broken

CHANGELOG.md

@@ -15,6 +15,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 - Improved ergonomics allowing separation of task signatures to actual implementation in extern block `extern "C" { #[task(..)] fn t(..); }`.
 
+- Experimental support for async/await.
+
 ### Changed
 
 - [breaking-change] [PR 400] Move dispatchers from extern block to app argument.

examples/async_systick.rs

@@ -0,0 +1,218 @@
+//! examples/async_task2
+#![no_main]
+#![no_std]
+#![feature(const_fn)]
+#![feature(type_alias_impl_trait)]
+
+// use core::cell::Cell;
+// use core::cell::UnsafeCell;
+use core::future::Future;
+use core::mem;
+// use core::mem::MaybeUninit;
+use core::pin::Pin;
+// use core::ptr;
+// use core::ptr::NonNull;
+// use core::sync::atomic::{AtomicPtr, AtomicU32, Ordering};
+use core::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
+
+use cortex_m_semihosting::{debug, hprintln};
+use panic_semihosting as _;
+
+#[rtic::app(device = lm3s6965, dispatchers = [SSI0], peripherals = true)]
+mod app {
+    use crate::*;
+
+    #[resources]
+    struct Resources {
+        syst: cortex_m::peripheral::SYST,
+    }
+
+    #[init]
+    fn init(cx: init::Context) -> init::LateResources {
+        // foo::spawn().unwrap();
+        let mut syst = cx.core.SYST;
+        syst.set_reload(100000);
+        syst.enable_interrupt();
+        syst.enable_counter();
+
+        hprintln!("init").unwrap();
+
+        init::LateResources { syst }
+    }
+
+    #[idle]
+    fn idle(_: idle::Context) -> ! {
+        // foo::spawn().unwrap();
+        // debug::exit(debug::EXIT_SUCCESS);
+        loop {
+            continue;
+        }
+    }
+
+    #[task]
+    fn foo(_c: foo::Context) {
+        // BEGIN BOILERPLATE
+        type F = impl Future + 'static;
+        fn create() -> F {
+            task()
+        }
+
+        static mut TASK: Task<F> = Task::new();
+
+        hprintln!("foo trampoline").ok();
+        unsafe {
+            match TASK {
+                Task::Idle | Task::Done(_) => {
+                    hprintln!("create task").ok();
+                    TASK.spawn(create);
+                }
+                _ => {}
+            };
+            hprintln!("poll").ok();
+
+            TASK.poll(|| {});
+
+            match TASK {
+                Task::Done(ref r) => {
+                    hprintln!("done").ok();
+                    hprintln!("r = {:?}", mem::transmute::<_, &u32>(r)).ok();
+                }
+                _ => {
+                    hprintln!("running").ok();
+                }
+            }
+        }
+        // END BOILERPLATE
+
+        async fn task() -> u32 {
+            hprintln!("foo1").ok();
+            // let a: u32 = bar::spawn().await;
+            // hprintln!("foo2 {}", a).ok();
+            5
+        }
+    }
+
+    #[task(resources = [syst])]
+    fn timer(cx: timer::Context<'static>) {
+        // BEGIN BOILERPLATE
+        type F = impl Future + 'static;
+        fn create(cx: timer::Context<'static>) -> F {
+            task(cx)
+        }
+
+        static mut TASK: Task<F> = Task::new();
+
+        hprintln!("timer trampoline").ok();
+        unsafe {
+            match TASK {
+                Task::Idle | Task::Done(_) => {
+                    hprintln!("create task").ok();
+                    TASK.spawn(|| create(cx));
+                }
+                _ => {}
+            };
+            hprintln!("timer poll").ok();
+
+            TASK.poll(|| {});
+
+            match TASK {
+                Task::Done(_) => {
+                    hprintln!("timer done").ok();
+                }
+                _ => {
+                    hprintln!("running").ok();
+                }
+            }
+        }
+        // END BOILERPLATE
+
+        // for now assume this async task is done directly
+        async fn task(cx: timer::Context<'static>) {
+            hprintln!("SysTick ").ok();
+        }
+    }
+
+    // This the actual RTIC task, binds to systic.
+    #[task(binds = SysTick)]
+    fn systic(cx: systic::Context) {}
+}
+
+//=============
+// Waker
+
+static WAKER_VTABLE: RawWakerVTable =
+    RawWakerVTable::new(waker_clone, waker_wake, waker_wake, waker_drop);
+
+unsafe fn waker_clone(p: *const ()) -> RawWaker {
+    RawWaker::new(p, &WAKER_VTABLE)
+}
+
+unsafe fn waker_wake(p: *const ()) {
+    let f: fn() = mem::transmute(p);
+    f();
+}
+
+unsafe fn waker_drop(_: *const ()) {
+    // nop
+}
+
+//============
+// Task
+
+enum Task<F: Future + 'static> {
+    Idle,
+    Running(F),
+    Done(F::Output),
+}
+
+impl<F: Future + 'static> Task<F> {
+    const fn new() -> Self {
+        Self::Idle
+    }
+
+    fn spawn(&mut self, future: impl FnOnce() -> F) {
+        *self = Task::Running(future());
+    }
+
+    unsafe fn poll(&mut self, wake: fn()) {
+        match self {
+            Task::Idle => {}
+            Task::Running(future) => {
+                let future = Pin::new_unchecked(future);
+                let waker_data: *const () = mem::transmute(wake);
+                let waker = Waker::from_raw(RawWaker::new(waker_data, &WAKER_VTABLE));
+                let mut cx = Context::from_waker(&waker);
+
+                match future.poll(&mut cx) {
+                    Poll::Ready(r) => *self = Task::Done(r),
+                    Poll::Pending => {}
+                };
+            }
+            Task::Done(_) => {}
+        }
+    }
+}
+
+//=============
+// Yield
+
+struct Yield {
+    done: bool,
+}
+
+impl Future for Yield {
+    type Output = u32;
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        if self.done {
+            Poll::Ready(73)
+        } else {
+            cx.waker().wake_by_ref();
+            self.done = true;
+            Poll::Pending
+        }
+    }
+}
+
+fn please_yield() -> Yield {
+    Yield { done: false }
+}

examples/systic.rs

@@ -0,0 +1,50 @@
+//! examples/systic.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+use panic_semihosting as _;
+
+#[rtic::app(device = lm3s6965)]
+mod app {
+    use cortex_m_semihosting::{debug, hprintln};
+
+    #[resources]
+    struct Resources {
+        #[init(0)]
+        #[task_local]
+        counter: i32,
+    }
+
+    #[init]
+    fn init(cx: init::Context) -> init::LateResources {
+        let mut syst = cx.core.SYST;
+        syst.set_reload(100000);
+        syst.enable_interrupt();
+        syst.enable_counter();
+
+        hprintln!("init").unwrap();
+        init::LateResources {}
+    }
+
+    #[idle]
+    fn idle(_: idle::Context) -> ! {
+        hprintln!("idle").unwrap();
+        loop {
+            cortex_m::asm::nop();
+        }
+    }
+
+    #[task(binds = SysTick, resources = [counter])]
+    fn systic(cx: systic::Context) {
+        let counter = cx.resources.counter;
+
+        *counter += 1;
+        hprintln!("SysTick #{}", counter).unwrap();
+        if *counter == 10 {
+            debug::exit(debug::EXIT_SUCCESS);
+        }
+    }
+}