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//! Even parity check for [`U256`] values.
use super::U256;
impl U256 {
/// Returns `true` if the least significant bit is clear (the value is even).
///
/// # Examples
///
/// ```
/// use cnfy_uint::u256::U256;
///
/// assert!(U256::ZERO.is_even());
/// assert!(!U256::ONE.is_even());
/// assert!(U256::from_be_limbs([0, 0, 0, 2]).is_even());
/// ```
#[inline]
pub fn is_even(&self) -> bool {
self.0[0] & 1 == 0
}
}
#[cfg(test)]
mod ai_tests {
use super::*;
/// Zero is even.
#[test]
fn zero() {
assert!(U256::ZERO.is_even());
}
/// One is not even.
#[test]
fn one() {
assert!(!U256::ONE.is_even());
}
/// Two is even.
#[test]
fn two() {
assert!(U256::from_be_limbs([0, 0, 0, 2]).is_even());
}
/// MAX is not even.
#[test]
fn max() {
assert!(!U256::MAX.is_even());
}
/// is_even is the complement of is_odd.
#[test]
fn complement_of_is_odd() {
for &v in &[U256::ZERO, U256::ONE, U256::MAX, U256::from_be_limbs([0x8000_0000_0000_0000, 0, 0, 0])] {
assert_eq!(v.is_even(), !v.is_odd());
}
}
}