s_nearbyintf.c

来自「glibc 2.9,最新版的C语言库函数」· C语言 代码 · 共 41 行

/* Copyright (C) 2007 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Richard Henderson.

   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 <math.h>

#ifdef _IEEE_FP_INEXACT
#error "Don't compile with -mieee-with-inexact"
#endif

float
__nearbyintf (float x)
{
  float two23 = copysignf (0x1.0p23, x);
  float r;

  r = x + two23;
  r = r - two23;

  /* nearbyint(-0.1) == -0, and in general we'll always have the same sign
     as our input.  */
  return copysign (r, x);
}

weak_alias (__nearbyintf, nearbyintf)