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// SPDX-License-Identifier: GPL-2.0

//! Pre-defined atomic types

// SAFETY: `i32` has the same size and alignment with itself, and is round-trip transmutable to
// itself.
unsafe impl super::AtomicType for i32 {
    type Repr = i32;
}

// SAFETY: The wrapping add result of two `i32`s is a valid `i32`.
unsafe impl super::AtomicAdd<i32> for i32 {
    fn rhs_into_delta(rhs: i32) -> i32 {
        rhs
    }
}

// SAFETY: `i64` has the same size and alignment with itself, and is round-trip transmutable to
// itself.
unsafe impl super::AtomicType for i64 {
    type Repr = i64;
}

// SAFETY: The wrapping add result of two `i64`s is a valid `i64`.
unsafe impl super::AtomicAdd<i64> for i64 {
    fn rhs_into_delta(rhs: i64) -> i64 {
        rhs
    }
}

// SAFETY: `u32` and `i32` has the same size and alignment, and `u32` is round-trip transmutable to
// `i32`.
unsafe impl super::AtomicType for u32 {
    type Repr = i32;
}

// SAFETY: The wrapping add result of two `i32`s is a valid `u32`.
unsafe impl super::AtomicAdd<u32> for u32 {
    fn rhs_into_delta(rhs: u32) -> i32 {
        rhs as i32
    }
}

// SAFETY: `u64` and `i64` has the same size and alignment, and `u64` is round-trip transmutable to
// `i64`.
unsafe impl super::AtomicType for u64 {
    type Repr = i64;
}

// SAFETY: The wrapping add result of two `i64`s is a valid `u64`.
unsafe impl super::AtomicAdd<u64> for u64 {
    fn rhs_into_delta(rhs: u64) -> i64 {
        rhs as i64
    }
}

use crate::macros::kunit_tests;

#[kunit_tests(rust_atomics)]
mod tests {
    use super::super::*;

    // Call $fn($val) with each $type of $val.
    macro_rules! for_each_type {
        ($val:literal in [$($type:ty),*] $fn:expr) => {
            $({
                let v: $type = $val;

                $fn(v);
            })*
        }
    }

    #[test]
    fn atomic_basic_tests() {
        for_each_type!(42 in [i32, i64, u32, u64] |v| {
            let x = Atomic::new(v);

            assert_eq!(v, x.load(Relaxed));
        });
    }

    #[test]
    fn atomic_xchg_tests() {
        for_each_type!(42 in [i32, i64, u32, u64] |v| {
            let x = Atomic::new(v);

            let old = v;
            let new = v + 1;

            assert_eq!(old, x.xchg(new, Full));
            assert_eq!(new, x.load(Relaxed));
        });
    }

    #[test]
    fn atomic_cmpxchg_tests() {
        for_each_type!(42 in [i32, i64, u32, u64] |v| {
            let x = Atomic::new(v);

            let old = v;
            let new = v + 1;

            assert_eq!(Err(old), x.cmpxchg(new, new, Full));
            assert_eq!(old, x.load(Relaxed));
            assert_eq!(Ok(old), x.cmpxchg(old, new, Relaxed));
            assert_eq!(new, x.load(Relaxed));
        });
    }

    #[test]
    fn atomic_arithmetic_tests() {
        for_each_type!(42 in [i32, i64, u32, u64] |v| {
            let x = Atomic::new(v);

            assert_eq!(v, x.fetch_add(12, Full));
            assert_eq!(v + 12, x.load(Relaxed));

            x.add(13, Relaxed);

            assert_eq!(v + 25, x.load(Relaxed));
        });
    }
}