sysdeps/i386/fpu/feholdexcpt.c

   1 /* Store current floating-point environment and clear exceptions.
   2    Copyright (C) 1997, 1999, 2003, 2004, 2005, 2007
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #include <fenv.h>
  22 #include <unistd.h>
  23 #include <ldsodefs.h>
  24 #include <dl-procinfo.h>
  25
  26 int
  27 feholdexcept (fenv_t *envp)
  28 {
  29   fenv_t temp;
  30
  31   /* Store the environment.  */
  32   __asm__ ("fnstenv %0" : "=m" (temp));
  33   *envp = temp;
  34
  35   /* Now set all exceptions to non-stop.  */
  36   temp.__control_word |= 0x3f;
  37
  38   /* And clear all exceptions.  */
  39   temp.__status_word &= ~0x3f;
  40
  41   __asm__ ("fldenv %0" : : "m" (temp));
  42
  43   /* If the CPU supports SSE we set the MXCSR as well.  */
  44   if ((GLRO(dl_hwcap) & HWCAP_I386_XMM) != 0)
  45     {
  46       unsigned int xwork;
  47
  48       /* Get the current control word.  */
  49       __asm__ ("stmxcsr %0" : "=m" (*&xwork));
  50
  51       /* Set all exceptions to non-stop and clear them.  */
  52       xwork = (xwork | 0x1f80) & ~0x3f;
  53
  54       __asm__ ("ldmxcsr %0" : : "m" (*&xwork));
  55     }
  56
  57   return 0;
  58 }
  59 libm_hidden_def (feholdexcept)