glibc/sysdeps/alpha/fpu/s_nearbyint.c

/* 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, see
   <http://www.gnu.org/licenses/>.  */

#include <math.h>
#include <math_ldbl_opt.h>

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

double
__nearbyint (double x)
{
  double two52 = copysign (0x1.0p52, x);
  double r;
  
  r = x + two52;
  r = r - two52;

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

weak_alias (__nearbyint, nearbyint)
#ifdef NO_LONG_DOUBLE
strong_alias (__nearbyint, __nearbyintl)
weak_alias (__nearbyint, nearbyintl)
#endif
#if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
compat_symbol (libm, __nearbyint, nearbyintl, GLIBC_2_1);
#endif