xref: /linux/lib/clz_ctz.c (revision a1c613ae4c322ddd58d5a8539dbfba2a0380a8c0) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * lib/clz_ctz.c
4  *
5  * Copyright (C) 2013 Chanho Min <chanho.min@lge.com>
6  *
7  * The functions in this file aren't called directly, but are required by
8  * GCC builtins such as __builtin_ctz, and therefore they can't be removed
9  * despite appearing unreferenced in kernel source.
10  *
11  * __c[lt]z[sd]i2 can be overridden by linking arch-specific versions.
12  */
13 
14 #include <linux/export.h>
15 #include <linux/kernel.h>
16 
17 int __weak __ctzsi2(int val);
__ctzsi2(int val)18 int __weak __ctzsi2(int val)
19 {
20 	return __ffs(val);
21 }
22 EXPORT_SYMBOL(__ctzsi2);
23 
24 int __weak __clzsi2(int val);
__clzsi2(int val)25 int __weak __clzsi2(int val)
26 {
27 	return 32 - fls(val);
28 }
29 EXPORT_SYMBOL(__clzsi2);
30 
31 int __weak __clzdi2(u64 val);
__clzdi2(u64 val)32 int __weak __clzdi2(u64 val)
33 {
34 	return 64 - fls64(val);
35 }
36 EXPORT_SYMBOL(__clzdi2);
37 
38 int __weak __ctzdi2(u64 val);
__ctzdi2(u64 val)39 int __weak __ctzdi2(u64 val)
40 {
41 	return __ffs64(val);
42 }
43 EXPORT_SYMBOL(__ctzdi2);
44