1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
23 */
24/*
25 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
26 * Use is subject to license terms.
27 */
28
29#pragma weak __floor = floor
30
31/*
32 * floor(x) returns the biggest integral value less than or equal to x.
33 * NOTE: floor(x) returns result with the same sign as x's, including 0.
34 *
35 * Modified 8/4/04 for performance.
36 */
37
38#include "libm.h"
39
40static const double
41	zero = 0.0,
42	one = 1.0,
43	two52 = 4503599627370496.0;
44
45double
46floor(double x) {
47	double	t, w;
48	int	hx, lx, ix;
49
50	hx = ((int *)&x)[HIWORD];
51	lx = ((int *)&x)[LOWORD];
52	ix = hx & ~0x80000000;
53	if (ix >= 0x43300000)	/* return x if |x| >= 2^52, or x is NaN */
54		return (x * one);
55	t = (hx >= 0)? two52 : -two52;
56	w = x + t;
57	t = w - t;
58	if (ix < 0x3ff00000) {
59		if ((ix | lx) == 0)
60			return (x);
61		else
62			return ((hx < 0)? -one : zero);
63	}
64	return ((t <= x)? t : t - one);
65}
66