itoa/
u128_ext.rs

1#[cfg(feature = "no-panic")]
2use no_panic::no_panic;
3
4/// Multiply unsigned 128 bit integers, return upper 128 bits of the result
5#[inline]
6#[cfg_attr(feature = "no-panic", no_panic)]
7pub(crate) fn mulhi(x: u128, y: u128) -> u128 {
8    let x_lo = x as u64;
9    let x_hi = (x >> 64) as u64;
10    let y_lo = y as u64;
11    let y_hi = (y >> 64) as u64;
12
13    // handle possibility of overflow
14    let carry = (u128::from(x_lo) * u128::from(y_lo)) >> 64;
15    let m = u128::from(x_lo) * u128::from(y_hi) + carry;
16    let high1 = m >> 64;
17
18    let m_lo = m as u64;
19    let high2 = (u128::from(x_hi) * u128::from(y_lo) + u128::from(m_lo)) >> 64;
20
21    u128::from(x_hi) * u128::from(y_hi) + high1 + high2
22}
itoa/u128_ext.rs

itoa/
u128_ext.rs
