contrib/gdtoa/strtopdd.c

   1 /****************************************************************
   2
   3 The author of this software is David M. Gay.
   4
   5 Copyright (C) 1998, 2000 by Lucent Technologies
   6 All Rights Reserved
   7
   8 Permission to use, copy, modify, and distribute this software and
   9 its documentation for any purpose and without fee is hereby
  10 granted, provided that the above copyright notice appear in all
  11 copies and that both that the copyright notice and this
  12 permission notice and warranty disclaimer appear in supporting
  13 documentation, and that the name of Lucent or any of its entities
  14 not be used in advertising or publicity pertaining to
  15 distribution of the software without specific, written prior
  16 permission.
  17
  18 LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  19 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
  20 IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
  21 SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  22 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
  23 IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  24 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
  25 THIS SOFTWARE.
  26
  27 ****************************************************************/
  28
  29 /* Please send bug reports to
  30         David M. Gay
  31         Bell Laboratories, Room 2C-463
  32         600 Mountain Avenue
  33         Murray Hill, NJ 07974-0636
  34         U.S.A.
  35         dmg@bell-labs.com
  36  */
  37
  38 #include "gdtoaimp.h"
  39
  40  int
  41 #ifdef KR_headers
  42 strtopdd(s, sp, dd) CONST char *s; char **sp; double *dd;
  43 #else
  44 strtopdd(CONST char *s, char **sp, double *dd)
  45 #endif
  46 {
  47 #ifdef Sudden_Underflow
  48         static FPI fpi = { 106, 1-1023, 2046-1023-106+1, 1, 1 };
  49 #else
  50         static FPI fpi = { 106, 1-1023-53+1, 2046-1023-106+1, 1, 0 };
  51 #endif
  52         ULong bits[4];
  53         Long exp;
  54         int i, j, rv;
  55         typedef union {
  56                 double d[2];
  57                 ULong L[4];
  58                 } U;
  59         U *u;
  60
  61         rv = strtodg(s, sp, &fpi, &exp, bits);
  62         u = (U*)dd;
  63         switch(rv & STRTOG_Retmask) {
  64           case STRTOG_NoNumber:
  65           case STRTOG_Zero:
  66                 u->d[0] = u->d[1] = 0.;
  67                 break;
  68
  69           case STRTOG_Normal:
  70                 u->L[_1] = (bits[1] >> 21 | bits[2] << 11) & 0xffffffffL;
  71                 u->L[_0] = bits[2] >> 21 | bits[3] << 11 & 0xfffff
  72                           | exp + 0x3ff + 105 << 20;
  73                 exp += 0x3ff + 52;
  74                 if (bits[1] &= 0x1fffff) {
  75                         i = hi0bits(bits[1]) - 11;
  76                         if (i >= exp) {
  77                                 i = exp - 1;
  78                                 exp = 0;
  79                                 }
  80                         else
  81                                 exp -= i;
  82                         if (i > 0) {
  83                                 bits[1] = bits[1] << i | bits[0] >> 32-i;
  84                                 bits[0] = bits[0] << i & 0xffffffffL;
  85                                 }
  86                         }
  87                 else if (bits[0]) {
  88                         i = hi0bits(bits[0]) + 21;
  89                         if (i >= exp) {
  90                                 i = exp - 1;
  91                                 exp = 0;
  92                                 }
  93                         else
  94                                 exp -= i;
  95                         if (i < 32) {
  96                                 bits[1] = bits[0] >> 32 - i;
  97                                 bits[0] = bits[0] << i & 0xffffffffL;
  98                                 }
  99                         else {
 100                                 bits[1] = bits[0] << i - 32;
 101                                 bits[0] = 0;
 102                                 }
 103                         }
 104                 else {
 105                         u->L[2] = u->L[3] = 0;
 106                         break;
 107                         }
 108                 u->L[2+_1] = bits[0];
 109                 u->L[2+_0] = bits[1] & 0xfffff | exp << 20;
 110                 break;
 111
 112           case STRTOG_Denormal:
 113                 if (bits[3])
 114                         goto nearly_normal;
 115                 if (bits[2])
 116                         goto partly_normal;
 117                 if (bits[1] & 0xffe00000)
 118                         goto hardly_normal;
 119                 /* completely denormal */
 120                 u->L[2] = u->L[3] = 0;
 121                 u->L[_1] = bits[0];
 122                 u->L[_0] = bits[1];
 123                 break;
 124
 125           nearly_normal:
 126                 i = hi0bits(bits[3]) - 11;      /* i >= 12 */
 127                 j = 32 - i;
 128                 u->L[_0] = (bits[3] << i | bits[2] >> j) & 0xfffff
 129                         | 65 - i << 20;
 130                 u->L[_1] = (bits[2] << i | bits[1] >> j) & 0xffffffffL;
 131                 u->L[2+_0] = bits[1] & (1L << j) - 1;
 132                 u->L[2+_1] = bits[0];
 133                 break;
 134
 135           partly_normal:
 136                 i = hi0bits(bits[2]) - 11;
 137                 if (i < 0) {
 138                         j = -i;
 139                         i += 32;
 140                         u->L[_0] = bits[2] >> j & 0xfffff | (33 + j) << 20;
 141                         u->L[_1] = (bits[2] << i | bits[1] >> j) & 0xffffffffL;
 142                         u->L[2+_0] = bits[1] & (1L << j) - 1;
 143                         u->L[2+_1] = bits[0];
 144                         break;
 145                         }
 146                 if (i == 0) {
 147                         u->L[_0] = bits[2] & 0xfffff | 33 << 20;
 148                         u->L[_1] = bits[1];
 149                         u->L[2+_0] = 0;
 150                         u->L[2+_1] = bits[0];
 151                         break;
 152                         }
 153                 j = 32 - i;
 154                 u->L[_0] = (bits[2] << i | bits[1] >> j) & 0xfffff
 155                                 | j + 1 << 20;
 156                 u->L[_1] = (bits[1] << i | bits[0] >> j) & 0xffffffffL;
 157                 u->L[2+_0] = 0;
 158                 u->L[2+_1] = bits[0] & (1L << j) - 1;
 159                 break;
 160
 161           hardly_normal:
 162                 j = 11 - hi0bits(bits[1]);
 163                 i = 32 - j;
 164                 u->L[_0] = bits[1] >> j & 0xfffff | j + 1 << 20;
 165                 u->L[_1] = (bits[1] << i | bits[0] >> j) & 0xffffffffL;
 166                 u->L[2+_0] = 0;
 167                 u->L[2+_1] = bits[0] & (1L << j) - 1;
 168                 break;
 169
 170           case STRTOG_Infinite:
 171                 u->L[_0] = u->L[2+_0] = 0x7ff00000;
 172                 u->L[_1] = u->L[2+_1] = 0;
 173                 break;
 174
 175           case STRTOG_NaN:
 176                 u->L[_0] = u->L[2+_0] = 0x7fffffff;
 177                 u->L[_1] = u->L[2+_1] = (ULong)-1;
 178           }
 179         if (rv & STRTOG_Neg) {
 180                 u->L[  _0] |= 0x80000000L;
 181                 u->L[2+_0] |= 0x80000000L;
 182                 }
 183         return rv;
 184         }