/* Copyright (C) 2005-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Richard Henderson <rth@redhat.com>, 2005.

   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 <stdbool.h>

#include <math.h>

#include <complex.h>

attribute_hidden

long double _Complex

__multc3 (long double a, long double b, long double c, long double d)

{

  long double ac, bd, ad, bc, x, y;

  ac = a * c;

  bd = b * d;

  ad = a * d;

  bc = b * c;

  x = ac - bd;

  y = ad + bc;

  if (isnan (x) && isnan (y))

    {

      /* Recover infinities that computed as NaN + iNaN.  */

      bool recalc = 0;

      if (isinf (a) || isinf (b))

	{

	  /* z is infinite.  "Box" the infinity and change NaNs in

	     the other factor to 0.  */

	  a = __copysignl (isinf (a) ? 1 : 0, a);

	  b = __copysignl (isinf (b) ? 1 : 0, b);

	  if (isnan (c)) c = __copysignl (0, c);

	  if (isnan (d)) d = __copysignl (0, d);

	  recalc = 1;

	}

     if (isinf (c) || isinf (d))

	{

	  /* w is infinite.  "Box" the infinity and change NaNs in

	     the other factor to 0.  */

	  c = __copysignl (isinf (c) ? 1 : 0, c);

	  d = __copysignl (isinf (d) ? 1 : 0, d);

	  if (isnan (a)) a = __copysignl (0, a);

	  if (isnan (b)) b = __copysignl (0, b);

	  recalc = 1;

	}

     if (!recalc

	  && (isinf (ac) || isinf (bd)

	      || isinf (ad) || isinf (bc)))

	{

	  /* Recover infinities from overflow by changing NaNs to 0.  */

	  if (isnan (a)) a = __copysignl (0, a);

	  if (isnan (b)) b = __copysignl (0, b);

	  if (isnan (c)) c = __copysignl (0, c);

	  if (isnan (d)) d = __copysignl (0, d);

	  recalc = 1;

	}

      if (recalc)

	{

	  x = INFINITY * (a * c - b * d);

	  y = INFINITY * (a * d + b * c);

	}

    }

  return x + I * y;

}