1/* Install given floating-point environment and raise exceptions.
2 Copyright (C) 1997-2022 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#include <fpu_control.h>
21#include <arm-features.h>
22
23
24int
25__feupdateenv (const fenv_t *envp)
26{
27 fpu_control_t fpscr, new_fpscr, updated_fpscr;
28 int excepts;
29
30 /* Fail if a VFP unit isn't present. */
31 if (!ARM_HAVE_VFP)
32 return 1;
33
34 _FPU_GETCW (fpscr);
35 excepts = fpscr & FE_ALL_EXCEPT;
36
37 if ((envp != FE_DFL_ENV) && (envp != FE_NOMASK_ENV))
38 {
39 /* Merge current exception flags with the saved fenv. */
40 new_fpscr = envp->__cw | excepts;
41
42 /* Write new FPSCR if different (ignoring NZCV flags). */
43 if (((fpscr ^ new_fpscr) & ~_FPU_MASK_NZCV) != 0)
44 _FPU_SETCW (new_fpscr);
45
46 /* Raise the exceptions if enabled in the new FP state. */
47 if (excepts & (new_fpscr >> FE_EXCEPT_SHIFT))
48 return __feraiseexcept (excepts: excepts);
49
50 return 0;
51 }
52
53 /* Preserve the reserved FPSCR flags. */
54 new_fpscr = fpscr & (_FPU_RESERVED | FE_ALL_EXCEPT);
55 new_fpscr |= (envp == FE_DFL_ENV) ? _FPU_DEFAULT : _FPU_IEEE;
56
57 if (((new_fpscr ^ fpscr) & ~_FPU_MASK_NZCV) != 0)
58 {
59 _FPU_SETCW (new_fpscr);
60
61 /* Not all VFP architectures support trapping exceptions, so
62 test whether the relevant bits were set and fail if not. */
63 _FPU_GETCW (updated_fpscr);
64
65 if (new_fpscr & ~updated_fpscr)
66 return 1;
67 }
68
69 /* Raise the exceptions if enabled in the new FP state. */
70 if (excepts & (new_fpscr >> FE_EXCEPT_SHIFT))
71 return __feraiseexcept (excepts: excepts);
72
73 return 0;
74}
75libm_hidden_def (__feupdateenv)
76weak_alias (__feupdateenv, feupdateenv)
77libm_hidden_weak (feupdateenv)
78

source code of glibc/sysdeps/arm/feupdateenv.c