1  /* Copyright (C) 1997-2023 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  __fesetenv (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  
      31    _FPU_GETCW (fpcr);
      32  
      33    if ((envp != FE_DFL_ENV) && (envp != FE_NOMASK_ENV))
      34      {
      35        /* The new FPCR/FPSR are valid, so don't merge the reserved flags.  */
      36        fpcr_new = envp->__fpcr;
      37  
      38        if (fpcr != fpcr_new)
      39  	_FPU_SETCW (fpcr_new);
      40  
      41        _FPU_SETFPSR (envp->__fpsr);
      42        return 0;
      43      }
      44  
      45    _FPU_GETFPSR (fpsr);
      46    fpcr_new = fpcr & _FPU_RESERVED;
      47    fpsr_new = fpsr & _FPU_FPSR_RESERVED;
      48  
      49    if (envp == FE_DFL_ENV)
      50      {
      51        fpcr_new |= _FPU_DEFAULT;
      52        fpsr_new |= _FPU_FPSR_DEFAULT;
      53      }
      54    else
      55      {
      56        fpcr_new |= _FPU_FPCR_IEEE;
      57        fpsr_new |= _FPU_FPSR_IEEE;
      58      }
      59  
      60    _FPU_SETFPSR (fpsr_new);
      61  
      62    if (fpcr != fpcr_new)
      63      {
      64        _FPU_SETCW (fpcr_new);
      65  
      66        /* Trapping exceptions are optional in AArch64; the relevant enable
      67  	 bits in FPCR are RES0 hence the absence of support can be detected
      68  	 by reading back the FPCR and comparing with the required value.  */
      69        _FPU_GETCW (updated_fpcr);
      70  
      71        return fpcr_new & ~updated_fpcr;
      72      }
      73  
      74    return 0;
      75  }
      76  libm_hidden_def (__fesetenv)
      77  weak_alias (__fesetenv, fesetenv)
      78  libm_hidden_weak (fesetenv)