125c28e8Piotr Jasiukajtis/*
225c28e8Piotr Jasiukajtis * CDDL HEADER START
325c28e8Piotr Jasiukajtis *
425c28e8Piotr Jasiukajtis * The contents of this file are subject to the terms of the
525c28e8Piotr Jasiukajtis * Common Development and Distribution License (the "License").
625c28e8Piotr Jasiukajtis * You may not use this file except in compliance with the License.
725c28e8Piotr Jasiukajtis *
825c28e8Piotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
925c28e8Piotr Jasiukajtis * or http://www.opensolaris.org/os/licensing.
1025c28e8Piotr Jasiukajtis * See the License for the specific language governing permissions
1125c28e8Piotr Jasiukajtis * and limitations under the License.
1225c28e8Piotr Jasiukajtis *
1325c28e8Piotr Jasiukajtis * When distributing Covered Code, include this CDDL HEADER in each
1425c28e8Piotr Jasiukajtis * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
1525c28e8Piotr Jasiukajtis * If applicable, add the following below this CDDL HEADER, with the
1625c28e8Piotr Jasiukajtis * fields enclosed by brackets "[]" replaced with your own identifying
1725c28e8Piotr Jasiukajtis * information: Portions Copyright [yyyy] [name of copyright owner]
1825c28e8Piotr Jasiukajtis *
1925c28e8Piotr Jasiukajtis * CDDL HEADER END
2025c28e8Piotr Jasiukajtis */
2125c28e8Piotr Jasiukajtis/*
2225c28e8Piotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
2325c28e8Piotr Jasiukajtis */
2425c28e8Piotr Jasiukajtis/*
2525c28e8Piotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
2625c28e8Piotr Jasiukajtis * Use is subject to license terms.
2725c28e8Piotr Jasiukajtis */
2825c28e8Piotr Jasiukajtis
29ddc0e0bRichard Lowe#pragma weak __exp2 = exp2
3025c28e8Piotr Jasiukajtis
3125c28e8Piotr Jasiukajtis/* INDENT OFF */
3225c28e8Piotr Jasiukajtis/*
3325c28e8Piotr Jasiukajtis * exp2(x)
3425c28e8Piotr Jasiukajtis * Code by K.C. Ng for SUN 4.0 libm.
3525c28e8Piotr Jasiukajtis * Method :
3625c28e8Piotr Jasiukajtis *	exp2(x) = 2**x = 2**((x-anint(x))+anint(x))
3725c28e8Piotr Jasiukajtis *		= 2**anint(x)*2**(x-anint(x))
3825c28e8Piotr Jasiukajtis *		= 2**anint(x)*exp((x-anint(x))*ln2)
3925c28e8Piotr Jasiukajtis */
4025c28e8Piotr Jasiukajtis/* INDENT ON */
4125c28e8Piotr Jasiukajtis
4225c28e8Piotr Jasiukajtis#include "libm.h"
4325c28e8Piotr Jasiukajtis
4425c28e8Piotr Jasiukajtisstatic const double C[] = {
4525c28e8Piotr Jasiukajtis	0.0,
4625c28e8Piotr Jasiukajtis	1.0,
4725c28e8Piotr Jasiukajtis	0.5,
4825c28e8Piotr Jasiukajtis	6.93147180559945286227e-01,
4925c28e8Piotr Jasiukajtis	1.0e300,
5025c28e8Piotr Jasiukajtis	1.0e-300,
5125c28e8Piotr Jasiukajtis};
5225c28e8Piotr Jasiukajtis
5325c28e8Piotr Jasiukajtis#define	zero	C[0]
5425c28e8Piotr Jasiukajtis#define	one	C[1]
5525c28e8Piotr Jasiukajtis#define	half	C[2]
5625c28e8Piotr Jasiukajtis#define	ln2	C[3]
5725c28e8Piotr Jasiukajtis#define	huge	C[4]
5825c28e8Piotr Jasiukajtis#define	tiny	C[5]
5925c28e8Piotr Jasiukajtis
6025c28e8Piotr Jasiukajtisdouble
6125c28e8Piotr Jasiukajtisexp2(double x) {
6225c28e8Piotr Jasiukajtis	int	ix, hx, k;
6325c28e8Piotr Jasiukajtis	double	t;
6425c28e8Piotr Jasiukajtis
6525c28e8Piotr Jasiukajtis	ix = ((int *)&x)[HIWORD];
6625c28e8Piotr Jasiukajtis	hx = ix & ~0x80000000;
6725c28e8Piotr Jasiukajtis
6825c28e8Piotr Jasiukajtis	if (hx >= 0x4090e000) {	/* |x| >= 1080 or x is nan */
6925c28e8Piotr Jasiukajtis		if (hx >= 0x7ff00000) {	/* x is inf or nan */
7025c28e8Piotr Jasiukajtis			if (ix == 0xfff00000 && ((int *)&x)[LOWORD] == 0)
7125c28e8Piotr Jasiukajtis				return (zero);
7225c28e8Piotr Jasiukajtis			return (x * x);
7325c28e8Piotr Jasiukajtis		}
7425c28e8Piotr Jasiukajtis		t = (ix < 0)? tiny : huge;
7525c28e8Piotr Jasiukajtis		return (t * t);
7625c28e8Piotr Jasiukajtis	}
7725c28e8Piotr Jasiukajtis
7825c28e8Piotr Jasiukajtis	if (hx < 0x3fe00000) {	/* |x| < 0.5 */
7925c28e8Piotr Jasiukajtis		if (hx < 0x3c000000)
8025c28e8Piotr Jasiukajtis			return (one + x);
8125c28e8Piotr Jasiukajtis		return (exp(ln2 * x));
8225c28e8Piotr Jasiukajtis	}
8325c28e8Piotr Jasiukajtis
8425c28e8Piotr Jasiukajtis	k = (int)x;
8525c28e8Piotr Jasiukajtis	if (x != (double)k)
8625c28e8Piotr Jasiukajtis		k = (int)((ix < 0)? x - half : x + half);
8725c28e8Piotr Jasiukajtis	return (scalbn(exp(ln2 * (x - (double)k)), k));
8825c28e8Piotr Jasiukajtis}