigits; |
||
731 | goto ret; |
||
732 | } |
||
733 | one_digit: |
||
734 | *s++ = '1'; |
||
735 | k++; |
||
736 | goto ret; |
||
737 | } |
||
738 | if (leftright) |
||
739 | { |
||
740 | if (m2 > 0) |
||
741 | mhi = lshift (ptr, mhi, m2); |
||
742 | |||
743 | /* Compute mlo -- check for special case |
||
744 | * that d is a normalized power of 2. |
||
745 | */ |
||
746 | |||
747 | mlo = mhi; |
||
748 | if (spec_case) |
||
749 | { |
||
750 | mhi = Balloc (ptr, mhi->_k); |
||
751 | Bcopy (mhi, mlo); |
||
752 | mhi = lshift (ptr, mhi, Log2P); |
||
753 | } |
||
754 | |||
755 | for (i = 1;; i++) |
||
756 | { |
||
757 | dig = quorem (b, S) + '0'; |
||
758 | /* Do we yet have the shortest decimal string |
||
759 | * that will round to d? |
||
760 | */ |
||
761 | j = cmp (b, mlo); |
||
762 | delta = diff (ptr, S, mhi); |
||
763 | j1 = delta->_sign ? 1 : cmp (b, delta); |
||
764 | Bfree (ptr, delta); |
||
765 | #ifndef ROUND_BIASED |
||
766 | if (j1 == 0 && !mode && !(word1 (d) & 1)) |
||
767 | { |
||
768 | if (dig == '9') |
||
769 | goto round_9_up; |
||
770 | if (j > 0) |
||
771 | dig++; |
||
772 | *s++ = dig; |
||
773 | goto ret; |
||
774 | } |
||
775 | #endif |
||
776 | if ((j < 0) || ((j == 0) && !mode |
||
777 | #ifndef ROUND_BIASED |
||
778 | && !(word1 (d) & 1) |
||
779 | #endif |
||
780 | )) |
||
781 | { |
||
782 | if (j1 > 0) |
||
783 | { |
||
784 | b = lshift (ptr, b, 1); |
||
785 | j1 = cmp (b, S); |
||
786 | if (((j1 > 0) || ((j1 == 0) && (dig & 1))) |
||
787 | && dig++ == '9') |
||
788 | goto round_9_up; |
||
789 | } |
||
790 | *s++ = dig; |
||
791 | goto ret; |
||
792 | } |
||
793 | if (j1 > 0) |
||
794 | { |
||
795 | if (dig == '9') |
||
796 | { /* possible if i == 1 */ |
||
797 | round_9_up: |
||
798 | *s++ = '9'; |
||
799 | goto roundoff; |
||
800 | } |
||
801 | *s++ = dig + 1; |
||
802 | goto ret; |
||
803 | } |
||
804 | *s++ = dig; |
||
805 | if (i == ilim) |
||
806 | break; |
||
807 | b = multadd (ptr, b, 10, 0); |
||
808 | if (mlo == mhi) |
||
809 | mlo = mhi = multadd (ptr, mhi, 10, 0); |
||
810 | else |
||
811 | { |
||
812 | mlo = multadd (ptr, mlo, 10, 0); |
||
813 | mhi = multadd (ptr, mhi, 10, 0); |
||
814 | } |
||
815 | } |
||
816 | } |
||
817 | else |
||
818 | for (i = 1;; i++) |
||
819 | { |
||
820 | *s++ = dig = quorem (b, S) + '0'; |
||
821 | if (i >= ilim) |
||
822 | break; |
||
823 | b = multadd (ptr, b, 10, 0); |
||
824 | } |
||
825 | |||
826 | /* Round off last digit */ |
||
827 | |||
828 | b = lshift (ptr, b, 1); |
||
829 | j = cmp (b, S); |
||
830 | if ((j > 0) || ((j == 0) && (dig & 1))) |
||
831 | { |
||
832 | roundoff: |
||
833 | while (*--s == '9') |
||
834 | if (s == s0) |
||
835 | { |
||
836 | k++; |
||
837 | *s++ = '1'; |
||
838 | goto ret; |
||
839 | } |
||
840 | ++*s++; |
||
841 | } |
||
842 | else |
||
843 | { |
||
844 | while (*--s == '0'); |
||
845 | s++; |
||
846 | } |
||
847 | ret: |
||
848 | Bfree (ptr, S); |
||
849 | if (mhi) |
||
850 | { |
||
851 | if (mlo && mlo != mhi) |
||
852 | Bfree (ptr, mlo); |
||
853 | Bfree (ptr, mhi); |
||
854 | } |
||
855 | ret1: |
||
856 | Bfree (ptr, b); |
||
857 | *s = 0; |
||
858 | *decpt = k + 1; |
||
859 | if (rve) |
||
860 | *rve = s; |
||
861 | return s0; |
||
862 | }>=>>=>>>>>>>>=>>=>>=>>>>>=>>=>=><=>=>=>=>>>=>>><>><>><>=><=>=>><>><>=>=>=>=>=>> |