bitmap.h revision 9663:ace9a2ac3683 
1/*
2 * bitmap.h - Exports for bitmap handling. Part of the Linux-NTFS project.
3 *
4 * Copyright (c) 2000-2004 Anton Altaparmakov
5 * Copyright (c) 2004-2005 Richard Russon
6 *
7 * This program/include file is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as published
9 * by the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program/include file is distributed in the hope that it will be
13 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program (in the main directory of the Linux-NTFS
19 * distribution in the file COPYING); if not, write to the Free Software
20 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
21 */
22
23#ifndef _NTFS_BITMAP_H
24#define _NTFS_BITMAP_H
25
26#include "types.h"
27#include "attrib.h"
28
29/*
30 * NOTES:
31 *
32 * - Operations are 8-bit only to ensure the functions work both on little
33 *   and big endian machines! So don't make them 32-bit ops!
34 * - bitmap starts at bit = 0 and ends at bit = bitmap size - 1.
35 * - _Caller_ has to make sure that the bit to operate on is less than the
36 *   size of the bitmap.
37 */
38
39/**
40 * ntfs_bit_set - set a bit in a field of bits
41 * @bitmap:	field of bits
42 * @bit:	bit to set
43 * @new_value:	value to set bit to (0 or 1)
44 *
45 * Set the bit @bit in the @bitmap to @new_value. Ignore all errors.
46 */
47static __inline__ void ntfs_bit_set(u8 *bitmap, const u64 bit,
48		const u8 new_value)
49{
50	if (!bitmap || new_value > 1)
51		return;
52	if (!new_value)
53		bitmap[bit >> 3] &= ~(1 << (bit & 7));
54	else
55		bitmap[bit >> 3] |= (1 << (bit & 7));
56}
57
58/**
59 * ntfs_bit_get - get value of a bit in a field of bits
60 * @bitmap:	field of bits
61 * @bit:	bit to get
62 *
63 * Get and return the value of the bit @bit in @bitmap (0 or 1).
64 * Return -1 on error.
65 */
66static __inline__ char ntfs_bit_get(const u8 *bitmap, const u64 bit)
67{
68	if (!bitmap)
69		return -1;
70	return (bitmap[bit >> 3] >> (bit & 7)) & 1;
71}
72
73static __inline__ void ntfs_bit_change(u8 *bitmap, const u64 bit)
74{
75	if (!bitmap)
76		return;
77	bitmap[bit >> 3] ^= 1 << (bit & 7);
78}
79
80/**
81 * ntfs_bit_get_and_set - get value of a bit in a field of bits and set it
82 * @bitmap:	field of bits
83 * @bit:	bit to get/set
84 * @new_value:	value to set bit to (0 or 1)
85 *
86 * Return the value of the bit @bit and set it to @new_value (0 or 1).
87 * Return -1 on error.
88 */
89static __inline__ char ntfs_bit_get_and_set(u8 *bitmap, const u64 bit,
90		const u8 new_value)
91{
92	register u8 old_bit, shift;
93
94	if (!bitmap || new_value > 1)
95		return -1;
96	shift = bit & 7;
97	old_bit = (bitmap[bit >> 3] >> shift) & 1;
98	if (new_value != old_bit)
99		bitmap[bit >> 3] ^= 1 << shift;
100	return old_bit;
101}
102
103extern int ntfs_bitmap_set_run(ntfs_attr *na, s64 start_bit, s64 count);
104extern int ntfs_bitmap_clear_run(ntfs_attr *na, s64 start_bit, s64 count);
105
106/**
107 * ntfs_bitmap_set_bit - set a bit in a bitmap
108 * @na:		attribute containing the bitmap
109 * @bit:	bit to set
110 *
111 * Set the @bit in the bitmap described by the attribute @na.
112 *
113 * On success return 0 and on error return -1 with errno set to the error code.
114 */
115static __inline__ int ntfs_bitmap_set_bit(ntfs_attr *na, s64 bit)
116{
117	return ntfs_bitmap_set_run(na, bit, 1);
118}
119
120/**
121 * ntfs_bitmap_clear_bit - clear a bit in a bitmap
122 * @na:		attribute containing the bitmap
123 * @bit:	bit to clear
124 *
125 * Clear @bit in the bitmap described by the attribute @na.
126 *
127 * On success return 0 and on error return -1 with errno set to the error code.
128 */
129static __inline__ int ntfs_bitmap_clear_bit(ntfs_attr *na, s64 bit)
130{
131	return ntfs_bitmap_clear_run(na, bit, 1);
132}
133
134#endif /* defined _NTFS_BITMAP_H */
135