include/asm-generic/bitops/hweight.h

#ifndef _ASM_GENERIC_BITOPS_HWEIGHT_H_
#define _ASM_GENERIC_BITOPS_HWEIGHT_H_

#include <asm/types.h>

/*
 * hweightN: returns the hamming weight (i.e. the number
 * of bits set) of a N-bit word
 */

static inline unsigned int hweight32(unsigned int w)
{
	unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
	res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
	res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
	res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
	return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
}

static inline unsigned int hweight16(unsigned int w)
{
	unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
	res = (res & 0x3333) + ((res >> 2) & 0x3333);
	res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
	return (res & 0x00FF) + ((res >> 8) & 0x00FF);
}

static inline unsigned int hweight8(unsigned int w)
{
	unsigned int res = (w & 0x55) + ((w >> 1) & 0x55);
	res = (res & 0x33) + ((res >> 2) & 0x33);
	return (res & 0x0F) + ((res >> 4) & 0x0F);
}

#endif				/* _ASM_GENERIC_BITOPS_HWEIGHT_H_ */