lib/libc/gdtoa/strtodI.c

   1 /* $NetBSD: strtodI.c,v 1.2 2008/03/21 23:13:48 christos Exp $ */
   2
   3 /****************************************************************
   4
   5 The author of this software is David M. Gay.
   6
   7 Copyright (C) 1998, 2000 by Lucent Technologies
   8 All Rights Reserved
   9
  10 Permission to use, copy, modify, and distribute this software and
  11 its documentation for any purpose and without fee is hereby
  12 granted, provided that the above copyright notice appear in all
  13 copies and that both that the copyright notice and this
  14 permission notice and warranty disclaimer appear in supporting
  15 documentation, and that the name of Lucent or any of its entities
  16 not be used in advertising or publicity pertaining to
  17 distribution of the software without specific, written prior
  18 permission.
  19
  20 LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  21 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
  22 IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
  23 SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  24 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
  25 IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  26 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
  27 THIS SOFTWARE.
  28
  29 ****************************************************************/
  30
  31 /* Please send bug reports to David M. Gay (dmg at acm dot org,
  32  * with " at " changed at "@" and " dot " changed to ".").      */
  33
  34 #include "gdtoaimp.h"
  35
  36  static double
  37 #ifdef KR_headers
  38 ulpdown(d) double *d;
  39 #else
  40 ulpdown(double *d)
  41 #endif
  42 {
  43         double u;
  44         ULong *L = (ULong*)d;
  45
  46         u = ulp(*d);
  47         if (!(L[_1] | L[_0] & 0xfffff)
  48          && (L[_0] & 0x7ff00000) > 0x00100000)
  49                 u *= 0.5;
  50         return u;
  51         }
  52
  53  int
  54 #ifdef KR_headers
  55 strtodI(s, sp, dd) CONST char *s; char **sp; double *dd;
  56 #else
  57 strtodI(CONST char *s, char **sp, double *dd)
  58 #endif
  59 {
  60         static FPI fpi = { 53, 1-1023-53+1, 2046-1023-53+1, 1, SI };
  61         ULong bits[2], sign;
  62         Long exp;
  63         int j, k;
  64         typedef union {
  65                 double d[2];
  66                 ULong L[4];
  67                 } U;
  68         U *u;
  69
  70         k = strtodg(s, sp, &fpi, &exp, bits);
  71         if (k == STRTOG_NoMemory)
  72                 return k;
  73         u = (U*)dd;
  74         sign = k & STRTOG_Neg ? 0x80000000L : 0;
  75         switch(k & STRTOG_Retmask) {
  76           case STRTOG_NoNumber:
  77                 u->d[0] = u->d[1] = 0.;
  78                 break;
  79
  80           case STRTOG_Zero:
  81                 u->d[0] = u->d[1] = 0.;
  82 #ifdef Sudden_Underflow
  83                 if (k & STRTOG_Inexact) {
  84                         if (sign)
  85                                 u->L[_0] = 0x80100000L;
  86                         else
  87                                 u->L[2+_0] = 0x100000L;
  88                         }
  89                 break;
  90 #else
  91                 goto contain;
  92 #endif
  93
  94           case STRTOG_Denormal:
  95                 u->L[_1] = bits[0];
  96                 u->L[_0] = bits[1];
  97                 goto contain;
  98
  99           case STRTOG_Normal:
 100                 u->L[_1] = bits[0];
 101                 u->L[_0] = (bits[1] & ~0x100000) | ((exp + 0x3ff + 52) << 20);
 102           contain:
 103                 j = k & STRTOG_Inexact;
 104                 if (sign) {
 105                         u->L[_0] |= sign;
 106                         j = STRTOG_Inexact - j;
 107                         }
 108                 switch(j) {
 109                   case STRTOG_Inexlo:
 110 #ifdef Sudden_Underflow
 111                         if ((u->L[_0] & 0x7ff00000) < 0x3500000) {
 112                                 u->L[2+_0] = u->L[_0] + 0x3500000;
 113                                 u->L[2+_1] = u->L[_1];
 114                                 u->d[1] += ulp(u->d[1]);
 115                                 u->L[2+_0] -= 0x3500000;
 116                                 if (!(u->L[2+_0] & 0x7ff00000)) {
 117                                         u->L[2+_0] = sign;
 118                                         u->L[2+_1] = 0;
 119                                         }
 120                                 }
 121                         else
 122 #endif
 123                         u->d[1] = u->d[0] + ulp(u->d[0]);
 124                         break;
 125                   case STRTOG_Inexhi:
 126                         u->d[1] = u->d[0];
 127 #ifdef Sudden_Underflow
 128                         if ((u->L[_0] & 0x7ff00000) < 0x3500000) {
 129                                 u->L[_0] += 0x3500000;
 130                                 u->d[0] -= ulpdown(u->d);
 131                                 u->L[_0] -= 0x3500000;
 132                                 if (!(u->L[_0] & 0x7ff00000)) {
 133                                         u->L[_0] = sign;
 134                                         u->L[_1] = 0;
 135                                         }
 136                                 }
 137                         else
 138 #endif
 139                         u->d[0] -= ulpdown(u->d);
 140                         break;
 141                   default:
 142                         u->d[1] = u->d[0];
 143                   }
 144                 break;
 145
 146           case STRTOG_Infinite:
 147                 u->L[_0] = u->L[2+_0] = sign | 0x7ff00000;
 148                 u->L[_1] = u->L[2+_1] = 0;
 149                 if (k & STRTOG_Inexact) {
 150                         if (sign) {
 151                                 u->L[2+_0] = 0xffefffffL;
 152                                 u->L[2+_1] = 0xffffffffL;
 153                                 }
 154                         else {
 155                                 u->L[_0] = 0x7fefffffL;
 156                                 u->L[_1] = 0xffffffffL;
 157                                 }
 158                         }
 159                 break;
 160
 161           case STRTOG_NaN:
 162                 u->L[0] = u->L[2] = d_QNAN0;
 163                 u->L[1] = u->L[3] = d_QNAN1;
 164                 break;
 165
 166           case STRTOG_NaNbits:
 167                 u->L[_0] = u->L[2+_0] = 0x7ff00000 | sign | bits[1];
 168                 u->L[_1] = u->L[2+_1] = bits[0];
 169           }
 170         return k;
 171         }