120 lines
3.2 KiB
Rust
120 lines
3.2 KiB
Rust
use embassy::executor::{raw, Spawner};
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use embassy::time::TICKS_PER_SECOND;
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use embassy::time::{Alarm, Clock};
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use std::marker::PhantomData;
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use std::mem::MaybeUninit;
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use std::ptr;
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use std::sync::{Condvar, Mutex};
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use std::time::{Duration as StdDuration, Instant as StdInstant};
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static mut CLOCK_ZERO: MaybeUninit<StdInstant> = MaybeUninit::uninit();
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struct StdClock;
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impl Clock for StdClock {
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fn now(&self) -> u64 {
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let zero = unsafe { CLOCK_ZERO.as_ptr().read() };
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let dur = StdInstant::now().duration_since(zero);
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dur.as_secs() * (TICKS_PER_SECOND as u64)
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+ (dur.subsec_nanos() as u64) * (TICKS_PER_SECOND as u64) / 1_000_000_000
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}
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}
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static mut ALARM_AT: u64 = u64::MAX;
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pub struct StdAlarm;
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impl Alarm for StdAlarm {
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fn set_callback(&self, _callback: fn(*mut ()), _ctx: *mut ()) {}
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fn set(&self, timestamp: u64) {
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unsafe { ALARM_AT = timestamp }
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}
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fn clear(&self) {
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unsafe { ALARM_AT = u64::MAX }
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}
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}
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struct Signaler {
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mutex: Mutex<bool>,
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condvar: Condvar,
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}
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impl Signaler {
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fn new() -> Self {
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Self {
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mutex: Mutex::new(false),
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condvar: Condvar::new(),
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}
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}
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fn wait(&self) {
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let mut signaled = self.mutex.lock().unwrap();
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while !*signaled {
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let alarm_at = unsafe { ALARM_AT };
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if alarm_at == u64::MAX {
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signaled = self.condvar.wait(signaled).unwrap();
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} else {
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let now = StdClock.now();
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if now >= alarm_at {
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break;
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}
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let left = alarm_at - now;
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let dur = StdDuration::new(
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left / (TICKS_PER_SECOND as u64),
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(left % (TICKS_PER_SECOND as u64) * 1_000_000_000 / (TICKS_PER_SECOND as u64))
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as u32,
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);
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let (signaled2, timeout) = self.condvar.wait_timeout(signaled, dur).unwrap();
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signaled = signaled2;
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if timeout.timed_out() {
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break;
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}
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}
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}
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*signaled = false;
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}
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fn signal(ctx: *mut ()) {
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let this = unsafe { &*(ctx as *mut Self) };
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let mut signaled = this.mutex.lock().unwrap();
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*signaled = true;
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this.condvar.notify_one();
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}
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}
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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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signaler: Signaler,
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}
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impl Executor {
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pub fn new() -> Self {
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unsafe {
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CLOCK_ZERO.as_mut_ptr().write(StdInstant::now());
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embassy::time::set_clock(&StdClock);
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}
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Self {
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inner: raw::Executor::new(Signaler::signal, ptr::null_mut()),
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not_send: PhantomData,
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signaler: Signaler::new(),
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}
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}
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/// Runs the executor.
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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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self.inner.set_signal_ctx(&self.signaler as *const _ as _);
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self.inner.set_alarm(&StdAlarm);
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init(unsafe { self.inner.spawner() });
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loop {
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unsafe { self.inner.run_queued() };
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self.signaler.wait();
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}
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}
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}
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