sysdeps/x86_64/fpu/fsetexcptflg.c

   1 /* Set floating-point environment exception handling.
   2    Copyright (C) 2001, 2003 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <fenv.h>
  21 #include <math.h>
  22
  23 int
  24 fesetexceptflag (const fexcept_t *flagp, int excepts)
  25 {
  26   fenv_t temp;
  27   unsigned int mxcsr;
  28
  29   /* XXX: Do we really need to set both the exception in both units?
  30      Shouldn't it be enough to set only the SSE unit?  */
  31
  32   /* Get the current x87 FPU environment.  We have to do this since we
  33      cannot separately set the status word.  */
  34   __asm__ ("fnstenv %0" : "=m" (*&temp));
  35
  36   temp.__status_word &= ~(excepts & FE_ALL_EXCEPT);
  37   temp.__status_word |= *flagp & excepts & FE_ALL_EXCEPT;
  38
  39   /* Store the new status word (along with the rest of the environment.
  40      Possibly new exceptions are set but they won't get executed unless
  41      the next floating-point instruction.  */
  42   __asm__ ("fldenv %0" : : "m" (*&temp));
  43
  44   /* And now the same for SSE.  */
  45   __asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
  46
  47   mxcsr &= ~(excepts & FE_ALL_EXCEPT);
  48   mxcsr |= *flagp & excepts & FE_ALL_EXCEPT;
  49
  50   __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
  51
  52   /* Success.  */
  53   return 0;
  54 }