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
35 double
nextafter(double x,double y)36 nextafter(double x, double y) {
37 int hx, hy, k;
38 double ans;
39 unsigned lx;
40 volatile double dummy;
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