linux/include/asm-generic/bitops/builtin-fls.h
Catalin Marinas 048fa2df92 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>
2012-09-14 17:15:41 +01:00

17 lines
364 B
C

#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