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/*
23 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
24 */
25/*
26 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
27 * Use is subject to license terms.
28 */
29
30#pragma weak __trunc = trunc
31
32#include "libm.h"
33
34double
35trunc(double x) {
36	union {
37		unsigned i[2];
38		double d;
39	} xx;
40	unsigned hx, sx, i;
41
42	xx.d = x;
43	hx = xx.i[HIWORD] & ~0x80000000;
44	sx = xx.i[HIWORD] & 0x80000000;
45	if (hx < 0x43300000) {	/* |x| < 2^52 */
46		if (hx < 0x3ff00000)	/* |x| < 1 */
47			return (sx ? -0.0 : 0.0);
48
49		/* chop x at the integer bit */
50		if (hx < 0x41300000) {
51			i = 1 << (0x412 - (hx >> 20));
52			xx.i[HIWORD] &= ~(i | (i - 1));
53			xx.i[LOWORD] = 0;
54		} else {
55			i = 1 << (0x432 - (hx >> 20));
56			xx.i[LOWORD] &= ~(i | (i - 1));
57		}
58		return (xx.d);
59	} else if (hx < 0x7ff00000)
60		return (x);
61	else
62#if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
63		return (hx >= 0x7ff80000 ? x : x + x);
64		/* assumes sparc-like QNaN */
65#else
66		return (x + x);
67#endif
68}
69