]> git.saurik.com Git - apple/xnu.git/blame - osfmk/kern/bits.c
xnu-344.12.2.tar.gz
[apple/xnu.git] / osfmk / kern / bits.c
CommitLineData
1c79356b
A
1/*
2 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * The contents of this file constitute Original Code as defined in and
7 * are subject to the Apple Public Source License Version 1.1 (the
8 * "License"). You may not use this file except in compliance with the
9 * License. Please obtain a copy of the License at
10 * http://www.apple.com/publicsource and read it before using this file.
11 *
12 * This Original Code and all software distributed under the License are
13 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
14 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
15 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
17 * License for the specific language governing rights and limitations
18 * under the License.
19 *
20 * @APPLE_LICENSE_HEADER_END@
21 */
22/*
23 * @OSF_COPYRIGHT@
24 */
25/*
26 * HISTORY
27 *
28 * Revision 1.1.1.1 1998/09/22 21:05:35 wsanchez
29 * Import of Mac OS X kernel (~semeria)
30 *
31 * Revision 1.2 1998/04/29 17:35:55 mburg
32 * MK7.3 merger
33 *
34 * Revision 1.1.24.1 1998/02/03 09:27:19 gdt
35 * Merge up to MK7.3
36 * [1998/02/03 09:12:57 gdt]
37 *
38 * Revision 1.1.21.1 1996/11/29 16:57:21 stephen
39 * nmklinux_1.0b3_shared into pmk1.1
40 * Added explanatory note.
41 * [1996/04/10 16:54:46 emcmanus]
42 *
43 * Revision 1.1.22.1 1997/06/17 02:57:05 devrcs
44 * Added `testbit()' routine.
45 * [1996/03/18 15:21:50 rkc]
46 *
47 * Revision 1.1.7.3 1995/01/10 05:10:36 devrcs
48 * mk6 CR801 - copyright marker not FREE_
49 * [1994/12/01 19:24:54 dwm]
50 *
51 * Revision 1.1.7.1 1994/06/14 16:59:49 bolinger
52 * Merge up to NMK17.2.
53 * [1994/06/14 16:53:29 bolinger]
54 *
55 * Revision 1.1.5.1 1994/04/11 09:36:31 bernadat
56 * Checked in NMK16_2 revision
57 * [94/03/15 bernadat]
58 *
59 * Revision 1.1.3.1 1993/12/23 08:53:13 bernadat
60 * Checked in bolinger_860ci revision.
61 * [93/11/29 bernadat]
62 *
63 * Revision 1.1.1.2 1993/09/12 15:44:20 bolinger
64 * Initial checkin of 860 modifications; MD files from NMK14.8.
65 *
66 * $EndLog$
67 */
68/*
69 * C version of bit manipulation routines now required by kernel.
70 * Should be replaced with assembler versions in any real port.
71 *
72 * Note that these routines use little-endian numbering for bits (i.e.,
73 * the bit number corresponds to the associated power-of-2).
74 */
75#include <mach/machine/vm_param.h> /* for BYTE_SIZE */
76
77#define INT_SIZE (BYTE_SIZE * sizeof (int))
78
79/*
80 * Set indicated bit in bit string.
81 */
82void
83setbit(int bitno, int *s)
84{
85 for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
86 ;
87 *s |= 1 << bitno;
88}
89
90/*
91 * Clear indicated bit in bit string.
92 */
93void
94clrbit(int bitno, int *s)
95{
96 for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
97 ;
98 *s &= ~(1 << bitno);
99}
100
101/*
102 * Find first bit set in bit string.
103 */
104int
105ffsbit(int *s)
106{
107 int offset, mask;
108
109 for (offset = 0; !*s; offset += INT_SIZE, ++s)
110 ;
111 for (mask = 1; mask; mask <<= 1, ++offset)
112 if (mask & *s)
113 return (offset);
114 /*
115 * Shouldn't get here
116 */
117 return (0);
118}
119
120/*
121 * Test if indicated bit is set in bit string.
122 */
123int
124testbit(int bitno, int *s)
125{
126 for ( ; INT_SIZE <= bitno; bitno -= INT_SIZE, ++s)
127 ;
128 return(*s & (1 << bitno));
129}