libm/x86_64/fsetexcptflg.c

   1 /* Set floating-point environment exception handling.
   2    Copyright (C) 2001-2017 Free Software Foundation, Inc.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <fenv.h>
  19 #include <math.h>
  20
  21 int
  22 fesetexceptflag (const fexcept_t *flagp, int excepts)
  23 {
  24   fenv_t temp;
  25   unsigned int mxcsr;
  26
  27   /* XXX: Do we really need to set both the exception in both units?
  28      Shouldn't it be enough to set only the SSE unit?  */
  29
  30   /* Get the current x87 FPU environment.  We have to do this since we
  31      cannot separately set the status word.  */
  32   __asm__ ("fnstenv %0" : "=m" (*&temp));
  33
  34   temp.__status_word &= ~(excepts & FE_ALL_EXCEPT);
  35   temp.__status_word |= *flagp & excepts & FE_ALL_EXCEPT;
  36
  37   /* Store the new status word (along with the rest of the environment.
  38      Possibly new exceptions are set but they won't get executed unless
  39      the next floating-point instruction.  */
  40   __asm__ ("fldenv %0" : : "m" (*&temp));
  41
  42   /* And now the same for SSE.  */
  43   __asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
  44
  45   mxcsr &= ~(excepts & FE_ALL_EXCEPT);
  46   mxcsr |= *flagp & excepts & FE_ALL_EXCEPT;
  47
  48   __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
  49
  50   /* Success.  */
  51   return 0;
  52 }