1/* Copyright (C) 1997-2026 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18/*
19 * ISO C99 7.6: Floating-point environment <fenv.h>
20 */
21
22#ifndef _FENV_H
23#define _FENV_H 1
24
25#define __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION
26#include <bits/libc-header-start.h>
27
28/* Get the architecture dependent definitions. The following definitions
29 are expected to be done:
30
31 fenv_t type for object representing an entire floating-point
32 environment
33
34 FE_DFL_ENV macro of type pointer to fenv_t to be used as the argument
35 to functions taking an argument of type fenv_t; in this
36 case the default environment will be used
37
38 fexcept_t type for object representing the floating-point exception
39 flags including status associated with the flags
40
41 femode_t type for object representing floating-point control modes
42
43 FE_DFL_MODE macro of type pointer to const femode_t to be used as the
44 argument to fesetmode; in this case the default control
45 modes will be used
46
47 The following macros are defined iff the implementation supports this
48 kind of exception.
49 FE_INEXACT inexact result
50 FE_DIVBYZERO division by zero
51 FE_UNDERFLOW result not representable due to underflow
52 FE_OVERFLOW result not representable due to overflow
53 FE_INVALID invalid operation
54
55 FE_ALL_EXCEPT bitwise OR of all supported exceptions
56
57 The next macros are defined iff the appropriate rounding mode is
58 supported by the implementation.
59 FE_TONEAREST round to nearest
60 FE_UPWARD round toward +Inf
61 FE_DOWNWARD round toward -Inf
62 FE_TOWARDZERO round toward 0
63*/
64#include <bits/fenv.h>
65
66__BEGIN_DECLS
67
68#if __GLIBC_USE (ISOC23)
69# define __STDC_VERSION_FENV_H__ 202311L
70#endif
71
72/* Floating-point exception handling. */
73
74/* Clear the supported exceptions represented by EXCEPTS. */
75extern int feclearexcept (int __excepts) __THROW;
76
77/* Store implementation-defined representation of the exception flags
78 indicated by EXCEPTS in the object pointed to by FLAGP. */
79extern int fegetexceptflag (fexcept_t *__flagp, int __excepts) __THROW;
80
81/* Raise the supported exceptions represented by EXCEPTS. */
82extern int feraiseexcept (int __excepts) __THROW;
83
84#if __GLIBC_USE (IEC_60559_BFP_EXT_C23)
85/* Set the supported exception flags represented by EXCEPTS, without
86 causing enabled traps to be taken. */
87extern int fesetexcept (int __excepts) __THROW;
88#endif
89
90/* Set complete status for exceptions indicated by EXCEPTS according to
91 the representation in the object pointed to by FLAGP. */
92extern int fesetexceptflag (const fexcept_t *__flagp, int __excepts) __THROW;
93
94/* Determine which of subset of the exceptions specified by EXCEPTS are
95 currently set. */
96extern int fetestexcept (int __excepts) __THROW;
97
98#if __GLIBC_USE (IEC_60559_BFP_EXT_C23)
99/* Determine which of subset of the exceptions specified by EXCEPTS
100 are set in *FLAGP. */
101extern int fetestexceptflag (const fexcept_t *__flagp, int __excepts) __THROW;
102#endif
103
104
105/* Rounding control. */
106
107/* Get current rounding direction. */
108extern int fegetround (void) __THROW __attribute_pure__;
109
110/* Establish the rounding direction represented by ROUND. */
111extern int fesetround (int __rounding_direction) __THROW;
112
113
114/* Floating-point environment. */
115
116/* Store the current floating-point environment in the object pointed
117 to by ENVP. */
118extern int fegetenv (fenv_t *__envp) __THROW;
119
120/* Save the current environment in the object pointed to by ENVP, clear
121 exception flags and install a non-stop mode (if available) for all
122 exceptions. */
123extern int feholdexcept (fenv_t *__envp) __THROW;
124
125/* Establish the floating-point environment represented by the object
126 pointed to by ENVP. */
127extern int fesetenv (const fenv_t *__envp) __THROW;
128
129/* Save current exceptions in temporary storage, install environment
130 represented by object pointed to by ENVP and raise exceptions
131 according to saved exceptions. */
132extern int feupdateenv (const fenv_t *__envp) __THROW;
133
134
135/* Control modes. */
136
137#if __GLIBC_USE (IEC_60559_BFP_EXT_C23)
138/* Store the current floating-point control modes in the object
139 pointed to by MODEP. */
140extern int fegetmode (femode_t *__modep) __THROW;
141
142/* Establish the floating-point control modes represented by the
143 object pointed to by MODEP. */
144extern int fesetmode (const femode_t *__modep) __THROW;
145#endif
146
147
148/* NaN support. */
149
150#if (__GLIBC_USE (IEC_60559_BFP_EXT_C23) \
151 && defined FE_INVALID \
152 && defined __SUPPORT_SNAN__)
153# define FE_SNANS_ALWAYS_SIGNAL 1
154#endif
155
156#ifdef __USE_GNU
157
158/* Enable individual exceptions. Will not enable more exceptions than
159 EXCEPTS specifies. Returns the previous enabled exceptions if all
160 exceptions are successfully set, otherwise returns -1. */
161extern int feenableexcept (int __excepts) __THROW;
162
163/* Disable individual exceptions. Will not disable more exceptions than
164 EXCEPTS specifies. Returns the previous enabled exceptions if all
165 exceptions are successfully disabled, otherwise returns -1. */
166extern int fedisableexcept (int __excepts) __THROW;
167
168/* Return enabled exceptions. */
169extern int fegetexcept (void) __THROW;
170#endif
171
172__END_DECLS
173
174#endif /* fenv.h */
175