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
|
// SPDX-License-Identifier: GPL-2.0
#ifndef __BITOPS_H__
#define __BITOPS_H__
/*
* fls: find last bit set.
*/
static inline int fls(int x)
{
int r = 32;
if (!x)
return 0;
if (!(x & 0xffff0000u)) {
x = (x & 0xffffu) << 16;
r -= 16;
}
if (!(x & 0xff000000u)) {
x = (x & 0xffffffu) << 8;
r -= 8;
}
if (!(x & 0xf0000000u)) {
x = (x & 0xfffffffu) << 4;
r -= 4;
}
if (!(x & 0xc0000000u)) {
x = (x & 0x3fffffffu) << 2;
r -= 2;
}
if (!(x & 0x80000000u)) {
r -= 1;
}
return r;
}
static inline int fls64(__u64 x)
{
__u32 h = x >> 32;
if (h)
return fls(h) + 32;
return fls(x);
}
static inline unsigned fls_long(unsigned long l)
{
if (sizeof(l) == 4)
return fls(l);
return fls64(l);
}
/*
* ffz: find first zero bit.
* Result is undefined if no zero bit exists.
*/
#define ffz(x) ffs(~(x))
/*
* XFS bit manipulation routines. Repeated here so that some programs
* don't have to link in all of libxfs just to have bit manipulation.
*/
/*
* masks with n high/low bits set, 64-bit values
*/
static inline uint64_t mask64hi(int n)
{
return (uint64_t)-1 << (64 - (n));
}
static inline uint32_t mask32lo(int n)
{
return ((uint32_t)1 << (n)) - 1;
}
static inline uint64_t mask64lo(int n)
{
return ((uint64_t)1 << (n)) - 1;
}
/* Get high bit set out of 32-bit argument, -1 if none set */
static inline int highbit32(uint32_t v)
{
return fls(v) - 1;
}
/* Get high bit set out of 64-bit argument, -1 if none set */
static inline int highbit64(uint64_t v)
{
return fls64(v) - 1;
}
/* Get low bit set out of 32-bit argument, -1 if none set */
static inline int lowbit32(uint32_t v)
{
return ffs(v) - 1;
}
/* Get low bit set out of 64-bit argument, -1 if none set */
static inline int lowbit64(uint64_t v)
{
uint32_t w = (uint32_t)v;
int n = 0;
if (w) { /* lower bits */
n = ffs(w);
} else { /* upper bits */
w = (uint32_t)(v >> 32);
if (w) {
n = ffs(w);
if (n)
n += 32;
}
}
return n - 1;
}
/**
* __rounddown_pow_of_two() - round down to nearest power of two
* @n: value to round down
*/
static inline __attribute__((const))
unsigned long __rounddown_pow_of_two(unsigned long n)
{
return 1UL << (fls_long(n) - 1);
}
#define rounddown_pow_of_two(n) __rounddown_pow_of_two(n)
#endif
|
