sysdeps/i386/fpu/feenablxcpt.c

   1 /* Enable floating-point exceptions.
   2    Copyright (C) 1999, 2000, 2003, 2004 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Andreas Jaeger <aj@suse.de>, 1999.
   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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <fenv.h>
  22 #include <unistd.h>
  23 #include <ldsodefs.h>
  24 #include <dl-procinfo.h>
  25
  26 int
  27 feenableexcept (int excepts)
  28 {
  29   unsigned short int new_exc;
  30   unsigned short int old_exc;
  31
  32   /* Get the current control word.  */
  33   __asm__ ("fstcw %0" : "=m" (*&new_exc));
  34
  35   excepts &= FE_ALL_EXCEPT;
  36   old_exc = (~new_exc) & FE_ALL_EXCEPT;
  37
  38   new_exc &= ~excepts;
  39   __asm__ ("fldcw %0" : : "m" (*&new_exc));
  40
  41   /* If the CPU supports SSE we set the MXCSR as well.  */
  42   if ((GLRO(dl_hwcap) & HWCAP_I386_XMM) != 0)
  43     {
  44       unsigned int xnew_exc;
  45
  46       /* Get the current control word.  */
  47       __asm__ ("stmxcsr %0" : "=m" (*&xnew_exc));
  48
  49       xnew_exc &= ~(excepts << 7);
  50
  51       __asm__ ("ldmxcsr %0" : : "m" (*&xnew_exc));
  52     }
  53
  54   return old_exc;
  55 }