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(long val);
32 int __weak __ctzdi2(long val);
33 #if BITS_PER_LONG == 32
34 
__clzdi2(long val)35 int __weak __clzdi2(long val)
36 {
37 	return 32 - fls((int)val);
38 }
39 EXPORT_SYMBOL(__clzdi2);
40 
__ctzdi2(long val)41 int __weak __ctzdi2(long val)
42 {
43 	return __ffs((u32)val);
44 }
45 EXPORT_SYMBOL(__ctzdi2);
46 
47 #elif BITS_PER_LONG == 64
48 
__clzdi2(long val)49 int __weak __clzdi2(long val)
50 {
51 	return 64 - fls64((u64)val);
52 }
53 EXPORT_SYMBOL(__clzdi2);
54 
__ctzdi2(long val)55 int __weak __ctzdi2(long val)
56 {
57 	return __ffs64((u64)val);
58 }
59 EXPORT_SYMBOL(__ctzdi2);
60 
61 #else
62 #error BITS_PER_LONG not 32 or 64
63 #endif
64