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//! Bitwise NOT via the [`Not`] trait.
use super::U256;
use core::ops::Not;
/// Computes the bitwise complement of a 256-bit integer, flipping
/// every bit.
///
/// Applied independently to each of the four `u64` limbs via the
/// `!` operator.
///
/// # Examples
///
/// ```
/// use cnfy_uint::u256::U256;
///
/// assert_eq!(!U256::ZERO, U256::MAX);
/// assert_eq!(!U256::MAX, U256::ZERO);
/// ```
impl Not for U256 {
type Output = U256;
#[inline]
fn not(self) -> U256 {
U256([!self.0[0], !self.0[1], !self.0[2], !self.0[3]])
}
}
#[cfg(test)]
mod ai_tests {
use super::*;
/// NOT zero is MAX.
#[test]
fn not_zero() {
assert_eq!(!U256::ZERO, U256::MAX);
}
/// NOT MAX is zero.
#[test]
fn not_max() {
assert_eq!(!U256::MAX, U256::ZERO);
}
/// Double NOT is identity.
#[test]
fn double_not() {
let a = U256::from_be_limbs([0x1234, 0x5678, 0x9ABC, 0xDEF0]);
assert_eq!(!!a, a);
}
/// NOT flips specific bits.
#[test]
fn flips_bits() {
let a = U256::from_be_limbs([0, 0, 0, 0xFF]);
let expected = U256::from_be_limbs([u64::MAX, u64::MAX, u64::MAX, u64::MAX ^ 0xFF]);
assert_eq!(!a, expected);
}
}