[mirror_ubuntu-bionic-kernel.git] / include / asm-generic / bitops / ffs.h

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

/**
 * ffs - find first bit set
 * @x: the word to search
 *
 * This is defined the same way as
 * the libc and compiler builtin ffs routines, therefore
 * differs in spirit from the above ffz (man ffs).
 */
static inline int ffs(int x)
{
	int r = 1;

	if (!x)
		return 0;
	if (!(x & 0xffff)) {
		x >>= 16;
		r += 16;
	}
	if (!(x & 0xff)) {
		x >>= 8;
		r += 8;
	}
	if (!(x & 0xf)) {
		x >>= 4;
		r += 4;
	}
	if (!(x & 3)) {
		x >>= 2;
		r += 2;
	}
	if (!(x & 1)) {
		x >>= 1;
		r += 1;
	}
	return r;
}

#endif /* _ASM_GENERIC_BITOPS_FFS_H_ */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
09020adb AM	2	#ifndef _ASM_GENERIC_BITOPS_FFS_H_
	3	#define _ASM_GENERIC_BITOPS_FFS_H_
	4
	5	/**
	6	* ffs - find first bit set
	7	* @x: the word to search
	8	*
	9	* This is defined the same way as
	10	* the libc and compiler builtin ffs routines, therefore
	11	* differs in spirit from the above ffz (man ffs).
	12	*/
	13	static inline int ffs(int x)
	14	{
	15	int r = 1;
	16
	17	if (!x)
	18	return 0;
	19	if (!(x & 0xffff)) {
	20	x >>= 16;
	21	r += 16;
	22	}
	23	if (!(x & 0xff)) {
	24	x >>= 8;
	25	r += 8;
	26	}
	27	if (!(x & 0xf)) {
	28	x >>= 4;
	29	r += 4;
	30	}
	31	if (!(x & 3)) {
	32	x >>= 2;
	33	r += 2;
	34	}
	35	if (!(x & 1)) {
	36	x >>= 1;
	37	r += 1;
	38	}
	39	return r;
	40	}
	41
	42	#endif /* _ASM_GENERIC_BITOPS_FFS_H_ */