#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);