sysdeps/x86_64/fpu/fclrexcpt.c

   1 /* Clear given exceptions in current floating-point environment.
   2    Copyright (C) 2001 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
  21 int
  22 feclearexcept (int excepts)
  23 {
  24   fenv_t temp;
  25   unsigned int mxcsr;
  26
  27   /* Mask out unsupported bits/exceptions.  */
  28   excepts &= FE_ALL_EXCEPT;
  29
  30   /* Bah, we have to clear selected exceptions.  Since there is no
  31      `fldsw' instruction we have to do it the hard way.  */
  32   __asm__ ("fnstenv %0" : "=m" (*&temp));
  33
  34   /* Clear the relevant bits.  */
  35   temp.__status_word &= excepts ^ FE_ALL_EXCEPT;
  36
  37   /* Put the new data in effect.  */
  38   __asm__ ("fldenv %0" : : "m" (*&temp));
  39
  40   /* And the same procedure for SSE.  */
  41   __asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
  42
  43   /* Clear the relevant bits.  */
  44   mxcsr &= ~excepts;
  45
  46   /* And put them into effect.  */
  47   __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
  48
  49   /* Success.  */
  50   return 0;
  51 }