sysdeps/x86_64/fpu/fsetexcptflg.c

   1 /* Set floating-point environment exception handling.
   2    Copyright (C) 2001-2015 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 <math.h>
  21
  22 int
  23 fesetexceptflag (const fexcept_t *flagp, int excepts)
  24 {
  25   fenv_t temp;
  26   unsigned int mxcsr;
  27
  28   /* XXX: Do we really need to set both the exception in both units?
  29      Shouldn't it be enough to set only the SSE unit?  */
  30
  31   /* Get the current x87 FPU environment.  We have to do this since we
  32      cannot separately set the status word.  */
  33   __asm__ ("fnstenv %0" : "=m" (*&temp));
  34
  35   temp.__status_word &= ~(excepts & FE_ALL_EXCEPT);
  36   temp.__status_word |= *flagp & excepts & FE_ALL_EXCEPT;
  37
  38   /* Store the new status word (along with the rest of the environment.
  39      Possibly new exceptions are set but they won't get executed unless
  40      the next floating-point instruction.  */
  41   __asm__ ("fldenv %0" : : "m" (*&temp));
  42
  43   /* And now the same for SSE.  */
  44   __asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
  45
  46   mxcsr &= ~(excepts & FE_ALL_EXCEPT);
  47   mxcsr |= *flagp & excepts & FE_ALL_EXCEPT;
  48
  49   __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
  50
  51   /* Success.  */
  52   return 0;
  53 }