add time::Ticker

embassy/src/time/mod.rs

@@ -5,7 +5,7 @@ mod traits;
 
 pub use duration::Duration;
 pub use instant::Instant;
-pub use timer::Timer;
+pub use timer::{Ticker, Timer};
 pub use traits::*;
 
 use crate::fmt::*;

embassy/src/time/timer.rs

@@ -1,6 +1,7 @@
 use core::future::Future;
 use core::pin::Pin;
 use core::task::{Context, Poll};
+use futures::Stream;
 use futures_intrusive::timer::{LocalTimer, LocalTimerFuture};
 
 use super::{Duration, Instant};
@@ -28,3 +29,35 @@ impl Future for Timer {
         unsafe { Pin::new_unchecked(&mut self.get_unchecked_mut().inner) }.poll(cx)
     }
 }
+
+pub struct Ticker {
+    inner: LocalTimerFuture<'static>,
+    next: Instant,
+    dur: Duration,
+}
+
+impl Ticker {
+    pub fn every(dur: Duration) -> Self {
+        let next = Instant::now() + dur;
+        Self {
+            inner: current_timer_queue().deadline(next.as_ticks()),
+            next,
+            dur,
+        }
+    }
+}
+
+impl Stream for Ticker {
+    type Item = ();
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        let this = unsafe { self.get_unchecked_mut() };
+        match unsafe { Pin::new_unchecked(&mut this.inner) }.poll(cx) {
+            Poll::Ready(_) => {
+                this.next += this.dur;
+                this.inner = current_timer_queue().deadline(this.next.as_ticks());
+                Poll::Ready(Some(()))
+            }
+            Poll::Pending => Poll::Pending,
+        }
+    }
+}