1 /* Copyright (C) 2009-2021 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
__feupdateenv(const fenv_t * envp)23 __feupdateenv (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   int excepts;
31 
32   _FPU_GETCW (fpcr);
33   _FPU_GETFPSR (fpsr);
34   excepts = fpsr & FE_ALL_EXCEPT;
35 
36   if ((envp != FE_DFL_ENV) && (envp != FE_NOMASK_ENV))
37     {
38       fpcr_new = envp->__fpcr;
39       fpsr_new = envp->__fpsr | excepts;
40 
41       if (fpcr != fpcr_new)
42         _FPU_SETCW (fpcr_new);
43 
44       if (fpsr != fpsr_new)
45         _FPU_SETFPSR (fpsr_new);
46 
47       if (excepts & (fpcr_new >> FE_EXCEPT_SHIFT))
48         return __feraiseexcept (excepts);
49 
50       return 0;
51     }
52 
53   fpcr_new = fpcr & _FPU_RESERVED;
54   fpsr_new = fpsr & (_FPU_FPSR_RESERVED | FE_ALL_EXCEPT);
55 
56   if (envp == FE_DFL_ENV)
57     {
58       fpcr_new |= _FPU_DEFAULT;
59       fpsr_new |= _FPU_FPSR_DEFAULT;
60     }
61   else
62     {
63       fpcr_new |= _FPU_FPCR_IEEE;
64       fpsr_new |= _FPU_FPSR_IEEE;
65     }
66 
67   _FPU_SETFPSR (fpsr_new);
68 
69   if (fpcr != fpcr_new)
70     {
71       _FPU_SETCW (fpcr_new);
72 
73       /* Trapping exceptions are optional in AArch64; the relevant enable
74 	 bits in FPCR are RES0 hence the absence of support can be detected
75 	 by reading back the FPCR and comparing with the required value.  */
76       _FPU_GETCW (updated_fpcr);
77 
78       if (fpcr_new & ~updated_fpcr)
79         return 1;
80     }
81 
82   if (excepts & (fpcr_new >> FE_EXCEPT_SHIFT))
83     return __feraiseexcept (excepts);
84 
85   return 0;
86 }
87 libm_hidden_def (__feupdateenv)
88 weak_alias (__feupdateenv, feupdateenv)
89 libm_hidden_weak (feupdateenv)
90