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 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /*
28 * Common implementation of ffs for kernel, mdb, and libc. Note that mdb
29 * renames ffs into mdb_ffs to avoid user-space clashes with the signature of
30 * ffs(3C).
31 */
32
33 #if defined(_KERNEL) || defined(ffs)
34 #include <sys/int_types.h>
35 #define arg_t uintmax_t
36 #else
37 #define arg_t int
38 #include "lint.h"
39 #endif
40
41 int
ffs(arg_t bits)42 ffs(arg_t bits)
43 {
44 int i;
45
46 if (bits == 0)
47 return (0);
48 for (i = 1; ; i++, bits >>= 1) {
49 if (bits & 1)
50 break;
51 }
52 return (i);
53 }
54