xref: /freebsd/lib/msun/src/s_fmaximum_magl.c (revision f6e1f27e9f005447e88a9b37df8a75751b1e0c3a)

/*
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2004 David Schultz <das@FreeBSD.ORG>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <math.h>

#include "fpmath.h"

long double
fmaximum_magl(long double x, long double y)
{
	union IEEEl2bits u[2];

	u[0].e = x;
	mask_nbit_l(u[0]);
	u[1].e = y;
	mask_nbit_l(u[1]);

	/* Handle NaN according to ISO/IEC 60559. NaN argument -> NaN return */
	if (isnan(x) || isnan(y))
		return (NAN);

	long double ax = fabsl(x);
	long double ay = fabsl(y);

	if (ay > ax)
		return (y);
	if (ax > ay)
		return (x);

	/* If magnitudes are equal, we break the tie with the sign */
	if (u[0].bits.sign != u[1].bits.sign)
		return (u[0].bits.sign ? y : x);

	return (x);
}