1 /* Copyright (C) 1997-2021 Free Software Foundation, Inc.
2 
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 License as
7    published by the Free Software Foundation; either version 2.1 of the
8    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 
22 int
__fesetenv(const fenv_t * envp)23 __fesetenv (const fenv_t *envp)
24 {
25   fpu_control_t fpcr;
26   fpu_control_t fpcr_new;
27   fpu_control_t updated_fpcr;
28   fpu_fpsr_t fpsr;
29   fpu_fpsr_t fpsr_new;
30 
31   _FPU_GETCW (fpcr);
32 
33   if ((envp != FE_DFL_ENV) && (envp != FE_NOMASK_ENV))
34     {
35       /* The new FPCR/FPSR are valid, so don't merge the reserved flags.  */
36       fpcr_new = envp->__fpcr;
37 
38       if (fpcr != fpcr_new)
39 	_FPU_SETCW (fpcr_new);
40 
41       _FPU_SETFPSR (envp->__fpsr);
42       return 0;
43     }
44 
45   _FPU_GETFPSR (fpsr);
46   fpcr_new = fpcr & _FPU_RESERVED;
47   fpsr_new = fpsr & _FPU_FPSR_RESERVED;
48 
49   if (envp == FE_DFL_ENV)
50     {
51       fpcr_new |= _FPU_DEFAULT;
52       fpsr_new |= _FPU_FPSR_DEFAULT;
53     }
54   else
55     {
56       fpcr_new |= _FPU_FPCR_IEEE;
57       fpsr_new |= _FPU_FPSR_IEEE;
58     }
59 
60   _FPU_SETFPSR (fpsr_new);
61 
62   if (fpcr != fpcr_new)
63     {
64       _FPU_SETCW (fpcr_new);
65 
66       /* Trapping exceptions are optional in AArch64; the relevant enable
67 	 bits in FPCR are RES0 hence the absence of support can be detected
68 	 by reading back the FPCR and comparing with the required value.  */
69       _FPU_GETCW (updated_fpcr);
70 
71       return fpcr_new & ~updated_fpcr;
72     }
73 
74   return 0;
75 }
76 libm_hidden_def (__fesetenv)
77 weak_alias (__fesetenv, fesetenv)
78 libm_hidden_weak (fesetenv)
79