1/* Clear given exceptions in current floating-point environment.
2 Copyright (C) 2001-2022 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#include <fenv.h>
20
21int
22feclearexcept (int excepts)
23{
24 fenv_t temp;
25 unsigned int mxcsr;
26
27 /* Mask out unsupported bits/exceptions. */
28 excepts &= FE_ALL_EXCEPT;
29
30 /* Bah, we have to clear selected exceptions. Since there is no
31 `fldsw' instruction we have to do it the hard way. */
32 __asm__ ("fnstenv %0" : "=m" (*&temp));
33
34 /* Clear the relevant bits. */
35 temp.__status_word &= excepts ^ FE_ALL_EXCEPT;
36
37 /* Put the new data in effect. */
38 __asm__ ("fldenv %0" : : "m" (*&temp));
39
40 /* And the same procedure for SSE. */
41 __asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
42
43 /* Clear the relevant bits. */
44 mxcsr &= ~excepts;
45
46 /* And put them into effect. */
47 __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
48
49 /* Success. */
50 return 0;
51}
52libm_hidden_def (feclearexcept)
53

source code of glibc/sysdeps/x86_64/fpu/fclrexcpt.c