Rebase on master

1 files changed, 58 insertions, 0 deletions

diff --git a/embassy-time/src/queue.rs b/embassy-time/src/queue.rs
new file mode 100644
index 000000000..c6f8b440a
--- /dev/null
+++ b/embassy-time/src/queue.rs
@@ -0,0 +1,58 @@
+//! Timer queue implementation
+//!
+//! This module defines the interface a timer queue needs to implement to power the `embassy_time` module.
+//!
+//! # Implementing a timer queue
+//!
+//! - Define a struct `MyTimerQueue`
+//! - Implement [`TimerQueue`] for it
+//! - Register it as the global timer queue with [`timer_queue_impl`](crate::timer_queue_impl).
+//!
+//! # Linkage details
+//!
+//! Check the documentation of the [`driver`](crate::driver) module for more information.
+//!
+//! Similarly to driver, if there is none or multiple timer queues in the crate tree, linking will fail.
+//!
+//! # Example
+//!
+//! ```
+//! use core::task::Waker;
+//!
+//! use embassy_time::Instant;
+//! use embassy_time::queue::{TimerQueue};
+//!
+//! struct MyTimerQueue{}; // not public!
+//! embassy_time::timer_queue_impl!(static QUEUE: MyTimerQueue = MyTimerQueue{});
+//!
+//! impl TimerQueue for MyTimerQueue {
+//!     fn schedule_wake(&'static self, at: Instant, waker: &Waker) {
+//!         todo!()
+//!     }
+//! }
+//! ```
+use core::task::Waker;
+
+use crate::Instant;
+
+/// Timer queue
+pub trait TimerQueue {
+    /// Schedules a waker in the queue to be awoken at moment `at`.
+    /// If this moment is in the past, the waker might be awoken immediately.
+    fn schedule_wake(&'static self, at: Instant, waker: &Waker);
+}
+
+/// Set the TimerQueue implementation.
+///
+/// See the module documentation for an example.
+#[macro_export]
+macro_rules! timer_queue_impl {
+    (static $name:ident: $t: ty = $val:expr) => {
+        static $name: $t = $val;
+
+        #[no_mangle]
+        fn _embassy_time_schedule_wake(at: $crate::Instant, waker: &core::task::Waker) {
+            <$t as $crate::queue::TimerQueue>::schedule_wake(&$name, at, waker);
+        }
+    };
+}