sysdeps/arm/feenablxcpt.c

   1 /* Enable floating-point exceptions.
   2    Copyright (C) 2001-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Philip Blundell <philb@gnu.org>, 2001.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library.  If not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <fenv.h>
  21 #include <fpu_control.h>
  22 #include <arm-features.h>
  23
  24
  25 int
  26 feenableexcept (int excepts)
  27 {
  28   fpu_control_t fpscr, new_fpscr, updated_fpscr;
  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 &= FE_ALL_EXCEPT;
  36   new_fpscr = fpscr | (excepts << FE_EXCEPT_SHIFT);
  37
  38   if (new_fpscr != fpscr)
  39     {
  40       _FPU_SETCW (new_fpscr);
  41
  42       /* Not all VFP architectures support trapping exceptions, so
  43          test whether the relevant bits were set and fail if not.  */
  44       _FPU_GETCW (updated_fpscr);
  45
  46       if (new_fpscr & ~updated_fpscr)
  47         return -1;
  48     }
  49
  50   return (fpscr >> FE_EXCEPT_SHIFT) & FE_ALL_EXCEPT;
  51 }