1/*	$OpenBSD: ldtoa.c,v 1.2 2014/08/10 02:15:18 guenther Exp $	*/
2/*-
3 * Copyright (c) 2003 David Schultz <das@FreeBSD.ORG>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/types.h>
29#ifndef __vax__
30#include <machine/ieee.h>
31#endif /* !__vax__ */
32#include <float.h>
33#include <stdint.h>
34#include <limits.h>
35#include <math.h>
36#include <stdlib.h>
37#include "gdtoaimp.h"
38
39#if (LDBL_MANT_DIG > DBL_MANT_DIG)
40
41/*
42 * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
43 * except that the floating point argument is passed by reference.
44 * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
45 * However, a long double could have a valid exponent of 9999, so we
46 * use INT_MAX in ldtoa() instead.
47 */
48char *
49__ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
50    char **rve)
51{
52	FPI fpi = {
53		LDBL_MANT_DIG,			/* nbits */
54		LDBL_MIN_EXP - LDBL_MANT_DIG,	/* emin */
55		LDBL_MAX_EXP - LDBL_MANT_DIG,	/* emax */
56		FLT_ROUNDS,	       		/* rounding */
57#ifdef Sudden_Underflow	/* unused, but correct anyway */
58		1
59#else
60		0
61#endif
62	};
63	int be, kind;
64	char *ret;
65	struct ieee_ext *p = (struct ieee_ext *)ld;
66	uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
67	void *vbits = bits;
68
69	/*
70	 * gdtoa doesn't know anything about the sign of the number, so
71	 * if the number is negative, we need to swap rounding modes of
72	 * 2 (upwards) and 3 (downwards).
73	 */
74	*sign = p->ext_sign;
75	fpi.rounding ^= (fpi.rounding >> 1) & p->ext_sign;
76
77	be = p->ext_exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
78	EXT_TO_ARRAY32(p, bits);
79
80	switch (fpclassify(*ld)) {
81	case FP_NORMAL:
82		kind = STRTOG_Normal;
83#ifdef EXT_IMPLICIT_NBIT
84		bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
85#endif /* EXT_IMPLICIT_NBIT */
86		break;
87	case FP_ZERO:
88		kind = STRTOG_Zero;
89		break;
90	case FP_SUBNORMAL:
91		kind = STRTOG_Denormal;
92		be++;
93		break;
94	case FP_INFINITE:
95		kind = STRTOG_Infinite;
96		break;
97	case FP_NAN:
98		kind = STRTOG_NaN;
99		break;
100	default:
101		abort();
102	}
103
104	ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve);
105	if (*decpt == -32768)
106		*decpt = INT_MAX;
107	return ret;
108}
109
110#else   /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
111
112char *
113__ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
114    char **rve)
115{
116	char *ret;
117
118	ret = dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
119	if (*decpt == 9999)
120		*decpt = INT_MAX;
121	return ret;
122}
123
124#endif  /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
125