From 5b1c0dbb0aa0f4a3cb0f21ee7531c21558f4a7c3 Mon Sep 17 00:00:00 2001
From: Per Lindgren <per.lindgren@ltu.se>
Date: Mon, 26 Oct 2020 17:16:51 +0100
Subject: [PATCH] async_util

---
 Cargo.toml                 |  2 ++
 examples/async_systick2.rs | 10 ++++++----
 src/lib.rs                 |  7 +++++++
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 6fe5fce38f..9521998397 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -82,6 +82,8 @@ version = "0.5.2"
 trybuild = "1"
 
 [features]
+# experimental support for async/await
+async = []
 # used for testing this crate; do not use in applications
 __v7 =[]
 __min_r1_43 =[]
diff --git a/examples/async_systick2.rs b/examples/async_systick2.rs
index 3f1245332a..618baf61c6 100644
--- a/examples/async_systick2.rs
+++ b/examples/async_systick2.rs
@@ -91,8 +91,10 @@ mod app {
         async fn task(mut cx: foo::Context<'static>) {
             hprintln!("foo task").ok();
 
-            hprintln!("delay long time").ok();
-            timer_delay(&mut cx.resources.systick, 5000000).await;
+            hprintln!("prepare two futures").ok();
+            let d1 = timer_delay(&mut cx.resources.systick, 5000000);
+            let d2 = timer_delay(&mut cx.resources.systick, 1000000);
+
             hprintln!("foo task resumed").ok();
 
             hprintln!("delay short time").ok();
@@ -182,6 +184,7 @@ impl<F: Future + 'static> Task<F> {
 use core::cmp::Ordering;
 use heapless::binary_heap::{BinaryHeap, Max};
 use heapless::consts::U8;
+use heapless::Vec;
 
 pub enum State {
     Started,
@@ -217,7 +220,6 @@ pub struct Systick {
     syst: cortex_m::peripheral::SYST,
     state: State,
     queue: BinaryHeap<Timeout, U8, Max>,
-    // waker: Option<Waker>,
 }
 
 //=============
@@ -260,7 +262,7 @@ impl<'a, T: Mutex<T = Systick>> Future for Timer<'a, T> {
 fn timer_delay<'a, T: Mutex<T = Systick>>(systick: &'a mut T, t: u32) -> Timer<'a, T> {
     hprintln!("timer_delay {}", t);
     Timer {
-        request: Some(t),
+        request: heapless,
         systick,
     }
 }
diff --git a/src/lib.rs b/src/lib.rs
index a7d399cd45..5a17c9c50a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -34,9 +34,16 @@
 #![deny(rust_2018_idioms)]
 #![deny(warnings)]
 #![no_std]
+// async currently requires nightly
+#![cfg_attr(feature = "async", feature(const_fn))]
+#![cfg_attr(feature = "async", feature(type_alias_impl_trait))]
 
 use core::ops::Sub;
 
+// currently requires nightly
+#[cfg(feature = "async")]
+pub mod async_util;
+
 use cortex_m::{
     interrupt::Nr,
     peripheral::{CBP, CPUID, DCB, DWT, FPB, FPU, ITM, MPU, NVIC, SCB, TPIU},