lib/libc/gdtoa/strtodI.c

   1 /* $NetBSD: strtodI.c,v 1.3 2011/03/20 23:15:35 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) U *d;
  39 #else
  40 ulpdown(U *d)
  41 #endif
  42 {
  43         double u;
  44         ULong *L = d->L;
  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         U *u;
  65
  66         k = strtodg(s, sp, &fpi, &exp, bits);
  67         if (k == STRTOG_NoMemory)
  68                 return k;
  69         u = (U*)dd;
  70         sign = k & STRTOG_Neg ? 0x80000000L : 0;
  71         switch(k & STRTOG_Retmask) {
  72           case STRTOG_NoNumber:
  73                 dval(&u[0]) = dval(&u[1]) = 0.;
  74                 break;
  75
  76           case STRTOG_Zero:
  77                 dval(&u[0]) = dval(&u[1]) = 0.;
  78 #ifdef Sudden_Underflow
  79                 if (k & STRTOG_Inexact) {
  80                         if (sign)
  81                                 word0(&u[0]) = 0x80100000L;
  82                         else
  83                                 word0(&u[1]) = 0x100000L;
  84                         }
  85                 break;
  86 #else
  87                 goto contain;
  88 #endif
  89
  90           case STRTOG_Denormal:
  91                 word1(&u[0]) = bits[0];
  92                 word0(&u[0]) = bits[1];
  93                 goto contain;
  94
  95           case STRTOG_Normal:
  96                 word1(&u[0]) = bits[0];
  97                 word0(&u[0]) = (bits[1] & ~0x100000) | ((exp + 0x3ff + 52) << 20);
  98           contain:
  99                 j = k & STRTOG_Inexact;
 100                 if (sign) {
 101                         word0(&u[0]) |= sign;
 102                         j = STRTOG_Inexact - j;
 103                         }
 104                 switch(j) {
 105                   case STRTOG_Inexlo:
 106 #ifdef Sudden_Underflow
 107                         if ((u->L[_0] & 0x7ff00000) < 0x3500000) {
 108                                 word0(&u[1]) = word0(&u[0]) + 0x3500000;
 109                                 word1(&u[1]) = word1(&u[0]);
 110                                 dval(&u[1]) += ulp(&u[1]);
 111                                 word0(&u[1]) -= 0x3500000;
 112                                 if (!(word0(&u[1]) & 0x7ff00000)) {
 113                                         word0(&u[1]) = sign;
 114                                         word1(&u[1]) = 0;
 115                                         }
 116                                 }
 117                         else
 118 #endif
 119                         dval(&u[1]) = dval(&u[0]) + ulp(&u[0]);
 120                         break;
 121                   case STRTOG_Inexhi:
 122                         dval(&u[1]) = dval(&u[0]);
 123 #ifdef Sudden_Underflow
 124                         if ((word0(&u[0]) & 0x7ff00000) < 0x3500000) {
 125                                 word0(&u[0]) += 0x3500000;
 126                                 dval(&u[0]) -= ulpdown(u);
 127                                 word0(&u[0]) -= 0x3500000;
 128                                 if (!(word0(&u[0]) & 0x7ff00000)) {
 129                                         word0(&u[0]) = sign;
 130                                         word1(&u[0]) = 0;
 131                                         }
 132                                 }
 133                         else
 134 #endif
 135                         dval(&u[0]) -= ulpdown(u);
 136                         break;
 137                   default:
 138                         dval(&u[1]) = dval(&u[0]);
 139                   }
 140                 break;
 141
 142           case STRTOG_Infinite:
 143                 word0(&u[0]) = word0(&u[1]) = sign | 0x7ff00000;
 144                 word1(&u[0]) = word1(&u[1]) = 0;
 145                 if (k & STRTOG_Inexact) {
 146                         if (sign) {
 147                                 word0(&u[1]) = 0xffefffffL;
 148                                 word1(&u[1]) = 0xffffffffL;
 149                                 }
 150                         else {
 151                                 word0(&u[0]) = 0x7fefffffL;
 152                                 word1(&u[0]) = 0xffffffffL;
 153                                 }
 154                         }
 155                 break;
 156
 157           case STRTOG_NaN:
 158                 u->L[0] = (u+1)->L[0] = d_QNAN0;
 159                 u->L[1] = (u+1)->L[1] = d_QNAN1;
 160                 break;
 161
 162           case STRTOG_NaNbits:
 163                 word0(&u[0]) = word0(&u[1]) = 0x7ff00000 | sign | bits[1];
 164                 word1(&u[0]) = word1(&u[1]) = bits[0];
 165           }
 166         return k;
 167         }