1  /* Install given floating-point environment.
       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_libc.h>
      20  
      21  int
      22  __fesetenv (const fenv_t *envp)
      23  {
      24    unsigned long int fpcr;
      25    fenv_t env;
      26  
      27    /* Magic encoding of default values: high bit set (never possible for a
      28       user-space address) is not indirect.  And we don't even have to get
      29       rid of it since we mask things around just below.  */
      30    if ((long int) envp >= 0)
      31      env = *envp;
      32    else
      33      env = (unsigned long int) envp;
      34  
      35    /* Reset the rounding mode with the hardware fpcr.  Note that the following
      36       system call is an implied trap barrier for our modification.  */
      37    __asm__ __volatile__ ("excb; mf_fpcr %0" : "=f" (fpcr));
      38    fpcr = (fpcr & ~FPCR_ROUND_MASK) | (env & FPCR_ROUND_MASK);
      39    __asm__ __volatile__ ("mt_fpcr %0" : : "f" (fpcr));
      40  
      41    /* Reset the exception status and mask with the kernel's FP code.  */
      42    __ieee_set_fp_control (env & SWCR_ALL_MASK);
      43  
      44    /* Success.  */
      45    return 0;
      46  }
      47  
      48  #include <shlib-compat.h>
      49  #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
      50  strong_alias (__fesetenv, __old_fesetenv)
      51  compat_symbol (libm, __old_fesetenv, fesetenv, GLIBC_2_1);
      52  #endif
      53  
      54  libm_hidden_def (__fesetenv)
      55  libm_hidden_ver (__fesetenv, fesetenv)
      56  versioned_symbol (libm, __fesetenv, fesetenv, GLIBC_2_2);