lib/libc/gdtoa/g_ddfmt.c

   1 /* $NetBSD: g_ddfmt.c,v 1.3 2011/03/20 23:15:35 christos Exp $ */
   2
   3 /****************************************************************
   4
   5 The author of this software is David M. Gay.
   6
   7 Copyright (C) 1998 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@acm.org). */
  32
  33 #include "gdtoaimp.h"
  34 #include <string.h>
  35
  36  char *
  37 #ifdef KR_headers
  38 g_ddfmt(buf, dd0, ndig, bufsize) char *buf; double *dd0; int ndig; size_t bufsize;
  39 #else
  40 g_ddfmt(char *buf, double *dd0, int ndig, size_t bufsize)
  41 #endif
  42 {
  43         FPI fpi;
  44         char *b, *s, *se;
  45         ULong *L, bits0[4], *bits, *zx;
  46         int bx, by, decpt, ex, ey, i, j, mode;
  47         Bigint *x, *y, *z;
  48         U *dd, ddx[2];
  49 #ifdef Honor_FLT_ROUNDS /*{{*/
  50         int Rounding;
  51 #ifdef Trust_FLT_ROUNDS /*{{ only define this if FLT_ROUNDS really works! */
  52         Rounding = Flt_Rounds;
  53 #else /*}{*/
  54         Rounding = 1;
  55         switch(fegetround()) {
  56           case FE_TOWARDZERO:   Rounding = 0; break;
  57           case FE_UPWARD:       Rounding = 2; break;
  58           case FE_DOWNWARD:     Rounding = 3;
  59           }
  60 #endif /*}}*/
  61 #else /*}{*/
  62 #define Rounding FPI_Round_near
  63 #endif /*}}*/
  64
  65         if (bufsize < 10 || bufsize < ndig + 8)
  66                 return 0;
  67
  68         dd = (U*)dd0;
  69         L = dd->L;
  70         if ((L[_0] & 0x7ff00000L) == 0x7ff00000L) {
  71                 /* Infinity or NaN */
  72                 if (L[_0] & 0xfffff || L[_1]) {
  73  nanret:
  74                         return strcp(buf, "NaN");
  75                         }
  76                 if ((L[2+_0] & 0x7ff00000) == 0x7ff00000) {
  77                         if (L[2+_0] & 0xfffff || L[2+_1])
  78                                 goto nanret;
  79                         if ((L[_0] ^ L[2+_0]) & 0x80000000L)
  80                                 goto nanret;    /* Infinity - Infinity */
  81                         }
  82  infret:
  83                 b = buf;
  84                 if (L[_0] & 0x80000000L)
  85                         *b++ = '-';
  86                 return strcp(b, "Infinity");
  87                 }
  88         if ((L[2+_0] & 0x7ff00000) == 0x7ff00000) {
  89                 L += 2;
  90                 if (L[_0] & 0xfffff || L[_1])
  91                         goto nanret;
  92                 goto infret;
  93                 }
  94         if (dval(&dd[0]) + dval(&dd[1]) == 0.) {
  95                 b = buf;
  96 #ifndef IGNORE_ZERO_SIGN
  97                 if (L[_0] & L[2+_0] & 0x80000000L)
  98                         *b++ = '-';
  99 #endif
 100                 *b++ = '0';
 101                 *b = 0;
 102                 return b;
 103                 }
 104         if ((L[_0] & 0x7ff00000L) < (L[2+_0] & 0x7ff00000L)) {
 105                 dval(&ddx[1]) = dval(&dd[0]);
 106                 dval(&ddx[0]) = dval(&dd[1]);
 107                 dd = ddx;
 108                 L = dd->L;
 109                 }
 110         z = d2b(dval(&dd[0]), &ex, &bx);
 111         if (z == NULL)
 112                 return NULL;
 113         if (dval(&dd[1]) == 0.)
 114                 goto no_y;
 115         x = z;
 116         y = d2b(dval(&dd[1]), &ey, &by);
 117         if (y == NULL)
 118                 return NULL;
 119         if ( (i = ex - ey) !=0) {
 120                 if (i > 0) {
 121                         x = lshift(x, i);
 122                         if (x == NULL)
 123                                 return NULL;
 124                         ex = ey;
 125                         }
 126                 else {
 127                         y = lshift(y, -i);
 128                         if (y == NULL)
 129                                 return NULL;
 130                         }
 131                 }
 132         if ((L[_0] ^ L[2+_0]) & 0x80000000L) {
 133                 z = diff(x, y);
 134                 if (z == NULL)
 135                         return NULL;
 136                 if (L[_0] & 0x80000000L)
 137                         z->sign = 1 - z->sign;
 138                 }
 139         else {
 140                 z = sum(x, y);
 141                 if (z == NULL)
 142                         return NULL;
 143                 if (L[_0] & 0x80000000L)
 144                         z->sign = 1;
 145                 }
 146         Bfree(x);
 147         Bfree(y);
 148  no_y:
 149         bits = zx = z->x;
 150         for(i = 0; !*zx; zx++)
 151                 i += 32;
 152         i += lo0bits(zx);
 153         if (i) {
 154                 rshift(z, i);
 155                 ex += i;
 156                 }
 157         fpi.nbits = z->wds * 32 - hi0bits(z->x[j = z->wds-1]);
 158         if (fpi.nbits < 106) {
 159                 fpi.nbits = 106;
 160                 if (j < 3) {
 161                         for(i = 0; i <= j; i++)
 162                                 bits0[i] = bits[i];
 163                         while(i < 4)
 164                                 bits0[i++] = 0;
 165                         bits = bits0;
 166                         }
 167                 }
 168         mode = 2;
 169         if (ndig <= 0) {
 170                 if (bufsize < (int)(fpi.nbits * .301029995664) + 10) {
 171                         Bfree(z);
 172                         return 0;
 173                         }
 174                 mode = 0;
 175                 }
 176         fpi.emin = 1-1023-53+1;
 177         fpi.emax = 2046-1023-106+1;
 178         fpi.rounding = Rounding;
 179         fpi.sudden_underflow = 0;
 180         i = STRTOG_Normal;
 181         s = gdtoa(&fpi, ex, bits, &i, mode, ndig, &decpt, &se);
 182         if (s == NULL)
 183                 return NULL;
 184         b = g__fmt(buf, s, se, decpt, z->sign, bufsize);
 185         if (b == NULL)
 186                 return NULL;
 187         Bfree(z);
 188         return b;
 189         }