forked from M-Labs/zynq-rs
60 lines
1.3 KiB
Rust
60 lines
1.3 KiB
Rust
use core::ops::{Deref, DerefMut};
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use core::sync::atomic::{AtomicU32, Ordering};
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use core::cell::UnsafeCell;
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use super::asm::*;
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const LOCKED: u32 = 1;
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const UNLOCKED: u32 = 0;
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pub struct Mutex<T> {
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locked: AtomicU32,
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inner: UnsafeCell<T>,
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}
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unsafe impl<T: Send> Sync for Mutex<T> {}
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unsafe impl<T: Send> Send for Mutex<T> {}
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impl<T> Mutex<T> {
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pub const fn new(inner: T) -> Self {
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Mutex{
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locked: AtomicU32::new(UNLOCKED),
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inner: UnsafeCell::new(inner),
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}
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}
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pub fn lock(&self) -> MutexGuard<T> {
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while self.locked.compare_and_swap(UNLOCKED, LOCKED, Ordering::Acquire) != UNLOCKED {}
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dmb();
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MutexGuard { mutex: self }
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}
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fn unlock(&self) {
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dmb();
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self.locked.store(UNLOCKED, Ordering::Release);
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dsb();
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}
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}
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pub struct MutexGuard<'a, T> {
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mutex: &'a Mutex<T>,
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}
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impl<'a, T> Deref for MutexGuard<'a, T> {
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type Target = T;
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fn deref(&self) -> &T {
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unsafe { &*self.mutex.inner.get() }
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}
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}
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impl<'a, T> DerefMut for MutexGuard<'a, T> {
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fn deref_mut(&mut self) -> &mut T {
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unsafe { &mut *self.mutex.inner.get() }
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}
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}
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impl<'a, T> Drop for MutexGuard<'a, T> {
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fn drop(&mut self) {
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self.mutex.unlock();
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}
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}
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