the-tree/lib/clz_ctz.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * lib/clz_ctz.c
0004  *
0005  * Copyright (C) 2013 Chanho Min <chanho.min@lge.com>
0006  *
0007  * The functions in this file aren't called directly, but are required by
0008  * GCC builtins such as __builtin_ctz, and therefore they can't be removed
0009  * despite appearing unreferenced in kernel source.
0010  *
0011  * __c[lt]z[sd]i2 can be overridden by linking arch-specific versions.
0012  */
0013
0014 #include <linux/export.h>
0015 #include <linux/kernel.h>
0016
0017 int __weak __ctzsi2(int val);
0018 int __weak __ctzsi2(int val)
0019 {
0020     return __ffs(val);
0021 }
0022 EXPORT_SYMBOL(__ctzsi2);
0023
0024 int __weak __clzsi2(int val);
0025 int __weak __clzsi2(int val)
0026 {
0027     return 32 - fls(val);
0028 }
0029 EXPORT_SYMBOL(__clzsi2);
0030
0031 int __weak __clzdi2(long val);
0032 int __weak __ctzdi2(long val);
0033 #if BITS_PER_LONG == 32
0034
0035 int __weak __clzdi2(long val)
0036 {
0037     return 32 - fls((int)val);
0038 }
0039 EXPORT_SYMBOL(__clzdi2);
0040
0041 int __weak __ctzdi2(long val)
0042 {
0043     return __ffs((u32)val);
0044 }
0045 EXPORT_SYMBOL(__ctzdi2);
0046
0047 #elif BITS_PER_LONG == 64
0048
0049 int __weak __clzdi2(long val)
0050 {
0051     return 64 - fls64((u64)val);
0052 }
0053 EXPORT_SYMBOL(__clzdi2);
0054
0055 int __weak __ctzdi2(long val)
0056 {
0057     return __ffs64((u64)val);
0058 }
0059 EXPORT_SYMBOL(__ctzdi2);
0060
0061 #else
0062 #error BITS_PER_LONG not 32 or 64
0063 #endif