sysdeps/arm/feupdateenv.c

   1 /* Install given floating-point environment and raise exceptions.
   2    Copyright (C) 1997-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   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 feupdateenv (const fenv_t *envp)
  27 {
  28   fpu_control_t fpscr, new_fpscr, updated_fpscr;
  29   int excepts;
  30
  31   /* Fail if a VFP unit isn't present.  */
  32   if (!ARM_HAVE_VFP)
  33     return 1;
  34
  35   _FPU_GETCW (fpscr);
  36   excepts = fpscr & FE_ALL_EXCEPT;
  37
  38   if ((envp != FE_DFL_ENV) && (envp != FE_NOMASK_ENV))
  39     {
  40       /* Merge current exception flags with the saved fenv.  */
  41       new_fpscr = envp->__cw | excepts;
  42
  43       /* Write new FPSCR if different (ignoring NZCV flags).  */
  44       if (((fpscr ^ new_fpscr) & ~_FPU_MASK_NZCV) != 0)
  45         _FPU_SETCW (new_fpscr);
  46
  47       /* Raise the exceptions if enabled in the new FP state.  */
  48       if (excepts & (new_fpscr >> FE_EXCEPT_SHIFT))
  49         return __feraiseexcept (excepts);
  50
  51       return 0;
  52     }
  53
  54   /* Preserve the reserved FPSCR flags.  */
  55   new_fpscr = fpscr & (_FPU_RESERVED | FE_ALL_EXCEPT);
  56   new_fpscr |= (envp == FE_DFL_ENV) ? _FPU_DEFAULT : _FPU_IEEE;
  57
  58   if (((new_fpscr ^ fpscr) & ~_FPU_MASK_NZCV) != 0)
  59     {
  60       _FPU_SETCW (new_fpscr);
  61
  62       /* Not all VFP architectures support trapping exceptions, so
  63          test whether the relevant bits were set and fail if not.  */
  64       _FPU_GETCW (updated_fpscr);
  65
  66       if (new_fpscr & ~updated_fpscr)
  67         return 1;
  68     }
  69
  70   /* Raise the exceptions if enabled in the new FP state.  */
  71   if (excepts & (new_fpscr >> FE_EXCEPT_SHIFT))
  72     return __feraiseexcept (excepts);
  73
  74   return 0;
  75 }
  76 libm_hidden_def (feupdateenv)