File: bitops.h

package info (click to toggle)
xfsprogs 3.2.1
  • links: PTS
  • area: main
  • in suites: jessie, jessie-kfreebsd
  • size: 7,276 kB
  • ctags: 9,584
  • sloc: ansic: 96,643; sh: 10,603; makefile: 806
file content (51 lines) | stat: -rw-r--r-- 653 bytes parent folder | download
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
#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 <<= 16;
		r -= 16;
	}
	if (!(x & 0xff000000u)) {
		x <<= 8;
		r -= 8;
	}
	if (!(x & 0xf0000000u)) {
		x <<= 4;
		r -= 4;
	}
	if (!(x & 0xc0000000u)) {
		x <<= 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);
}

#endif