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: src/lib/libc/gdtoa/_ldtoa.c,v 1.5 2007/12/09 19:48:57 das Exp $");
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#if defined(__arm__)
50	/* On arm, double == long double, so short circuit this */
51	char * ret = __dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
52	if (*decpt == 9999)
53		*decpt = INT_MAX;
54	return ret;
55#else
56	FPI fpi = {
57		LDBL_MANT_DIG,			/* nbits */
58		LDBL_MIN_EXP - LDBL_MANT_DIG,	/* emin */
59		LDBL_MAX_EXP - LDBL_MANT_DIG,	/* emax */
60		FLT_ROUNDS,	       		/* rounding */
61#ifdef Sudden_Underflow	/* unused, but correct anyway */
62		1
63#else
64		0
65#endif
66	};
67	int be, kind;
68	char *ret;
69	union IEEEl2bits u;
70	uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
71	void *vbits = bits;
72	int type;
73
74	u.e = *ld;
75	type = fpclassify(u.e);
76
77	/*
78	 * gdtoa doesn't know anything about the sign of the number, so
79	 * if the number is negative, we need to swap rounding modes of
80	 * 2 (upwards) and 3 (downwards).
81	 */
82	*sign = u.bits.sign;
83	fpi.rounding ^= (fpi.rounding >> 1) & u.bits.sign;
84
85	be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
86	LDBL_TO_ARRAY32(u, bits);
87
88	switch (type) {
89	case FP_NORMAL:
90	case FP_SUPERNORMAL:
91		kind = STRTOG_Normal;
92#ifdef	LDBL_IMPLICIT_NBIT
93		bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
94#endif /* LDBL_IMPLICIT_NBIT */
95		break;
96	case FP_ZERO:
97		kind = STRTOG_Zero;
98		break;
99	case FP_SUBNORMAL:
100		kind = STRTOG_Denormal;
101		be++;
102		break;
103	case FP_INFINITE:
104		kind = STRTOG_Infinite;
105		break;
106	case FP_NAN:
107		kind = STRTOG_NaN;
108		break;
109	default:
110		LIBC_ABORT("fpclassify returned %d", type);
111	}
112
113	ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve);
114	if (*decpt == -32768)
115		*decpt = INT_MAX;
116	return ret;
117#endif
118}
119