1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
// SPDX-License-Identifier: GPL-2.0
/*
*
* Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
*
*/
#include <linux/blkdev.h>
#include <linux/buffer_head.h>
#include <linux/fs.h>
#include <linux/nls.h>
#include "debug.h"
#include "ntfs.h"
#include "ntfs_fs.h"
#define BITS_IN_SIZE_T (sizeof(size_t) * 8)
/*
* fill_mask[i] - first i bits are '1' , i = 0,1,2,3,4,5,6,7,8
* fill_mask[i] = 0xFF >> (8-i)
*/
static const u8 fill_mask[] = { 0x00, 0x01, 0x03, 0x07, 0x0F,
0x1F, 0x3F, 0x7F, 0xFF };
/*
* zero_mask[i] - first i bits are '0' , i = 0,1,2,3,4,5,6,7,8
* zero_mask[i] = 0xFF << i
*/
static const u8 zero_mask[] = { 0xFF, 0xFE, 0xFC, 0xF8, 0xF0,
0xE0, 0xC0, 0x80, 0x00 };
/*
* are_bits_clear
*
* Return: True if all bits [bit, bit+nbits) are zeros "0".
*/
bool are_bits_clear(const ulong *lmap, size_t bit, size_t nbits)
{
size_t pos = bit & 7;
const u8 *map = (u8 *)lmap + (bit >> 3);
if (pos) {
if (8 - pos >= nbits)
return !nbits || !(*map & fill_mask[pos + nbits] &
zero_mask[pos]);
if (*map++ & zero_mask[pos])
return false;
nbits -= 8 - pos;
}
pos = ((size_t)map) & (sizeof(size_t) - 1);
if (pos) {
pos = sizeof(size_t) - pos;
if (nbits >= pos * 8) {
for (nbits -= pos * 8; pos; pos--, map++) {
if (*map)
return false;
}
}
}
for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {
if (*((size_t *)map))
return false;
}
for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {
if (*map)
return false;
}
pos = nbits & 7;
if (pos && (*map & fill_mask[pos]))
return false;
return true;
}
/*
* are_bits_set
*
* Return: True if all bits [bit, bit+nbits) are ones "1".
*/
bool are_bits_set(const ulong *lmap, size_t bit, size_t nbits)
{
u8 mask;
size_t pos = bit & 7;
const u8 *map = (u8 *)lmap + (bit >> 3);
if (pos) {
if (8 - pos >= nbits) {
mask = fill_mask[pos + nbits] & zero_mask[pos];
return !nbits || (*map & mask) == mask;
}
mask = zero_mask[pos];
if ((*map++ & mask) != mask)
return false;
nbits -= 8 - pos;
}
pos = ((size_t)map) & (sizeof(size_t) - 1);
if (pos) {
pos = sizeof(size_t) - pos;
if (nbits >= pos * 8) {
for (nbits -= pos * 8; pos; pos--, map++) {
if (*map != 0xFF)
return false;
}
}
}
for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {
if (*((size_t *)map) != MINUS_ONE_T)
return false;
}
for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {
if (*map != 0xFF)
return false;
}
pos = nbits & 7;
if (pos) {
u8 mask = fill_mask[pos];
if ((*map & mask) != mask)
return false;
}
return true;
}
|
