1  /* Copyright (C) 2001-2023 Free Software Foundation, Inc.
       2  
       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 License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     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 <fpu_control.h>
      21  
      22  int
      23  feenableexcept (int excepts)
      24  {
      25    fpu_control_t fpcr;
      26    fpu_control_t fpcr_new;
      27    fpu_control_t updated_fpcr;
      28  
      29    _FPU_GETCW (fpcr);
      30    excepts &= FE_ALL_EXCEPT;
      31    fpcr_new = fpcr | (excepts << FE_EXCEPT_SHIFT);
      32  
      33    if (fpcr != fpcr_new)
      34      {
      35        _FPU_SETCW (fpcr_new);
      36  
      37        /* Trapping exceptions are optional in AArch64; the relevant enable
      38  	 bits in FPCR are RES0 hence the absence of support can be detected
      39  	 by reading back the FPCR and comparing with the required value.  */
      40        _FPU_GETCW (updated_fpcr);
      41  
      42        if (fpcr_new & ~updated_fpcr)
      43  	return -1;
      44      }
      45  
      46    return (fpcr >> FE_EXCEPT_SHIFT) & FE_ALL_EXCEPT;
      47  }