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//! Bitwise XOR via the [`BitXor`] trait.
use super::U512;
use core::ops::BitXor;
/// Computes the bitwise XOR of two 512-bit integers, producing a
/// result where each bit is set if exactly one of the corresponding
/// input bits is set.
///
/// Applied independently to each of the eight `u64` limbs.
///
/// # Examples
///
/// ```
/// use cnfy_uint::u512::U512;
///
/// let a = U512::from_be_limbs([0, 0, 0, 0, 0, 0, 0, 0xFF]);
/// let b = U512::from_be_limbs([0, 0, 0, 0, 0, 0, 0, 0x0F]);
/// assert_eq!(a ^ b, U512::from_be_limbs([0, 0, 0, 0, 0, 0, 0, 0xF0]));
/// ```
impl BitXor for U512 {
type Output = U512;
#[inline]
fn bitxor(self, rhs: U512) -> U512 {
U512([
self.0[0] ^ rhs.0[0],
self.0[1] ^ rhs.0[1],
self.0[2] ^ rhs.0[2],
self.0[3] ^ rhs.0[3],
self.0[4] ^ rhs.0[4],
self.0[5] ^ rhs.0[5],
self.0[6] ^ rhs.0[6],
self.0[7] ^ rhs.0[7],
])
}
}
#[cfg(test)]
mod ai_tests {
use super::*;
/// XOR with self is zero.
#[test]
fn self_cancellation() {
let a = U512::from_be_limbs([0x1234, 0x5678, 0x9ABC, 0xDEF0, 1, 2, 3, 4]);
assert_eq!(a ^ a, U512::ZERO);
}
/// XOR with zero is identity.
#[test]
fn xor_zero() {
let a = U512::from_be_limbs([0x1234, 0x5678, 0x9ABC, 0xDEF0, 1, 2, 3, 4]);
assert_eq!(a ^ U512::ZERO, a);
}
/// XOR with MAX flips all bits.
#[test]
fn xor_max() {
let a = U512::from_be_limbs([0x1234, 0x5678, 0x9ABC, 0xDEF0, 1, 2, 3, 4]);
assert_eq!(a ^ U512::MAX, !a);
}
/// XOR is commutative.
#[test]
fn commutative() {
let a = U512::from_be_limbs([1, 2, 3, 4, 5, 6, 7, 8]);
let b = U512::from_be_limbs([8, 7, 6, 5, 4, 3, 2, 1]);
assert_eq!(a ^ b, b ^ a);
}
/// Double XOR is identity.
#[test]
fn double_xor() {
let a = U512::from_be_limbs([0xAB, 0xCD, 0xEF, 0x42, 1, 2, 3, 4]);
let b = U512::from_be_limbs([0x11, 0x22, 0x33, 0x44, 5, 6, 7, 8]);
assert_eq!((a ^ b) ^ b, a);
}
}