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 2006 Sun Microsystems, Inc.  All rights reserved.
26 * Use is subject to license terms.
27 */
28
29#pragma weak __rint = rint
30
31/*
32 * rint(x) return x rounded to integral according to the rounding direction
33 * rint(x) returns result with the same sign as x's,  including 0.0.
34 */
35
36#include "libm.h"
37
38#if defined(__i386) && !defined(__amd64) && (!defined(__FLT_EVAL_METHOD__) || \
39	__FLT_EVAL_METHOD__ != 0)
40extern enum fp_precision_type __swapRP(enum fp_precision_type);
41#define	DECLRP(x)	enum fp_precision_type x;
42#define	SWAPRP(new, x)	x = __swapRP(new);
43#define	RESTRP(x)	(void) __swapRP(x);
44#else
45#define	DECLRP(x)
46#define	SWAPRP(new, x)
47#define	RESTRP(x)
48#endif
49
50static const double
51	two52 = 4503599627370496.0,
52	zero = 0.0,
53	one = 1.0;
54
55double
56rint(double x) {
57	DECLRP(rp)
58	double	t, w;
59	int	ix, hx;
60
61	ix = ((int *)&x)[HIWORD];
62	hx = ix & ~0x80000000;
63
64	if (hx >= 0x43300000)
65		return (x * one);
66	t = (ix < 0)? -two52 : two52;
67	SWAPRP(fp_double, rp)		/* set precision mode to double */
68	w = x + t;			/* x+sign(x)*2**52 rounded */
69	RESTRP(rp)			/* restore precision mode */
70	if (w == t)
71		return ((ix < 0)? -zero : zero);
72	return (w - t);
73}
74