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strtoIg.c revision 1.1.1.2 
      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 	}
    138