sysdeps/i386/fpu/fedisblxcpt.c

   1 /* Disable floating-point exceptions.
   2    Copyright (C) 1999-2024 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <fenv.h>
  20 #include <unistd.h>
  21 #include <ldsodefs.h>
  22 #include <dl-procinfo.h>
  23
  24 int
  25 fedisableexcept (int excepts)
  26 {
  27   unsigned short int new_exc, old_exc;
  28
  29   /* Get the current control word.  */
  30   __asm__ ("fstcw %0" : "=m" (*&new_exc));
  31
  32   old_exc = (~new_exc) & FE_ALL_EXCEPT;
  33
  34   excepts &= FE_ALL_EXCEPT;
  35
  36   new_exc |= excepts;
  37   __asm__ ("fldcw %0" : : "m" (*&new_exc));
  38
  39   /* If the CPU supports SSE we set the MXCSR as well.  */
  40   if (CPU_FEATURE_USABLE (SSE))
  41     {
  42       unsigned int xnew_exc;
  43
  44       /* Get the current control word.  */
  45       __asm__ ("stmxcsr %0" : "=m" (*&xnew_exc));
  46
  47       xnew_exc |= excepts << 7;
  48
  49       __asm__ ("ldmxcsr %0" : : "m" (*&xnew_exc));
  50     }
  51
  52   return old_exc;
  53 }