1  /* Store current floating-point environment and clear exceptions.
       2     Copyright (C) 2000-2023 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 <string.h>
      21  
      22  int
      23  __feholdexcept (fenv_t *envp)
      24  {
      25    union { unsigned long long buf[4]; fenv_t env; } clear;
      26    unsigned long long *bufptr;
      27  
      28    /* Store the environment.  */
      29    bufptr = clear.buf;
      30    __asm__ (
      31  	   "fstd %%fr0,0(%1)\n"
      32  	   : "=m" (clear) : "r" (bufptr) : "%r0");
      33    memcpy (envp, &clear.env, sizeof (fenv_t));
      34  
      35    /* Clear exception queues */
      36    memset (clear.env.__exception, 0, sizeof (clear.env.__exception));
      37    /* And set all exceptions to non-stop.  */
      38    clear.env.__status_word &= ~FE_ALL_EXCEPT;
      39    /* Now clear all flags  */
      40    clear.env.__status_word &= ~(FE_ALL_EXCEPT << 27);
      41  
      42    /* Load the new environment. Note: fr0 must load last to enable T-bit.  */
      43    __asm__ (
      44  	   "fldd 0(%0),%%fr0\n"
      45  	   : : "r" (bufptr), "m" (clear) : "%r0");
      46  
      47    return 0;
      48  }
      49  
      50  libm_hidden_def (__feholdexcept)
      51  weak_alias (__feholdexcept, feholdexcept)
      52  libm_hidden_weak (feholdexcept)