[mirror_ubuntu-disco-kernel.git] / include / asm-generic / bitops / __fls.h

/* SPDX-License-Identifier: GPL-2.0 */
#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 __always_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_ */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
7d9dff22 AH	2	#ifndef _ASM_GENERIC_BITOPS___FLS_H_
	3	#define _ASM_GENERIC_BITOPS___FLS_H_
	4
	5	#include <asm/types.h>
	6
	7	/**
	8	* __fls - find last (most-significant) set bit in a long word
	9	* @word: the word to search
	10	*
	11	* Undefined if no set bit exists, so code should check against 0 first.
	12	*/
c8399943	13	static __always_inline unsigned long __fls(unsigned long word)
7d9dff22 AH	14	{
	15	int num = BITS_PER_LONG - 1;
	16
	17	#if BITS_PER_LONG == 64
	18	if (!(word & (~0ul << 32))) {
	19	num -= 32;
	20	word <<= 32;
	21	}
	22	#endif
	23	if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
	24	num -= 16;
	25	word <<= 16;
	26	}
	27	if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
	28	num -= 8;
	29	word <<= 8;
	30	}
	31	if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
	32	num -= 4;
	33	word <<= 4;
	34	}
	35	if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
	36	num -= 2;
	37	word <<= 2;
	38	}
	39	if (!(word & (~0ul << (BITS_PER_LONG-1))))
	40	num -= 1;
	41	return num;
	42	}
	43
	44	#endif /* _ASM_GENERIC_BITOPS___FLS_H_ */