sysdeps/i386/fpu/feholdexcpt.c

   1 /* Store current floating-point environment and clear exceptions.
   2    Copyright (C) 1997-2024 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 __feholdexcept (fenv_t *envp)
  26 {
  27   /* Store the environment.  Recall that fnstenv has a side effect of
  28      masking all exceptions.  Then clear all exceptions.  */
  29   __asm__ volatile ("fnstenv %0; fnclex" : "=m" (*envp));
  30
  31   /* If the CPU supports SSE we set the MXCSR as well.  */
  32   if (CPU_FEATURE_USABLE (SSE))
  33     {
  34       unsigned int xwork;
  35
  36       /* Get the current control word.  */
  37       __asm__ ("stmxcsr %0" : "=m" (envp->__eip));
  38
  39       /* Set all exceptions to non-stop and clear them.  */
  40       xwork = (envp->__eip | 0x1f80) & ~0x3f;
  41
  42       __asm__ ("ldmxcsr %0" : : "m" (*&xwork));
  43     }
  44
  45   return 0;
  46 }
  47 libm_hidden_def (__feholdexcept)
  48 weak_alias (__feholdexcept, feholdexcept)
  49 libm_hidden_weak (feholdexcept)