fesetround.c

来自「Glibc 2.3.2源代码(解压后有100多M)」· C语言 代码 · 共 44 行

/* Set current rounding direction.
   Copyright (C) 1998 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Andreas Jaeger <[e-mail]>, 1998.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <fenv.h>
#include <fpu_control.h>

int
fesetround (int round)
{
  unsigned short int cw;

  if ((round & ~0x3) != 0)
    /* ROUND is no valid rounding mode.  */
    return 1;

  /* Get current state.  */
  _FPU_GETCW (cw);

  /* Set rounding bits.  */
  cw &= ~0x3;
  cw |= round;
  /* Set new state.  */
  _FPU_SETCW (cw);

  return 0;
}