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// Copyright © 2026 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
use crate::num::arithmetic::traits::{
ModMulPrecomputed, ModPow, ModPowAssign, ModSquare, ModSquareAssign, ModSquarePrecomputed,
ModSquarePrecomputedAssign,
};
// `$mul_data` projects the modular-exponentiation data onto the modular-multiplication data it
// contains: the pow data is `(mul_inverse, shift)` for every type except `u128`, whose pow and mul
// data are both `()`.
macro_rules! impl_mod_square {
($t:ident, $mul_data:path) => {
impl ModSquare for $t {
type Output = $t;
/// Squares a number modulo another number $m$. The input must be already reduced modulo
/// $m$.
///
/// $f(x, m) = y$, where $x, y < m$ and $x^2 \equiv y \mod m$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// See [here](super::mod_square#mod_square).
#[inline]
fn mod_square(self, m: $t) -> $t {
self.mod_pow(2, m)
}
}
impl ModSquareAssign for $t {
/// Squares a number modulo another number $m$, in place. The input must be already
/// reduced modulo $m$.
///
/// $x \gets y$, where $x, y < m$ and $x^2 \equiv y \mod m$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// See [here](super::mod_square#mod_square_assign).
#[inline]
fn mod_square_assign(&mut self, m: $t) {
self.mod_pow_assign(2, m);
}
}
impl ModSquarePrecomputed<u64, $t> for $t {
/// Squares a number modulo another number $m$. The input must be already reduced modulo
/// $m$.
///
/// Some precomputed data is provided; this speeds up computations involving several
/// modular squarings with the same modulus. The precomputed data should be obtained
/// using [`precompute_mod_pow_data`](super::traits::ModPowPrecomputed).
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// See [here](super::mod_square#mod_square_precomputed).
#[inline]
fn mod_square_precomputed(self, m: $t, data: &Self::Data) -> Self::Output {
self.mod_mul_precomputed(self, m, $mul_data(data))
}
}
impl ModSquarePrecomputedAssign<u64, $t> for $t {
/// Squares a number modulo another number $m$, in place. The input must be already
/// reduced modulo $m$.
///
/// Some precomputed data is provided; this speeds up computations involving several
/// modular squarings with the same modulus. The precomputed data should be obtained
/// using [`precompute_mod_pow_data`](super::traits::ModPowPrecomputed).
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `self` is greater than or equal to `m`.
///
/// # Examples
/// See [here](super::mod_square#mod_square_precomputed_assign).
#[inline]
fn mod_square_precomputed_assign(&mut self, m: $t, data: &Self::Data) {
*self = self.mod_mul_precomputed(*self, m, $mul_data(data));
}
}
};
}
const fn pair_mul_data<A, B>(data: &(A, B)) -> &A {
&data.0
}
const fn unit_mul_data(data: &()) -> &() {
data
}
impl_mod_square!(u8, pair_mul_data);
impl_mod_square!(u16, pair_mul_data);
impl_mod_square!(u32, pair_mul_data);
impl_mod_square!(u64, pair_mul_data);
impl_mod_square!(u128, unit_mul_data);
impl_mod_square!(usize, pair_mul_data);