1  /* Set floating-point environment exception handling.
       2     Copyright (C) 2001-2023 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 <math.h>
      21  
      22  int
      23  fesetexceptflag (const fexcept_t *flagp, int excepts)
      24  {
      25    fenv_t temp;
      26    unsigned int mxcsr;
      27  
      28    /* XXX: Do we really need to set both the exception in both units?
      29       Shouldn't it be enough to set only the SSE unit?  */
      30  
      31    /* Get the current x87 FPU environment.  We have to do this since we
      32       cannot separately set the status word.  */
      33    __asm__ ("fnstenv %0" : "=m" (*&temp));
      34  
      35    temp.__status_word &= ~(excepts & FE_ALL_EXCEPT);
      36    temp.__status_word |= *flagp & excepts & FE_ALL_EXCEPT;
      37  
      38    /* Store the new status word (along with the rest of the environment.
      39       Possibly new exceptions are set but they won't get executed unless
      40       the next floating-point instruction.  */
      41    __asm__ ("fldenv %0" : : "m" (*&temp));
      42  
      43    /* And now the same for SSE.  */
      44    __asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
      45  
      46    mxcsr &= ~(excepts & FE_ALL_EXCEPT);
      47    mxcsr |= *flagp & excepts & FE_ALL_EXCEPT;
      48  
      49    __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
      50  
      51    /* Success.  */
      52    return 0;
      53  }