1/* $NetBSD: g_ddfmt.c,v 1.2 2008/03/21 23:13:48 christos Exp $ */
2
3/****************************************************************
4
5The author of this software is David M. Gay.
6
7Copyright (C) 1998 by Lucent Technologies
8All Rights Reserved
9
10Permission to use, copy, modify, and distribute this software and
11its documentation for any purpose and without fee is hereby
12granted, provided that the above copyright notice appear in all
13copies and that both that the copyright notice and this
14permission notice and warranty disclaimer appear in supporting
15documentation, and that the name of Lucent or any of its entities
16not be used in advertising or publicity pertaining to
17distribution of the software without specific, written prior
18permission.
19
20LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
21INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
22IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
23SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
24WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
25IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
26ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
27THIS 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
38g_ddfmt(buf, dd0, ndig, bufsize) char *buf; double *dd0; int ndig; size_t bufsize;
39#else
40g_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	}
190