sysdeps/x86_64/fpu/feenablxcpt.c

   1 /* Enable floating-point exceptions.
   2    Copyright (C) 2001-2024 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
  21 int
  22 feenableexcept (int excepts)
  23 {
  24   unsigned short int new_exc, old_exc;
  25   unsigned int new;
  26
  27   excepts &= FE_ALL_EXCEPT;
  28
  29   /* Get the current control word of the x87 FPU.  */
  30   __asm__ ("fstcw %0" : "=m" (*&new_exc));
  31
  32   old_exc = (~new_exc) & FE_ALL_EXCEPT;
  33
  34   new_exc &= ~excepts;
  35   __asm__ ("fldcw %0" : : "m" (*&new_exc));
  36
  37   /* And now the same for the SSE MXCSR register.  */
  38   __asm__ ("stmxcsr %0" : "=m" (*&new));
  39
  40   /* The SSE exception masks are shifted by 7 bits.  */
  41   new &= ~(excepts << 7);
  42   __asm__ ("ldmxcsr %0" : : "m" (*&new));
  43
  44   return old_exc;
  45 }