Log(N) method for calculating the number of bits set in a word

bits_set

/* Log(N) method for calculating the number of bits set in a word */
uint8_t bits_set(uint32_t word)
{
	word = (word & 0x55555555) + ((word >> 1) & 0x55555555);
	word = (word & 0x33333333) + ((word >> 2) & 0x33333333);
	word = (word & 0x0F0F0F0F) + ((word >> 4) & 0x0F0F0F0F);
	word = (word & 0x00FF00FF) + ((word >> 8) & 0x00FF00FF);
	word = (word & 0x0000FFFF) + ((word >> 16) & 0x0000FFFF);

	return (uint8_t)word;
}