1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
// 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::{ModPowerOf2AddMul, ModPowerOf2AddMulAssign};
use crate::num::basic::unsigneds::PrimitiveUnsigned;
fn assert_reduced<T: PrimitiveUnsigned>(x: T, y: T, z: T, pow: u64) {
assert!(pow <= T::WIDTH);
assert!(
x.significant_bits() <= pow,
"x must be reduced mod 2^pow, but {x} >= 2^{pow}"
);
assert!(
y.significant_bits() <= pow,
"y must be reduced mod 2^pow, but {y} >= 2^{pow}"
);
assert!(
z.significant_bits() <= pow,
"z must be reduced mod 2^pow, but {z} >= 2^{pow}"
);
}
#[inline]
fn mod_power_of_2_add_mul<T: PrimitiveUnsigned>(x: T, y: T, z: T, pow: u64) -> T {
assert_reduced(x, y, z, pow);
x.wrapping_add_mul(y, z).mod_power_of_2(pow)
}
#[inline]
fn mod_power_of_2_add_mul_assign<T: PrimitiveUnsigned>(x: &mut T, y: T, z: T, pow: u64) {
assert_reduced(*x, y, z, pow);
x.wrapping_add_mul_assign(y, z);
x.mod_power_of_2_assign(pow);
}
macro_rules! impl_mod_power_of_2_add_mul {
($t:ident) => {
impl ModPowerOf2AddMul<$t> for $t {
type Output = $t;
/// Adds a number and the product of two other numbers, modulo a fourth number $2^k$.
/// All three inputs must be already reduced modulo $2^k$.
///
/// $f(x, y, z, k) = w$, where $x, y, z, w < 2^k$ and $x + yz \equiv w \mod 2^k$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `pow` is greater than `Self::WIDTH` or if `self`, `y`, or `z` are greater
/// than or equal to $2^k$.
///
/// # Examples
/// See [here](super::mod_power_of_2_add_mul#mod_power_of_2_add_mul).
#[inline]
fn mod_power_of_2_add_mul(self, y: $t, z: $t, pow: u64) -> $t {
mod_power_of_2_add_mul(self, y, z, pow)
}
}
impl ModPowerOf2AddMulAssign<$t> for $t {
/// Adds the product of two numbers to a third number, modulo a fourth number $2^k$, in
/// place. All three inputs must be already reduced modulo $2^k$.
///
/// $x \gets w$, where $x, y, z, w < 2^k$ and $x + yz \equiv w \mod 2^k$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `pow` is greater than `Self::WIDTH` or if `self`, `y`, or `z` are greater
/// than or equal to $2^k$.
///
/// # Examples
/// See [here](super::mod_power_of_2_add_mul#mod_power_of_2_add_mul_assign).
#[inline]
fn mod_power_of_2_add_mul_assign(&mut self, y: $t, z: $t, pow: u64) {
mod_power_of_2_add_mul_assign(self, y, z, pow);
}
}
};
}
apply_to_unsigneds!(impl_mod_power_of_2_add_mul);