sysdeps/aarch64/fpu/feupdateenv.c

   1 /* Copyright (C) 2009-2023 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
  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)