Add "async task with infinite loop" example

examples/async-infinite-loop.rs

@@ -0,0 +1,57 @@
+#![no_main]
+#![no_std]
+#![feature(type_alias_impl_trait)]
+
+use panic_semihosting as _;
+
+#[rtic::app(device = lm3s6965, dispatchers = [SSI0, UART0], peripherals = true)]
+mod app {
+    use cortex_m_semihosting::{debug, hprintln};
+    use systick_monotonic::*;
+
+    #[shared]
+    struct Shared {}
+
+    #[local]
+    struct Local {}
+
+    #[monotonic(binds = SysTick, default = true)]
+    type MyMono = Systick<100>;
+
+    #[init]
+    fn init(cx: init::Context) -> (Shared, Local, init::Monotonics) {
+        hprintln!("init").unwrap();
+
+        foo::spawn().ok();
+
+        (
+            Shared {},
+            Local {},
+            init::Monotonics(Systick::new(cx.core.SYST, 12_000_000)),
+        )
+    }
+
+    #[idle]
+    fn idle(_: idle::Context) -> ! {
+        loop {
+            cortex_m::asm::wfi(); // put the MCU in sleep mode until interrupt occurs
+        }
+    }
+
+    // Infinite loops are not allowed in RTIC, however in async tasks they are - in there is an
+    // await inside the loop.
+    #[task]
+    async fn foo(_cx: foo::Context) {
+        let mut i = 0;
+        loop {
+            if i == 5 {
+                debug::exit(debug::EXIT_SUCCESS);
+            }
+
+            hprintln!("hello from async {}", i).ok();
+            monotonics::delay(100.millis()).await; // This makes it okey!
+
+            i += 1;
+        }
+    }
+}