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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::{
ShlRound, ShlRoundAssign, ShrRound, ShrRoundAssign, UnsignedAbs,
};
use crate::num::basic::integers::PrimitiveInt;
use crate::num::basic::signeds::PrimitiveSigned;
use crate::rounding_modes::RoundingMode;
use core::cmp::Ordering::{self, *};
use core::ops::{Shl, ShlAssign};
fn shl_round<
T: PrimitiveInt + Shl<U, Output = T> + ShrRound<U, Output = T>,
U,
S: PrimitiveSigned + UnsignedAbs<Output = U>,
>(
x: T,
bits: S,
rm: RoundingMode,
) -> (T, Ordering) {
if bits >= S::ZERO {
let width = S::wrapping_from(T::WIDTH);
(
if width >= S::ZERO && bits >= width {
T::ZERO
} else {
x << bits.unsigned_abs()
},
Equal,
)
} else {
x.shr_round(bits.unsigned_abs(), rm)
}
}
fn shl_round_assign<
T: PrimitiveInt + ShlAssign<U> + ShrRoundAssign<U>,
U,
S: PrimitiveSigned + UnsignedAbs<Output = U>,
>(
x: &mut T,
bits: S,
rm: RoundingMode,
) -> Ordering {
if bits >= S::ZERO {
let width = S::wrapping_from(T::WIDTH);
if width >= S::ZERO && bits >= width {
*x = T::ZERO;
} else {
*x <<= bits.unsigned_abs();
}
Equal
} else {
x.shr_round_assign(bits.unsigned_abs(), rm)
}
}
macro_rules! impl_shl_round {
($t:ident) => {
macro_rules! impl_shl_round_inner {
($u:ident) => {
impl ShlRound<$u> for $t {
type Output = $t;
/// Left-shifts a number (multiplies it by a power of 2 or divides it by a power
/// of 2 and takes the floor) and rounds according to the specified rounding
/// mode. An [`Ordering`] is also returned, indicating whether the returned
/// value is less than, equal to, or greater than the exact value. If `bits` is
/// non-negative, then the returned [`Ordering`] is always `Equal`, even if the
/// higher bits of the result are lost.
///
/// Passing `Floor` or `Down` is equivalent to using `>>`. To test whether
/// `Exact` can be passed, use `bits > 0 || self.divisible_by_power_of_2(bits)`.
/// Rounding might only be necessary if `bits` is negative.
///
/// Let $q = x2^k$, and let $g$ be the function that just returns the first
/// element of the pair, without the [`Ordering`]:
///
/// $g(x, k, \mathrm{Down}) = g(x, y, \mathrm{Floor}) = \lfloor q \rfloor.$
///
/// $g(x, k, \mathrm{Up}) = g(x, y, \mathrm{Ceiling}) = \lceil q \rceil.$
///
/// $$
/// g(x, k, \mathrm{Nearest}) = \begin{cases}
/// \lfloor q \rfloor & \text{if}
/// \\quad q - \lfloor q \rfloor < \frac{1}{2}, \\\\
/// \lceil q \rceil & \text{if}
/// \\quad q - \lfloor q \rfloor > \frac{1}{2}, \\\\
/// \lfloor q \rfloor & \text{if} \\quad q - \lfloor q \rfloor =
/// \frac{1}{2} \\ \text{and} \\ \lfloor q \rfloor
/// \\ \text{is even}, \\\\
/// \lceil q \rceil &
/// \text{if} \\quad q - \lfloor q \rfloor = \frac{1}{2} \\ \text{and}
/// \\ \lfloor q \rfloor \\ \text{is odd}.
/// \end{cases}
/// $$
///
/// $g(x, k, \mathrm{Exact}) = q$, but panics if $q \notin \N$.
///
/// Then
///
/// $f(x, k, r) = (g(x, k, r), \operatorname{cmp}(g(x, k, r), q))$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `bits` is positive and `rm` is `Exact` but `self` is not divisible
/// by $2^b$.
///
/// # Examples
/// See [here](super::shl_round#shl_round).
#[inline]
fn shl_round(self, bits: $u, rm: RoundingMode) -> ($t, Ordering) {
shl_round(self, bits, rm)
}
}
impl ShlRoundAssign<$u> for $t {
/// Left-shifts a number (multiplies it by a power of 2 or divides it by a power
/// of 2 and takes the floor) and rounds according to the specified rounding
/// mode, in place. An [`Ordering`] is returned, indicating whether the assigned
/// value is less than, equal to, or greater than the exact value. If `bits` is
/// non-negative, then the returned [`Ordering`] is always `Equal`, even if the
/// higher bits of the result are lost.
///
/// Passing `Floor` or `Down` is equivalent to using `>>`. To test whether
/// `Exact` can be passed, use `bits > 0 || self.divisible_by_power_of_2(bits)`.
/// Rounding might only be necessary if `bits` is negative.
///
/// See the [`ShlRound`] documentation for details.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if `bits` is positive and `rm` is `Exact` but `self` is not divisible
/// by $2^b$.
///
/// # Examples
/// See [here](super::shl_round#shl_round_assign).
#[inline]
fn shl_round_assign(&mut self, bits: $u, rm: RoundingMode) -> Ordering {
shl_round_assign(self, bits, rm)
}
}
};
}
apply_to_signeds!(impl_shl_round_inner);
};
}
apply_to_primitive_ints!(impl_shl_round);