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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/include/asm-generic/bitops/__fls.h
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/* SPDX-License-Identifier: GPL-2.0 */

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#ifndef _ASM_GENERIC_BITOPS___FLS_H_

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#define _ASM_GENERIC_BITOPS___FLS_H_

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#include <asm/types.h>

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/**

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

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 * @word: the word to search

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 *

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

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 */

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static __always_inline unsigned int generic___fls(unsigned long word)

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{

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	unsigned int num = BITS_PER_LONG - 1;

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#if BITS_PER_LONG == 64

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

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		num -= 32;

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		word <<= 32;

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	}

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#endif

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

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		num -= 16;

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		word <<= 16;

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	}

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

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		num -= 8;

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		word <<= 8;

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	}

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

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		num -= 4;

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		word <<= 4;

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	}

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

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		num -= 2;

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		word <<= 2;

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	}

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

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		num -= 1;

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	return num;

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}

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#ifndef __HAVE_ARCH___FLS

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#define __fls(word) generic___fls(word)

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#endif

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#endif /* _ASM_GENERIC_BITOPS___FLS_H_ */

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