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 __nextafter = nextafter
30#pragma weak _nextafter = nextafter
31
32#include "libm.h"
33#include <float.h>		/* DBL_MIN */
34
35double
36nextafter(double x, double y) {
37	int		hx, hy, k;
38	double		ans;
39	unsigned	lx;
40	volatile double dummy __unused;
41
42	hx = ((int *)&x)[HIWORD];
43	lx = ((int *)&x)[LOWORD];
44	hy = ((int *)&y)[HIWORD];
45	k = (hx & ~0x80000000) | lx;
46
47	if (x == y)
48		return (y);		/* C99 requirement */
49	if (x != x || y != y)
50		return (x * y);
51	if (k == 0) {			/* x = 0 */
52		k = hy & 0x80000000;
53		((int *)&ans)[HIWORD] = k;
54		((int *)&ans)[LOWORD] = 1;
55	} else if (hx >= 0) {
56		if (x > y) {
57			((int *)&ans)[LOWORD] = lx - 1;
58			k = (lx == 0)? hx - 1 : hx;
59			((int *)&ans)[HIWORD] = k;
60		} else {
61			((int *)&ans)[LOWORD] = lx + 1;
62			k  = (lx == 0xffffffff)? hx + 1 : hx;
63			((int *)&ans)[HIWORD] = k;
64		}
65	} else {
66		if (x < y) {
67			((int *)&ans)[LOWORD] = lx - 1;
68			k = (lx == 0)? hx - 1 : hx;
69			((int *)&ans)[HIWORD] = k;
70		} else {
71			((int *)&ans)[LOWORD] = lx + 1;
72			k  = (lx == 0xffffffff)? hx + 1 : hx;
73			((int *)&ans)[HIWORD] = k;
74		}
75	}
76	k = (k >> 20) & 0x7ff;
77	if (k == 0x7ff) {
78		/* overflow */
79		return (_SVID_libm_err(x, y, 46));
80#if !defined(__lint)
81	} else if (k == 0) {
82		/* underflow */
83		dummy = DBL_MIN * copysign(DBL_MIN, x);
84#endif
85	}
86	return (ans);
87}
88