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Commit 136abb32 authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
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[PATCH] bitops: generic fls() 



This patch introduces the C-language equivalent of the function: int fls(int
x);

In include/asm-generic/bitops/fls.h

This code largely copied from: include/linux/bitops.h

Signed-off-by: default avatarAkinobu Mita <mita@miraclelinux.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 176d8b0c

include/asm-generic/bitops/fls.h

0 → 100644
+41 −0
Original line number Diff line number Diff line 
#ifndef _ASM_GENERIC_BITOPS_FLS_H_

#define _ASM_GENERIC_BITOPS_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 inline int fls(int x)

{

	int r = 32;



	if (!x)

		return 0;

	if (!(x & 0xffff0000u)) {

		x <<= 16;

		r -= 16;

	}

	if (!(x & 0xff000000u)) {

		x <<= 8;

		r -= 8;

	}

	if (!(x & 0xf0000000u)) {

		x <<= 4;

		r -= 4;

	}

	if (!(x & 0xc0000000u)) {

		x <<= 2;

		r -= 2;

	}

	if (!(x & 0x80000000u)) {

		x <<= 1;

		r -= 1;

	}

	return r;

}



#endif /* _ASM_GENERIC_BITOPS_FLS_H_ */