[linux-block.git] / tools / include / asm-generic / bitops / __ffs.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_
#define _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_

#include <asm/types.h>
#include <asm/bitsperlong.h>

/**
 * __ffs - find first bit in word.
 * @word: The word to search
 *
 * Undefined if no bit exists, so code should check against 0 first.
 */
static __always_inline unsigned long __ffs(unsigned long word)
{
	int num = 0;

#if __BITS_PER_LONG == 64
	if ((word & 0xffffffff) == 0) {
		num += 32;
		word >>= 32;
	}
#endif
	if ((word & 0xffff) == 0) {
		num += 16;
		word >>= 16;
	}
	if ((word & 0xff) == 0) {
		num += 8;
		word >>= 8;
	}
	if ((word & 0xf) == 0) {
		num += 4;
		word >>= 4;
	}
	if ((word & 0x3) == 0) {
		num += 2;
		word >>= 2;
	}
	if ((word & 0x1) == 0)
		num += 1;
	return num;
}

#endif /* _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
2dc0b972 ACM	2	#ifndef _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_
	3	#define _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_
	4
	5	#include <asm/types.h>
bb970707	6	#include <asm/bitsperlong.h>
2dc0b972 ACM	7
	8	/**
	9	* __ffs - find first bit in word.
	10	* @word: The word to search
	11	*
	12	* Undefined if no bit exists, so code should check against 0 first.
	13	*/
	14	static __always_inline unsigned long __ffs(unsigned long word)
	15	{
	16	int num = 0;
	17
	18	#if __BITS_PER_LONG == 64
	19	if ((word & 0xffffffff) == 0) {
	20	num += 32;
	21	word >>= 32;
	22	}
	23	#endif
	24	if ((word & 0xffff) == 0) {
	25	num += 16;
	26	word >>= 16;
	27	}
	28	if ((word & 0xff) == 0) {
	29	num += 8;
	30	word >>= 8;
	31	}
	32	if ((word & 0xf) == 0) {
	33	num += 4;
	34	word >>= 4;
	35	}
	36	if ((word & 0x3) == 0) {
	37	num += 2;
	38	word >>= 2;
	39	}
	40	if ((word & 0x1) == 0)
	41	num += 1;
	42	return num;
	43	}
	44
	45	#endif /* _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ */