1  /* Copyright (C) 2009-2023 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  __feupdateenv (const fenv_t *envp)
      24  {
      25    fpu_control_t fpcr;
      26    fpu_control_t fpcr_new;
      27    fpu_control_t updated_fpcr;
      28    fpu_fpsr_t fpsr;
      29    fpu_fpsr_t fpsr_new;
      30    int excepts;
      31  
      32    _FPU_GETCW (fpcr);
      33    _FPU_GETFPSR (fpsr);
      34    excepts = fpsr & FE_ALL_EXCEPT;
      35  
      36    if ((envp != FE_DFL_ENV) && (envp != FE_NOMASK_ENV))
      37      {
      38        fpcr_new = envp->__fpcr;
      39        fpsr_new = envp->__fpsr | excepts;
      40  
      41        if (fpcr != fpcr_new)
      42          _FPU_SETCW (fpcr_new);
      43  
      44        if (fpsr != fpsr_new)
      45          _FPU_SETFPSR (fpsr_new);
      46  
      47        if (excepts & (fpcr_new >> FE_EXCEPT_SHIFT))
      48          return __feraiseexcept (excepts);
      49  
      50        return 0;
      51      }
      52  
      53    fpcr_new = fpcr & _FPU_RESERVED;
      54    fpsr_new = fpsr & (_FPU_FPSR_RESERVED | FE_ALL_EXCEPT);
      55  
      56    if (envp == FE_DFL_ENV)
      57      {
      58        fpcr_new |= _FPU_DEFAULT;
      59        fpsr_new |= _FPU_FPSR_DEFAULT;
      60      }
      61    else
      62      {
      63        fpcr_new |= _FPU_FPCR_IEEE;
      64        fpsr_new |= _FPU_FPSR_IEEE;
      65      }
      66  
      67    _FPU_SETFPSR (fpsr_new);
      68  
      69    if (fpcr != fpcr_new)
      70      {
      71        _FPU_SETCW (fpcr_new);
      72  
      73        /* Trapping exceptions are optional in AArch64; the relevant enable
      74  	 bits in FPCR are RES0 hence the absence of support can be detected
      75  	 by reading back the FPCR and comparing with the required value.  */
      76        _FPU_GETCW (updated_fpcr);
      77  
      78        if (fpcr_new & ~updated_fpcr)
      79          return 1;
      80      }
      81  
      82    if (excepts & (fpcr_new >> FE_EXCEPT_SHIFT))
      83      return __feraiseexcept (excepts);
      84  
      85    return 0;
      86  }
      87  libm_hidden_def (__feupdateenv)
      88  weak_alias (__feupdateenv, feupdateenv)
      89  libm_hidden_weak (feupdateenv)