lib/libc/gdtoa/g_ddfmt.c

   1 /* $NetBSD: g_ddfmt.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 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, dd, ndig, bufsize) char *buf; double *dd; int ndig; unsigned bufsize;
  39 #else
  40 g_ddfmt(char *buf, double *dd, int ndig, unsigned 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         double ddx[2];
  49
  50         if (bufsize < 10 || bufsize < ndig + 8)
  51                 return 0;
  52
  53         L = (ULong*)dd;
  54         if ((L[_0] & 0x7ff00000L) == 0x7ff00000L) {
  55                 /* Infinity or NaN */
  56                 if (L[_0] & 0xfffff || L[_1]) {
  57  nanret:
  58                         return strcp(buf, "NaN");
  59                         }
  60                 if ((L[2+_0] & 0x7ff00000) == 0x7ff00000) {
  61                         if (L[2+_0] & 0xfffff || L[2+_1])
  62                                 goto nanret;
  63                         if ((L[_0] ^ L[2+_0]) & 0x80000000L)
  64                                 goto nanret;    /* Infinity - Infinity */
  65                         }
  66  infret:
  67                 b = buf;
  68                 if (L[_0] & 0x80000000L)
  69                         *b++ = '-';
  70                 return strcp(b, "Infinity");
  71                 }
  72         if ((L[2+_0] & 0x7ff00000) == 0x7ff00000) {
  73                 L += 2;
  74                 if (L[_0] & 0xfffff || L[_1])
  75                         goto nanret;
  76                 goto infret;
  77                 }
  78         if (dd[0] + dd[1] == 0.) {
  79                 b = buf;
  80 #ifndef IGNORE_ZERO_SIGN
  81                 if (L[_0] & L[2+_0] & 0x80000000L)
  82                         *b++ = '-';
  83 #endif
  84                 *b++ = '0';
  85                 *b = 0;
  86                 return b;
  87                 }
  88         if ((L[_0] & 0x7ff00000L) < (L[2+_0] & 0x7ff00000L)) {
  89                 ddx[1] = dd[0];
  90                 ddx[0] = dd[1];
  91                 dd = ddx;
  92                 L = (ULong*)dd;
  93                 }
  94         z = d2b(dd[0], &ex, &bx);
  95         if (z == NULL)
  96                 return NULL;
  97         if (dd[1] == 0.)
  98                 goto no_y;
  99         x = z;
 100         y = d2b(dd[1], &ey, &by);
 101         if (y == NULL)
 102                 return NULL;
 103         if ( (i = ex - ey) !=0) {
 104                 if (i > 0) {
 105                         x = lshift(x, i);
 106                         if (x == NULL)
 107                                 return NULL;
 108                         ex = ey;
 109                         }
 110                 else {
 111                         y = lshift(y, -i);
 112                         if (y == NULL)
 113                                 return NULL;
 114                         }
 115                 }
 116         if ((L[_0] ^ L[2+_0]) & 0x80000000L) {
 117                 z = diff(x, y);
 118                 if (z == NULL)
 119                         return NULL;
 120                 if (L[_0] & 0x80000000L)
 121                         z->sign = 1 - z->sign;
 122                 }
 123         else {
 124                 z = sum(x, y);
 125                 if (z == NULL)
 126                         return NULL;
 127                 if (L[_0] & 0x80000000L)
 128                         z->sign = 1;
 129                 }
 130         Bfree(x);
 131         Bfree(y);
 132  no_y:
 133         bits = zx = z->x;
 134         for(i = 0; !*zx; zx++)
 135                 i += 32;
 136         i += lo0bits(zx);
 137         if (i) {
 138                 rshift(z, i);
 139                 ex += i;
 140                 }
 141         fpi.nbits = z->wds * 32 - hi0bits(z->x[j = z->wds-1]);
 142         if (fpi.nbits < 106) {
 143                 fpi.nbits = 106;
 144                 if (j < 3) {
 145                         for(i = 0; i <= j; i++)
 146                                 bits0[i] = bits[i];
 147                         while(i < 4)
 148                                 bits0[i++] = 0;
 149                         bits = bits0;
 150                         }
 151                 }
 152         mode = 2;
 153         if (ndig <= 0) {
 154                 if (bufsize < (int)(fpi.nbits * .301029995664) + 10) {
 155                         Bfree(z);
 156                         return 0;
 157                         }
 158                 mode = 0;
 159                 }
 160         fpi.emin = 1-1023-53+1;
 161         fpi.emax = 2046-1023-106+1;
 162         fpi.rounding = FPI_Round_near;
 163         fpi.sudden_underflow = 0;
 164         i = STRTOG_Normal;
 165         s = gdtoa(&fpi, ex, bits, &i, mode, ndig, &decpt, &se);
 166         if (s == NULL)
 167                 return NULL;
 168         b = g__fmt(buf, s, se, decpt, z->sign);
 169         if (b == NULL)
 170                 return NULL;
 171         Bfree(z);
 172         return b;
 173         }