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