contrib/gdtoa/strtoIg.c

   1 /****************************************************************
   2
   3 The author of this software is David M. Gay.
   4
   5 Copyright (C) 1998 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 strtoIg(s00, se, fpi, exp, B, rvp) CONST char *s00; char **se; FPI *fpi; Long *exp; Bigint **B; int *rvp;
  37 #else
  38 strtoIg(CONST char *s00, char **se, FPI *fpi, Long *exp, Bigint **B, int *rvp)
  39 #endif
  40 {
  41         Bigint *b, *b1;
  42         int i, nb, nw, nw1, rv, rv1, swap;
  43         unsigned int nb1, nb11;
  44         Long e1;
  45
  46         b = *B;
  47         rv = strtodg(s00, se, fpi, exp, b->x);
  48         if (!(rv & STRTOG_Inexact)) {
  49                 B[1] = 0;
  50                 return *rvp = rv;
  51                 }
  52         e1 = exp[0];
  53         rv1 = rv ^ STRTOG_Inexact;
  54         b1 = Balloc(b->k);
  55         Bcopy(b1, b);
  56         nb = fpi->nbits;
  57         nb1 = nb & 31;
  58         nb11 = (nb1 - 1) & 31;
  59         nw = b->wds;
  60         nw1 = nw - 1;
  61         if (rv & STRTOG_Inexlo) {
  62                 swap = 0;
  63                 b1 = increment(b1);
  64                 if ((rv & STRTOG_Retmask) == STRTOG_Zero) {
  65                         if (fpi->sudden_underflow) {
  66                                 b1->x[0] = 0;
  67                                 b1->x[nw1] = 1L << nb11;
  68                                 rv1 += STRTOG_Normal - STRTOG_Zero;
  69                                 rv1 &= ~STRTOG_Underflow;
  70                                 goto swapcheck;
  71                                 }
  72                         rv1 &= STRTOG_Inexlo | STRTOG_Underflow | STRTOG_Zero;
  73                         rv1 |= STRTOG_Inexhi | STRTOG_Denormal;
  74                         goto swapcheck;
  75                         }
  76                 if (b1->wds > nw
  77                  || nb1 && b1->x[nw1] & 1L << nb1) {
  78                         if (++e1 > fpi->emax)
  79                                 rv1 = STRTOG_Infinite | STRTOG_Inexhi;
  80                         rshift(b1, 1);
  81                         }
  82                 else if ((rv & STRTOG_Retmask) == STRTOG_Denormal) {
  83                         if (b1->x[nw1] & 1L << nb11) {
  84                                 rv1 += STRTOG_Normal - STRTOG_Denormal;
  85                                 rv1 &= ~STRTOG_Underflow;
  86                                 }
  87                         }
  88                 }
  89         else {
  90                 swap = STRTOG_Neg;
  91                 if ((rv & STRTOG_Retmask) == STRTOG_Infinite) {
  92                         b1 = set_ones(b1, nb);
  93                         e1 = fpi->emax;
  94                         rv1 = STRTOG_Normal | STRTOG_Inexlo;
  95                         goto swapcheck;
  96                         }
  97                 decrement(b1);
  98                 if ((rv & STRTOG_Retmask) == STRTOG_Denormal) {
  99                         for(i = nw1; !b1->x[i]; --i)
 100                                 if (!i) {
 101                                         rv1 = STRTOG_Zero | STRTOG_Inexlo;
 102                                         break;
 103                                         }
 104                         goto swapcheck;
 105                         }
 106                 if (!(b1->x[nw1] & 1L << nb11)) {
 107                         if (e1 == fpi->emin) {
 108                                 if (fpi->sudden_underflow)
 109                                         rv1 += STRTOG_Zero - STRTOG_Normal;
 110                                 else
 111                                         rv1 += STRTOG_Denormal - STRTOG_Normal;
 112                                 rv1 |= STRTOG_Underflow;
 113                                 }
 114                         else {
 115                                 b1 = lshift(b1, 1);
 116                                 b1->x[0] |= 1;
 117                                 --e1;
 118                                 }
 119                         }
 120                 }
 121  swapcheck:
 122         if (swap ^ (rv & STRTOG_Neg)) {
 123                 rvp[0] = rv1;
 124                 rvp[1] = rv;
 125                 B[0] = b1;
 126                 B[1] = b;
 127                 exp[1] = exp[0];
 128                 exp[0] = e1;
 129                 }
 130         else {
 131                 rvp[0] = rv;
 132                 rvp[1] = rv1;
 133                 B[1] = b1;
 134                 exp[1] = e1;
 135                 }
 136         return rv;
 137         }