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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::{
OverflowingAddAssign, OverflowingAddMul, OverflowingAddMulAssign, UnsignedAbs,
};
use crate::num::basic::signeds::PrimitiveSigned;
use crate::num::basic::unsigneds::PrimitiveUnsigned;
fn overflowing_add_mul_unsigned<T: PrimitiveUnsigned>(x: T, y: T, z: T) -> (T, bool) {
let (product, overflow_1) = y.overflowing_mul(z);
let (result, overflow_2) = x.overflowing_add(product);
(result, overflow_1 | overflow_2)
}
macro_rules! impl_overflowing_add_mul_unsigned {
($t:ident) => {
impl OverflowingAddMul<$t> for $t {
type Output = $t;
/// Adds a number and the product of two other numbers.
///
/// Returns a tuple containing the result and a boolean indicating whether an arithmetic
/// overflow occurred. If an overflow occurred, then the wrapped value is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::overflowing_add_mul#overflowing_add_mul).
#[inline]
fn overflowing_add_mul(self, y: $t, z: $t) -> ($t, bool) {
overflowing_add_mul_unsigned(self, y, z)
}
}
impl OverflowingAddMulAssign<$t> for $t {
/// Adds a number and the product of two other numbers, in place.
///
/// Returns a boolean indicating whether an arithmetic overflow occurred. If an overflow
/// occurred, then the wrapped value is assigned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::overflowing_add_mul#overflowing_add_mul_assign).
#[inline]
fn overflowing_add_mul_assign(&mut self, y: $t, z: $t) -> bool {
let (product, overflow) = y.overflowing_mul(z);
self.overflowing_add_assign(product) | overflow
}
}
};
}
apply_to_unsigneds!(impl_overflowing_add_mul_unsigned);
fn overflowing_add_mul_signed<
U: PrimitiveUnsigned,
S: PrimitiveSigned + UnsignedAbs<Output = U>,
>(
x: S,
y: S,
z: S,
) -> (S, bool) {
if y == S::ZERO || z == S::ZERO {
return (x, false);
}
let x_sign = x >= S::ZERO;
if x_sign == ((y >= S::ZERO) == (z >= S::ZERO)) {
let (product, overflow_1) = y.overflowing_mul(z);
let (result, overflow_2) = x.overflowing_add(product);
(result, overflow_1 | overflow_2)
} else {
let result = x.wrapping_add(y.wrapping_mul(z));
let overflow = {
let x = x.unsigned_abs();
match y.unsigned_abs().checked_mul(z.unsigned_abs()) {
Some(product) => {
x < product
&& if x_sign {
!x.wrapping_sub(product).get_highest_bit()
} else {
product.wrapping_sub(x).get_highest_bit()
}
}
None => true,
}
};
(result, overflow)
}
}
macro_rules! impl_overflowing_add_mul_signed {
($t:ident) => {
impl OverflowingAddMul<$t> for $t {
type Output = $t;
/// Adds a number and the product of two other numbers.
///
/// Returns a tuple containing the result and a boolean indicating whether an arithmetic
/// overflow occurred. If an overflow occurred, then the wrapped value is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::overflowing_add_mul#overflowing_add_mul).
#[inline]
fn overflowing_add_mul(self, y: $t, z: $t) -> ($t, bool) {
overflowing_add_mul_signed(self, y, z)
}
}
impl OverflowingAddMulAssign<$t> for $t {
/// Adds a number and the product of two other numbers, in place.
///
/// Returns a boolean indicating whether an arithmetic overflow occurred. If an overflow
/// occurred, then the wrapped value is assigned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::overflowing_add_mul#overflowing_add_mul_assign).
#[inline]
fn overflowing_add_mul_assign(&mut self, y: $t, z: $t) -> bool {
let overflow;
(*self, overflow) = self.overflowing_add_mul(y, z);
overflow
}
}
};
}
apply_to_signeds!(impl_overflowing_add_mul_signed);