sysdeps/arm/fesetenv.c

   1 /* Install given floating-point environment.
   2    Copyright (C) 2004-2017 Free Software Foundation, Inc.
   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
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <fenv.h>
  20 #include <fpu_control.h>
  21 #include <arm-features.h>
  22
  23
  24 int
  25 __fesetenv (const fenv_t *envp)
  26 {
  27   fpu_control_t fpscr, new_fpscr, updated_fpscr;
  28
  29   /* Fail if a VFP unit isn't present.  */
  30   if (!ARM_HAVE_VFP)
  31     return 1;
  32
  33   _FPU_GETCW (fpscr);
  34
  35   if ((envp != FE_DFL_ENV) && (envp != FE_NOMASK_ENV))
  36     {
  37       /* The new FPSCR is valid, so don't merge the reserved flags.  */
  38       new_fpscr = envp->__cw;
  39
  40       /* Write new FPSCR if different (ignoring NZCV flags).  */
  41       if (((fpscr ^ new_fpscr) & ~_FPU_MASK_NZCV) != 0)
  42         _FPU_SETCW (new_fpscr);
  43
  44       return 0;
  45     }
  46
  47   /* Preserve the reserved FPSCR flags.  */
  48   new_fpscr = fpscr & _FPU_RESERVED;
  49   new_fpscr |= (envp == FE_DFL_ENV) ? _FPU_DEFAULT : _FPU_IEEE;
  50
  51   if (((new_fpscr ^ fpscr) & ~_FPU_MASK_NZCV) != 0)
  52     {
  53       _FPU_SETCW (new_fpscr);
  54
  55       /* Not all VFP architectures support trapping exceptions, so
  56          test whether the relevant bits were set and fail if not.  */
  57       _FPU_GETCW (updated_fpscr);
  58
  59       return new_fpscr & ~updated_fpscr;
  60     }
  61
  62   return 0;
  63 }
  64 libm_hidden_def (__fesetenv)
  65 weak_alias (__fesetenv, fesetenv)
  66 libm_hidden_weak (fesetenv)