1  /* Install given floating-point environment.
       2     Copyright (C) 2004-2023 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 <fpu_control.h>
      21  #include <arm-features.h>
      22  
      23  
      24  int
      25  __fesetenv (const fenv_t *envp)
      26  {
      27    fpu_control_t fpscr, new_fpscr, updated_fpscr;
      28  
      29    /* Fail if a VFP unit isn't present.  */
      30    if (!ARM_HAVE_VFP)
      31      return 1;
      32  
      33    _FPU_GETCW (fpscr);
      34  
      35    if ((envp != FE_DFL_ENV) && (envp != FE_NOMASK_ENV))
      36      {
      37        /* The new FPSCR is valid, so don't merge the reserved flags.  */
      38        new_fpscr = envp->__cw;
      39  
      40        /* Write new FPSCR if different (ignoring NZCV flags).  */
      41        if (((fpscr ^ new_fpscr) & ~_FPU_MASK_NZCV) != 0)
      42  	_FPU_SETCW (new_fpscr);
      43  
      44        return 0;
      45      }
      46  
      47    /* Preserve the reserved FPSCR flags.  */
      48    new_fpscr = fpscr & _FPU_RESERVED;
      49    new_fpscr |= (envp == FE_DFL_ENV) ? _FPU_DEFAULT : _FPU_IEEE;
      50  
      51    if (((new_fpscr ^ fpscr) & ~_FPU_MASK_NZCV) != 0)
      52      {
      53        _FPU_SETCW (new_fpscr);
      54  
      55        /* Not all VFP architectures support trapping exceptions, so
      56  	 test whether the relevant bits were set and fail if not.  */
      57        _FPU_GETCW (updated_fpscr);
      58  
      59        return new_fpscr & ~updated_fpscr;
      60      }
      61  
      62    return 0;
      63  }
      64  libm_hidden_def (__fesetenv)
      65  weak_alias (__fesetenv, fesetenv)
      66  libm_hidden_weak (fesetenv)