crypto_bigint/boxed/uint/
add.rs

1//! [`BoxedUint`] addition operations.
2
3use crate::{BoxedUint, CheckedAdd, Limb, Zero};
4use subtle::CtOption;
5
6impl BoxedUint {
7    /// Computes `a + b + carry`, returning the result along with the new carry.
8    #[inline(always)]
9    pub fn adc(&self, rhs: &Self, carry: Limb) -> (Self, Limb) {
10        Self::chain(self, rhs, carry, |a, b, c| a.adc(b, c))
11    }
12
13    /// Perform wrapping addition, discarding overflow.
14    pub fn wrapping_add(&self, rhs: &Self) -> Self {
15        self.adc(rhs, Limb::ZERO).0
16    }
17}
18
19impl CheckedAdd<&BoxedUint> for BoxedUint {
20    type Output = Self;
21
22    fn checked_add(&self, rhs: &Self) -> CtOption<Self> {
23        let (result, carry) = self.adc(rhs, Limb::ZERO);
24        CtOption::new(result, carry.is_zero())
25    }
26}
27
28#[cfg(test)]
29#[allow(clippy::unwrap_used)]
30mod tests {
31    use super::{BoxedUint, CheckedAdd, Limb};
32
33    #[test]
34    fn adc_no_carry() {
35        let (res, carry) = BoxedUint::zero().adc(&BoxedUint::one(), Limb::ZERO);
36        assert_eq!(res, BoxedUint::one());
37        assert_eq!(carry, Limb::ZERO);
38    }
39
40    #[test]
41    fn adc_with_carry() {
42        let (res, carry) = BoxedUint::max(Limb::BITS)
43            .unwrap()
44            .adc(&BoxedUint::one(), Limb::ZERO);
45        assert_eq!(res, BoxedUint::zero());
46        assert_eq!(carry, Limb::ONE);
47    }
48
49    #[test]
50    fn checked_add_ok() {
51        let result = BoxedUint::zero().checked_add(&BoxedUint::one());
52        assert_eq!(result.unwrap(), BoxedUint::one());
53    }
54
55    #[test]
56    fn checked_add_overflow() {
57        let result = BoxedUint::max(Limb::BITS)
58            .unwrap()
59            .checked_add(&BoxedUint::one());
60        assert!(!bool::from(result.is_some()));
61    }
62}
crypto_bigint/boxed/uint/add.rs

crypto_bigint/boxed/uint/
add.rs
