1/*	$OpenBSD: ldtoa.c,v 1.4 2016/03/09 16:28:47 deraadt 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#include <machine/ieee.h>
30#include <float.h>
31#include <stdint.h>
32#include <limits.h>
33#include <math.h>
34#include <stdlib.h>
35#include "gdtoaimp.h"
36
37#if (LDBL_MANT_DIG > DBL_MANT_DIG)
38
39/*
40 * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
41 * except that the floating point argument is passed by reference.
42 * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
43 * However, a long double could have a valid exponent of 9999, so we
44 * use INT_MAX in ldtoa() instead.
45 */
46char *
47__ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
48    char **rve)
49{
50	FPI fpi = {
51		LDBL_MANT_DIG,			/* nbits */
52		LDBL_MIN_EXP - LDBL_MANT_DIG,	/* emin */
53		LDBL_MAX_EXP - LDBL_MANT_DIG,	/* emax */
54		FLT_ROUNDS,	       		/* rounding */
55#ifdef Sudden_Underflow	/* unused, but correct anyway */
56		1
57#else
58		0
59#endif
60	};
61	int be, kind;
62	char *ret;
63	struct ieee_ext *p = (struct ieee_ext *)ld;
64	uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
65	void *vbits = bits;
66
67	/*
68	 * gdtoa doesn't know anything about the sign of the number, so
69	 * if the number is negative, we need to swap rounding modes of
70	 * 2 (upwards) and 3 (downwards).
71	 */
72	*sign = p->ext_sign;
73	fpi.rounding ^= (fpi.rounding >> 1) & p->ext_sign;
74
75	be = p->ext_exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
76	EXT_TO_ARRAY32(p, bits);
77
78	switch (fpclassify(*ld)) {
79	case FP_NORMAL:
80		kind = STRTOG_Normal;
81#ifdef EXT_IMPLICIT_NBIT
82		bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
83#endif /* EXT_IMPLICIT_NBIT */
84		break;
85	case FP_ZERO:
86		kind = STRTOG_Zero;
87		break;
88	case FP_SUBNORMAL:
89		kind = STRTOG_Denormal;
90		be++;
91		break;
92	case FP_INFINITE:
93		kind = STRTOG_Infinite;
94		break;
95	case FP_NAN:
96		kind = STRTOG_NaN;
97		break;
98	default:
99		abort();
100	}
101
102	ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve);
103	if (*decpt == -32768)
104		*decpt = INT_MAX;
105	return ret;
106}
107DEF_STRONG(__ldtoa);
108
109#else   /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
110
111char *
112__ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
113    char **rve)
114{
115	char *ret;
116
117	ret = dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
118	if (*decpt == 9999)
119		*decpt = INT_MAX;
120	return ret;
121}
122DEF_STRONG(__ldtoa);
123
124#endif  /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
125