Function div_2x1 

pub fn div_2x1(u: u128, d: u64, v: u64) -> (u64, u64)

⚠️ Computes the quotient and remainder of a u128 divided by a u64.

⚠️ This function is not part of the stable API.

Requires * `u < d * 2**64`, * `d >= 2**63`, and * `v = reciprocal(d)`.

Implements algorithm 4 from MG10.