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use crate::num::arithmetic::traits::{ModPowerOf2Sub, ModPowerOf2SubAssign};
use crate::num::basic::unsigneds::PrimitiveUnsigned;
fn mod_power_of_2_sub<T: PrimitiveUnsigned>(x: T, other: T, pow: u64) -> T {
assert!(pow <= T::WIDTH);
x.wrapping_sub(other).mod_power_of_2(pow)
}
fn mod_power_of_2_sub_assign<T: PrimitiveUnsigned>(x: &mut T, other: T, pow: u64) {
assert!(pow <= T::WIDTH);
x.wrapping_sub_assign(other);
x.mod_power_of_2_assign(pow);
}
macro_rules! impl_mod_power_of_2_sub {
($t:ident) => {
impl ModPowerOf2Sub<$t> for $t {
type Output = $t;
/// Subtracts two numbers modulo a third number $2^k$. Assumes the inputs are already
/// reduced modulo $2^k$.
///
/// $f(x, y, k) = z$, where $x, y, z < 2^k$ and $x - y \equiv z \mod 2^k$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `pow` is greater than `Self::WIDTH`.
///
/// # Examples
/// See [here](super::mod_power_of_2_sub#mod_power_of_2_sub).
#[inline]
fn mod_power_of_2_sub(self, other: $t, pow: u64) -> $t {
mod_power_of_2_sub(self, other, pow)
}
}
impl ModPowerOf2SubAssign<$t> for $t {
/// Subtracts two numbers modulo a third number $2^k$, in place. Assumes the inputs are
/// already reduced modulo $2^k$.
///
/// $x \gets z$, where $x, y, z < 2^k$ and $x - y \equiv z \mod 2^k$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `pow` is greater than `Self::WIDTH`.
///
/// # Examples
/// See [here](super::mod_power_of_2_sub#mod_power_of_2_sub_assign).
#[inline]
fn mod_power_of_2_sub_assign(&mut self, other: $t, pow: u64) {
mod_power_of_2_sub_assign(self, other, pow);
}
}
};
}
apply_to_unsigneds!(impl_mod_power_of_2_sub);