The popcount function has the prototype:
fun popcount = (any integer_or_offset) int<32>:
{ ... }
It returns number of 1 bits in the given input integer_or_offset.
Examples:
assert (popcount (1) == 1); assert (popcount (5) == 2); assert (popcount (-1) == 32); assert (popcount (-1L) == 64); assert (popcount (0#B) == 0); assert (popcount (0xff#B) == 8);