Function popCount [src]

r = @popCount(a) with 2s-complement semantics. r and a may be aliases. Assets the result fits in r. Upper bound on the number of limbs needed by r is calcTwosCompLimbCount(bit_count).

Prototype

pub fn popCount(r: *Mutable, a: Const, bit_count: usize) void

Parameters

r: *Mutablea: Constbit_count: usize

Source

  pub fn popCount(r: *Mutable, a: Const, bit_count: usize) void {
    r.copy(a);

    if (!a.positive) {
        r.positive = true; // Negate.
        r.bitNotWrap(r.toConst(), .unsigned, bit_count); // Bitwise NOT.
        r.addScalar(r.toConst(), 1); // Add one.
    }

    var sum: Limb = 0;
    for (r.limbs[0..r.len]) |limb| {
        sum += @popCount(limb);
    }
    r.set(sum);
}  