forked from M-Labs/zynq-rs
add cortex_a9::mutex
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85f29ace6b
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@ -2,5 +2,6 @@ pub mod asm;
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pub mod regs;
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pub mod cache;
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pub mod mmu;
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pub mod mutex;
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global_asm!(include_str!("exceptions.s"));
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@ -0,0 +1,73 @@
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use core::ops::{Deref, DerefMut};
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use core::sync::atomic::{AtomicBool, Ordering};
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use core::cell::UnsafeCell;
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use super::asm::*;
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#[inline]
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fn wait_for_update() {
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wfe();
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}
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#[inline]
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fn signal_update() {
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dsb();
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sev();
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}
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pub struct Mutex<T> {
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locked: AtomicBool,
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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: AtomicBool::new(false),
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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(false, true, Ordering::Acquire) {
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while self.locked.load(Ordering::Relaxed) {
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wait_for_update();
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}
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}
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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(false, Ordering::Release);
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signal_update();
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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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