88 lines
3.3 KiB
Rust
88 lines
3.3 KiB
Rust
#[cfg(feature = "executor-interrupt")]
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compile_error!("`executor-interrupt` is not supported with `arch-riscv32`.");
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#[cfg(feature = "executor-thread")]
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pub use thread::*;
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#[cfg(feature = "executor-thread")]
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mod thread {
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use core::marker::PhantomData;
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use core::sync::atomic::{AtomicBool, Ordering};
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#[cfg(feature = "nightly")]
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pub use embassy_macros::main_riscv as main;
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use crate::raw::{Pender, PenderInner};
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use crate::{raw, Spawner};
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#[derive(Copy, Clone)]
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pub(crate) struct ThreadPender;
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impl ThreadPender {
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#[allow(unused)]
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pub(crate) fn pend(self) {
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SIGNAL_WORK_THREAD_MODE.store(true, core::sync::atomic::Ordering::SeqCst);
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}
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}
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/// global atomic used to keep track of whether there is work to do since sev() is not available on RISCV
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static SIGNAL_WORK_THREAD_MODE: AtomicBool = AtomicBool::new(false);
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/// RISCV32 Executor
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pub struct Executor {
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inner: raw::Executor,
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not_send: PhantomData<*mut ()>,
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}
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impl Executor {
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/// Create a new Executor.
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pub fn new() -> Self {
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Self {
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inner: raw::Executor::new(Pender(PenderInner::Thread(ThreadPender))),
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not_send: PhantomData,
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}
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}
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/// Run the executor.
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///
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/// The `init` closure is called with a [`Spawner`] that spawns tasks on
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/// this executor. Use it to spawn the initial task(s). After `init` returns,
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/// the executor starts running the tasks.
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///
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/// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`),
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/// for example by passing it as an argument to the initial tasks.
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///
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/// This function requires `&'static mut self`. This means you have to store the
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/// Executor instance in a place where it'll live forever and grants you mutable
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/// access. There's a few ways to do this:
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///
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/// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe)
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/// - a `static mut` (unsafe)
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/// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe)
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///
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/// This function never returns.
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pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! {
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init(self.inner.spawner());
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loop {
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unsafe {
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self.inner.poll();
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// we do not care about race conditions between the load and store operations, interrupts
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//will only set this value to true.
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critical_section::with(|_| {
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// if there is work to do, loop back to polling
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// TODO can we relax this?
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if SIGNAL_WORK_THREAD_MODE.load(Ordering::SeqCst) {
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SIGNAL_WORK_THREAD_MODE.store(false, Ordering::SeqCst);
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}
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// if not, wait for interrupt
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else {
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core::arch::asm!("wfi");
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}
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});
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// if an interrupt occurred while waiting, it will be serviced here
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}
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}
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}
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}
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}
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