Desugar some async fns

embassy-sync/src/mutex.rs

@@ -2,7 +2,7 @@
 //!
 //! This module provides a mutex that can be used to synchronize data between asynchronous tasks.
 use core::cell::{RefCell, UnsafeCell};
-use core::future::poll_fn;
+use core::future::{poll_fn, Future};
 use core::ops::{Deref, DerefMut};
 use core::task::Poll;
 use core::{fmt, mem};
@@ -73,7 +73,7 @@ where
     /// Lock the mutex.
     ///
     /// This will wait for the mutex to be unlocked if it's already locked.
-    pub async fn lock(&self) -> MutexGuard<'_, M, T> {
+    pub fn lock(&self) -> impl Future<Output = MutexGuard<'_, M, T>> {
         poll_fn(|cx| {
             let ready = self.state.lock(|s| {
                 let mut s = s.borrow_mut();
@@ -92,7 +92,6 @@ where
                 Poll::Pending
             }
         })
-        .await
     }
 
     /// Attempt to immediately lock the mutex.

embassy-sync/src/once_lock.rs

@@ -1,7 +1,7 @@
 //! Synchronization primitive for initializing a value once, allowing others to await a reference to the value.
 
 use core::cell::Cell;
-use core::future::poll_fn;
+use core::future::{poll_fn, Future};
 use core::mem::MaybeUninit;
 use core::sync::atomic::{AtomicBool, Ordering};
 use core::task::Poll;
@@ -55,7 +55,7 @@ impl<T> OnceLock<T> {
 
     /// Get a reference to the underlying value, waiting for it to be set.
     /// If the value is already set, this will return immediately.
-    pub async fn get(&self) -> &T {
+    pub fn get(&self) -> impl Future<Output = &T> {
         poll_fn(|cx| match self.try_get() {
             Some(data) => Poll::Ready(data),
             None => {
@@ -63,7 +63,6 @@ impl<T> OnceLock<T> {
                 Poll::Pending
             }
         })
-        .await
     }
 
     /// Try to get a reference to the underlying value if it exists.

embassy-sync/src/watch.rs

@@ -1,7 +1,7 @@
 //! A synchronization primitive for passing the latest value to **multiple** receivers.
 
 use core::cell::RefCell;
-use core::future::poll_fn;
+use core::future::{poll_fn, Future};
 use core::marker::PhantomData;
 use core::ops::{Deref, DerefMut};
 use core::task::{Context, Poll};
@@ -547,8 +547,8 @@ impl<'a, T: Clone, W: WatchBehavior<T> + ?Sized> Rcv<'a, T, W> {
     /// Returns the current value of the `Watch` once it is initialized, marking it as seen.
     ///
     /// **Note**: Futures do nothing unless you `.await` or poll them.
-    pub async fn get(&mut self) -> T {
-        poll_fn(|cx| self.watch.poll_get(&mut self.at_id, cx)).await
+    pub fn get(&mut self) -> impl Future<Output = T> + '_ {
+        poll_fn(|cx| self.watch.poll_get(&mut self.at_id, cx))
     }
 
     /// Tries to get the current value of the `Watch` without waiting, marking it as seen.

embassy-sync/src/zerocopy_channel.rs

@@ -15,7 +15,7 @@
 //! another message will result in an error being returned.
 
 use core::cell::RefCell;
-use core::future::poll_fn;
+use core::future::{poll_fn, Future};
 use core::marker::PhantomData;
 use core::task::{Context, Poll};
 
@@ -131,12 +131,15 @@ impl<'a, M: RawMutex, T> Sender<'a, M, T> {
     }
 
     /// Asynchronously send a value over the channel.
-    pub async fn send(&mut self) -> &mut T {
-        let i = poll_fn(|cx| {
+    pub fn send(&mut self) -> impl Future<Output = &mut T> {
+        poll_fn(|cx| {
             self.channel.state.lock(|s| {
                 let s = &mut *s.borrow_mut();
                 match s.push_index() {
-                    Some(i) => Poll::Ready(i),
+                    Some(i) => {
+                        let r = unsafe { &mut *self.channel.buf.add(i) };
+                        Poll::Ready(r)
+                    }
                     None => {
                         s.receive_waker.register(cx.waker());
                         Poll::Pending
@@ -144,8 +147,6 @@ impl<'a, M: RawMutex, T> Sender<'a, M, T> {
                 }
             })
         })
-        .await;
-        unsafe { &mut *self.channel.buf.add(i) }
     }
 
     /// Notify the channel that the sending of the value has been finalized.
@@ -213,12 +214,15 @@ impl<'a, M: RawMutex, T> Receiver<'a, M, T> {
     }
 
     /// Asynchronously receive a value over the channel.
-    pub async fn receive(&mut self) -> &mut T {
-        let i = poll_fn(|cx| {
+    pub fn receive(&mut self) -> impl Future<Output = &mut T> {
+        poll_fn(|cx| {
             self.channel.state.lock(|s| {
                 let s = &mut *s.borrow_mut();
                 match s.pop_index() {
-                    Some(i) => Poll::Ready(i),
+                    Some(i) => {
+                        let r = unsafe { &mut *self.channel.buf.add(i) };
+                        Poll::Ready(r)
+                    }
                     None => {
                         s.send_waker.register(cx.waker());
                         Poll::Pending
@@ -226,8 +230,6 @@ impl<'a, M: RawMutex, T> Receiver<'a, M, T> {
                 }
             })
         })
-        .await;
-        unsafe { &mut *self.channel.buf.add(i) }
     }
 
     /// Notify the channel that the receiving of the value has been finalized.