glibc/sysdeps/libm-ieee754/s_lrintl.c

/* Round argument to nearest integral value according to current rounding
   direction.
   Copyright (C) 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

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

#include <math.h>

#include "math_private.h"

static const long double two63[2] =
{
  9.223372036854775808000000e+18, /* 0x403E, 0x00000000, 0x00000000 */
 -9.223372036854775808000000e+18  /* 0xC03E, 0x00000000, 0x00000000 */
};


long int
__lrintl (long double x)
{
  int32_t se,j0;
  u_int32_t i0, i1;
  long int result;
  volatile long double w;
  long double t;
  int sx;

  GET_LDOUBLE_WORDS (se, i0, i1, x);

  sx = (se >> 15) & 1;
  j0 = (se & 0x7fff) - 0x3fff;

  if (j0 < 31)
    {
      if (j0 < -1)
	return 0;
      else
	{
	  w = two63[sx] + x;
	  t = w - two63[sx];
	  GET_LDOUBLE_WORDS (se, i0, i1, t);
	  j0 = (se & 0x7fff) - 0x3fff;

	  result = i0 >> (31 - j0);
	}
    }
  else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
    {
      if (j0 >= 63)
	result = ((long int) i0 << (j0 - 31)) | (i1 << (j0 - 63));
      else
	{
	  w = two63[sx] + x;
	  t = w - two63[sx];
	  GET_LDOUBLE_WORDS (se, i0, i1, t);
	  j0 = (se & 0x7fff) - 0x3fff;

	  result = ((long int) i0 << (j0 - 31)) | (i1 >> (63 - j0));
	}
    }
  else
    {
      /* The number is too large.  It is left implementation defined
	 what happens.  */
      return (long int) x;
    }

  return sx ? -result : result;
}

weak_alias (__lrintl, lrintl)