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use core::cell::Cell;
use critical_section::Mutex;
/// Task is spawned (has a future)
pub(crate) const STATE_SPAWNED: u32 = 1 << 0;
/// Task is in the executor run queue
pub(crate) const STATE_RUN_QUEUED: u32 = 1 << 1;
/// Task is in the executor timer queue
#[cfg(feature = "integrated-timers")]
pub(crate) const STATE_TIMER_QUEUED: u32 = 1 << 2;
pub(crate) struct State {
state: Mutex<Cell<u32>>,
}
impl State {
pub const fn new() -> State {
Self {
state: Mutex::new(Cell::new(0)),
}
}
fn update<R>(&self, f: impl FnOnce(&mut u32) -> R) -> R {
critical_section::with(|cs| {
let s = self.state.borrow(cs);
let mut val = s.get();
let r = f(&mut val);
s.set(val);
r
})
}
/// If task is idle, mark it as spawned + run_queued and return true.
#[inline(always)]
pub fn spawn(&self) -> bool {
self.update(|s| {
if *s == 0 {
*s = STATE_SPAWNED | STATE_RUN_QUEUED;
true
} else {
false
}
})
}
/// Unmark the task as spawned.
#[inline(always)]
pub fn despawn(&self) {
self.update(|s| *s &= !STATE_SPAWNED);
}
/// Mark the task as run-queued if it's spawned and isn't already run-queued. Return true on success.
#[inline(always)]
pub fn run_enqueue(&self) -> bool {
self.update(|s| {
if (*s & STATE_RUN_QUEUED != 0) || (*s & STATE_SPAWNED == 0) {
false
} else {
*s |= STATE_RUN_QUEUED;
true
}
})
}
/// Unmark the task as run-queued. Return whether the task is spawned.
#[inline(always)]
pub fn run_dequeue(&self) -> bool {
self.update(|s| {
let ok = *s & STATE_SPAWNED != 0;
*s &= !STATE_RUN_QUEUED;
ok
})
}
/// Mark the task as timer-queued. Return whether it was newly queued (i.e. not queued before)
#[cfg(feature = "integrated-timers")]
#[inline(always)]
pub fn timer_enqueue(&self) -> bool {
self.update(|s| {
let ok = *s & STATE_TIMER_QUEUED == 0;
*s |= STATE_TIMER_QUEUED;
ok
})
}
/// Unmark the task as timer-queued.
#[cfg(feature = "integrated-timers")]
#[inline(always)]
pub fn timer_dequeue(&self) {
self.update(|s| *s &= !STATE_TIMER_QUEUED);
}
}
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