generic: introduce a generic __fls implementation

#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_ */