1  /* Set current rounding direction.
       2     Copyright (C) 2000-2023 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  
      21  int
      22  __fesetround (int round)
      23  {
      24    union { unsigned long long l; unsigned int sw[2]; } s;
      25  
      26    if (round & ~FE_DOWNWARD)
      27      /* round is not a valid rounding mode. */
      28      return 1;
      29  
      30    /* Get the current status word. */
      31    __asm__ ("fstd %%fr0,0(%1)" : "=m" (s.l) : "r" (&s.l) : "%r0");
      32    s.sw[0] &= ~FE_DOWNWARD;
      33    s.sw[0] |= round & FE_DOWNWARD;
      34    __asm__ ("fldd 0(%0),%%fr0" : : "r" (&s.l), "m" (s.l) : "%r0");
      35  
      36    return 0;
      37  }
      38  
      39  libm_hidden_def (__fesetround)
      40  weak_alias (__fesetround, fesetround)
      41  libm_hidden_weak (fesetround)