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// Copyright © 2026 Mikhail Hogrefe
//
// Uses code adopted from the FLINT Library.
//
// Copyright © 1991, 1992, 1993, 1994, 1996, 1997, 1999, 2000, 2001, 2002, 2003, 2004, 2005
// Free Software Foundation, Inc.
//
// Copyright © 2009, 2015, 2016 William Hart
//
// Copyright © 2011 Fredrik Johansson
//
// 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::XXXAddYYYToZZZ;
use crate::num::basic::integers::USIZE_IS_U32;
use crate::num::basic::unsigneds::PrimitiveUnsigned;
use crate::num::conversion::traits::WrappingFrom;
// A single folded chain per word ((flag_a | flag_b), with the previous flag folded in before the
// next word) lets LLVM fuse the whole sequence into branchless adds/adcs (or subs/sbcs) on aarch64
// and adc/sbb chains on x86_64; the previous per-word branches did not fuse, and this kernel is hot
// in the fft_small CRT reconstruction.
pub_test! {xxx_add_yyy_to_zzz<T: PrimitiveUnsigned>(
x_2: T,
x_1: T,
x_0: T,
y_2: T,
y_1: T,
y_0: T,
) -> (T, T, T) {
let (z_0, carry) = x_0.overflowing_add(y_0);
let (z_1, carry_a) = x_1.overflowing_add(y_1);
let (z_1, carry_b) = z_1.overflowing_add(if carry { T::ONE } else { T::ZERO });
let carry = carry_a | carry_b;
let z_2 = x_2.wrapping_add(y_2).wrapping_add(if carry { T::ONE } else { T::ZERO });
(z_2, z_1, z_0)
}}
macro_rules! impl_xxx_add_yyy_to_zzz {
($t:ident) => {
impl XXXAddYYYToZZZ for $t {
/// Adds two numbers, each composed of three `Self` values, returning the sum as a
/// triple of `Self` values.
///
/// The more significant value always comes first. Addition is wrapping, and overflow is
/// not indicated.
///
/// $$
/// f(x_2, x_1, x_0, y_2, y_1, y_0) = (z_2, z_1, z_0),
/// $$
/// where $W$ is `Self::WIDTH`,
///
/// $x_2, x_1, x_0, y_2, y_1, y_0, z_2, z_1, z_0 < 2^W$, and
/// $$
/// (2^{2W}x_2 + 2^Wx_1 + x_0) + (2^{2W}y_2 + 2^Wy_1 + y_0)
/// \equiv 2^{2W}z_2 + 2^Wz_1 + z_0 \mod 2^{3W}.
/// $$
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::xxx_add_yyy_to_zzz#xxx_add_yyy_to_zzz).
///
/// This is equivalent to `add_sssaaaaaa` from `longlong.h`, FLINT 2.7.1, where `(sh,
/// sm, sl)` is returned.
#[inline]
fn xxx_add_yyy_to_zzz(
x_2: $t,
x_1: $t,
x_0: $t,
y_2: $t,
y_1: $t,
y_0: $t,
) -> ($t, $t, $t) {
xxx_add_yyy_to_zzz::<$t>(x_2, x_1, x_0, y_2, y_1, y_0)
}
}
};
}
impl_xxx_add_yyy_to_zzz!(u8);
impl_xxx_add_yyy_to_zzz!(u16);
impl_xxx_add_yyy_to_zzz!(u32);
impl_xxx_add_yyy_to_zzz!(u64);
impl_xxx_add_yyy_to_zzz!(u128);
impl XXXAddYYYToZZZ for usize {
/// Adds two numbers, each composed of three [`usize`] values, returning the sum as a triple of
/// [`usize`] values.
///
/// The more significant value always comes first. Addition is wrapping, and overflow is not
/// indicated.
///
/// $$
/// f(x_2, x_1, x_0, y_2, y_1, y_0) = (z_2, z_1, z_0),
/// $$
/// where $W$ is `Self::WIDTH`,
///
/// $x_2, x_1, x_0, y_2, y_1, y_0, z_2, z_1, z_0 < 2^W$, and
/// $$
/// (2^{2W}x_2 + 2^Wx_1 + x_0) + (2^{2W}y_2 + 2^Wy_1 + y_0)
/// \equiv 2^{2W}z_2 + 2^Wz_1 + z_0 \mod 2^{3W}.
/// $$
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::xxx_add_yyy_to_zzz#xxx_add_yyy_to_zzz).
///
/// This is equivalent to `add_sssaaaaaa` from `longlong.h`, FLINT 2.7.1, where `(sh, sm, sl)`
/// is returned.
fn xxx_add_yyy_to_zzz(
x_2: Self,
x_1: Self,
x_0: Self,
y_2: Self,
y_1: Self,
y_0: Self,
) -> (Self, Self, Self) {
if USIZE_IS_U32 {
let (z_2, z_1, z_0) = u32::xxx_add_yyy_to_zzz(
u32::wrapping_from(x_2),
u32::wrapping_from(x_1),
u32::wrapping_from(x_0),
u32::wrapping_from(y_2),
u32::wrapping_from(y_1),
u32::wrapping_from(y_0),
);
(
Self::wrapping_from(z_2),
Self::wrapping_from(z_1),
Self::wrapping_from(z_0),
)
} else {
let (z_2, z_1, z_0) = u64::xxx_add_yyy_to_zzz(
u64::wrapping_from(x_2),
u64::wrapping_from(x_1),
u64::wrapping_from(x_0),
u64::wrapping_from(y_2),
u64::wrapping_from(y_1),
u64::wrapping_from(y_0),
);
(
Self::wrapping_from(z_2),
Self::wrapping_from(z_1),
Self::wrapping_from(z_0),
)
}
}
}