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/*
2325c28e8Piotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
2425c28e8Piotr Jasiukajtis */
2525c28e8Piotr Jasiukajtis/*
2625c28e8Piotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
2725c28e8Piotr Jasiukajtis * Use is subject to license terms.
2825c28e8Piotr Jasiukajtis */
2925c28e8Piotr Jasiukajtis
30ddc0e0bRichard Lowe#pragma weak __log1pl = log1pl
3125c28e8Piotr Jasiukajtis
3225c28e8Piotr Jasiukajtis/*
3325c28e8Piotr Jasiukajtis * log1pl(x)
3425c28e8Piotr Jasiukajtis * Kahan's trick based on log(1+x)/x being a slow varying function.
3525c28e8Piotr Jasiukajtis */
3625c28e8Piotr Jasiukajtis
3725c28e8Piotr Jasiukajtis#include "libm.h"
3825c28e8Piotr Jasiukajtis
3925c28e8Piotr Jasiukajtis#if defined(__x86)
4025c28e8Piotr Jasiukajtis#define	__swapRD	__swap87RD
4125c28e8Piotr Jasiukajtis#endif
4225c28e8Piotr Jasiukajtisextern enum fp_direction_type __swapRD(enum fp_direction_type);
4325c28e8Piotr Jasiukajtis
4425c28e8Piotr Jasiukajtislong double
4525c28e8Piotr Jasiukajtislog1pl(long double x) {
4625c28e8Piotr Jasiukajtis	long double y;
4725c28e8Piotr Jasiukajtis	enum fp_direction_type rd;
4825c28e8Piotr Jasiukajtis
4925c28e8Piotr Jasiukajtis	if (x != x)
5025c28e8Piotr Jasiukajtis		return (x + x);
5125c28e8Piotr Jasiukajtis	if (x < -1.L)
5225c28e8Piotr Jasiukajtis		return (logl(x));
5325c28e8Piotr Jasiukajtis	rd = __swapRD(fp_nearest);
5425c28e8Piotr Jasiukajtis	y = 1.L + x;
5525c28e8Piotr Jasiukajtis	if (y != 1.L) {
5625c28e8Piotr Jasiukajtis		if (y == x)
5725c28e8Piotr Jasiukajtis			x = logl(x);
5825c28e8Piotr Jasiukajtis		else
5925c28e8Piotr Jasiukajtis			x *= logl(y) / (y - 1.L);
6025c28e8Piotr Jasiukajtis	}
6125c28e8Piotr Jasiukajtis	if (rd != fp_nearest)
6225c28e8Piotr Jasiukajtis		(void) __swapRD(rd);
6325c28e8Piotr Jasiukajtis	return (x);
6425c28e8Piotr Jasiukajtis}