Overview

Computes the population count (popcnt), or Hamming distance of a binary string. This kernel takes in a single unsigned 64-bit value and returns the count of 1's that the value contains.

Dispatcher Prototype

void volk_64u_popcnt(uint64_t* ret, const uint64_t value)

Inputs

• value: The input value.

Outputs

• ret: The return value containing the popcnt.

Example

int N = 10;
unsigned int alignment = volk_get_alignment();
 
uint64_t bitstring[] = {0x0, 0x1, 0xf, 0xffffffffffffffff,
    0x5555555555555555, 0xaaaaaaaaaaaaaaaa, 0x2a2a2a2a2a2a2a2a,
    0xffffffff, 0x32, 0x64};
uint64_t hamming_distance = 0;
 
for(unsigned int ii=0; ii<N; ++ii){
    volk_64u_popcnt(&hamming_distance, bitstring[ii]);
    printf("hamming distance of %lx = %li\n", bitstring[ii], hamming_distance);
}