1  /* Install given floating-point environment and raise exceptions.
       2     Copyright (C) 1997-2023 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  __feupdateenv (const fenv_t *envp)
      26  {
      27    fpu_control_t fpscr, new_fpscr, updated_fpscr;
      28    int excepts;
      29  
      30    /* Fail if a VFP unit isn't present.  */
      31    if (!ARM_HAVE_VFP)
      32      return 1;
      33  
      34    _FPU_GETCW (fpscr);
      35    excepts = fpscr & FE_ALL_EXCEPT;
      36  
      37    if ((envp != FE_DFL_ENV) && (envp != FE_NOMASK_ENV))
      38      {
      39        /* Merge current exception flags with the saved fenv.  */
      40        new_fpscr = envp->__cw | excepts;
      41  
      42        /* Write new FPSCR if different (ignoring NZCV flags).  */
      43        if (((fpscr ^ new_fpscr) & ~_FPU_MASK_NZCV) != 0)
      44  	_FPU_SETCW (new_fpscr);
      45  
      46        /* Raise the exceptions if enabled in the new FP state.  */
      47        if (excepts & (new_fpscr >> FE_EXCEPT_SHIFT))
      48  	return __feraiseexcept (excepts);
      49  
      50        return 0;
      51      }
      52  
      53    /* Preserve the reserved FPSCR flags.  */
      54    new_fpscr = fpscr & (_FPU_RESERVED | FE_ALL_EXCEPT);
      55    new_fpscr |= (envp == FE_DFL_ENV) ? _FPU_DEFAULT : _FPU_IEEE;
      56  
      57    if (((new_fpscr ^ fpscr) & ~_FPU_MASK_NZCV) != 0)
      58      {
      59        _FPU_SETCW (new_fpscr);
      60  
      61        /* Not all VFP architectures support trapping exceptions, so
      62  	 test whether the relevant bits were set and fail if not.  */
      63        _FPU_GETCW (updated_fpscr);
      64  
      65        if (new_fpscr & ~updated_fpscr)
      66  	return 1;
      67      }
      68  
      69    /* Raise the exceptions if enabled in the new FP state.  */
      70    if (excepts & (new_fpscr >> FE_EXCEPT_SHIFT))
      71      return __feraiseexcept (excepts);
      72  
      73    return 0;
      74  }
      75  libm_hidden_def (__feupdateenv)
      76  weak_alias (__feupdateenv, feupdateenv)
      77  libm_hidden_weak (feupdateenv)