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| author | Catalin Marinas <catalin.marinas@arm.com> | 2012-09-12 23:00:53 +0200 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2012-09-14 18:15:41 +0200 |
| commit | 048fa2df92c325cb4425dccd66c8922c8342b507 (patch) | |
| tree | a76ddbd3f05752f27e0867906a34e102cb76b4e4 /include/asm-generic/bitops/builtin-fls.h | |
| parent | fs: Build sys_stat64() and friends if __ARCH_WANT_COMPAT_STAT64 (diff) | |
| download | linux-048fa2df92c325cb4425dccd66c8922c8342b507.tar.xz linux-048fa2df92c325cb4425dccd66c8922c8342b507.zip | |
generic: Implement generic ffs/fls using __builtin_* functions
This patch implements ffs, __ffs, fls, __fls using __builtin_* gcc
functions. These header files can be used by other architectures that
rely on the gcc builtins.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'include/asm-generic/bitops/builtin-fls.h')
| -rw-r--r-- | include/asm-generic/bitops/builtin-fls.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/include/asm-generic/bitops/builtin-fls.h b/include/asm-generic/bitops/builtin-fls.h new file mode 100644 index 000000000000..eda652d0ac7f --- /dev/null +++ b/include/asm-generic/bitops/builtin-fls.h @@ -0,0 +1,16 @@ +#ifndef _ASM_GENERIC_BITOPS_BUILTIN_FLS_H_ +#define _ASM_GENERIC_BITOPS_BUILTIN_FLS_H_ + +/** + * fls - find last (most-significant) bit set + * @x: the word to search + * + * This is defined the same way as ffs. + * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32. + */ +static __always_inline int fls(int x) +{ + return x ? sizeof(x) * 8 - __builtin_clz(x) : 0; +} + +#endif |