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//! 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::Timer;
use crate::*;
#[resources]
struct Resources {
syst: cortex_m::peripheral::SYST,
}
#[init]
fn init(cx: init::Context) -> init::LateResources {
hprintln!("init").unwrap();
foo::spawn().unwrap();
init::LateResources { syst: cx.core.SYST }
}
#[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(resources = [syst])]
fn foo(mut cx: foo::Context) {
// BEGIN BOILERPLATE
type F = impl Future + 'static;
fn create(cx: foo::Context<'static>) -> F {
task(cx)
}
static mut TASK: Task<F> = Task::new();
hprintln!("foo trampoline").ok();
unsafe {
match TASK {
Task::Idle | Task::Done(_) => {
hprintln!("foo spawn task").ok();
TASK.spawn(|| create(mem::transmute(cx)));
}
_ => {}
};
hprintln!("foo trampoline poll").ok();
TASK.poll(|| {});
match TASK {
Task::Done(ref r) => {
hprintln!("foo trampoline done").ok();
// hprintln!("r = {:?}", mem::transmute::<_, &u32>(r)).ok();
}
_ => {
hprintln!("foo trampoline running").ok();
}
}
}
// END BOILERPLATE
async fn task(mut cx: foo::Context<'static>) {
hprintln!("foo task").ok();
hprintln!("delay long time").ok();
let fut = cx.resources.syst.lock(|syst| timer_delay(syst, 5000000));
hprintln!("we have just created the future");
fut.await; // this calls poll on the timer future
hprintln!("foo task resumed").ok();
hprintln!("delay short time").ok();
cx.resources
.syst
.lock(|syst| timer_delay(syst, 1000000))
.await;
hprintln!("foo task resumed").ok();
}
}
// #[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(mem::transmute(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(mut cx: timer::Context<'static>) {
// hprintln!("SysTick").ok();
// Timer::delay(100000).await;
// // cx.resources.waker.lock(|w| *w = Some())
// }
// }
// This the actual RTIC task, binds to systic.
#[task(binds = SysTick, resources = [syst], priority = 2)]
fn systic(mut cx: systic::Context) {
hprintln!("systic interrupt").ok();
cx.resources.syst.lock(|syst| syst.disable_interrupt());
crate::app::foo::spawn(); // this should be from a Queue later
}
}
//=============
// 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(_) => {}
}
}
}
//=============
// Timer
// Later we want a proper queue
use heapless;
pub struct Timer {
pub done: bool,
// pub waker_task: Option<fn() -> Result<(), ()>>,
}
impl Future for Timer {
type Output = ();
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
if self.done {
Poll::Ready(())
} else {
hprintln!("timer polled");
cx.waker().wake_by_ref();
hprintln!("after wake_by_ref");
self.done = true;
Poll::Pending
}
}
}
fn timer_delay(syst: &mut cortex_m::peripheral::SYST, t: u32) -> Timer {
hprintln!("timer_delay {}", t);
syst.set_reload(t);
syst.enable_counter();
syst.enable_interrupt();
Timer {
done: false,
// waker_task: Some(app::foo::spawn), // we should add waker field to async task context i RTIC
}
}
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