1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2003 David Schultz <das@FreeBSD.ORG>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <float.h>
30 #include <inttypes.h>
31 #include <limits.h>
32 #include <math.h>
33 #include <stdlib.h>
34 #include "../stdio/floatio.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 */
45 char *
__ldtoa(long double * ld,int mode,int ndigits,int * decpt,int * sign,char ** rve)46 __ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
47 char **rve)
48 {
49 FPI fpi = {
50 LDBL_MANT_DIG, /* nbits */
51 LDBL_MIN_EXP - LDBL_MANT_DIG, /* emin */
52 LDBL_MAX_EXP - LDBL_MANT_DIG, /* emax */
53 FLT_ROUNDS, /* 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 void *vbits = bits;
65
66 u.e = *ld;
67
68 /*
69 * gdtoa doesn't know anything about the sign of the number, so
70 * if the number is negative, we need to swap rounding modes of
71 * 2 (upwards) and 3 (downwards).
72 */
73 *sign = u.bits.sign;
74 fpi.rounding ^= (fpi.rounding >> 1) & u.bits.sign;
75
76 be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
77 LDBL_TO_ARRAY32(u, bits);
78
79 switch (fpclassify(u.e)) {
80 case FP_NORMAL:
81 kind = STRTOG_Normal;
82 #ifdef LDBL_IMPLICIT_NBIT
83 bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
84 #endif /* LDBL_IMPLICIT_NBIT */
85 break;
86 case FP_ZERO:
87 kind = STRTOG_Zero;
88 break;
89 case FP_SUBNORMAL:
90 kind = STRTOG_Denormal;
91 be++;
92 break;
93 case FP_INFINITE:
94 kind = STRTOG_Infinite;
95 break;
96 case FP_NAN:
97 kind = STRTOG_NaN;
98 break;
99 default:
100 abort();
101 }
102
103 ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve);
104 if (*decpt == -32768)
105 *decpt = INT_MAX;
106 return ret;
107 }
108