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#![no_main]
#![no_std]
#![feature(type_alias_impl_trait)]
use core::future::Future;
use core::pin::Pin;
use core::task::{Context, Poll, Waker};
use cortex_m_semihosting::{debug, hprintln};
use panic_semihosting as _;
use systick_monotonic::*;
// NOTES:
//
// - Async tasks cannot have `#[lock_free]` resources, as they can interleve and each async
// task can have a mutable reference stored.
// - Spawning an async task equates to it being polled at least once.
// - ...
#[rtic::app(device = lm3s6965, dispatchers = [SSI0, UART0], peripherals = true)]
mod app {
use crate::*;
pub type AppInstant = <Systick<100> as rtic::Monotonic>::Instant;
pub type AppDuration = <Systick<100> as rtic::Monotonic>::Duration;
#[shared]
struct Shared {
s: u32,
}
#[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();
(
Shared { s: 0 },
Local {},
init::Monotonics(Systick::new(cx.core.SYST, 12_000_000)),
)
}
#[idle]
fn idle(_: idle::Context) -> ! {
// debug::exit(debug::EXIT_SUCCESS);
loop {
// hprintln!("idle");
cortex_m::asm::wfi(); // put the MCU in sleep mode until interrupt occurs
}
}
#[task(priority = 2)]
async fn task(cx: task::Context) {
hprintln!("delay long time").ok();
let fut = Delay::spawn(2500.millis());
hprintln!("we have just created the future").ok();
fut.await;
hprintln!("long delay done").ok();
hprintln!("delay short time").ok();
delay(500.millis()).await;
hprintln!("short delay done").ok();
hprintln!("test timeout").ok();
let res = timeout(NeverEndingFuture {}, 1.secs()).await;
hprintln!("timeout done: {:?}", res).ok();
hprintln!("test timeout 2").ok();
let res = timeout(delay(500.millis()), 1.secs()).await;
hprintln!("timeout done 2: {:?}", res).ok();
debug::exit(debug::EXIT_SUCCESS);
}
#[task(capacity = 12)]
fn delay_handler(_: delay_handler::Context, waker: Waker) {
waker.wake();
}
}
// Delay
pub struct Delay {
until: crate::app::AppInstant,
}
impl Delay {
pub fn spawn(duration: crate::app::AppDuration) -> Self {
let until = crate::app::monotonics::now() + duration;
Delay { until }
}
}
#[inline(always)]
pub fn delay(duration: crate::app::AppDuration) -> Delay {
Delay::spawn(duration)
}
impl Future for Delay {
type Output = ();
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let s = self.as_mut();
let now = crate::app::monotonics::now();
hprintln!(" poll Delay").ok();
if now >= s.until {
Poll::Ready(())
} else {
let waker = cx.waker().clone();
crate::app::delay_handler::spawn_after(s.until - now, waker).ok();
Poll::Pending
}
}
}
//=============
// Timeout future
#[derive(Copy, Clone, Debug)]
pub struct TimeoutError;
pub struct Timeout<F: Future> {
future: F,
until: crate::app::AppInstant,
cancel_handle: Option<crate::app::delay_handler::SpawnHandle>,
}
impl<F> Timeout<F>
where
F: Future,
{
pub fn timeout(future: F, duration: crate::app::AppDuration) -> Self {
let until = crate::app::monotonics::now() + duration;
Self {
future,
until,
cancel_handle: None,
}
}
}
#[inline(always)]
pub fn timeout<F: Future>(future: F, duration: crate::app::AppDuration) -> Timeout<F> {
Timeout::timeout(future, duration)
}
impl<F> Future for Timeout<F>
where
F: Future,
{
type Output = Result<F::Output, TimeoutError>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let now = crate::app::monotonics::now();
// SAFETY: We don't move the underlying pinned value.
let mut s = unsafe { self.get_unchecked_mut() };
let future = unsafe { Pin::new_unchecked(&mut s.future) };
hprintln!(" poll Timeout").ok();
match future.poll(cx) {
Poll::Ready(r) => {
if let Some(ch) = s.cancel_handle.take() {
ch.cancel().ok();
}
Poll::Ready(Ok(r))
}
Poll::Pending => {
if now >= s.until {
Poll::Ready(Err(TimeoutError))
} else if s.cancel_handle.is_none() {
let waker = cx.waker().clone();
let sh = crate::app::delay_handler::spawn_after(s.until - now, waker)
.expect("Internal RTIC bug, this should never fail");
s.cancel_handle = Some(sh);
Poll::Pending
} else {
Poll::Pending
}
}
}
}
}
pub struct NeverEndingFuture {}
impl Future for NeverEndingFuture {
type Output = ();
fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Self::Output> {
// Never finish
hprintln!(" polling NeverEndingFuture").ok();
Poll::Pending
}
}
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