Due to not requiring Unpin, it's not really possible to call it
after having polled it, you can only call it right after constructing it,
so in practice it's not very useful.
As per Tokio and others, this commit provides a `poll_flush` method on `AsyncWrite` so that a best-effort attempt at wakening once all bytes are flushed can be made.
467: docs: fix some `cargo doc` warnings r=lulf a=numero-744
There are still 3 warnings (below)
```
Documenting embassy v0.1.0 (embassy)
warning: unresolved link to `channel`
--> src/channel/mpsc.rs:241:22
|
241 | /// [`channel`]: channel
| ^^^^^^^ no item named `channel` in scope
|
= note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default
= help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
warning: unresolved link to `Task::spawn`
--> src/executor/raw/mod.rs:105:12
|
105 | /// with [`Task::spawn()`], which will fail if it is already spawned.
| ^^^^^^^^^^^^^ no item named `Task` in scope
warning: public documentation for `spawn` links to private item `Executor::spawn`
--> src/executor/raw/mod.rs:156:17
|
156 | /// cause [`Executor::spawn()`] to return the error.
| ^^^^^^^^^^^^^^^^^ this item is private
|
= note: `#[warn(rustdoc::private_intra_doc_links)]` on by default
= note: this link will resolve properly if you pass `--document-private-items`
warning: `embassy` (lib doc) generated 3 warnings
```
Co-authored-by: Côme ALLART <come.allart@etu.emse.fr>
This prevents the std time driver from overflowing when setting the next
wakeup time. If an overflow occurs, default to sleeping up to 1 second.
Fixes#438
428: executor: Use critical sections instead of atomic CAS loops r=lulf a=Dirbaio
Optimize executor wakes.
CAS loops (either `fetch_update`, or manual `load + compare_exchange_weak`) generate surprisingly horrible code: https://godbolt.org/z/zhscnM1cb
This switches to using critical sections, which makes it faster. On thumbv6 (Cortex-M0) it should make it even faster, as it is currently using `atomic-polyfill`, which will make many critical sections for each `compare_exchange_weak` anyway.
```
opt-level=3 opt-level=s
atmics: 105 cycles 101 cycles
CS: 76 cycles 72 cycles
CS+inline: 72 cycles 64 cycles
```
Measured in nrf52 with icache disabled, with this code:
```rust
poll_fn(|cx| {
let task = unsafe { task_from_waker(cx.waker()) };
compiler_fence(Ordering::SeqCst);
let a = cortex_m::peripheral::DWT::get_cycle_count();
compiler_fence(Ordering::SeqCst);
unsafe { wake_task(task) }
compiler_fence(Ordering::SeqCst);
let b = cortex_m::peripheral::DWT::get_cycle_count();
compiler_fence(Ordering::SeqCst);
defmt::info!("cycles: {=u32}", b.wrapping_sub(a));
Poll::Ready(())
})
.await;
````
Co-authored-by: Dario Nieuwenhuis <dirbaio@dirbaio.net>
That steal method has a TAKEN=true write [here](6b013138b7/src/peripheral/mod.rs (L180)).
This is not zero cost, we don't want it. Transmute instead, which is zero cost.
* Adds an executor for WASM runtimes based on wasm_bindgen.
* Add time driver based on JS time handling.
* Add example that can run in browser locally.
* Update to critical-section version that supports 'std' flag
