1/* Header file for constants used in floating point <-> decimal conversions.
2 Copyright (C) 1995-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#ifndef _FPIOCONST_H
20#define _FPIOCONST_H
21
22#include <float.h>
23#include <math.h>
24#include <gmp.h>
25
26
27/* These values are used by __printf_fp, where they are noncritical (if the
28 value is not large enough, it will just be slower); and by
29 strtof/strtod/strtold, where it is critical (it's used for overflow
30 detection).
31
32 XXX These should be defined in <float.h>. For the time being, we have the
33 IEEE754 values here. */
34
35#if !defined __NO_LONG_DOUBLE_MATH && __LDBL_MAX_EXP__ > 1024
36# define LDBL_MAX_10_EXP_LOG 12 /* = floor(log_2(LDBL_MAX_10_EXP)) */
37#else
38# define LDBL_MAX_10_EXP_LOG 8 /* = floor(log_2(LDBL_MAX_10_EXP)) */
39#endif
40#define DBL_MAX_10_EXP_LOG 8 /* = floor(log_2(DBL_MAX_10_EXP)) */
41#define FLT_MAX_10_EXP_LOG 5 /* = floor(log_2(FLT_MAX_10_EXP)) */
42
43/* On some machines, _Float128 may be ABI-distinct from long double (e.g
44 IBM extended precision). */
45#include <bits/floatn.h>
46
47#if __HAVE_DISTINCT_FLOAT128
48# define FLT128_MAX_10_EXP_LOG 12 /* = floor(log_2(FLT128_MAX_10_EXP)) */
49#endif
50
51/* For strtold, we need powers of 10 up to floor (log_2 (LDBL_MANT_DIG
52 - LDBL_MIN_EXP + 2)). When _Float128 is enabled in libm and it is
53 ABI-distinct from long double (e.g. on powerpc64le), we also need powers
54 of 10 up to floor (log_2 (FLT128_MANT_DIG - FLT128_MIN_EXP + 2)). */
55#if (!defined __NO_LONG_DOUBLE_MATH && __LDBL_MAX_EXP__ > 1024) \
56 || __HAVE_DISTINCT_FLOAT128
57# define FPIOCONST_HAVE_EXTENDED_RANGE 1
58#else
59# define FPIOCONST_HAVE_EXTENDED_RANGE 0
60#endif
61
62#if FPIOCONST_HAVE_EXTENDED_RANGE
63# define FPIOCONST_POW10_ARRAY_SIZE 15
64#else
65# define FPIOCONST_POW10_ARRAY_SIZE 11
66#endif
67
68/* The array with the number representation. */
69extern const mp_limb_t __tens[] attribute_hidden;
70
71/* Table of powers of ten. This is used by __printf_fp and by
72 strtof/strtod/strtold. */
73struct mp_power
74 {
75 size_t arrayoff; /* Offset in `__tens'. */
76 mp_size_t arraysize; /* Size of the array. */
77 int p_expo; /* Exponent of the number 10^(2^i). */
78 int m_expo; /* Exponent of the number 10^-(2^i-1). */
79 };
80extern const struct mp_power _fpioconst_pow10[FPIOCONST_POW10_ARRAY_SIZE]
81 attribute_hidden;
82
83/* The constants in the array `_fpioconst_pow10' have an offset. */
84#if BITS_PER_MP_LIMB == 32
85# define _FPIO_CONST_OFFSET 2
86#else
87# define _FPIO_CONST_OFFSET 1
88#endif
89
90
91#endif /* fpioconst.h */
92