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//! Checked addition for [`U384`].
use super::U384;
impl U384 {
/// Computes `self + other`, returning `None` if the addition would
/// overflow `2^384 - 1`.
///
/// # Examples
///
/// ```
/// use cnfy_uint::u384::U384;
///
/// let a = U384::from_be_limbs([0, 0, 0, 0, 0, 10]);
/// let b = U384::from_be_limbs([0, 0, 0, 0, 0, 20]);
/// assert_eq!(a.checked_add(&b), Some(U384::from_be_limbs([0, 0, 0, 0, 0, 30])));
///
/// assert_eq!(U384::MAX.checked_add(&U384::ONE), None);
/// ```
#[inline]
pub const fn checked_add(&self, other: &U384) -> Option<U384> {
let (result, overflow) = self.overflowing_add(other);
if overflow {
None
} else {
Some(result)
}
}
}
#[cfg(test)]
mod ai_tests {
use super::*;
/// Small addition succeeds.
#[test]
fn small() {
let a = U384::from_be_limbs([0, 0, 0, 0, 0, 100]);
let b = U384::from_be_limbs([0, 0, 0, 0, 0, 200]);
assert_eq!(
a.checked_add(&b),
Some(U384::from_be_limbs([0, 0, 0, 0, 0, 300])),
);
}
/// MAX + 1 returns None.
#[test]
fn overflow() {
assert_eq!(U384::MAX.checked_add(&U384::ONE), None);
}
/// Adding zero always succeeds.
#[test]
fn zero() {
assert_eq!(U384::MAX.checked_add(&U384::ZERO), Some(U384::MAX));
}
/// MAX + MAX returns None.
#[test]
fn double_max() {
assert_eq!(U384::MAX.checked_add(&U384::MAX), None);
}
}