_ldtoa.c revision 113145 
1/*-
2 * Copyright (c) 2003 David Schultz <das@FreeBSD.ORG>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/lib/libc/gdtoa/_ldtoa.c 113145 2003-04-05 22:10:13Z das $");
29
30#include <float.h>
31#include <inttypes.h>
32#include <limits.h>
33#include <math.h>
34#include <stdlib.h>
35#include "fpmath.h"
36#include "gdtoaimp.h"
37
38/*
39 * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
40 * except that the floating point argument is passed by reference.
41 * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
42 * However, a long double could have a valid exponent of 9999, so we
43 * use INT_MAX in ldtoa() instead.
44 */
45char *
46__ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
47    char **rve)
48{
49	static FPI fpi = {
50		LDBL_MANT_DIG,			/* nbits */
51		LDBL_MIN_EXP - LDBL_MANT_DIG,	/* emin */
52		LDBL_MAX_EXP - LDBL_MANT_DIG,	/* emax */
53		FPI_Round_near,	       		/* rounding */
54#ifdef Sudden_Underflow	/* unused, but correct anyway */
55		1
56#else
57		0
58#endif
59	};
60	int be, kind;
61	char *ret;
62	union IEEEl2bits u;
63	uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
64
65	u.e = *ld;
66	*sign = u.bits.sign;
67	be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
68	LDBL_TO_ARRAY32(u, bits);
69
70	switch (fpclassify(u.e)) {
71	case FP_NORMAL:
72		kind = STRTOG_Normal;
73#ifdef	LDBL_IMPLICIT_NBIT
74		bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
75#endif /* LDBL_IMPLICIT_NBIT */
76		break;
77	case FP_ZERO:
78		kind = STRTOG_Zero;
79		break;
80	case FP_SUBNORMAL:
81		kind = STRTOG_Denormal;
82		break;
83	case FP_INFINITE:
84		kind = STRTOG_Infinite;
85		break;
86	case FP_NAN:
87		kind = STRTOG_NaN;
88		break;
89	default:
90		abort();
91	}
92
93	ret = gdtoa(&fpi, be, (ULong *)bits, &kind, mode, ndigits, decpt, rve);
94	if (*decpt == -32768)
95		*decpt = INT_MAX;
96	return ret;
97}
98