67 lines
2.3 KiB
Rust
67 lines
2.3 KiB
Rust
use core::marker::PhantomData;
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use core::ptr;
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use atomic_polyfill::{AtomicBool, Ordering};
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use super::{raw, Spawner};
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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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///
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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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// use Signal_Work_Thread_Mode as substitute for local interrupt register
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inner: raw::Executor::new(
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|_| {
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SIGNAL_WORK_THREAD_MODE.store(true, Ordering::SeqCst);
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},
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ptr::null_mut(),
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),
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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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// if there is work to do, loop back to polling
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if !SIGNAL_WORK_THREAD_MODE.fetch_and(false, Ordering::SeqCst) {
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core::arch::asm!("wfi");
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}
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}
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}
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}
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}
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