vendor/crypto-bigint/src/uint/neg.rs


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

use core::ops::Neg;

use crate::{CtChoice, Uint, Wrapping};

impl<const LIMBS: usize> Neg for Wrapping<Uint<LIMBS>> {
    type Output = Self;

    fn neg(self) -> Self::Output {
        let shifted = Wrapping(self.0.shl_vartime(1));
        self - shifted
    }
}

impl<const LIMBS: usize> Uint<LIMBS> {
    /// Negates based on `choice` by wrapping the integer.
    pub(crate) const fn conditional_wrapping_neg(&self, choice: CtChoice) -> Uint<LIMBS> {
        let (shifted, _) = self.shl_1();
        let negated_self = self.wrapping_sub(&shifted);

        Uint::ct_select(self, &negated_self, choice)
    }
}