1  /* Store current floating-point environment and clear exceptions.
       2     Copyright (C) 1997-2023 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)