urng 0.6.0

//! Macros for quick random number generation.
//!
//! These macros provide a convenient way to generate random numbers using various
//! algorithms with seeds generated from the current system time.

#[macro_export]
/// Wraps a value in a `Wrapping` type.
///
/// Can also be used to create arrays of `Wrapping` values.
///
/// # Examples
/// ```
/// use urng::wrap;
///
/// // Single value
/// let val = wrap!(1);
/// assert_eq!(val, std::num::Wrapping(1));
///
/// // Array with repeated value
/// let arr = wrap![1; 3];
/// assert_eq!(arr, [std::num::Wrapping(1), std::num::Wrapping(1), std::num::Wrapping(1)]);
///
/// // Array with specific values
/// let arr2 = wrap![1, 2, 3];
/// assert_eq!(arr2, [std::num::Wrapping(1), std::num::Wrapping(2), std::num::Wrapping(3)]);
/// ```
macro_rules! wrap {
    ($a:expr) => {
        ::std::num::Wrapping($a)
    };

    ($elem:expr; $n:expr) => (
        [::std::num::Wrapping($elem); $n]
    );

    ($($x:expr),+ $(,)?) => (
        [$(::std::num::Wrapping($x)),+]
    );

}

#[macro_export]
/// Dispatches to an AVX-512 optimized path on x86_64 when available, otherwise falls back.
///
/// Two forms:
/// - `dispatch_simd!(RetType, fallback_fn, avx512_fn, seed)` — allocate and return a raw pointer.
/// - `dispatch_simd!(Avx512T, FallbackT, fallback_fn, avx512_fn, ptr [, args])` — operate in-place.
macro_rules! dispatch_simd {
    ($ret_type:ty, $fallback_fn:ident, $avx512_fn:ident, $seed:expr) => {{
        #[cfg(target_arch = "x86_64")]
        if std::arch::is_x86_feature_detected!("avx512f") {
            return $avx512_fn($seed) as *mut $ret_type;
        }
        $fallback_fn($seed) as *mut $ret_type
    }};
    ($avx512_type:ty, $fallback_type:ty, $fallback_fn:ident, $avx512_fn:ident, $ptr:expr $(, $arg:expr)*) => {{
        #[cfg(target_arch = "x86_64")]
        if std::arch::is_x86_feature_detected!("avx512f") {
            $avx512_fn($ptr as *mut $avx512_type $(, $arg)*);
            return;
        }
        $fallback_fn($ptr as *mut $fallback_type $(, $arg)*);
    }};
}

#[macro_export]
macro_rules! safe_test {
    ($name:ident, $ctor:expr $(,)?) => {
        paste::paste! {
            #[test]
            fn [<test_ $name:snake>]() {
                let mut rng1 = $ctor;
                let mut rng2 = $ctor;
                assert_eq!(rng1.nextu(), rng2.nextu());
                assert_eq!(rng1.nextf(), rng2.nextf());
            }
        }
    };
    ($name:ident) => {
        paste::paste! {
            #[test]
            fn [<test_ $name:snake>]() {
                let mut rng1 = $name::new(0);
                let mut rng2 = $name::new(0);
                assert_eq!(rng1.nextu(), rng2.nextu());
                assert_eq!(rng1.nextf(), rng2.nextf());
            }
        }
    };
}

#[macro_export]
macro_rules! unsafe_test {
    ($name:ident, $ctor:expr $(,)?) => {
        paste::paste! {
            #[test]
            fn [<test_ $name:snake>]() {
                unsafe {
                    let mut rng1 = $ctor;
                    let mut rng2 = $ctor;
                    assert_eq!(rng1.nextu(), rng2.nextu());
                    assert_eq!(rng1.nextf(), rng2.nextf());
                }
            }
        }
    };
    ($name:ident) => {
        paste::paste! {
            #[test]
            fn [<test_ $name:snake>]() {
                unsafe {
                    let mut rng1 = $name::new(0);
                    let mut rng2 = $name::new(0);
                    assert_eq!(rng1.nextu(), rng2.nextu());
                    assert_eq!(rng1.nextf(), rng2.nextf());
                }
            }
        }
    };
}

#[macro_export]
macro_rules! impl_try_rng_trait {
    ($($type:ty),* $(,)?) => {
        $(
            impl rand_core::TryRng for $type {
                type Error = std::convert::Infallible;

                fn try_next_u32(&mut self) -> Result<u32, Self::Error> {
                    Ok(self.nextu())
                }

                fn try_next_u64(&mut self) -> Result<u64, Self::Error> {
                    let hi = self.nextu() as u64;
                    let lo = self.nextu() as u64;
                    Ok(hi << 32 | lo)
                }

                fn try_fill_bytes(&mut self, dst: &mut [u8]) -> Result<(), Self::Error> {
                    let mut i = 0;
                    while i < dst.len() {
                        let remaining = dst.len() - i;
                        if remaining >= 4 {
                            let val = self.nextu();
                            dst[i..i + 4].copy_from_slice(&val.to_le_bytes());
                            i += 4;
                        } else {
                            let val = self.nextu();
                            dst[i..].copy_from_slice(&val.to_le_bytes()[..remaining]);
                            i += remaining;
                        }
                    }
                    Ok(())
                }
            }
        )*
    };
}

#[macro_export]
macro_rules! impl_rand_trait {
    ($($type:ty),* $(,)?) => {
        $(
            impl rand_core::SeedableRng for $type {
                type Seed = [u8; 4];

                fn from_seed(seed: Self::Seed) -> Self {
                    let seed = u32::from_ne_bytes(seed);
                    Self::new(seed.into())
                }
            }
        )*
    };
}