Function popcount

Source/astcenc_vecmathlib_common_4.h:342–354

* @brief Population bit count. * * @param v The value to population count. * * @return The number of 1 bits. */

 * @return The number of 1 bits.
 */
static inline int popcount(uint64_t v)
{
	uint64_t mask1 = 0x5555555555555555ULL;
	uint64_t mask2 = 0x3333333333333333ULL;
	uint64_t mask3 = 0x0F0F0F0F0F0F0F0FULL;
	v -= (v >> 1) & mask1;
	v = (v & mask2) + ((v >> 2) & mask2);
	v += v >> 4;
	v &= mask3;
	v *= 0x0101010101010101ULL;
	v >>= 56;
	return static_cast<int>(v);
}

#endif