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 David M. Gay (dmg at acm dot org,
  30  * with " at " changed at "@" and " dot " changed to ".").      */
  31
  32 #include "gdtoaimp.h"
  33
  34  int
  35 #ifdef KR_headers
  36 strtopdd(s, sp, dd) CONST char *s; char **sp; double *dd;
  37 #else
  38 strtopdd(CONST char *s, char **sp, double *dd)
  39 #endif
  40 {
  41 #ifdef Sudden_Underflow
  42         static FPI fpi0 = { 106, 1-1023, 2046-1023-106+1, 1, 1 };
  43 #else
  44         static FPI fpi0 = { 106, 1-1023-53+1, 2046-1023-106+1, 1, 0 };
  45 #endif
  46         ULong bits[4];
  47         Long exp;
  48         int i, j, rv;
  49         typedef union {
  50                 double d[2];
  51                 ULong L[4];
  52                 } U;
  53         U *u;
  54 #ifdef Honor_FLT_ROUNDS
  55 #include "gdtoa_fltrnds.h"
  56 #else
  57 #define fpi &fpi0
  58 #endif
  59
  60         rv = strtodg(s, sp, fpi, &exp, bits);
  61         u = (U*)dd;
  62         switch(rv & STRTOG_Retmask) {
  63           case STRTOG_NoNumber:
  64           case STRTOG_Zero:
  65                 u->d[0] = u->d[1] = 0.;
  66                 break;
  67
  68           case STRTOG_Normal:
  69                 u->L[_1] = (bits[1] >> 21 | bits[2] << 11) & 0xffffffffL;
  70                 u->L[_0] = bits[2] >> 21 | bits[3] << 11 & 0xfffff
  71                           | exp + 0x3ff + 105 << 20;
  72                 exp += 0x3ff + 52;
  73                 if (bits[1] &= 0x1fffff) {
  74                         i = hi0bits(bits[1]) - 11;
  75                         if (i >= exp) {
  76                                 i = exp - 1;
  77                                 exp = 0;
  78                                 }
  79                         else
  80                                 exp -= i;
  81                         if (i > 0) {
  82                                 bits[1] = bits[1] << i | bits[0] >> 32-i;
  83                                 bits[0] = bits[0] << i & 0xffffffffL;
  84                                 }
  85                         }
  86                 else if (bits[0]) {
  87                         i = hi0bits(bits[0]) + 21;
  88                         if (i >= exp) {
  89                                 i = exp - 1;
  90                                 exp = 0;
  91                                 }
  92                         else
  93                                 exp -= i;
  94                         if (i < 32) {
  95                                 bits[1] = bits[0] >> 32 - i;
  96                                 bits[0] = bits[0] << i & 0xffffffffL;
  97                                 }
  98                         else {
  99                                 bits[1] = bits[0] << i - 32;
 100                                 bits[0] = 0;
 101                                 }
 102                         }
 103                 else {
 104                         u->L[2] = u->L[3] = 0;
 105                         break;
 106                         }
 107                 u->L[2+_1] = bits[0];
 108                 u->L[2+_0] = bits[1] & 0xfffff | exp << 20;
 109                 break;
 110
 111           case STRTOG_Denormal:
 112                 if (bits[3])
 113                         goto nearly_normal;
 114                 if (bits[2])
 115                         goto partly_normal;
 116                 if (bits[1] & 0xffe00000)
 117                         goto hardly_normal;
 118                 /* completely denormal */
 119                 u->L[2] = u->L[3] = 0;
 120                 u->L[_1] = bits[0];
 121                 u->L[_0] = bits[1];
 122                 break;
 123
 124           nearly_normal:
 125                 i = hi0bits(bits[3]) - 11;      /* i >= 12 */
 126                 j = 32 - i;
 127                 u->L[_0] = (bits[3] << i | bits[2] >> j) & 0xfffff
 128                         | 65 - i << 20;
 129                 u->L[_1] = (bits[2] << i | bits[1] >> j) & 0xffffffffL;
 130                 u->L[2+_0] = bits[1] & (1L << j) - 1;
 131                 u->L[2+_1] = bits[0];
 132                 break;
 133
 134           partly_normal:
 135                 i = hi0bits(bits[2]) - 11;
 136                 if (i < 0) {
 137                         j = -i;
 138                         i += 32;
 139                         u->L[_0] = bits[2] >> j & 0xfffff | (33 + j) << 20;
 140                         u->L[_1] = (bits[2] << i | bits[1] >> j) & 0xffffffffL;
 141                         u->L[2+_0] = bits[1] & (1L << j) - 1;
 142                         u->L[2+_1] = bits[0];
 143                         break;
 144                         }
 145                 if (i == 0) {
 146                         u->L[_0] = bits[2] & 0xfffff | 33 << 20;
 147                         u->L[_1] = bits[1];
 148                         u->L[2+_0] = 0;
 149                         u->L[2+_1] = bits[0];
 150                         break;
 151                         }
 152                 j = 32 - i;
 153                 u->L[_0] = (bits[2] << i | bits[1] >> j) & 0xfffff
 154                                 | j + 1 << 20;
 155                 u->L[_1] = (bits[1] << i | bits[0] >> j) & 0xffffffffL;
 156                 u->L[2+_0] = 0;
 157                 u->L[2+_1] = bits[0] & (1L << j) - 1;
 158                 break;
 159
 160           hardly_normal:
 161                 j = 11 - hi0bits(bits[1]);
 162                 i = 32 - j;
 163                 u->L[_0] = bits[1] >> j & 0xfffff | j + 1 << 20;
 164                 u->L[_1] = (bits[1] << i | bits[0] >> j) & 0xffffffffL;
 165                 u->L[2+_0] = 0;
 166                 u->L[2+_1] = bits[0] & (1L << j) - 1;
 167                 break;
 168
 169           case STRTOG_Infinite:
 170                 u->L[_0] = u->L[2+_0] = 0x7ff00000;
 171                 u->L[_1] = u->L[2+_1] = 0;
 172                 break;
 173
 174           case STRTOG_NaN:
 175                 u->L[0] = u->L[2] = d_QNAN0;
 176                 u->L[1] = u->L[3] = d_QNAN1;
 177           }
 178         if (rv & STRTOG_Neg) {
 179                 u->L[  _0] |= 0x80000000L;
 180                 u->L[2+_0] |= 0x80000000L;
 181                 }
 182         return rv;
 183         }