/* @(#)s_rint.c 5.1 93/09/24 */

/*

 * ====================================================

 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

 *

 * Developed at SunPro, a Sun Microsystems, Inc. business.

 * Permission to use, copy, modify, and distribute this

 * software is freely granted, provided that this notice

 * is preserved.

 * ====================================================

 */

/*

 * rint(x)

 * Return x rounded to integral value according to the prevailing

 * rounding mode.

 * Method:

 *	Using floating addition.

 * Exception:

 *	Inexact flag raised if x not equal to rint(x).

 */

#include <math.h>

#include <math_private.h>

#include <libm-alias-double.h>

static const double

  TWO52[2] = {

  4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */

 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */

};

double

__rint (double x)

{

  int32_t i0, j0, sx;

  double w, t;

  GET_HIGH_WORD (i0, x);

  sx = (i0 >> 31) & 1;

  j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;

  if (j0 < 52)

    {

      if (j0 < 0)

	{

	  w = TWO52[sx] + x;

	  t = w - TWO52[sx];

	  GET_HIGH_WORD (i0, t);

	  SET_HIGH_WORD (t, (i0 & 0x7fffffff) | (sx << 31));

	  return t;

	}

    }

  else

    {

      if (j0 == 0x400)

	return x + x;                   /* inf or NaN */

      else

	return x;                       /* x is integral */

    }

  w = TWO52[sx] + x;

  return w - TWO52[sx];

}

#ifndef __rint

libm_alias_double (__rint, rint)

#endif