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authorEmil Fresk <emil.fresk@gmail.com>2023-01-29 20:16:23 +0100
committerHenrik Tjäder <henrik@tjaders.com>2023-03-01 00:33:38 +0100
commite65e532c2a342f77080ac6fc8e5be11aa7d82575 (patch)
tree5a1f21ad66e277bd13e75c8f29bbd89ba4e10a46 /rtic-channel/src/wait_queue.rs
parent58692a35e87ddc8b8faca5bb262070d343ceb869 (diff)
Move common data structures to `rtic-common`
Diffstat (limited to 'rtic-channel/src/wait_queue.rs')
-rw-r--r--rtic-channel/src/wait_queue.rs268
1 files changed, 0 insertions, 268 deletions
diff --git a/rtic-channel/src/wait_queue.rs b/rtic-channel/src/wait_queue.rs
deleted file mode 100644
index 2de6311..0000000
--- a/rtic-channel/src/wait_queue.rs
+++ /dev/null
@@ -1,268 +0,0 @@
-//! ...
-
-use core::marker::PhantomPinned;
-use core::pin::Pin;
-use core::ptr::null_mut;
-use core::sync::atomic::{AtomicBool, AtomicPtr, Ordering};
-use core::task::Waker;
-use critical_section as cs;
-
-pub type WaitQueue = LinkedList<Waker>;
-
-/// A FIFO linked list for a wait queue.
-pub struct LinkedList<T> {
- head: AtomicPtr<Link<T>>, // UnsafeCell<*mut Link<T>>
- tail: AtomicPtr<Link<T>>,
-}
-
-impl<T> LinkedList<T> {
- /// Create a new linked list.
- pub const fn new() -> Self {
- Self {
- head: AtomicPtr::new(null_mut()),
- tail: AtomicPtr::new(null_mut()),
- }
- }
-}
-
-impl<T: Clone> LinkedList<T> {
- const R: Ordering = Ordering::Relaxed;
-
- /// Pop the first element in the queue.
- pub fn pop(&self) -> Option<T> {
- cs::with(|_| {
- // Make sure all previous writes are visible
- core::sync::atomic::fence(Ordering::SeqCst);
-
- let head = self.head.load(Self::R);
-
- // SAFETY: `as_ref` is safe as `insert` requires a valid reference to a link
- if let Some(head_ref) = unsafe { head.as_ref() } {
- // Move head to the next element
- self.head.store(head_ref.next.load(Self::R), Self::R);
-
- // We read the value at head
- let head_val = head_ref.val.clone();
-
- let tail = self.tail.load(Self::R);
- if head == tail {
- // The queue is empty
- self.tail.store(null_mut(), Self::R);
- }
-
- if let Some(next_ref) = unsafe { head_ref.next.load(Self::R).as_ref() } {
- next_ref.prev.store(null_mut(), Self::R);
- }
-
- // Clear the pointers in the node.
- head_ref.next.store(null_mut(), Self::R);
- head_ref.prev.store(null_mut(), Self::R);
- head_ref.is_poped.store(true, Self::R);
-
- return Some(head_val);
- }
-
- None
- })
- }
-
- /// Put an element at the back of the queue.
- pub fn push(&self, link: Pin<&mut Link<T>>) {
- cs::with(|_| {
- // Make sure all previous writes are visible
- core::sync::atomic::fence(Ordering::SeqCst);
-
- let tail = self.tail.load(Self::R);
-
- // SAFETY: This datastructure does not move the underlying value.
- let link = unsafe { link.get_unchecked_mut() };
-
- if let Some(tail_ref) = unsafe { tail.as_ref() } {
- // Queue is not empty
- link.prev.store(tail, Self::R);
- self.tail.store(link, Self::R);
- tail_ref.next.store(link, Self::R);
- } else {
- // Queue is empty
- self.tail.store(link, Self::R);
- self.head.store(link, Self::R);
- }
- });
- }
-
- /// Check if the queue is empty.
- pub fn is_empty(&self) -> bool {
- self.head.load(Self::R).is_null()
- }
-}
-
-/// A link in the linked list.
-pub struct Link<T> {
- pub(crate) val: T,
- next: AtomicPtr<Link<T>>,
- prev: AtomicPtr<Link<T>>,
- is_poped: AtomicBool,
- _up: PhantomPinned,
-}
-
-impl<T: Clone> Link<T> {
- const R: Ordering = Ordering::Relaxed;
-
- /// Create a new link.
- pub const fn new(val: T) -> Self {
- Self {
- val,
- next: AtomicPtr::new(null_mut()),
- prev: AtomicPtr::new(null_mut()),
- is_poped: AtomicBool::new(false),
- _up: PhantomPinned,
- }
- }
-
- pub fn is_poped(&self) -> bool {
- self.is_poped.load(Self::R)
- }
-
- pub fn remove_from_list(&mut self, list: &LinkedList<T>) {
- cs::with(|_| {
- // Make sure all previous writes are visible
- core::sync::atomic::fence(Ordering::SeqCst);
-
- let prev = self.prev.load(Self::R);
- let next = self.next.load(Self::R);
- self.is_poped.store(true, Self::R);
-
- match unsafe { (prev.as_ref(), next.as_ref()) } {
- (None, None) => {
- // Not in the list or alone in the list, check if list head == node address
- let sp = self as *const _;
-
- if sp == list.head.load(Ordering::Relaxed) {
- list.head.store(null_mut(), Self::R);
- list.tail.store(null_mut(), Self::R);
- }
- }
- (None, Some(next_ref)) => {
- // First in the list
- next_ref.prev.store(null_mut(), Self::R);
- list.head.store(next, Self::R);
- }
- (Some(prev_ref), None) => {
- // Last in the list
- prev_ref.next.store(null_mut(), Self::R);
- list.tail.store(prev, Self::R);
- }
- (Some(prev_ref), Some(next_ref)) => {
- // Somewhere in the list
-
- // Connect the `prev.next` and `next.prev` with each other to remove the node
- prev_ref.next.store(next, Self::R);
- next_ref.prev.store(prev, Self::R);
- }
- }
- })
- }
-}
-
-#[cfg(test)]
-impl<T: core::fmt::Debug + Clone> LinkedList<T> {
- fn print(&self) {
- cs::with(|_| {
- // Make sure all previous writes are visible
- core::sync::atomic::fence(Ordering::SeqCst);
-
- let mut head = self.head.load(Self::R);
- let tail = self.tail.load(Self::R);
-
- println!(
- "List - h = 0x{:x}, t = 0x{:x}",
- head as usize, tail as usize
- );
-
- let mut i = 0;
-
- // SAFETY: `as_ref` is safe as `insert` requires a valid reference to a link
- while let Some(head_ref) = unsafe { head.as_ref() } {
- println!(
- " {}: {:?}, s = 0x{:x}, n = 0x{:x}, p = 0x{:x}",
- i,
- head_ref.val,
- head as usize,
- head_ref.next.load(Ordering::Relaxed) as usize,
- head_ref.prev.load(Ordering::Relaxed) as usize
- );
-
- head = head_ref.next.load(Self::R);
-
- i += 1;
- }
- });
- }
-}
-
-#[cfg(test)]
-impl<T: core::fmt::Debug + Clone> Link<T> {
- fn print(&self) {
- cs::with(|_| {
- // Make sure all previous writes are visible
- core::sync::atomic::fence(Ordering::SeqCst);
-
- println!("Link:");
-
- println!(
- " val = {:?}, n = 0x{:x}, p = 0x{:x}",
- self.val,
- self.next.load(Ordering::Relaxed) as usize,
- self.prev.load(Ordering::Relaxed) as usize
- );
- });
- }
-}
-
-#[cfg(test)]
-mod tests {
- use super::*;
-
- #[test]
- fn linked_list() {
- let wq = LinkedList::<u32>::new();
-
- let mut i1 = Link::new(10);
- let mut i2 = Link::new(11);
- let mut i3 = Link::new(12);
- let mut i4 = Link::new(13);
- let mut i5 = Link::new(14);
-
- wq.push(unsafe { Pin::new_unchecked(&mut i1) });
- wq.push(unsafe { Pin::new_unchecked(&mut i2) });
- wq.push(unsafe { Pin::new_unchecked(&mut i3) });
- wq.push(unsafe { Pin::new_unchecked(&mut i4) });
- wq.push(unsafe { Pin::new_unchecked(&mut i5) });
-
- wq.print();
-
- wq.pop();
- i1.print();
-
- wq.print();
-
- i4.remove_from_list(&wq);
-
- wq.print();
-
- // i1.remove_from_list(&wq);
- // wq.print();
-
- println!("i2");
- i2.remove_from_list(&wq);
- wq.print();
-
- println!("i3");
- i3.remove_from_list(&wq);
- wq.print();
-
- println!("i5");
- i5.remove_from_list(&wq);
- wq.print();
- }
-}