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Commit 7d9dff22 authored by Alexander van Heukelum's avatar Alexander van Heukelum Committed by Ingo Molnar
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generic: introduce a generic __fls implementation 



Add a generic __fls implementation in the same spirit as
the generic __ffs one. It finds the last (most significant)
set bit in the given long value.

Signed-off-by: default avatarAlexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 12d9c842

include/asm-generic/bitops/__fls.h

0 → 100644
+43 −0
Original line number Diff line number Diff line 
#ifndef _ASM_GENERIC_BITOPS___FLS_H_

#define _ASM_GENERIC_BITOPS___FLS_H_



#include <asm/types.h>



/**

 * __fls - find last (most-significant) set bit in a long word

 * @word: the word to search

 *

 * Undefined if no set bit exists, so code should check against 0 first.

 */

static inline unsigned long __fls(unsigned long word)

{

	int num = BITS_PER_LONG - 1;



#if BITS_PER_LONG == 64

	if (!(word & (~0ul << 32))) {

		num -= 32;

		word <<= 32;

	}

#endif

	if (!(word & (~0ul << (BITS_PER_LONG-16)))) {

		num -= 16;

		word <<= 16;

	}

	if (!(word & (~0ul << (BITS_PER_LONG-8)))) {

		num -= 8;

		word <<= 8;

	}

	if (!(word & (~0ul << (BITS_PER_LONG-4)))) {

		num -= 4;

		word <<= 4;

	}

	if (!(word & (~0ul << (BITS_PER_LONG-2)))) {

		num -= 2;

		word <<= 2;

	}

	if (!(word & (~0ul << (BITS_PER_LONG-1))))

		num -= 1;

	return num;

}



#endif /* _ASM_GENERIC_BITOPS___FLS_H_ */