blob: b72ba3faa036b0262ee422a313bb23d8091ce48c (
plain) (
blame)
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
|
/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Count leading and trailing zeros functions
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#ifndef _LINUX_BITOPS_COUNT_ZEROS_H_
#define _LINUX_BITOPS_COUNT_ZEROS_H_
#include <asm/bitops.h>
/**
* count_leading_zeros - Count the number of zeros from the MSB back
* @x: The value
*
* Count the number of leading zeros from the MSB going towards the LSB in @x.
*
* If the MSB of @x is set, the result is 0.
* If only the LSB of @x is set, then the result is BITS_PER_LONG-1.
* If @x is 0 then the result is BITS_PER_LONG.
*/
static inline int count_leading_zeros(unsigned long x)
{
if (sizeof(x) == 4)
return BITS_PER_LONG - fls(x);
else
return BITS_PER_LONG - fls64(x);
}
/**
* count_trailing_zeros - Count the number of zeros from the LSB forwards
* @x: The value
*
* Count the number of trailing zeros from the LSB going towards the MSB in @x.
*
* If the LSB of @x is set, the result is 0.
* If only the MSB of @x is set, then the result is BITS_PER_LONG-1.
* If @x is 0 then the result is BITS_PER_LONG.
*/
static inline int count_trailing_zeros(unsigned long x)
{
return x ? __ffs(x) : BITS_PER_LONG;
}
#endif /* _LINUX_BITOPS_COUNT_ZEROS_H_ */
|
