sysdeps/x86_64/fpu/feenablxcpt.c

   1 /* Enable floating-point exceptions.
   2    Copyright (C) 2001-2013 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Andreas Jaeger <aj@suse.de>, 2001.
   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
  22 int
  23 feenableexcept (int excepts)
  24 {
  25   unsigned short int new_exc, old_exc;
  26   unsigned int new;
  27
  28   excepts &= FE_ALL_EXCEPT;
  29
  30   /* Get the current control word of the x87 FPU.  */
  31   __asm__ ("fstcw %0" : "=m" (*&new_exc));
  32
  33   old_exc = (~new_exc) & FE_ALL_EXCEPT;
  34
  35   new_exc &= ~excepts;
  36   __asm__ ("fldcw %0" : : "m" (*&new_exc));
  37
  38   /* And now the same for the SSE MXCSR register.  */
  39   __asm__ ("stmxcsr %0" : "=m" (*&new));
  40
  41   /* The SSE exception masks are shifted by 7 bits.  */
  42   new &= ~(excepts << 7);
  43   __asm__ ("ldmxcsr %0" : : "m" (*&new));
  44
  45   return old_exc;
  46 }