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strtodI.c revision 1.2 
      1 /* $NetBSD: strtodI.c,v 1.2 2008/03/21 23:13:48 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) double *d;
     39 #else
     40 ulpdown(double *d)
     41 #endif
     42 {
     43 	double u;
     44 	ULong *L = (ULong*)d;
     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 	typedef union {
     65 		double d[2];
     66 		ULong L[4];
     67 		} U;
     68 	U *u;
     69 
     70 	k = strtodg(s, sp, &fpi, &exp, bits);
     71 	if (k == STRTOG_NoMemory)
     72 		return k;
     73 	u = (U*)dd;
     74 	sign = k & STRTOG_Neg ? 0x80000000L : 0;
     75 	switch(k & STRTOG_Retmask) {
     76 	  case STRTOG_NoNumber:
     77 		u->d[0] = u->d[1] = 0.;
     78 		break;
     79 
     80 	  case STRTOG_Zero:
     81 		u->d[0] = u->d[1] = 0.;
     82 #ifdef Sudden_Underflow
     83 		if (k & STRTOG_Inexact) {
     84 			if (sign)
     85 				u->L[_0] = 0x80100000L;
     86 			else
     87 				u->L[2+_0] = 0x100000L;
     88 			}
     89 		break;
     90 #else
     91 		goto contain;
     92 #endif
     93 
     94 	  case STRTOG_Denormal:
     95 		u->L[_1] = bits[0];
     96 		u->L[_0] = bits[1];
     97 		goto contain;
     98 
     99 	  case STRTOG_Normal:
    100 		u->L[_1] = bits[0];
    101 		u->L[_0] = (bits[1] & ~0x100000) | ((exp + 0x3ff + 52) << 20);
    102 	  contain:
    103 		j = k & STRTOG_Inexact;
    104 		if (sign) {
    105 			u->L[_0] |= sign;
    106 			j = STRTOG_Inexact - j;
    107 			}
    108 		switch(j) {
    109 		  case STRTOG_Inexlo:
    110 #ifdef Sudden_Underflow
    111 			if ((u->L[_0] & 0x7ff00000) < 0x3500000) {
    112 				u->L[2+_0] = u->L[_0] + 0x3500000;
    113 				u->L[2+_1] = u->L[_1];
    114 				u->d[1] += ulp(u->d[1]);
    115 				u->L[2+_0] -= 0x3500000;
    116 				if (!(u->L[2+_0] & 0x7ff00000)) {
    117 					u->L[2+_0] = sign;
    118 					u->L[2+_1] = 0;
    119 					}
    120 				}
    121 			else
    122 #endif
    123 			u->d[1] = u->d[0] + ulp(u->d[0]);
    124 			break;
    125 		  case STRTOG_Inexhi:
    126 			u->d[1] = u->d[0];
    127 #ifdef Sudden_Underflow
    128 			if ((u->L[_0] & 0x7ff00000) < 0x3500000) {
    129 				u->L[_0] += 0x3500000;
    130 				u->d[0] -= ulpdown(u->d);
    131 				u->L[_0] -= 0x3500000;
    132 				if (!(u->L[_0] & 0x7ff00000)) {
    133 					u->L[_0] = sign;
    134 					u->L[_1] = 0;
    135 					}
    136 				}
    137 			else
    138 #endif
    139 			u->d[0] -= ulpdown(u->d);
    140 			break;
    141 		  default:
    142 			u->d[1] = u->d[0];
    143 		  }
    144 		break;
    145 
    146 	  case STRTOG_Infinite:
    147 		u->L[_0] = u->L[2+_0] = sign | 0x7ff00000;
    148 		u->L[_1] = u->L[2+_1] = 0;
    149 		if (k & STRTOG_Inexact) {
    150 			if (sign) {
    151 				u->L[2+_0] = 0xffefffffL;
    152 				u->L[2+_1] = 0xffffffffL;
    153 				}
    154 			else {
    155 				u->L[_0] = 0x7fefffffL;
    156 				u->L[_1] = 0xffffffffL;
    157 				}
    158 			}
    159 		break;
    160 
    161 	  case STRTOG_NaN:
    162 		u->L[0] = u->L[2] = d_QNAN0;
    163 		u->L[1] = u->L[3] = d_QNAN1;
    164 		break;
    165 
    166 	  case STRTOG_NaNbits:
    167 		u->L[_0] = u->L[2+_0] = 0x7ff00000 | sign | bits[1];
    168 		u->L[_1] = u->L[2+_1] = bits[0];
    169 	  }
    170 	return k;
    171 	}
    172