#[cfg(target_arch = "wasm32")]
use core::arch::wasm32 as wasm;
#[cfg(target_arch = "wasm64")]
use core::arch::wasm64 as wasm;

use crate::sync::atomic::AtomicU32;
use crate::time::Duration;

/// An atomic for use as a futex that is at least 8-bits but may be larger.
pub type SmallAtomic = AtomicU32;
/// Must be the underlying type of SmallAtomic
pub type SmallPrimitive = u32;

/// Wait for a futex_wake operation to wake us.
///
/// Returns directly if the futex doesn't hold the expected value.
///
/// Returns false on timeout, and true in all other cases.
pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -> bool {
    let timeout = timeout.and_then(|t| t.as_nanos().try_into().ok()).unwrap_or(-1);
    unsafe {
        wasm::memory_atomic_wait32(futex as *const AtomicU32 as *mut i32, expected as i32, timeout)
            < 2
    }
}

/// Wakes up one thread that's blocked on `futex_wait` on this futex.
///
/// Returns true if this actually woke up such a thread,
/// or false if no thread was waiting on this futex.
pub fn futex_wake(futex: &AtomicU32) -> bool {
    unsafe { wasm::memory_atomic_notify(futex as *const AtomicU32 as *mut i32, 1) > 0 }
}

/// Wakes up all threads that are waiting on `futex_wait` on this futex.
pub fn futex_wake_all(futex: &AtomicU32) {
    unsafe {
        wasm::memory_atomic_notify(futex as *const AtomicU32 as *mut i32, i32::MAX as u32);
    }
}