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#![no_std]
#![doc = include_str!("../README.md")]
#![warn(missing_docs)]
//! This crate is an implementation detail of `embassy-time-driver`.
//!
//! As a HAL user, you should only depend on this crate if your application does not use
//! `embassy-executor` and your HAL does not configure a generic queue by itself.
//!
//! As a HAL implementer, you need to depend on this crate if you want to implement a time driver,
//! but how you should do so is documented in `embassy-time-driver`.
use core::task::Waker;
#[cfg(feature = "_generic-queue")]
pub mod queue_generic;
#[cfg(not(feature = "_generic-queue"))]
pub mod queue_integrated;
#[cfg(feature = "_generic-queue")]
pub use queue_generic::Queue;
#[cfg(not(feature = "_generic-queue"))]
pub use queue_integrated::Queue;
extern "Rust" {
fn _embassy_time_schedule_wake(at: u64, waker: &Waker);
}
/// Schedule the given waker to be woken at `at`.
pub fn schedule_wake(at: u64, waker: &Waker) {
// This function is not implemented in embassy-time-driver because it needs access to executor
// internals. The function updates task state, then delegates to the implementation provided
// by the time driver.
#[cfg(not(feature = "_generic-queue"))]
{
use embassy_executor::raw::task_from_waker;
use embassy_executor::raw::timer_queue::TimerEnqueueOperation;
// The very first thing we must do, before we even access the timer queue, is to
// mark the task a TIMER_QUEUED. This ensures that the task that is being scheduled
// can not be respawn while we are accessing the timer queue.
let task = task_from_waker(waker);
if unsafe { task.timer_enqueue() } == TimerEnqueueOperation::Ignore {
// We are not allowed to enqueue the task in the timer queue. This is because the
// task is not spawned, and so it makes no sense to schedule it.
return;
}
}
unsafe { _embassy_time_schedule_wake(at, waker) }
}
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