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#include <linux/module.h>

#include <linux/bitops.h>

#include <asm/types.h>

/**

 * hweightN - returns the hamming weight of a N-bit word

 * @x: the word to weigh

 *

 * The Hamming Weight of a number is the total number of bits set in it.

 */

unsigned int hweight32(unsigned int w)

{

        unsigned int res = w - ((w >> 1) & 0x55555555);

        res = (res & 0x33333333) + ((res >> 2) & 0x33333333);

        res = (res + (res >> 4)) & 0x0F0F0F0F;

        res = res + (res >> 8);

        return (res + (res >> 16)) & 0x000000FF;

}

EXPORT_SYMBOL(hweight32);

unsigned int hweight16(unsigned int w)

{

        unsigned int res = w - ((w >> 1) & 0x5555);

        res = (res & 0x3333) + ((res >> 2) & 0x3333);

        res = (res + (res >> 4)) & 0x0F0F;

        return (res + (res >> 8)) & 0x00FF;

}

EXPORT_SYMBOL(hweight16);

unsigned int hweight8(unsigned int w)

{

        unsigned int res = w - ((w >> 1) & 0x55);

        res = (res & 0x33) + ((res >> 2) & 0x33);

        return (res + (res >> 4)) & 0x0F;

}

EXPORT_SYMBOL(hweight8);

unsigned long hweight64(__u64 w)

{

#if BITS_PER_LONG == 32

        return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);

#elif BITS_PER_LONG == 64

#ifdef ARCH_HAS_FAST_MULTIPLIER

        w -= (w >> 1) & 0x5555555555555555ul;

        w =  (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);

        w =  (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;

        return (w * 0x0101010101010101ul) >> 56;

#else

        __u64 res = w - ((w >> 1) & 0x5555555555555555ul);

        res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);

        res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;

        res = res + (res >> 8);

        res = res + (res >> 16);

        return (res + (res >> 32)) & 0x00000000000000FFul;

#endif

#endif

}

EXPORT_SYMBOL(hweight64);