feat: example of wait-queue

ci/expected/lm3s6965/wait-queue.run

@@ -0,0 +1,4 @@
+Inc
+Inc
+Inc
+Got 3

examples/lm3s6965/Cargo.toml

@@ -16,6 +16,7 @@ bare-metal = "1.0.0"
 cortex-m-semihosting = "0.5.0"
 rtic-time = { path = "../../rtic-time" }
 rtic-sync = { path = "../../rtic-sync" }
+rtic-common = { path = "../../rtic-common" }
 rtic-monotonics = { path = "../../rtic-monotonics", features = ["cortex-m-systick"] }
 rtic = { path = "../../rtic" }
 cfg-if = "1.0"

examples/lm3s6965/examples/wait-queue.rs

@@ -0,0 +1,64 @@
+//! examples/wait-queue.rs
+
+#![no_main]
+#![no_std]
+#![deny(warnings)]
+#![deny(unsafe_code)]
+#![deny(missing_docs)]
+
+use panic_semihosting as _;
+
+#[rtic::app(device = lm3s6965, dispatchers = [GPIOA])]
+mod app {
+    use cortex_m_semihosting::{debug, hprintln};
+    use rtic_common::wait_queue::WaitQueue;
+
+    use rtic_monotonics::systick::prelude::*;
+    systick_monotonic!(Mono, 100);
+
+    #[shared]
+    struct Shared {
+        count: u32,
+    }
+
+    #[local]
+    struct Local {}
+
+    #[init(local = [wait_queue: WaitQueue = WaitQueue::new()])]
+    fn init(cx: init::Context) -> (Shared, Local) {
+        Mono::start(cx.core.SYST, 12_000_000);
+
+        incrementer::spawn(cx.local.wait_queue).ok().unwrap();
+        waiter::spawn(cx.local.wait_queue).ok().unwrap();
+
+        let count = 0;
+
+        (Shared { count }, Local {})
+    }
+
+    #[task(shared = [count])]
+    async fn incrementer(mut c: incrementer::Context, wait_queue: &'static WaitQueue) {
+        loop {
+            hprintln!("Inc");
+
+            c.shared.count.lock(|c| *c += 1);
+
+            while let Some(waker) = wait_queue.pop() {
+                waker.wake();
+            }
+
+            Mono::delay(10.millis()).await;
+        }
+    }
+
+    #[task(shared = [count])]
+    async fn waiter(mut c: waiter::Context, wait_queue: &'static WaitQueue) {
+        let value = wait_queue
+            .wait_until(|| c.shared.count.lock(|c| (*c >= 3).then_some(*c)))
+            .await;
+
+        hprintln!("Got {}", value);
+
+        debug::exit(debug::EXIT_SUCCESS); // Exit QEMU simulator
+    }
+}