Function hamming_distance 

pub fn hamming_distance(
    df: &mut DramDataflow,
    a: &[usize],
    b: &[usize],
    out_width: usize,
    zero: usize,
) -> Vec<usize>

Per-lane HAMMING DISTANCE between two bit-serial codes a/b (K planes each): popcount(a XOR b). The core kernel of vector similarity search (ANN over binary codes) and binary-net inference.