feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/embassy-sync-0.5.0/.cargo-checksum.json

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vendor/embassy-sync-0.5.0/.cargo_vcs_info.json

@@ -0,0 +1,6 @@
+{
+  "git": {
+    "sha1": "d2dcbed920f116368dd00ee997e93dcd90270ca5"
+  },
+  "path_in_vcs": "embassy-sync"
+}

vendor/embassy-sync-0.5.0/CHANGELOG.md

@@ -0,0 +1,41 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## 0.5.0 - 2023-12-04
+
+- Add a PriorityChannel.
+- Remove nightly and unstable-traits features in preparation for 1.75.
+- Upgrade heapless to 0.8.
+- Upgrade static-cell to 2.0.
+
+## 0.4.0 - 2023-10-31
+
+- Re-add impl_trait_projections
+- switch to `embedded-io 0.6`
+
+## 0.3.0 - 2023-09-14
+
+- switch to `embedded-io 0.5`
+- add api for polling channels with context
+- standardise fn names on channels
+- add zero-copy channel
+
+## 0.2.0 - 2023-04-13
+
+- pubsub: Fix messages not getting popped when the last subscriber that needed them gets dropped.
+- pubsub: Move instead of clone messages when the last subscriber pops them.
+- pubsub: Pop messages which count is 0 after unsubscribe.
+- Update `embedded-io` from `0.3` to `0.4` (uses `async fn` in traits).
+- impl `Default` for `WakerRegistration`
+- impl `Default` for `Signal`
+- Remove unnecessary uses of `atomic-polyfill`
+- Add `#[must_use]` to all futures.
+
+
+## 0.1.0 - 2022-08-26
+
+- First release

vendor/embassy-sync-0.5.0/Cargo.toml

@@ -0,0 +1,79 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2021"
+name = "embassy-sync"
+version = "0.5.0"
+description = "no-std, no-alloc synchronization primitives with async support"
+readme = "README.md"
+categories = [
+    "embedded",
+    "no-std",
+    "concurrency",
+    "asynchronous",
+]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/embassy-rs/embassy"
+
+[package.metadata.embassy_docs]
+src_base = "https://github.com/embassy-rs/embassy/blob/embassy-sync-v$VERSION/embassy-sync/src/"
+src_base_git = "https://github.com/embassy-rs/embassy/blob/$COMMIT/embassy-sync/src/"
+target = "thumbv7em-none-eabi"
+
+[dependencies.cfg-if]
+version = "1.0.0"
+
+[dependencies.critical-section]
+version = "1.1"
+
+[dependencies.defmt]
+version = "0.3"
+optional = true
+
+[dependencies.embedded-io-async]
+version = "0.6.1"
+
+[dependencies.futures-util]
+version = "0.3.17"
+default-features = false
+
+[dependencies.heapless]
+version = "0.8"
+
+[dependencies.log]
+version = "0.4.14"
+optional = true
+
+[dev-dependencies.critical-section]
+version = "1.1"
+features = ["std"]
+
+[dev-dependencies.futures-executor]
+version = "0.3.17"
+features = ["thread-pool"]
+
+[dev-dependencies.futures-test]
+version = "0.3.17"
+
+[dev-dependencies.futures-timer]
+version = "3.0.2"
+
+[dev-dependencies.futures-util]
+version = "0.3.17"
+features = ["channel"]
+
+[dev-dependencies.static_cell]
+version = "2"
+
+[features]
+std = []
+turbowakers = []

vendor/embassy-sync-0.5.0/README.md

@@ -0,0 +1,33 @@
+# embassy-sync
+
+An [Embassy](https://embassy.dev) project.
+
+Synchronization primitives and data structures with async support:
+
+- [`Channel`](channel::Channel) - A Multiple Producer Multiple Consumer (MPMC) channel. Each message is only received by a single consumer.
+- [`PriorityChannel`](channel::priority::PriorityChannel) - A Multiple Producer Multiple Consumer (MPMC) channel. Each message is only received by a single consumer. Higher priority items are sifted to the front of the channel.
+- [`PubSubChannel`](pubsub::PubSubChannel) - A broadcast channel (publish-subscribe) channel. Each message is received by all consumers.
+- [`Signal`](signal::Signal) - Signalling latest value to a single consumer.
+- [`Mutex`](mutex::Mutex) - Mutex for synchronizing state between asynchronous tasks.
+- [`Pipe`](pipe::Pipe) - Byte stream implementing `embedded_io` traits.
+- [`WakerRegistration`](waitqueue::WakerRegistration) - Utility to register and wake a `Waker`.
+- [`AtomicWaker`](waitqueue::AtomicWaker) - A variant of `WakerRegistration` accessible using a non-mut API.
+- [`MultiWakerRegistration`](waitqueue::MultiWakerRegistration) - Utility registering and waking multiple `Waker`'s.
+
+## Interoperability
+
+Futures from this crate can run on any executor.
+
+## Minimum supported Rust version (MSRV)
+
+Embassy is guaranteed to compile on the latest stable Rust version at the time of release. It might compile with older versions but that may change in any new patch release.
+
+## License
+
+This work is licensed under either of
+
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
+  <http://www.apache.org/licenses/LICENSE-2.0>)
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)
+
+at your option.

vendor/embassy-sync-0.5.0/build.rs

@@ -0,0 +1,44 @@
+use std::env;
+use std::ffi::OsString;
+use std::process::Command;
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+
+    let rustc = env::var_os("RUSTC").unwrap_or_else(|| OsString::from("rustc"));
+
+    let output = Command::new(rustc)
+        .arg("--version")
+        .output()
+        .expect("failed to run `rustc --version`");
+
+    if String::from_utf8_lossy(&output.stdout).contains("nightly") {
+        println!("cargo:rustc-cfg=nightly");
+    }
+
+    let target = env::var("TARGET").unwrap();
+
+    if target.starts_with("thumbv6m-") {
+        println!("cargo:rustc-cfg=cortex_m");
+        println!("cargo:rustc-cfg=armv6m");
+    } else if target.starts_with("thumbv7m-") {
+        println!("cargo:rustc-cfg=cortex_m");
+        println!("cargo:rustc-cfg=armv7m");
+    } else if target.starts_with("thumbv7em-") {
+        println!("cargo:rustc-cfg=cortex_m");
+        println!("cargo:rustc-cfg=armv7m");
+        println!("cargo:rustc-cfg=armv7em"); // (not currently used)
+    } else if target.starts_with("thumbv8m.base") {
+        println!("cargo:rustc-cfg=cortex_m");
+        println!("cargo:rustc-cfg=armv8m");
+        println!("cargo:rustc-cfg=armv8m_base");
+    } else if target.starts_with("thumbv8m.main") {
+        println!("cargo:rustc-cfg=cortex_m");
+        println!("cargo:rustc-cfg=armv8m");
+        println!("cargo:rustc-cfg=armv8m_main");
+    }
+
+    if target.ends_with("-eabihf") {
+        println!("cargo:rustc-cfg=has_fpu");
+    }
+}

vendor/embassy-sync-0.5.0/src/blocking_mutex/mod.rs

@@ -0,0 +1,189 @@
+//! Blocking mutex.
+//!
+//! This module provides a blocking mutex that can be used to synchronize data.
+pub mod raw;
+
+use core::cell::UnsafeCell;
+
+use self::raw::RawMutex;
+
+/// Blocking mutex (not async)
+///
+/// Provides a blocking mutual exclusion primitive backed by an implementation of [`raw::RawMutex`].
+///
+/// Which implementation you select depends on the context in which you're using the mutex, and you can choose which kind
+/// of interior mutability fits your use case.
+///
+/// Use [`CriticalSectionMutex`] when data can be shared between threads and interrupts.
+///
+/// Use [`NoopMutex`] when data is only shared between tasks running on the same executor.
+///
+/// Use [`ThreadModeMutex`] when data is shared between tasks running on the same executor but you want a global singleton.
+///
+/// In all cases, the blocking mutex is intended to be short lived and not held across await points.
+/// Use the async [`Mutex`](crate::mutex::Mutex) if you need a lock that is held across await points.
+pub struct Mutex<R, T: ?Sized> {
+    // NOTE: `raw` must be FIRST, so when using ThreadModeMutex the "can't drop in non-thread-mode" gets
+    // to run BEFORE dropping `data`.
+    raw: R,
+    data: UnsafeCell<T>,
+}
+
+unsafe impl<R: RawMutex + Send, T: ?Sized + Send> Send for Mutex<R, T> {}
+unsafe impl<R: RawMutex + Sync, T: ?Sized + Send> Sync for Mutex<R, T> {}
+
+impl<R: RawMutex, T> Mutex<R, T> {
+    /// Creates a new mutex in an unlocked state ready for use.
+    #[inline]
+    pub const fn new(val: T) -> Mutex<R, T> {
+        Mutex {
+            raw: R::INIT,
+            data: UnsafeCell::new(val),
+        }
+    }
+
+    /// Creates a critical section and grants temporary access to the protected data.
+    pub fn lock<U>(&self, f: impl FnOnce(&T) -> U) -> U {
+        self.raw.lock(|| {
+            let ptr = self.data.get() as *const T;
+            let inner = unsafe { &*ptr };
+            f(inner)
+        })
+    }
+}
+
+impl<R, T> Mutex<R, T> {
+    /// Creates a new mutex based on a pre-existing raw mutex.
+    ///
+    /// This allows creating a mutex in a constant context on stable Rust.
+    #[inline]
+    pub const fn const_new(raw_mutex: R, val: T) -> Mutex<R, T> {
+        Mutex {
+            raw: raw_mutex,
+            data: UnsafeCell::new(val),
+        }
+    }
+
+    /// Consumes this mutex, returning the underlying data.
+    #[inline]
+    pub fn into_inner(self) -> T {
+        self.data.into_inner()
+    }
+
+    /// Returns a mutable reference to the underlying data.
+    ///
+    /// Since this call borrows the `Mutex` mutably, no actual locking needs to
+    /// take place---the mutable borrow statically guarantees no locks exist.
+    #[inline]
+    pub fn get_mut(&mut self) -> &mut T {
+        unsafe { &mut *self.data.get() }
+    }
+}
+
+/// A mutex that allows borrowing data across executors and interrupts.
+///
+/// # Safety
+///
+/// This mutex is safe to share between different executors and interrupts.
+pub type CriticalSectionMutex<T> = Mutex<raw::CriticalSectionRawMutex, T>;
+
+/// A mutex that allows borrowing data in the context of a single executor.
+///
+/// # Safety
+///
+/// **This Mutex is only safe within a single executor.**
+pub type NoopMutex<T> = Mutex<raw::NoopRawMutex, T>;
+
+impl<T> Mutex<raw::CriticalSectionRawMutex, T> {
+    /// Borrows the data for the duration of the critical section
+    pub fn borrow<'cs>(&'cs self, _cs: critical_section::CriticalSection<'cs>) -> &'cs T {
+        let ptr = self.data.get() as *const T;
+        unsafe { &*ptr }
+    }
+}
+
+impl<T> Mutex<raw::NoopRawMutex, T> {
+    /// Borrows the data
+    pub fn borrow(&self) -> &T {
+        let ptr = self.data.get() as *const T;
+        unsafe { &*ptr }
+    }
+}
+
+// ThreadModeMutex does NOT use the generic mutex from above because it's special:
+// it's Send+Sync even if T: !Send. There's no way to do that without specialization (I think?).
+//
+// There's still a ThreadModeRawMutex for use with the generic Mutex (handy with Channel, for example),
+// but that will require T: Send even though it shouldn't be needed.
+
+#[cfg(any(cortex_m, feature = "std"))]
+pub use thread_mode_mutex::*;
+#[cfg(any(cortex_m, feature = "std"))]
+mod thread_mode_mutex {
+    use super::*;
+
+    /// A "mutex" that only allows borrowing from thread mode.
+    ///
+    /// # Safety
+    ///
+    /// **This Mutex is only safe on single-core systems.**
+    ///
+    /// On multi-core systems, a `ThreadModeMutex` **is not sufficient** to ensure exclusive access.
+    pub struct ThreadModeMutex<T: ?Sized> {
+        inner: UnsafeCell<T>,
+    }
+
+    // NOTE: ThreadModeMutex only allows borrowing from one execution context ever: thread mode.
+    // Therefore it cannot be used to send non-sendable stuff between execution contexts, so it can
+    // be Send+Sync even if T is not Send (unlike CriticalSectionMutex)
+    unsafe impl<T: ?Sized> Sync for ThreadModeMutex<T> {}
+    unsafe impl<T: ?Sized> Send for ThreadModeMutex<T> {}
+
+    impl<T> ThreadModeMutex<T> {
+        /// Creates a new mutex
+        pub const fn new(value: T) -> Self {
+            ThreadModeMutex {
+                inner: UnsafeCell::new(value),
+            }
+        }
+    }
+
+    impl<T: ?Sized> ThreadModeMutex<T> {
+        /// Lock the `ThreadModeMutex`, granting access to the data.
+        ///
+        /// # Panics
+        ///
+        /// This will panic if not currently running in thread mode.
+        pub fn lock<R>(&self, f: impl FnOnce(&T) -> R) -> R {
+            f(self.borrow())
+        }
+
+        /// Borrows the data
+        ///
+        /// # Panics
+        ///
+        /// This will panic if not currently running in thread mode.
+        pub fn borrow(&self) -> &T {
+            assert!(
+                raw::in_thread_mode(),
+                "ThreadModeMutex can only be borrowed from thread mode."
+            );
+            unsafe { &*self.inner.get() }
+        }
+    }
+
+    impl<T: ?Sized> Drop for ThreadModeMutex<T> {
+        fn drop(&mut self) {
+            // Only allow dropping from thread mode. Dropping calls drop on the inner `T`, so
+            // `drop` needs the same guarantees as `lock`. `ThreadModeMutex<T>` is Send even if
+            // T isn't, so without this check a user could create a ThreadModeMutex in thread mode,
+            // send it to interrupt context and drop it there, which would "send" a T even if T is not Send.
+            assert!(
+                raw::in_thread_mode(),
+                "ThreadModeMutex can only be dropped from thread mode."
+            );
+
+            // Drop of the inner `T` happens after this.
+        }
+    }
+}

vendor/embassy-sync-0.5.0/src/blocking_mutex/raw.rs

@@ -0,0 +1,149 @@
+//! Mutex primitives.
+//!
+//! This module provides a trait for mutexes that can be used in different contexts.
+use core::marker::PhantomData;
+
+/// Raw mutex trait.
+///
+/// This mutex is "raw", which means it does not actually contain the protected data, it
+/// just implements the mutex mechanism. For most uses you should use [`super::Mutex`] instead,
+/// which is generic over a RawMutex and contains the protected data.
+///
+/// Note that, unlike other mutexes, implementations only guarantee no
+/// concurrent access from other threads: concurrent access from the current
+/// thread is allowed. For example, it's possible to lock the same mutex multiple times reentrantly.
+///
+/// Therefore, locking a `RawMutex` is only enough to guarantee safe shared (`&`) access
+/// to the data, it is not enough to guarantee exclusive (`&mut`) access.
+///
+/// # Safety
+///
+/// RawMutex implementations must ensure that, while locked, no other thread can lock
+/// the RawMutex concurrently.
+///
+/// Unsafe code is allowed to rely on this fact, so incorrect implementations will cause undefined behavior.
+pub unsafe trait RawMutex {
+    /// Create a new `RawMutex` instance.
+    ///
+    /// This is a const instead of a method to allow creating instances in const context.
+    const INIT: Self;
+
+    /// Lock this `RawMutex`.
+    fn lock<R>(&self, f: impl FnOnce() -> R) -> R;
+}
+
+/// A mutex that allows borrowing data across executors and interrupts.
+///
+/// # Safety
+///
+/// This mutex is safe to share between different executors and interrupts.
+pub struct CriticalSectionRawMutex {
+    _phantom: PhantomData<()>,
+}
+unsafe impl Send for CriticalSectionRawMutex {}
+unsafe impl Sync for CriticalSectionRawMutex {}
+
+impl CriticalSectionRawMutex {
+    /// Create a new `CriticalSectionRawMutex`.
+    pub const fn new() -> Self {
+        Self { _phantom: PhantomData }
+    }
+}
+
+unsafe impl RawMutex for CriticalSectionRawMutex {
+    const INIT: Self = Self::new();
+
+    fn lock<R>(&self, f: impl FnOnce() -> R) -> R {
+        critical_section::with(|_| f())
+    }
+}
+
+// ================
+
+/// A mutex that allows borrowing data in the context of a single executor.
+///
+/// # Safety
+///
+/// **This Mutex is only safe within a single executor.**
+pub struct NoopRawMutex {
+    _phantom: PhantomData<*mut ()>,
+}
+
+unsafe impl Send for NoopRawMutex {}
+
+impl NoopRawMutex {
+    /// Create a new `NoopRawMutex`.
+    pub const fn new() -> Self {
+        Self { _phantom: PhantomData }
+    }
+}
+
+unsafe impl RawMutex for NoopRawMutex {
+    const INIT: Self = Self::new();
+    fn lock<R>(&self, f: impl FnOnce() -> R) -> R {
+        f()
+    }
+}
+
+// ================
+
+#[cfg(any(cortex_m, feature = "std"))]
+mod thread_mode {
+    use super::*;
+
+    /// A "mutex" that only allows borrowing from thread mode.
+    ///
+    /// # Safety
+    ///
+    /// **This Mutex is only safe on single-core systems.**
+    ///
+    /// On multi-core systems, a `ThreadModeRawMutex` **is not sufficient** to ensure exclusive access.
+    pub struct ThreadModeRawMutex {
+        _phantom: PhantomData<()>,
+    }
+
+    unsafe impl Send for ThreadModeRawMutex {}
+    unsafe impl Sync for ThreadModeRawMutex {}
+
+    impl ThreadModeRawMutex {
+        /// Create a new `ThreadModeRawMutex`.
+        pub const fn new() -> Self {
+            Self { _phantom: PhantomData }
+        }
+    }
+
+    unsafe impl RawMutex for ThreadModeRawMutex {
+        const INIT: Self = Self::new();
+        fn lock<R>(&self, f: impl FnOnce() -> R) -> R {
+            assert!(in_thread_mode(), "ThreadModeMutex can only be locked from thread mode.");
+
+            f()
+        }
+    }
+
+    impl Drop for ThreadModeRawMutex {
+        fn drop(&mut self) {
+            // Only allow dropping from thread mode. Dropping calls drop on the inner `T`, so
+            // `drop` needs the same guarantees as `lock`. `ThreadModeMutex<T>` is Send even if
+            // T isn't, so without this check a user could create a ThreadModeMutex in thread mode,
+            // send it to interrupt context and drop it there, which would "send" a T even if T is not Send.
+            assert!(
+                in_thread_mode(),
+                "ThreadModeMutex can only be dropped from thread mode."
+            );
+
+            // Drop of the inner `T` happens after this.
+        }
+    }
+
+    pub(crate) fn in_thread_mode() -> bool {
+        #[cfg(feature = "std")]
+        return Some("main") == std::thread::current().name();
+
+        #[cfg(not(feature = "std"))]
+        // ICSR.VECTACTIVE == 0
+        return unsafe { (0xE000ED04 as *const u32).read_volatile() } & 0x1FF == 0;
+    }
+}
+#[cfg(any(cortex_m, feature = "std"))]
+pub use thread_mode::*;

vendor/embassy-sync-0.5.0/src/channel.rs

@@ -0,0 +1,708 @@
+//! A queue for sending values between asynchronous tasks.
+//!
+//! It can be used concurrently by multiple producers (senders) and multiple
+//! consumers (receivers), i.e. it is an  "MPMC channel".
+//!
+//! Receivers are competing for messages. So a message that is received by
+//! one receiver is not received by any other.
+//!
+//! This queue takes a Mutex type so that various
+//! targets can be attained. For example, a ThreadModeMutex can be used
+//! for single-core Cortex-M targets where messages are only passed
+//! between tasks running in thread mode. Similarly, a CriticalSectionMutex
+//! can also be used for single-core targets where messages are to be
+//! passed from exception mode e.g. out of an interrupt handler.
+//!
+//! This module provides a bounded channel that has a limit on the number of
+//! messages that it can store, and if this limit is reached, trying to send
+//! another message will result in an error being returned.
+//!
+
+use core::cell::RefCell;
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+
+use heapless::Deque;
+
+use crate::blocking_mutex::raw::RawMutex;
+use crate::blocking_mutex::Mutex;
+use crate::waitqueue::WakerRegistration;
+
+/// Send-only access to a [`Channel`].
+pub struct Sender<'ch, M, T, const N: usize>
+where
+    M: RawMutex,
+{
+    channel: &'ch Channel<M, T, N>,
+}
+
+impl<'ch, M, T, const N: usize> Clone for Sender<'ch, M, T, N>
+where
+    M: RawMutex,
+{
+    fn clone(&self) -> Self {
+        Sender { channel: self.channel }
+    }
+}
+
+impl<'ch, M, T, const N: usize> Copy for Sender<'ch, M, T, N> where M: RawMutex {}
+
+impl<'ch, M, T, const N: usize> Sender<'ch, M, T, N>
+where
+    M: RawMutex,
+{
+    /// Sends a value.
+    ///
+    /// See [`Channel::send()`]
+    pub fn send(&self, message: T) -> SendFuture<'ch, M, T, N> {
+        self.channel.send(message)
+    }
+
+    /// Attempt to immediately send a message.
+    ///
+    /// See [`Channel::send()`]
+    pub fn try_send(&self, message: T) -> Result<(), TrySendError<T>> {
+        self.channel.try_send(message)
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to send
+    ///
+    /// See [`Channel::poll_ready_to_send()`]
+    pub fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.channel.poll_ready_to_send(cx)
+    }
+}
+
+/// Send-only access to a [`Channel`] without knowing channel size.
+pub struct DynamicSender<'ch, T> {
+    pub(crate) channel: &'ch dyn DynamicChannel<T>,
+}
+
+impl<'ch, T> Clone for DynamicSender<'ch, T> {
+    fn clone(&self) -> Self {
+        DynamicSender { channel: self.channel }
+    }
+}
+
+impl<'ch, T> Copy for DynamicSender<'ch, T> {}
+
+impl<'ch, M, T, const N: usize> From<Sender<'ch, M, T, N>> for DynamicSender<'ch, T>
+where
+    M: RawMutex,
+{
+    fn from(s: Sender<'ch, M, T, N>) -> Self {
+        Self { channel: s.channel }
+    }
+}
+
+impl<'ch, T> DynamicSender<'ch, T> {
+    /// Sends a value.
+    ///
+    /// See [`Channel::send()`]
+    pub fn send(&self, message: T) -> DynamicSendFuture<'ch, T> {
+        DynamicSendFuture {
+            channel: self.channel,
+            message: Some(message),
+        }
+    }
+
+    /// Attempt to immediately send a message.
+    ///
+    /// See [`Channel::send()`]
+    pub fn try_send(&self, message: T) -> Result<(), TrySendError<T>> {
+        self.channel.try_send_with_context(message, None)
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to send
+    ///
+    /// See [`Channel::poll_ready_to_send()`]
+    pub fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.channel.poll_ready_to_send(cx)
+    }
+}
+
+/// Receive-only access to a [`Channel`].
+pub struct Receiver<'ch, M, T, const N: usize>
+where
+    M: RawMutex,
+{
+    channel: &'ch Channel<M, T, N>,
+}
+
+impl<'ch, M, T, const N: usize> Clone for Receiver<'ch, M, T, N>
+where
+    M: RawMutex,
+{
+    fn clone(&self) -> Self {
+        Receiver { channel: self.channel }
+    }
+}
+
+impl<'ch, M, T, const N: usize> Copy for Receiver<'ch, M, T, N> where M: RawMutex {}
+
+impl<'ch, M, T, const N: usize> Receiver<'ch, M, T, N>
+where
+    M: RawMutex,
+{
+    /// Receive the next value.
+    ///
+    /// See [`Channel::receive()`].
+    pub fn receive(&self) -> ReceiveFuture<'_, M, T, N> {
+        self.channel.receive()
+    }
+
+    /// Attempt to immediately receive the next value.
+    ///
+    /// See [`Channel::try_receive()`]
+    pub fn try_receive(&self) -> Result<T, TryReceiveError> {
+        self.channel.try_receive()
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to receive
+    ///
+    /// See [`Channel::poll_ready_to_receive()`]
+    pub fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.channel.poll_ready_to_receive(cx)
+    }
+
+    /// Poll the channel for the next item
+    ///
+    /// See [`Channel::poll_receive()`]
+    pub fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        self.channel.poll_receive(cx)
+    }
+}
+
+/// Receive-only access to a [`Channel`] without knowing channel size.
+pub struct DynamicReceiver<'ch, T> {
+    pub(crate) channel: &'ch dyn DynamicChannel<T>,
+}
+
+impl<'ch, T> Clone for DynamicReceiver<'ch, T> {
+    fn clone(&self) -> Self {
+        DynamicReceiver { channel: self.channel }
+    }
+}
+
+impl<'ch, T> Copy for DynamicReceiver<'ch, T> {}
+
+impl<'ch, T> DynamicReceiver<'ch, T> {
+    /// Receive the next value.
+    ///
+    /// See [`Channel::receive()`].
+    pub fn receive(&self) -> DynamicReceiveFuture<'_, T> {
+        DynamicReceiveFuture { channel: self.channel }
+    }
+
+    /// Attempt to immediately receive the next value.
+    ///
+    /// See [`Channel::try_receive()`]
+    pub fn try_receive(&self) -> Result<T, TryReceiveError> {
+        self.channel.try_receive_with_context(None)
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to receive
+    ///
+    /// See [`Channel::poll_ready_to_receive()`]
+    pub fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.channel.poll_ready_to_receive(cx)
+    }
+
+    /// Poll the channel for the next item
+    ///
+    /// See [`Channel::poll_receive()`]
+    pub fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        self.channel.poll_receive(cx)
+    }
+}
+
+impl<'ch, M, T, const N: usize> From<Receiver<'ch, M, T, N>> for DynamicReceiver<'ch, T>
+where
+    M: RawMutex,
+{
+    fn from(s: Receiver<'ch, M, T, N>) -> Self {
+        Self { channel: s.channel }
+    }
+}
+
+/// Future returned by [`Channel::receive`] and  [`Receiver::receive`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct ReceiveFuture<'ch, M, T, const N: usize>
+where
+    M: RawMutex,
+{
+    channel: &'ch Channel<M, T, N>,
+}
+
+impl<'ch, M, T, const N: usize> Future for ReceiveFuture<'ch, M, T, N>
+where
+    M: RawMutex,
+{
+    type Output = T;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
+        self.channel.poll_receive(cx)
+    }
+}
+
+/// Future returned by [`DynamicReceiver::receive`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct DynamicReceiveFuture<'ch, T> {
+    channel: &'ch dyn DynamicChannel<T>,
+}
+
+impl<'ch, T> Future for DynamicReceiveFuture<'ch, T> {
+    type Output = T;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
+        match self.channel.try_receive_with_context(Some(cx)) {
+            Ok(v) => Poll::Ready(v),
+            Err(TryReceiveError::Empty) => Poll::Pending,
+        }
+    }
+}
+
+/// Future returned by [`Channel::send`] and  [`Sender::send`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct SendFuture<'ch, M, T, const N: usize>
+where
+    M: RawMutex,
+{
+    channel: &'ch Channel<M, T, N>,
+    message: Option<T>,
+}
+
+impl<'ch, M, T, const N: usize> Future for SendFuture<'ch, M, T, N>
+where
+    M: RawMutex,
+{
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.message.take() {
+            Some(m) => match self.channel.try_send_with_context(m, Some(cx)) {
+                Ok(..) => Poll::Ready(()),
+                Err(TrySendError::Full(m)) => {
+                    self.message = Some(m);
+                    Poll::Pending
+                }
+            },
+            None => panic!("Message cannot be None"),
+        }
+    }
+}
+
+impl<'ch, M, T, const N: usize> Unpin for SendFuture<'ch, M, T, N> where M: RawMutex {}
+
+/// Future returned by [`DynamicSender::send`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct DynamicSendFuture<'ch, T> {
+    channel: &'ch dyn DynamicChannel<T>,
+    message: Option<T>,
+}
+
+impl<'ch, T> Future for DynamicSendFuture<'ch, T> {
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.message.take() {
+            Some(m) => match self.channel.try_send_with_context(m, Some(cx)) {
+                Ok(..) => Poll::Ready(()),
+                Err(TrySendError::Full(m)) => {
+                    self.message = Some(m);
+                    Poll::Pending
+                }
+            },
+            None => panic!("Message cannot be None"),
+        }
+    }
+}
+
+impl<'ch, T> Unpin for DynamicSendFuture<'ch, T> {}
+
+pub(crate) trait DynamicChannel<T> {
+    fn try_send_with_context(&self, message: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>>;
+
+    fn try_receive_with_context(&self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError>;
+
+    fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()>;
+    fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()>;
+
+    fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T>;
+}
+
+/// Error returned by [`try_receive`](Channel::try_receive).
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum TryReceiveError {
+    /// A message could not be received because the channel is empty.
+    Empty,
+}
+
+/// Error returned by [`try_send`](Channel::try_send).
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum TrySendError<T> {
+    /// The data could not be sent on the channel because the channel is
+    /// currently full and sending would require blocking.
+    Full(T),
+}
+
+struct ChannelState<T, const N: usize> {
+    queue: Deque<T, N>,
+    receiver_waker: WakerRegistration,
+    senders_waker: WakerRegistration,
+}
+
+impl<T, const N: usize> ChannelState<T, N> {
+    const fn new() -> Self {
+        ChannelState {
+            queue: Deque::new(),
+            receiver_waker: WakerRegistration::new(),
+            senders_waker: WakerRegistration::new(),
+        }
+    }
+
+    fn try_receive(&mut self) -> Result<T, TryReceiveError> {
+        self.try_receive_with_context(None)
+    }
+
+    fn try_receive_with_context(&mut self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError> {
+        if self.queue.is_full() {
+            self.senders_waker.wake();
+        }
+
+        if let Some(message) = self.queue.pop_front() {
+            Ok(message)
+        } else {
+            if let Some(cx) = cx {
+                self.receiver_waker.register(cx.waker());
+            }
+            Err(TryReceiveError::Empty)
+        }
+    }
+
+    fn poll_receive(&mut self, cx: &mut Context<'_>) -> Poll<T> {
+        if self.queue.is_full() {
+            self.senders_waker.wake();
+        }
+
+        if let Some(message) = self.queue.pop_front() {
+            Poll::Ready(message)
+        } else {
+            self.receiver_waker.register(cx.waker());
+            Poll::Pending
+        }
+    }
+
+    fn poll_ready_to_receive(&mut self, cx: &mut Context<'_>) -> Poll<()> {
+        self.receiver_waker.register(cx.waker());
+
+        if !self.queue.is_empty() {
+            Poll::Ready(())
+        } else {
+            Poll::Pending
+        }
+    }
+
+    fn try_send(&mut self, message: T) -> Result<(), TrySendError<T>> {
+        self.try_send_with_context(message, None)
+    }
+
+    fn try_send_with_context(&mut self, message: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>> {
+        match self.queue.push_back(message) {
+            Ok(()) => {
+                self.receiver_waker.wake();
+                Ok(())
+            }
+            Err(message) => {
+                if let Some(cx) = cx {
+                    self.senders_waker.register(cx.waker());
+                }
+                Err(TrySendError::Full(message))
+            }
+        }
+    }
+
+    fn poll_ready_to_send(&mut self, cx: &mut Context<'_>) -> Poll<()> {
+        self.senders_waker.register(cx.waker());
+
+        if !self.queue.is_full() {
+            Poll::Ready(())
+        } else {
+            Poll::Pending
+        }
+    }
+}
+
+/// A bounded channel for communicating between asynchronous tasks
+/// with backpressure.
+///
+/// The channel will buffer up to the provided number of messages.  Once the
+/// buffer is full, attempts to `send` new messages will wait until a message is
+/// received from the channel.
+///
+/// All data sent will become available in the same order as it was sent.
+pub struct Channel<M, T, const N: usize>
+where
+    M: RawMutex,
+{
+    inner: Mutex<M, RefCell<ChannelState<T, N>>>,
+}
+
+impl<M, T, const N: usize> Channel<M, T, N>
+where
+    M: RawMutex,
+{
+    /// Establish a new bounded channel. For example, to create one with a NoopMutex:
+    ///
+    /// ```
+    /// use embassy_sync::channel::Channel;
+    /// use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+    ///
+    /// // Declare a bounded channel of 3 u32s.
+    /// let mut channel = Channel::<NoopRawMutex, u32, 3>::new();
+    /// ```
+    pub const fn new() -> Self {
+        Self {
+            inner: Mutex::new(RefCell::new(ChannelState::new())),
+        }
+    }
+
+    fn lock<R>(&self, f: impl FnOnce(&mut ChannelState<T, N>) -> R) -> R {
+        self.inner.lock(|rc| f(&mut *unwrap!(rc.try_borrow_mut())))
+    }
+
+    fn try_receive_with_context(&self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError> {
+        self.lock(|c| c.try_receive_with_context(cx))
+    }
+
+    /// Poll the channel for the next message
+    pub fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        self.lock(|c| c.poll_receive(cx))
+    }
+
+    fn try_send_with_context(&self, m: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>> {
+        self.lock(|c| c.try_send_with_context(m, cx))
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to receive
+    pub fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.lock(|c| c.poll_ready_to_receive(cx))
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to send
+    pub fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.lock(|c| c.poll_ready_to_send(cx))
+    }
+
+    /// Get a sender for this channel.
+    pub fn sender(&self) -> Sender<'_, M, T, N> {
+        Sender { channel: self }
+    }
+
+    /// Get a receiver for this channel.
+    pub fn receiver(&self) -> Receiver<'_, M, T, N> {
+        Receiver { channel: self }
+    }
+
+    /// Send a value, waiting until there is capacity.
+    ///
+    /// Sending completes when the value has been pushed to the channel's queue.
+    /// This doesn't mean the value has been received yet.
+    pub fn send(&self, message: T) -> SendFuture<'_, M, T, N> {
+        SendFuture {
+            channel: self,
+            message: Some(message),
+        }
+    }
+
+    /// Attempt to immediately send a message.
+    ///
+    /// This method differs from [`send`](Channel::send) by returning immediately if the channel's
+    /// buffer is full, instead of waiting.
+    ///
+    /// # Errors
+    ///
+    /// If the channel capacity has been reached, i.e., the channel has `n`
+    /// buffered values where `n` is the argument passed to [`Channel`], then an
+    /// error is returned.
+    pub fn try_send(&self, message: T) -> Result<(), TrySendError<T>> {
+        self.lock(|c| c.try_send(message))
+    }
+
+    /// Receive the next value.
+    ///
+    /// If there are no messages in the channel's buffer, this method will
+    /// wait until a message is sent.
+    pub fn receive(&self) -> ReceiveFuture<'_, M, T, N> {
+        ReceiveFuture { channel: self }
+    }
+
+    /// Attempt to immediately receive a message.
+    ///
+    /// This method will either receive a message from the channel immediately or return an error
+    /// if the channel is empty.
+    pub fn try_receive(&self) -> Result<T, TryReceiveError> {
+        self.lock(|c| c.try_receive())
+    }
+}
+
+/// Implements the DynamicChannel to allow creating types that are unaware of the queue size with the
+/// tradeoff cost of dynamic dispatch.
+impl<M, T, const N: usize> DynamicChannel<T> for Channel<M, T, N>
+where
+    M: RawMutex,
+{
+    fn try_send_with_context(&self, m: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>> {
+        Channel::try_send_with_context(self, m, cx)
+    }
+
+    fn try_receive_with_context(&self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError> {
+        Channel::try_receive_with_context(self, cx)
+    }
+
+    fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        Channel::poll_ready_to_send(self, cx)
+    }
+
+    fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        Channel::poll_ready_to_receive(self, cx)
+    }
+
+    fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        Channel::poll_receive(self, cx)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use core::time::Duration;
+
+    use futures_executor::ThreadPool;
+    use futures_timer::Delay;
+    use futures_util::task::SpawnExt;
+    use static_cell::StaticCell;
+
+    use super::*;
+    use crate::blocking_mutex::raw::{CriticalSectionRawMutex, NoopRawMutex};
+
+    fn capacity<T, const N: usize>(c: &ChannelState<T, N>) -> usize {
+        c.queue.capacity() - c.queue.len()
+    }
+
+    #[test]
+    fn sending_once() {
+        let mut c = ChannelState::<u32, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert_eq!(capacity(&c), 2);
+    }
+
+    #[test]
+    fn sending_when_full() {
+        let mut c = ChannelState::<u32, 3>::new();
+        let _ = c.try_send(1);
+        let _ = c.try_send(1);
+        let _ = c.try_send(1);
+        match c.try_send(2) {
+            Err(TrySendError::Full(2)) => assert!(true),
+            _ => assert!(false),
+        }
+        assert_eq!(capacity(&c), 0);
+    }
+
+    #[test]
+    fn receiving_once_with_one_send() {
+        let mut c = ChannelState::<u32, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert_eq!(c.try_receive().unwrap(), 1);
+        assert_eq!(capacity(&c), 3);
+    }
+
+    #[test]
+    fn receiving_when_empty() {
+        let mut c = ChannelState::<u32, 3>::new();
+        match c.try_receive() {
+            Err(TryReceiveError::Empty) => assert!(true),
+            _ => assert!(false),
+        }
+        assert_eq!(capacity(&c), 3);
+    }
+
+    #[test]
+    fn simple_send_and_receive() {
+        let c = Channel::<NoopRawMutex, u32, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert_eq!(c.try_receive().unwrap(), 1);
+    }
+
+    #[test]
+    fn cloning() {
+        let c = Channel::<NoopRawMutex, u32, 3>::new();
+        let r1 = c.receiver();
+        let s1 = c.sender();
+
+        let _ = r1.clone();
+        let _ = s1.clone();
+    }
+
+    #[test]
+    fn dynamic_dispatch() {
+        let c = Channel::<NoopRawMutex, u32, 3>::new();
+        let s: DynamicSender<'_, u32> = c.sender().into();
+        let r: DynamicReceiver<'_, u32> = c.receiver().into();
+
+        assert!(s.try_send(1).is_ok());
+        assert_eq!(r.try_receive().unwrap(), 1);
+    }
+
+    #[futures_test::test]
+    async fn receiver_receives_given_try_send_async() {
+        let executor = ThreadPool::new().unwrap();
+
+        static CHANNEL: StaticCell<Channel<CriticalSectionRawMutex, u32, 3>> = StaticCell::new();
+        let c = &*CHANNEL.init(Channel::new());
+        let c2 = c;
+        assert!(executor
+            .spawn(async move {
+                assert!(c2.try_send(1).is_ok());
+            })
+            .is_ok());
+        assert_eq!(c.receive().await, 1);
+    }
+
+    #[futures_test::test]
+    async fn sender_send_completes_if_capacity() {
+        let c = Channel::<CriticalSectionRawMutex, u32, 1>::new();
+        c.send(1).await;
+        assert_eq!(c.receive().await, 1);
+    }
+
+    #[futures_test::test]
+    async fn senders_sends_wait_until_capacity() {
+        let executor = ThreadPool::new().unwrap();
+
+        static CHANNEL: StaticCell<Channel<CriticalSectionRawMutex, u32, 1>> = StaticCell::new();
+        let c = &*CHANNEL.init(Channel::new());
+        assert!(c.try_send(1).is_ok());
+
+        let c2 = c;
+        let send_task_1 = executor.spawn_with_handle(async move { c2.send(2).await });
+        let c2 = c;
+        let send_task_2 = executor.spawn_with_handle(async move { c2.send(3).await });
+        // Wish I could think of a means of determining that the async send is waiting instead.
+        // However, I've used the debugger to observe that the send does indeed wait.
+        Delay::new(Duration::from_millis(500)).await;
+        assert_eq!(c.receive().await, 1);
+        assert!(executor
+            .spawn(async move {
+                loop {
+                    c.receive().await;
+                }
+            })
+            .is_ok());
+        send_task_1.unwrap().await;
+        send_task_2.unwrap().await;
+    }
+}

vendor/embassy-sync-0.5.0/src/fmt.rs

@@ -0,0 +1,258 @@
+#![macro_use]
+#![allow(unused_macros)]
+
+use core::fmt::{Debug, Display, LowerHex};
+
+#[cfg(all(feature = "defmt", feature = "log"))]
+compile_error!("You may not enable both `defmt` and `log` features.");
+
+macro_rules! assert {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert!($($x)*);
+        }
+    };
+}
+
+macro_rules! assert_eq {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert_eq!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert_eq!($($x)*);
+        }
+    };
+}
+
+macro_rules! assert_ne {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert_ne!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert_ne!($($x)*);
+        }
+    };
+}
+
+macro_rules! debug_assert {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert!($($x)*);
+        }
+    };
+}
+
+macro_rules! debug_assert_eq {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert_eq!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert_eq!($($x)*);
+        }
+    };
+}
+
+macro_rules! debug_assert_ne {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert_ne!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert_ne!($($x)*);
+        }
+    };
+}
+
+macro_rules! todo {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::todo!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::todo!($($x)*);
+        }
+    };
+}
+
+#[cfg(not(feature = "defmt"))]
+macro_rules! unreachable {
+    ($($x:tt)*) => {
+        ::core::unreachable!($($x)*)
+    };
+}
+
+#[cfg(feature = "defmt")]
+macro_rules! unreachable {
+    ($($x:tt)*) => {
+        ::defmt::unreachable!($($x)*)
+    };
+}
+
+macro_rules! panic {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::panic!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::panic!($($x)*);
+        }
+    };
+}
+
+macro_rules! trace {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::trace!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::trace!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! debug {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::debug!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! info {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::info!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::info!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! warn {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::warn!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::warn!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! error {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::error!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::error!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+#[cfg(feature = "defmt")]
+macro_rules! unwrap {
+    ($($x:tt)*) => {
+        ::defmt::unwrap!($($x)*)
+    };
+}
+
+#[cfg(not(feature = "defmt"))]
+macro_rules! unwrap {
+    ($arg:expr) => {
+        match $crate::fmt::Try::into_result($arg) {
+            ::core::result::Result::Ok(t) => t,
+            ::core::result::Result::Err(e) => {
+                ::core::panic!("unwrap of `{}` failed: {:?}", ::core::stringify!($arg), e);
+            }
+        }
+    };
+    ($arg:expr, $($msg:expr),+ $(,)? ) => {
+        match $crate::fmt::Try::into_result($arg) {
+            ::core::result::Result::Ok(t) => t,
+            ::core::result::Result::Err(e) => {
+                ::core::panic!("unwrap of `{}` failed: {}: {:?}", ::core::stringify!($arg), ::core::format_args!($($msg,)*), e);
+            }
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub struct NoneError;
+
+pub trait Try {
+    type Ok;
+    type Error;
+    fn into_result(self) -> Result<Self::Ok, Self::Error>;
+}
+
+impl<T> Try for Option<T> {
+    type Ok = T;
+    type Error = NoneError;
+
+    #[inline]
+    fn into_result(self) -> Result<T, NoneError> {
+        self.ok_or(NoneError)
+    }
+}
+
+impl<T, E> Try for Result<T, E> {
+    type Ok = T;
+    type Error = E;
+
+    #[inline]
+    fn into_result(self) -> Self {
+        self
+    }
+}
+
+#[allow(unused)]
+pub(crate) struct Bytes<'a>(pub &'a [u8]);
+
+impl<'a> Debug for Bytes<'a> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:#02x?}", self.0)
+    }
+}
+
+impl<'a> Display for Bytes<'a> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:#02x?}", self.0)
+    }
+}
+
+impl<'a> LowerHex for Bytes<'a> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:#02x?}", self.0)
+    }
+}
+
+#[cfg(feature = "defmt")]
+impl<'a> defmt::Format for Bytes<'a> {
+    fn format(&self, fmt: defmt::Formatter) {
+        defmt::write!(fmt, "{:02x}", self.0)
+    }
+}

vendor/embassy-sync-0.5.0/src/lib.rs

@@ -0,0 +1,23 @@
+#![cfg_attr(not(any(feature = "std", feature = "wasm")), no_std)]
+#![cfg_attr(nightly, feature(async_fn_in_trait, impl_trait_projections))]
+#![cfg_attr(nightly, allow(stable_features, unknown_lints))]
+#![allow(async_fn_in_trait)]
+#![allow(clippy::new_without_default)]
+#![doc = include_str!("../README.md")]
+#![warn(missing_docs)]
+
+// This mod MUST go first, so that the others see its macros.
+pub(crate) mod fmt;
+
+// internal use
+mod ring_buffer;
+
+pub mod blocking_mutex;
+pub mod channel;
+pub mod mutex;
+pub mod pipe;
+pub mod priority_channel;
+pub mod pubsub;
+pub mod signal;
+pub mod waitqueue;
+pub mod zerocopy_channel;

vendor/embassy-sync-0.5.0/src/mutex.rs

@@ -0,0 +1,182 @@
+//! Async mutex.
+//!
+//! This module provides a mutex that can be used to synchronize data between asynchronous tasks.
+use core::cell::{RefCell, UnsafeCell};
+use core::future::poll_fn;
+use core::ops::{Deref, DerefMut};
+use core::task::Poll;
+
+use crate::blocking_mutex::raw::RawMutex;
+use crate::blocking_mutex::Mutex as BlockingMutex;
+use crate::waitqueue::WakerRegistration;
+
+/// Error returned by [`Mutex::try_lock`]
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct TryLockError;
+
+struct State {
+    locked: bool,
+    waker: WakerRegistration,
+}
+
+/// Async mutex.
+///
+/// The mutex is generic over a blocking [`RawMutex`](crate::blocking_mutex::raw::RawMutex).
+/// The raw mutex is used to guard access to the internal "is locked" flag. It
+/// is held for very short periods only, while locking and unlocking. It is *not* held
+/// for the entire time the async Mutex is locked.
+///
+/// Which implementation you select depends on the context in which you're using the mutex.
+///
+/// Use [`CriticalSectionRawMutex`](crate::blocking_mutex::raw::CriticalSectionRawMutex) when data can be shared between threads and interrupts.
+///
+/// Use [`NoopRawMutex`](crate::blocking_mutex::raw::NoopRawMutex) when data is only shared between tasks running on the same executor.
+///
+/// Use [`ThreadModeRawMutex`](crate::blocking_mutex::raw::ThreadModeRawMutex) when data is shared between tasks running on the same executor but you want a singleton.
+///
+pub struct Mutex<M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    state: BlockingMutex<M, RefCell<State>>,
+    inner: UnsafeCell<T>,
+}
+
+unsafe impl<M: RawMutex + Send, T: ?Sized + Send> Send for Mutex<M, T> {}
+unsafe impl<M: RawMutex + Sync, T: ?Sized + Send> Sync for Mutex<M, T> {}
+
+/// Async mutex.
+impl<M, T> Mutex<M, T>
+where
+    M: RawMutex,
+{
+    /// Create a new mutex with the given value.
+    pub const fn new(value: T) -> Self {
+        Self {
+            inner: UnsafeCell::new(value),
+            state: BlockingMutex::new(RefCell::new(State {
+                locked: false,
+                waker: WakerRegistration::new(),
+            })),
+        }
+    }
+}
+
+impl<M, T> Mutex<M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    /// Lock the mutex.
+    ///
+    /// This will wait for the mutex to be unlocked if it's already locked.
+    pub async fn lock(&self) -> MutexGuard<'_, M, T> {
+        poll_fn(|cx| {
+            let ready = self.state.lock(|s| {
+                let mut s = s.borrow_mut();
+                if s.locked {
+                    s.waker.register(cx.waker());
+                    false
+                } else {
+                    s.locked = true;
+                    true
+                }
+            });
+
+            if ready {
+                Poll::Ready(MutexGuard { mutex: self })
+            } else {
+                Poll::Pending
+            }
+        })
+        .await
+    }
+
+    /// Attempt to immediately lock the mutex.
+    ///
+    /// If the mutex is already locked, this will return an error instead of waiting.
+    pub fn try_lock(&self) -> Result<MutexGuard<'_, M, T>, TryLockError> {
+        self.state.lock(|s| {
+            let mut s = s.borrow_mut();
+            if s.locked {
+                Err(TryLockError)
+            } else {
+                s.locked = true;
+                Ok(())
+            }
+        })?;
+
+        Ok(MutexGuard { mutex: self })
+    }
+
+    /// Consumes this mutex, returning the underlying data.
+    pub fn into_inner(self) -> T
+    where
+        T: Sized,
+    {
+        self.inner.into_inner()
+    }
+
+    /// Returns a mutable reference to the underlying data.
+    ///
+    /// Since this call borrows the Mutex mutably, no actual locking needs to
+    /// take place -- the mutable borrow statically guarantees no locks exist.
+    pub fn get_mut(&mut self) -> &mut T {
+        self.inner.get_mut()
+    }
+}
+
+/// Async mutex guard.
+///
+/// Owning an instance of this type indicates having
+/// successfully locked the mutex, and grants access to the contents.
+///
+/// Dropping it unlocks the mutex.
+pub struct MutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    mutex: &'a Mutex<M, T>,
+}
+
+impl<'a, M, T> Drop for MutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    fn drop(&mut self) {
+        self.mutex.state.lock(|s| {
+            let mut s = unwrap!(s.try_borrow_mut());
+            s.locked = false;
+            s.waker.wake();
+        })
+    }
+}
+
+impl<'a, M, T> Deref for MutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    type Target = T;
+    fn deref(&self) -> &Self::Target {
+        // Safety: the MutexGuard represents exclusive access to the contents
+        // of the mutex, so it's OK to get it.
+        unsafe { &*(self.mutex.inner.get() as *const T) }
+    }
+}
+
+impl<'a, M, T> DerefMut for MutexGuard<'a, M, T>
+where
+    M: RawMutex,
+    T: ?Sized,
+{
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        // Safety: the MutexGuard represents exclusive access to the contents
+        // of the mutex, so it's OK to get it.
+        unsafe { &mut *(self.mutex.inner.get()) }
+    }
+}

vendor/embassy-sync-0.5.0/src/pipe.rs

@@ -0,0 +1,646 @@
+//! Async byte stream pipe.
+
+use core::cell::{RefCell, UnsafeCell};
+use core::convert::Infallible;
+use core::future::Future;
+use core::ops::Range;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+
+use crate::blocking_mutex::raw::RawMutex;
+use crate::blocking_mutex::Mutex;
+use crate::ring_buffer::RingBuffer;
+use crate::waitqueue::WakerRegistration;
+
+/// Write-only access to a [`Pipe`].
+pub struct Writer<'p, M, const N: usize>
+where
+    M: RawMutex,
+{
+    pipe: &'p Pipe<M, N>,
+}
+
+impl<'p, M, const N: usize> Clone for Writer<'p, M, N>
+where
+    M: RawMutex,
+{
+    fn clone(&self) -> Self {
+        Writer { pipe: self.pipe }
+    }
+}
+
+impl<'p, M, const N: usize> Copy for Writer<'p, M, N> where M: RawMutex {}
+
+impl<'p, M, const N: usize> Writer<'p, M, N>
+where
+    M: RawMutex,
+{
+    /// Write some bytes to the pipe.
+    ///
+    /// See [`Pipe::write()`]
+    pub fn write<'a>(&'a self, buf: &'a [u8]) -> WriteFuture<'a, M, N> {
+        self.pipe.write(buf)
+    }
+
+    /// Attempt to immediately write some bytes to the pipe.
+    ///
+    /// See [`Pipe::try_write()`]
+    pub fn try_write(&self, buf: &[u8]) -> Result<usize, TryWriteError> {
+        self.pipe.try_write(buf)
+    }
+}
+
+/// Future returned by [`Pipe::write`] and  [`Writer::write`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct WriteFuture<'p, M, const N: usize>
+where
+    M: RawMutex,
+{
+    pipe: &'p Pipe<M, N>,
+    buf: &'p [u8],
+}
+
+impl<'p, M, const N: usize> Future for WriteFuture<'p, M, N>
+where
+    M: RawMutex,
+{
+    type Output = usize;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.pipe.try_write_with_context(Some(cx), self.buf) {
+            Ok(n) => Poll::Ready(n),
+            Err(TryWriteError::Full) => Poll::Pending,
+        }
+    }
+}
+
+impl<'p, M, const N: usize> Unpin for WriteFuture<'p, M, N> where M: RawMutex {}
+
+/// Read-only access to a [`Pipe`].
+pub struct Reader<'p, M, const N: usize>
+where
+    M: RawMutex,
+{
+    pipe: &'p Pipe<M, N>,
+}
+
+impl<'p, M, const N: usize> Reader<'p, M, N>
+where
+    M: RawMutex,
+{
+    /// Read some bytes from the pipe.
+    ///
+    /// See [`Pipe::read()`]
+    pub fn read<'a>(&'a self, buf: &'a mut [u8]) -> ReadFuture<'a, M, N> {
+        self.pipe.read(buf)
+    }
+
+    /// Attempt to immediately read some bytes from the pipe.
+    ///
+    /// See [`Pipe::try_read()`]
+    pub fn try_read(&self, buf: &mut [u8]) -> Result<usize, TryReadError> {
+        self.pipe.try_read(buf)
+    }
+
+    /// Return the contents of the internal buffer, filling it with more data from the inner reader if it is empty.
+    ///
+    /// If no bytes are currently available to read, this function waits until at least one byte is available.
+    ///
+    /// If the reader is at end-of-file (EOF), an empty slice is returned.
+    pub fn fill_buf(&mut self) -> FillBufFuture<'_, M, N> {
+        FillBufFuture { pipe: Some(self.pipe) }
+    }
+
+    /// Try returning contents of the internal buffer.
+    ///
+    /// If no bytes are currently available to read, this function returns `Err(TryReadError::Empty)`.
+    ///
+    /// If the reader is at end-of-file (EOF), an empty slice is returned.
+    pub fn try_fill_buf(&mut self) -> Result<&[u8], TryReadError> {
+        unsafe { self.pipe.try_fill_buf_with_context(None) }
+    }
+
+    /// Tell this buffer that `amt` bytes have been consumed from the buffer, so they should no longer be returned in calls to `fill_buf`.
+    pub fn consume(&mut self, amt: usize) {
+        self.pipe.consume(amt)
+    }
+}
+
+/// Future returned by [`Pipe::read`] and  [`Reader::read`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct ReadFuture<'p, M, const N: usize>
+where
+    M: RawMutex,
+{
+    pipe: &'p Pipe<M, N>,
+    buf: &'p mut [u8],
+}
+
+impl<'p, M, const N: usize> Future for ReadFuture<'p, M, N>
+where
+    M: RawMutex,
+{
+    type Output = usize;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.pipe.try_read_with_context(Some(cx), self.buf) {
+            Ok(n) => Poll::Ready(n),
+            Err(TryReadError::Empty) => Poll::Pending,
+        }
+    }
+}
+
+impl<'p, M, const N: usize> Unpin for ReadFuture<'p, M, N> where M: RawMutex {}
+
+/// Future returned by [`Pipe::fill_buf`] and  [`Reader::fill_buf`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct FillBufFuture<'p, M, const N: usize>
+where
+    M: RawMutex,
+{
+    pipe: Option<&'p Pipe<M, N>>,
+}
+
+impl<'p, M, const N: usize> Future for FillBufFuture<'p, M, N>
+where
+    M: RawMutex,
+{
+    type Output = &'p [u8];
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let pipe = self.pipe.take().unwrap();
+        match unsafe { pipe.try_fill_buf_with_context(Some(cx)) } {
+            Ok(buf) => Poll::Ready(buf),
+            Err(TryReadError::Empty) => {
+                self.pipe = Some(pipe);
+                Poll::Pending
+            }
+        }
+    }
+}
+
+impl<'p, M, const N: usize> Unpin for FillBufFuture<'p, M, N> where M: RawMutex {}
+
+/// Error returned by [`try_read`](Pipe::try_read).
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum TryReadError {
+    /// No data could be read from the pipe because it is currently
+    /// empty, and reading would require blocking.
+    Empty,
+}
+
+/// Error returned by [`try_write`](Pipe::try_write).
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum TryWriteError {
+    /// No data could be written to the pipe because it is
+    /// currently full, and writing would require blocking.
+    Full,
+}
+
+struct PipeState<const N: usize> {
+    buffer: RingBuffer<N>,
+    read_waker: WakerRegistration,
+    write_waker: WakerRegistration,
+}
+
+#[repr(transparent)]
+struct Buffer<const N: usize>(UnsafeCell<[u8; N]>);
+
+impl<const N: usize> Buffer<N> {
+    unsafe fn get<'a>(&self, r: Range<usize>) -> &'a [u8] {
+        let p = self.0.get() as *const u8;
+        core::slice::from_raw_parts(p.add(r.start), r.end - r.start)
+    }
+
+    unsafe fn get_mut<'a>(&self, r: Range<usize>) -> &'a mut [u8] {
+        let p = self.0.get() as *mut u8;
+        core::slice::from_raw_parts_mut(p.add(r.start), r.end - r.start)
+    }
+}
+
+unsafe impl<const N: usize> Send for Buffer<N> {}
+unsafe impl<const N: usize> Sync for Buffer<N> {}
+
+/// A bounded byte-oriented pipe for communicating between asynchronous tasks
+/// with backpressure.
+///
+/// The pipe will buffer up to the provided number of bytes. Once the
+/// buffer is full, attempts to `write` new bytes will wait until buffer space is freed up.
+///
+/// All data written will become available in the same order as it was written.
+pub struct Pipe<M, const N: usize>
+where
+    M: RawMutex,
+{
+    buf: Buffer<N>,
+    inner: Mutex<M, RefCell<PipeState<N>>>,
+}
+
+impl<M, const N: usize> Pipe<M, N>
+where
+    M: RawMutex,
+{
+    /// Establish a new bounded pipe. For example, to create one with a NoopMutex:
+    ///
+    /// ```
+    /// use embassy_sync::pipe::Pipe;
+    /// use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+    ///
+    /// // Declare a bounded pipe, with a buffer of 256 bytes.
+    /// let mut pipe = Pipe::<NoopRawMutex, 256>::new();
+    /// ```
+    pub const fn new() -> Self {
+        Self {
+            buf: Buffer(UnsafeCell::new([0; N])),
+            inner: Mutex::new(RefCell::new(PipeState {
+                buffer: RingBuffer::new(),
+                read_waker: WakerRegistration::new(),
+                write_waker: WakerRegistration::new(),
+            })),
+        }
+    }
+
+    fn lock<R>(&self, f: impl FnOnce(&mut PipeState<N>) -> R) -> R {
+        self.inner.lock(|rc| f(&mut *rc.borrow_mut()))
+    }
+
+    fn try_read_with_context(&self, cx: Option<&mut Context<'_>>, buf: &mut [u8]) -> Result<usize, TryReadError> {
+        self.inner.lock(|rc: &RefCell<PipeState<N>>| {
+            let s = &mut *rc.borrow_mut();
+
+            if s.buffer.is_full() {
+                s.write_waker.wake();
+            }
+
+            let available = unsafe { self.buf.get(s.buffer.pop_buf()) };
+            if available.is_empty() {
+                if let Some(cx) = cx {
+                    s.read_waker.register(cx.waker());
+                }
+                return Err(TryReadError::Empty);
+            }
+
+            let n = available.len().min(buf.len());
+            buf[..n].copy_from_slice(&available[..n]);
+            s.buffer.pop(n);
+            Ok(n)
+        })
+    }
+
+    // safety: While the returned slice is alive,
+    // no `read` or `consume` methods in the pipe must be called.
+    unsafe fn try_fill_buf_with_context(&self, cx: Option<&mut Context<'_>>) -> Result<&[u8], TryReadError> {
+        self.inner.lock(|rc: &RefCell<PipeState<N>>| {
+            let s = &mut *rc.borrow_mut();
+
+            if s.buffer.is_full() {
+                s.write_waker.wake();
+            }
+
+            let available = unsafe { self.buf.get(s.buffer.pop_buf()) };
+            if available.is_empty() {
+                if let Some(cx) = cx {
+                    s.read_waker.register(cx.waker());
+                }
+                return Err(TryReadError::Empty);
+            }
+
+            Ok(available)
+        })
+    }
+
+    fn consume(&self, amt: usize) {
+        self.inner.lock(|rc: &RefCell<PipeState<N>>| {
+            let s = &mut *rc.borrow_mut();
+            let available = s.buffer.pop_buf();
+            assert!(amt <= available.len());
+            s.buffer.pop(amt);
+        })
+    }
+
+    fn try_write_with_context(&self, cx: Option<&mut Context<'_>>, buf: &[u8]) -> Result<usize, TryWriteError> {
+        self.inner.lock(|rc: &RefCell<PipeState<N>>| {
+            let s = &mut *rc.borrow_mut();
+
+            if s.buffer.is_empty() {
+                s.read_waker.wake();
+            }
+
+            let available = unsafe { self.buf.get_mut(s.buffer.push_buf()) };
+            if available.is_empty() {
+                if let Some(cx) = cx {
+                    s.write_waker.register(cx.waker());
+                }
+                return Err(TryWriteError::Full);
+            }
+
+            let n = available.len().min(buf.len());
+            available[..n].copy_from_slice(&buf[..n]);
+            s.buffer.push(n);
+            Ok(n)
+        })
+    }
+
+    /// Split this pipe into a BufRead-capable reader and a writer.
+    ///
+    /// The reader and writer borrow the current pipe mutably, so it is not
+    /// possible to use it directly while they exist. This is needed because
+    /// implementing `BufRead` requires there is a single reader.
+    ///
+    /// The writer is cloneable, the reader is not.
+    pub fn split(&mut self) -> (Reader<'_, M, N>, Writer<'_, M, N>) {
+        (Reader { pipe: self }, Writer { pipe: self })
+    }
+
+    /// Write some bytes to the pipe.
+    ///
+    /// This method writes a nonzero amount of bytes from `buf` into the pipe, and
+    /// returns the amount of bytes written.
+    ///
+    /// If it is not possible to write a nonzero amount of bytes because the pipe's buffer is full,
+    /// this method will wait until it isn't. See [`try_write`](Self::try_write) for a variant that
+    /// returns an error instead of waiting.
+    ///
+    /// It is not guaranteed that all bytes in the buffer are written, even if there's enough
+    /// free space in the pipe buffer for all. In other words, it is possible for `write` to return
+    /// without writing all of `buf` (returning a number less than `buf.len()`) and still leave
+    /// free space in the pipe buffer. You should always `write` in a loop, or use helpers like
+    /// `write_all` from the `embedded-io` crate.
+    pub fn write<'a>(&'a self, buf: &'a [u8]) -> WriteFuture<'a, M, N> {
+        WriteFuture { pipe: self, buf }
+    }
+
+    /// Write all bytes to the pipe.
+    ///
+    /// This method writes all bytes from `buf` into the pipe
+    pub async fn write_all(&self, mut buf: &[u8]) {
+        while !buf.is_empty() {
+            let n = self.write(buf).await;
+            buf = &buf[n..];
+        }
+    }
+
+    /// Attempt to immediately write some bytes to the pipe.
+    ///
+    /// This method will either write a nonzero amount of bytes to the pipe immediately,
+    /// or return an error if the pipe is empty. See [`write`](Self::write) for a variant
+    /// that waits instead of returning an error.
+    pub fn try_write(&self, buf: &[u8]) -> Result<usize, TryWriteError> {
+        self.try_write_with_context(None, buf)
+    }
+
+    /// Read some bytes from the pipe.
+    ///
+    /// This method reads a nonzero amount of bytes from the pipe into `buf` and
+    /// returns the amount of bytes read.
+    ///
+    /// If it is not possible to read a nonzero amount of bytes because the pipe's buffer is empty,
+    /// this method will wait until it isn't. See [`try_read`](Self::try_read) for a variant that
+    /// returns an error instead of waiting.
+    ///
+    /// It is not guaranteed that all bytes in the buffer are read, even if there's enough
+    /// space in `buf` for all. In other words, it is possible for `read` to return
+    /// without filling `buf` (returning a number less than `buf.len()`) and still leave bytes
+    /// in the pipe buffer. You should always `read` in a loop, or use helpers like
+    /// `read_exact` from the `embedded-io` crate.
+    pub fn read<'a>(&'a self, buf: &'a mut [u8]) -> ReadFuture<'a, M, N> {
+        ReadFuture { pipe: self, buf }
+    }
+
+    /// Attempt to immediately read some bytes from the pipe.
+    ///
+    /// This method will either read a nonzero amount of bytes from the pipe immediately,
+    /// or return an error if the pipe is empty. See [`read`](Self::read) for a variant
+    /// that waits instead of returning an error.
+    pub fn try_read(&self, buf: &mut [u8]) -> Result<usize, TryReadError> {
+        self.try_read_with_context(None, buf)
+    }
+
+    /// Clear the data in the pipe's buffer.
+    pub fn clear(&self) {
+        self.inner.lock(|rc: &RefCell<PipeState<N>>| {
+            let s = &mut *rc.borrow_mut();
+
+            s.buffer.clear();
+            s.write_waker.wake();
+        })
+    }
+
+    /// Return whether the pipe is full (no free space in the buffer)
+    pub fn is_full(&self) -> bool {
+        self.len() == N
+    }
+
+    /// Return whether the pipe is empty (no data buffered)
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// Total byte capacity.
+    ///
+    /// This is the same as the `N` generic param.
+    pub fn capacity(&self) -> usize {
+        N
+    }
+
+    /// Used byte capacity.
+    pub fn len(&self) -> usize {
+        self.lock(|c| c.buffer.len())
+    }
+
+    /// Free byte capacity.
+    ///
+    /// This is equivalent to `capacity() - len()`
+    pub fn free_capacity(&self) -> usize {
+        N - self.len()
+    }
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::ErrorType for Pipe<M, N> {
+    type Error = Infallible;
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::Read for Pipe<M, N> {
+    async fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        Ok(Pipe::read(self, buf).await)
+    }
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::Write for Pipe<M, N> {
+    async fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        Ok(Pipe::write(self, buf).await)
+    }
+
+    async fn flush(&mut self) -> Result<(), Self::Error> {
+        Ok(())
+    }
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::ErrorType for &Pipe<M, N> {
+    type Error = Infallible;
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::Read for &Pipe<M, N> {
+    async fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        Ok(Pipe::read(self, buf).await)
+    }
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::Write for &Pipe<M, N> {
+    async fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        Ok(Pipe::write(self, buf).await)
+    }
+
+    async fn flush(&mut self) -> Result<(), Self::Error> {
+        Ok(())
+    }
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::ErrorType for Reader<'_, M, N> {
+    type Error = Infallible;
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::Read for Reader<'_, M, N> {
+    async fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        Ok(Reader::read(self, buf).await)
+    }
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::BufRead for Reader<'_, M, N> {
+    async fn fill_buf(&mut self) -> Result<&[u8], Self::Error> {
+        Ok(Reader::fill_buf(self).await)
+    }
+
+    fn consume(&mut self, amt: usize) {
+        Reader::consume(self, amt)
+    }
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::ErrorType for Writer<'_, M, N> {
+    type Error = Infallible;
+}
+
+impl<M: RawMutex, const N: usize> embedded_io_async::Write for Writer<'_, M, N> {
+    async fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        Ok(Writer::write(self, buf).await)
+    }
+
+    async fn flush(&mut self) -> Result<(), Self::Error> {
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use futures_executor::ThreadPool;
+    use futures_util::task::SpawnExt;
+    use static_cell::StaticCell;
+
+    use super::*;
+    use crate::blocking_mutex::raw::{CriticalSectionRawMutex, NoopRawMutex};
+
+    #[test]
+    fn writing_once() {
+        let c = Pipe::<NoopRawMutex, 3>::new();
+        assert!(c.try_write(&[1]).is_ok());
+        assert_eq!(c.free_capacity(), 2);
+    }
+
+    #[test]
+    fn writing_when_full() {
+        let c = Pipe::<NoopRawMutex, 3>::new();
+        assert_eq!(c.try_write(&[42]), Ok(1));
+        assert_eq!(c.try_write(&[43]), Ok(1));
+        assert_eq!(c.try_write(&[44]), Ok(1));
+        assert_eq!(c.try_write(&[45]), Err(TryWriteError::Full));
+        assert_eq!(c.free_capacity(), 0);
+    }
+
+    #[test]
+    fn receiving_once_with_one_send() {
+        let c = Pipe::<NoopRawMutex, 3>::new();
+        assert!(c.try_write(&[42]).is_ok());
+        let mut buf = [0; 16];
+        assert_eq!(c.try_read(&mut buf), Ok(1));
+        assert_eq!(buf[0], 42);
+        assert_eq!(c.free_capacity(), 3);
+    }
+
+    #[test]
+    fn receiving_when_empty() {
+        let c = Pipe::<NoopRawMutex, 3>::new();
+        let mut buf = [0; 16];
+        assert_eq!(c.try_read(&mut buf), Err(TryReadError::Empty));
+        assert_eq!(c.free_capacity(), 3);
+    }
+
+    #[test]
+    fn simple_send_and_receive() {
+        let c = Pipe::<NoopRawMutex, 3>::new();
+        assert!(c.try_write(&[42]).is_ok());
+        let mut buf = [0; 16];
+        assert_eq!(c.try_read(&mut buf), Ok(1));
+        assert_eq!(buf[0], 42);
+    }
+
+    #[test]
+    fn read_buf() {
+        let mut c = Pipe::<NoopRawMutex, 3>::new();
+        let (mut r, w) = c.split();
+        assert!(w.try_write(&[42, 43]).is_ok());
+        let buf = r.try_fill_buf().unwrap();
+        assert_eq!(buf, &[42, 43]);
+        let buf = r.try_fill_buf().unwrap();
+        assert_eq!(buf, &[42, 43]);
+        r.consume(1);
+        let buf = r.try_fill_buf().unwrap();
+        assert_eq!(buf, &[43]);
+        r.consume(1);
+        assert_eq!(r.try_fill_buf(), Err(TryReadError::Empty));
+        assert_eq!(w.try_write(&[44, 45, 46]), Ok(1));
+        assert_eq!(w.try_write(&[45, 46]), Ok(2));
+        let buf = r.try_fill_buf().unwrap();
+        assert_eq!(buf, &[44]); // only one byte due to wraparound.
+        r.consume(1);
+        let buf = r.try_fill_buf().unwrap();
+        assert_eq!(buf, &[45, 46]);
+        assert!(w.try_write(&[47]).is_ok());
+        let buf = r.try_fill_buf().unwrap();
+        assert_eq!(buf, &[45, 46, 47]);
+        r.consume(3);
+    }
+
+    #[test]
+    fn writer_is_cloneable() {
+        let mut c = Pipe::<NoopRawMutex, 3>::new();
+        let (_r, w) = c.split();
+        let _ = w.clone();
+    }
+
+    #[futures_test::test]
+    async fn receiver_receives_given_try_write_async() {
+        let executor = ThreadPool::new().unwrap();
+
+        static CHANNEL: StaticCell<Pipe<CriticalSectionRawMutex, 3>> = StaticCell::new();
+        let c = &*CHANNEL.init(Pipe::new());
+        let c2 = c;
+        let f = async move {
+            assert_eq!(c2.try_write(&[42]), Ok(1));
+        };
+        executor.spawn(f).unwrap();
+        let mut buf = [0; 16];
+        assert_eq!(c.read(&mut buf).await, 1);
+        assert_eq!(buf[0], 42);
+    }
+
+    #[futures_test::test]
+    async fn sender_send_completes_if_capacity() {
+        let c = Pipe::<CriticalSectionRawMutex, 1>::new();
+        c.write(&[42]).await;
+        let mut buf = [0; 16];
+        assert_eq!(c.read(&mut buf).await, 1);
+        assert_eq!(buf[0], 42);
+    }
+}

vendor/embassy-sync-0.5.0/src/priority_channel.rs

@@ -0,0 +1,613 @@
+//! A queue for sending values between asynchronous tasks.
+//!
+//! Similar to a [`Channel`](crate::channel::Channel), however [`PriorityChannel`] sifts higher priority items to the front of the queue.
+//! Priority is determined by the `Ord` trait. Priority behavior is determined by the [`Kind`](heapless::binary_heap::Kind) parameter of the channel.
+
+use core::cell::RefCell;
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+
+pub use heapless::binary_heap::{Kind, Max, Min};
+use heapless::BinaryHeap;
+
+use crate::blocking_mutex::raw::RawMutex;
+use crate::blocking_mutex::Mutex;
+use crate::channel::{DynamicChannel, DynamicReceiver, DynamicSender, TryReceiveError, TrySendError};
+use crate::waitqueue::WakerRegistration;
+
+/// Send-only access to a [`PriorityChannel`].
+pub struct Sender<'ch, M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    channel: &'ch PriorityChannel<M, T, K, N>,
+}
+
+impl<'ch, M, T, K, const N: usize> Clone for Sender<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn clone(&self) -> Self {
+        Sender { channel: self.channel }
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> Copy for Sender<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+}
+
+impl<'ch, M, T, K, const N: usize> Sender<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    /// Sends a value.
+    ///
+    /// See [`PriorityChannel::send()`]
+    pub fn send(&self, message: T) -> SendFuture<'ch, M, T, K, N> {
+        self.channel.send(message)
+    }
+
+    /// Attempt to immediately send a message.
+    ///
+    /// See [`PriorityChannel::send()`]
+    pub fn try_send(&self, message: T) -> Result<(), TrySendError<T>> {
+        self.channel.try_send(message)
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to send
+    ///
+    /// See [`PriorityChannel::poll_ready_to_send()`]
+    pub fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.channel.poll_ready_to_send(cx)
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> From<Sender<'ch, M, T, K, N>> for DynamicSender<'ch, T>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn from(s: Sender<'ch, M, T, K, N>) -> Self {
+        Self { channel: s.channel }
+    }
+}
+
+/// Receive-only access to a [`PriorityChannel`].
+pub struct Receiver<'ch, M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    channel: &'ch PriorityChannel<M, T, K, N>,
+}
+
+impl<'ch, M, T, K, const N: usize> Clone for Receiver<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn clone(&self) -> Self {
+        Receiver { channel: self.channel }
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> Copy for Receiver<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+}
+
+impl<'ch, M, T, K, const N: usize> Receiver<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    /// Receive the next value.
+    ///
+    /// See [`PriorityChannel::receive()`].
+    pub fn receive(&self) -> ReceiveFuture<'_, M, T, K, N> {
+        self.channel.receive()
+    }
+
+    /// Attempt to immediately receive the next value.
+    ///
+    /// See [`PriorityChannel::try_receive()`]
+    pub fn try_receive(&self) -> Result<T, TryReceiveError> {
+        self.channel.try_receive()
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to receive
+    ///
+    /// See [`PriorityChannel::poll_ready_to_receive()`]
+    pub fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.channel.poll_ready_to_receive(cx)
+    }
+
+    /// Poll the channel for the next item
+    ///
+    /// See [`PriorityChannel::poll_receive()`]
+    pub fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        self.channel.poll_receive(cx)
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> From<Receiver<'ch, M, T, K, N>> for DynamicReceiver<'ch, T>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn from(s: Receiver<'ch, M, T, K, N>) -> Self {
+        Self { channel: s.channel }
+    }
+}
+
+/// Future returned by [`PriorityChannel::receive`] and  [`Receiver::receive`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct ReceiveFuture<'ch, M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    channel: &'ch PriorityChannel<M, T, K, N>,
+}
+
+impl<'ch, M, T, K, const N: usize> Future for ReceiveFuture<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    type Output = T;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
+        self.channel.poll_receive(cx)
+    }
+}
+
+/// Future returned by [`PriorityChannel::send`] and  [`Sender::send`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct SendFuture<'ch, M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    channel: &'ch PriorityChannel<M, T, K, N>,
+    message: Option<T>,
+}
+
+impl<'ch, M, T, K, const N: usize> Future for SendFuture<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.message.take() {
+            Some(m) => match self.channel.try_send_with_context(m, Some(cx)) {
+                Ok(..) => Poll::Ready(()),
+                Err(TrySendError::Full(m)) => {
+                    self.message = Some(m);
+                    Poll::Pending
+                }
+            },
+            None => panic!("Message cannot be None"),
+        }
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> Unpin for SendFuture<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+}
+
+struct ChannelState<T, K, const N: usize> {
+    queue: BinaryHeap<T, K, N>,
+    receiver_waker: WakerRegistration,
+    senders_waker: WakerRegistration,
+}
+
+impl<T, K, const N: usize> ChannelState<T, K, N>
+where
+    T: Ord,
+    K: Kind,
+{
+    const fn new() -> Self {
+        ChannelState {
+            queue: BinaryHeap::new(),
+            receiver_waker: WakerRegistration::new(),
+            senders_waker: WakerRegistration::new(),
+        }
+    }
+
+    fn try_receive(&mut self) -> Result<T, TryReceiveError> {
+        self.try_receive_with_context(None)
+    }
+
+    fn try_receive_with_context(&mut self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError> {
+        if self.queue.len() == self.queue.capacity() {
+            self.senders_waker.wake();
+        }
+
+        if let Some(message) = self.queue.pop() {
+            Ok(message)
+        } else {
+            if let Some(cx) = cx {
+                self.receiver_waker.register(cx.waker());
+            }
+            Err(TryReceiveError::Empty)
+        }
+    }
+
+    fn poll_receive(&mut self, cx: &mut Context<'_>) -> Poll<T> {
+        if self.queue.len() == self.queue.capacity() {
+            self.senders_waker.wake();
+        }
+
+        if let Some(message) = self.queue.pop() {
+            Poll::Ready(message)
+        } else {
+            self.receiver_waker.register(cx.waker());
+            Poll::Pending
+        }
+    }
+
+    fn poll_ready_to_receive(&mut self, cx: &mut Context<'_>) -> Poll<()> {
+        self.receiver_waker.register(cx.waker());
+
+        if !self.queue.is_empty() {
+            Poll::Ready(())
+        } else {
+            Poll::Pending
+        }
+    }
+
+    fn try_send(&mut self, message: T) -> Result<(), TrySendError<T>> {
+        self.try_send_with_context(message, None)
+    }
+
+    fn try_send_with_context(&mut self, message: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>> {
+        match self.queue.push(message) {
+            Ok(()) => {
+                self.receiver_waker.wake();
+                Ok(())
+            }
+            Err(message) => {
+                if let Some(cx) = cx {
+                    self.senders_waker.register(cx.waker());
+                }
+                Err(TrySendError::Full(message))
+            }
+        }
+    }
+
+    fn poll_ready_to_send(&mut self, cx: &mut Context<'_>) -> Poll<()> {
+        self.senders_waker.register(cx.waker());
+
+        if !self.queue.len() == self.queue.capacity() {
+            Poll::Ready(())
+        } else {
+            Poll::Pending
+        }
+    }
+}
+
+/// A bounded channel for communicating between asynchronous tasks
+/// with backpressure.
+///
+/// The channel will buffer up to the provided number of messages.  Once the
+/// buffer is full, attempts to `send` new messages will wait until a message is
+/// received from the channel.
+///
+/// Sent data may be reordered based on their priorty within the channel.
+/// For example, in a [`Max`](heapless::binary_heap::Max) [`PriorityChannel`]
+/// containing `u32`'s, data sent in the following order `[1, 2, 3]` will be recieved as `[3, 2, 1]`.
+pub struct PriorityChannel<M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    inner: Mutex<M, RefCell<ChannelState<T, K, N>>>,
+}
+
+impl<M, T, K, const N: usize> PriorityChannel<M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    /// Establish a new bounded channel. For example, to create one with a NoopMutex:
+    ///
+    /// ```
+    /// use embassy_sync::priority_channel::{PriorityChannel, Max};
+    /// use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+    ///
+    /// // Declare a bounded channel of 3 u32s.
+    /// let mut channel = PriorityChannel::<NoopRawMutex, u32, Max, 3>::new();
+    /// ```
+    pub const fn new() -> Self {
+        Self {
+            inner: Mutex::new(RefCell::new(ChannelState::new())),
+        }
+    }
+
+    fn lock<R>(&self, f: impl FnOnce(&mut ChannelState<T, K, N>) -> R) -> R {
+        self.inner.lock(|rc| f(&mut *unwrap!(rc.try_borrow_mut())))
+    }
+
+    fn try_receive_with_context(&self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError> {
+        self.lock(|c| c.try_receive_with_context(cx))
+    }
+
+    /// Poll the channel for the next message
+    pub fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        self.lock(|c| c.poll_receive(cx))
+    }
+
+    fn try_send_with_context(&self, m: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>> {
+        self.lock(|c| c.try_send_with_context(m, cx))
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to receive
+    pub fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.lock(|c| c.poll_ready_to_receive(cx))
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to send
+    pub fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.lock(|c| c.poll_ready_to_send(cx))
+    }
+
+    /// Get a sender for this channel.
+    pub fn sender(&self) -> Sender<'_, M, T, K, N> {
+        Sender { channel: self }
+    }
+
+    /// Get a receiver for this channel.
+    pub fn receiver(&self) -> Receiver<'_, M, T, K, N> {
+        Receiver { channel: self }
+    }
+
+    /// Send a value, waiting until there is capacity.
+    ///
+    /// Sending completes when the value has been pushed to the channel's queue.
+    /// This doesn't mean the value has been received yet.
+    pub fn send(&self, message: T) -> SendFuture<'_, M, T, K, N> {
+        SendFuture {
+            channel: self,
+            message: Some(message),
+        }
+    }
+
+    /// Attempt to immediately send a message.
+    ///
+    /// This method differs from [`send`](PriorityChannel::send) by returning immediately if the channel's
+    /// buffer is full, instead of waiting.
+    ///
+    /// # Errors
+    ///
+    /// If the channel capacity has been reached, i.e., the channel has `n`
+    /// buffered values where `n` is the argument passed to [`PriorityChannel`], then an
+    /// error is returned.
+    pub fn try_send(&self, message: T) -> Result<(), TrySendError<T>> {
+        self.lock(|c| c.try_send(message))
+    }
+
+    /// Receive the next value.
+    ///
+    /// If there are no messages in the channel's buffer, this method will
+    /// wait until a message is sent.
+    pub fn receive(&self) -> ReceiveFuture<'_, M, T, K, N> {
+        ReceiveFuture { channel: self }
+    }
+
+    /// Attempt to immediately receive a message.
+    ///
+    /// This method will either receive a message from the channel immediately or return an error
+    /// if the channel is empty.
+    pub fn try_receive(&self) -> Result<T, TryReceiveError> {
+        self.lock(|c| c.try_receive())
+    }
+}
+
+/// Implements the DynamicChannel to allow creating types that are unaware of the queue size with the
+/// tradeoff cost of dynamic dispatch.
+impl<M, T, K, const N: usize> DynamicChannel<T> for PriorityChannel<M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn try_send_with_context(&self, m: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>> {
+        PriorityChannel::try_send_with_context(self, m, cx)
+    }
+
+    fn try_receive_with_context(&self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError> {
+        PriorityChannel::try_receive_with_context(self, cx)
+    }
+
+    fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        PriorityChannel::poll_ready_to_send(self, cx)
+    }
+
+    fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        PriorityChannel::poll_ready_to_receive(self, cx)
+    }
+
+    fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        PriorityChannel::poll_receive(self, cx)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use core::time::Duration;
+
+    use futures_executor::ThreadPool;
+    use futures_timer::Delay;
+    use futures_util::task::SpawnExt;
+    use heapless::binary_heap::{Kind, Max};
+    use static_cell::StaticCell;
+
+    use super::*;
+    use crate::blocking_mutex::raw::{CriticalSectionRawMutex, NoopRawMutex};
+
+    fn capacity<T, K, const N: usize>(c: &ChannelState<T, K, N>) -> usize
+    where
+        T: Ord,
+        K: Kind,
+    {
+        c.queue.capacity() - c.queue.len()
+    }
+
+    #[test]
+    fn sending_once() {
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert_eq!(capacity(&c), 2);
+    }
+
+    #[test]
+    fn sending_when_full() {
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        let _ = c.try_send(1);
+        let _ = c.try_send(1);
+        let _ = c.try_send(1);
+        match c.try_send(2) {
+            Err(TrySendError::Full(2)) => assert!(true),
+            _ => assert!(false),
+        }
+        assert_eq!(capacity(&c), 0);
+    }
+
+    #[test]
+    fn send_priority() {
+        // Prio channel with kind `Max` sifts larger numbers to the front of the queue
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert!(c.try_send(2).is_ok());
+        assert!(c.try_send(3).is_ok());
+        assert_eq!(c.try_receive().unwrap(), 3);
+        assert_eq!(c.try_receive().unwrap(), 2);
+        assert_eq!(c.try_receive().unwrap(), 1);
+    }
+
+    #[test]
+    fn receiving_once_with_one_send() {
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert_eq!(c.try_receive().unwrap(), 1);
+        assert_eq!(capacity(&c), 3);
+    }
+
+    #[test]
+    fn receiving_when_empty() {
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        match c.try_receive() {
+            Err(TryReceiveError::Empty) => assert!(true),
+            _ => assert!(false),
+        }
+        assert_eq!(capacity(&c), 3);
+    }
+
+    #[test]
+    fn simple_send_and_receive() {
+        let c = PriorityChannel::<NoopRawMutex, u32, Max, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert_eq!(c.try_receive().unwrap(), 1);
+    }
+
+    #[test]
+    fn cloning() {
+        let c = PriorityChannel::<NoopRawMutex, u32, Max, 3>::new();
+        let r1 = c.receiver();
+        let s1 = c.sender();
+
+        let _ = r1.clone();
+        let _ = s1.clone();
+    }
+
+    #[test]
+    fn dynamic_dispatch() {
+        let c = PriorityChannel::<NoopRawMutex, u32, Max, 3>::new();
+        let s: DynamicSender<'_, u32> = c.sender().into();
+        let r: DynamicReceiver<'_, u32> = c.receiver().into();
+
+        assert!(s.try_send(1).is_ok());
+        assert_eq!(r.try_receive().unwrap(), 1);
+    }
+
+    #[futures_test::test]
+    async fn receiver_receives_given_try_send_async() {
+        let executor = ThreadPool::new().unwrap();
+
+        static CHANNEL: StaticCell<PriorityChannel<CriticalSectionRawMutex, u32, Max, 3>> = StaticCell::new();
+        let c = &*CHANNEL.init(PriorityChannel::new());
+        let c2 = c;
+        assert!(executor
+            .spawn(async move {
+                assert!(c2.try_send(1).is_ok());
+            })
+            .is_ok());
+        assert_eq!(c.receive().await, 1);
+    }
+
+    #[futures_test::test]
+    async fn sender_send_completes_if_capacity() {
+        let c = PriorityChannel::<CriticalSectionRawMutex, u32, Max, 1>::new();
+        c.send(1).await;
+        assert_eq!(c.receive().await, 1);
+    }
+
+    #[futures_test::test]
+    async fn senders_sends_wait_until_capacity() {
+        let executor = ThreadPool::new().unwrap();
+
+        static CHANNEL: StaticCell<PriorityChannel<CriticalSectionRawMutex, u32, Max, 1>> = StaticCell::new();
+        let c = &*CHANNEL.init(PriorityChannel::new());
+        assert!(c.try_send(1).is_ok());
+
+        let c2 = c;
+        let send_task_1 = executor.spawn_with_handle(async move { c2.send(2).await });
+        let c2 = c;
+        let send_task_2 = executor.spawn_with_handle(async move { c2.send(3).await });
+        // Wish I could think of a means of determining that the async send is waiting instead.
+        // However, I've used the debugger to observe that the send does indeed wait.
+        Delay::new(Duration::from_millis(500)).await;
+        assert_eq!(c.receive().await, 1);
+        assert!(executor
+            .spawn(async move {
+                loop {
+                    c.receive().await;
+                }
+            })
+            .is_ok());
+        send_task_1.unwrap().await;
+        send_task_2.unwrap().await;
+    }
+}

vendor/embassy-sync-0.5.0/src/pubsub/mod.rs

@@ -0,0 +1,658 @@
+//! Implementation of [PubSubChannel], a queue where published messages get received by all subscribers.
+
+#![deny(missing_docs)]
+
+use core::cell::RefCell;
+use core::fmt::Debug;
+use core::task::{Context, Poll};
+
+use heapless::Deque;
+
+use self::publisher::{ImmediatePub, Pub};
+use self::subscriber::Sub;
+use crate::blocking_mutex::raw::RawMutex;
+use crate::blocking_mutex::Mutex;
+use crate::waitqueue::MultiWakerRegistration;
+
+pub mod publisher;
+pub mod subscriber;
+
+pub use publisher::{DynImmediatePublisher, DynPublisher, ImmediatePublisher, Publisher};
+pub use subscriber::{DynSubscriber, Subscriber};
+
+/// A broadcast channel implementation where multiple publishers can send messages to multiple subscribers
+///
+/// Any published message can be read by all subscribers.
+/// A publisher can choose how it sends its message.
+///
+/// - With [Pub::publish()] the publisher has to wait until there is space in the internal message queue.
+/// - With [Pub::publish_immediate()] the publisher doesn't await and instead lets the oldest message
+/// in the queue drop if necessary. This will cause any [Subscriber] that missed the message to receive
+/// an error to indicate that it has lagged.
+///
+/// ## Example
+///
+/// ```
+/// # use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+/// # use embassy_sync::pubsub::WaitResult;
+/// # use embassy_sync::pubsub::PubSubChannel;
+/// # use futures_executor::block_on;
+/// # let test = async {
+/// // Create the channel. This can be static as well
+/// let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
+///
+/// // This is a generic subscriber with a direct reference to the channel
+/// let mut sub0 = channel.subscriber().unwrap();
+/// // This is a dynamic subscriber with a dynamic (trait object) reference to the channel
+/// let mut sub1 = channel.dyn_subscriber().unwrap();
+///
+/// let pub0 = channel.publisher().unwrap();
+///
+/// // Publish a message, but wait if the queue is full
+/// pub0.publish(42).await;
+///
+/// // Publish a message, but if the queue is full, just kick out the oldest message.
+/// // This may cause some subscribers to miss a message
+/// pub0.publish_immediate(43);
+///
+/// // Wait for a new message. If the subscriber missed a message, the WaitResult will be a Lag result
+/// assert_eq!(sub0.next_message().await, WaitResult::Message(42));
+/// assert_eq!(sub1.next_message().await, WaitResult::Message(42));
+///
+/// // Wait again, but this time ignore any Lag results
+/// assert_eq!(sub0.next_message_pure().await, 43);
+/// assert_eq!(sub1.next_message_pure().await, 43);
+///
+/// // There's also a polling interface
+/// assert_eq!(sub0.try_next_message(), None);
+/// assert_eq!(sub1.try_next_message(), None);
+/// # };
+/// #
+/// # block_on(test);
+/// ```
+///
+pub struct PubSubChannel<M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> {
+    inner: Mutex<M, RefCell<PubSubState<T, CAP, SUBS, PUBS>>>,
+}
+
+impl<M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize>
+    PubSubChannel<M, T, CAP, SUBS, PUBS>
+{
+    /// Create a new channel
+    pub const fn new() -> Self {
+        Self {
+            inner: Mutex::const_new(M::INIT, RefCell::new(PubSubState::new())),
+        }
+    }
+
+    /// Create a new subscriber. It will only receive messages that are published after its creation.
+    ///
+    /// If there are no subscriber slots left, an error will be returned.
+    pub fn subscriber(&self) -> Result<Subscriber<M, T, CAP, SUBS, PUBS>, Error> {
+        self.inner.lock(|inner| {
+            let mut s = inner.borrow_mut();
+
+            if s.subscriber_count >= SUBS {
+                Err(Error::MaximumSubscribersReached)
+            } else {
+                s.subscriber_count += 1;
+                Ok(Subscriber(Sub::new(s.next_message_id, self)))
+            }
+        })
+    }
+
+    /// Create a new subscriber. It will only receive messages that are published after its creation.
+    ///
+    /// If there are no subscriber slots left, an error will be returned.
+    pub fn dyn_subscriber(&self) -> Result<DynSubscriber<'_, T>, Error> {
+        self.inner.lock(|inner| {
+            let mut s = inner.borrow_mut();
+
+            if s.subscriber_count >= SUBS {
+                Err(Error::MaximumSubscribersReached)
+            } else {
+                s.subscriber_count += 1;
+                Ok(DynSubscriber(Sub::new(s.next_message_id, self)))
+            }
+        })
+    }
+
+    /// Create a new publisher
+    ///
+    /// If there are no publisher slots left, an error will be returned.
+    pub fn publisher(&self) -> Result<Publisher<M, T, CAP, SUBS, PUBS>, Error> {
+        self.inner.lock(|inner| {
+            let mut s = inner.borrow_mut();
+
+            if s.publisher_count >= PUBS {
+                Err(Error::MaximumPublishersReached)
+            } else {
+                s.publisher_count += 1;
+                Ok(Publisher(Pub::new(self)))
+            }
+        })
+    }
+
+    /// Create a new publisher
+    ///
+    /// If there are no publisher slots left, an error will be returned.
+    pub fn dyn_publisher(&self) -> Result<DynPublisher<'_, T>, Error> {
+        self.inner.lock(|inner| {
+            let mut s = inner.borrow_mut();
+
+            if s.publisher_count >= PUBS {
+                Err(Error::MaximumPublishersReached)
+            } else {
+                s.publisher_count += 1;
+                Ok(DynPublisher(Pub::new(self)))
+            }
+        })
+    }
+
+    /// Create a new publisher that can only send immediate messages.
+    /// This kind of publisher does not take up a publisher slot.
+    pub fn immediate_publisher(&self) -> ImmediatePublisher<M, T, CAP, SUBS, PUBS> {
+        ImmediatePublisher(ImmediatePub::new(self))
+    }
+
+    /// Create a new publisher that can only send immediate messages.
+    /// This kind of publisher does not take up a publisher slot.
+    pub fn dyn_immediate_publisher(&self) -> DynImmediatePublisher<T> {
+        DynImmediatePublisher(ImmediatePub::new(self))
+    }
+}
+
+impl<M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> PubSubBehavior<T>
+    for PubSubChannel<M, T, CAP, SUBS, PUBS>
+{
+    fn get_message_with_context(&self, next_message_id: &mut u64, cx: Option<&mut Context<'_>>) -> Poll<WaitResult<T>> {
+        self.inner.lock(|s| {
+            let mut s = s.borrow_mut();
+
+            // Check if we can read a message
+            match s.get_message(*next_message_id) {
+                // Yes, so we are done polling
+                Some(WaitResult::Message(message)) => {
+                    *next_message_id += 1;
+                    Poll::Ready(WaitResult::Message(message))
+                }
+                // No, so we need to reregister our waker and sleep again
+                None => {
+                    if let Some(cx) = cx {
+                        s.subscriber_wakers.register(cx.waker());
+                    }
+                    Poll::Pending
+                }
+                // We missed a couple of messages. We must do our internal bookkeeping and return that we lagged
+                Some(WaitResult::Lagged(amount)) => {
+                    *next_message_id += amount;
+                    Poll::Ready(WaitResult::Lagged(amount))
+                }
+            }
+        })
+    }
+
+    fn available(&self, next_message_id: u64) -> u64 {
+        self.inner.lock(|s| s.borrow().next_message_id - next_message_id)
+    }
+
+    fn publish_with_context(&self, message: T, cx: Option<&mut Context<'_>>) -> Result<(), T> {
+        self.inner.lock(|s| {
+            let mut s = s.borrow_mut();
+            // Try to publish the message
+            match s.try_publish(message) {
+                // We did it, we are ready
+                Ok(()) => Ok(()),
+                // The queue is full, so we need to reregister our waker and go to sleep
+                Err(message) => {
+                    if let Some(cx) = cx {
+                        s.publisher_wakers.register(cx.waker());
+                    }
+                    Err(message)
+                }
+            }
+        })
+    }
+
+    fn publish_immediate(&self, message: T) {
+        self.inner.lock(|s| {
+            let mut s = s.borrow_mut();
+            s.publish_immediate(message)
+        })
+    }
+
+    fn space(&self) -> usize {
+        self.inner.lock(|s| {
+            let s = s.borrow();
+            s.queue.capacity() - s.queue.len()
+        })
+    }
+
+    fn unregister_subscriber(&self, subscriber_next_message_id: u64) {
+        self.inner.lock(|s| {
+            let mut s = s.borrow_mut();
+            s.unregister_subscriber(subscriber_next_message_id)
+        })
+    }
+
+    fn unregister_publisher(&self) {
+        self.inner.lock(|s| {
+            let mut s = s.borrow_mut();
+            s.unregister_publisher()
+        })
+    }
+}
+
+/// Internal state for the PubSub channel
+struct PubSubState<T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> {
+    /// The queue contains the last messages that have been published and a countdown of how many subscribers are yet to read it
+    queue: Deque<(T, usize), CAP>,
+    /// Every message has an id.
+    /// Don't worry, we won't run out.
+    /// If a million messages were published every second, then the ID's would run out in about 584942 years.
+    next_message_id: u64,
+    /// Collection of wakers for Subscribers that are waiting.  
+    subscriber_wakers: MultiWakerRegistration<SUBS>,
+    /// Collection of wakers for Publishers that are waiting.  
+    publisher_wakers: MultiWakerRegistration<PUBS>,
+    /// The amount of subscribers that are active
+    subscriber_count: usize,
+    /// The amount of publishers that are active
+    publisher_count: usize,
+}
+
+impl<T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> PubSubState<T, CAP, SUBS, PUBS> {
+    /// Create a new internal channel state
+    const fn new() -> Self {
+        Self {
+            queue: Deque::new(),
+            next_message_id: 0,
+            subscriber_wakers: MultiWakerRegistration::new(),
+            publisher_wakers: MultiWakerRegistration::new(),
+            subscriber_count: 0,
+            publisher_count: 0,
+        }
+    }
+
+    fn try_publish(&mut self, message: T) -> Result<(), T> {
+        if self.subscriber_count == 0 {
+            // We don't need to publish anything because there is no one to receive it
+            return Ok(());
+        }
+
+        if self.queue.is_full() {
+            return Err(message);
+        }
+        // We just did a check for this
+        self.queue.push_back((message, self.subscriber_count)).ok().unwrap();
+
+        self.next_message_id += 1;
+
+        // Wake all of the subscribers
+        self.subscriber_wakers.wake();
+
+        Ok(())
+    }
+
+    fn publish_immediate(&mut self, message: T) {
+        // Make space in the queue if required
+        if self.queue.is_full() {
+            self.queue.pop_front();
+        }
+
+        // This will succeed because we made sure there is space
+        self.try_publish(message).ok().unwrap();
+    }
+
+    fn get_message(&mut self, message_id: u64) -> Option<WaitResult<T>> {
+        let start_id = self.next_message_id - self.queue.len() as u64;
+
+        if message_id < start_id {
+            return Some(WaitResult::Lagged(start_id - message_id));
+        }
+
+        let current_message_index = (message_id - start_id) as usize;
+
+        if current_message_index >= self.queue.len() {
+            return None;
+        }
+
+        // We've checked that the index is valid
+        let queue_item = self.queue.iter_mut().nth(current_message_index).unwrap();
+
+        // We're reading this item, so decrement the counter
+        queue_item.1 -= 1;
+
+        let message = if current_message_index == 0 && queue_item.1 == 0 {
+            let (message, _) = self.queue.pop_front().unwrap();
+            self.publisher_wakers.wake();
+            // Return pop'd message without clone
+            message
+        } else {
+            queue_item.0.clone()
+        };
+
+        Some(WaitResult::Message(message))
+    }
+
+    fn unregister_subscriber(&mut self, subscriber_next_message_id: u64) {
+        self.subscriber_count -= 1;
+
+        // All messages that haven't been read yet by this subscriber must have their counter decremented
+        let start_id = self.next_message_id - self.queue.len() as u64;
+        if subscriber_next_message_id >= start_id {
+            let current_message_index = (subscriber_next_message_id - start_id) as usize;
+            self.queue
+                .iter_mut()
+                .skip(current_message_index)
+                .for_each(|(_, counter)| *counter -= 1);
+
+            let mut wake_publishers = false;
+            while let Some((_, count)) = self.queue.front() {
+                if *count == 0 {
+                    self.queue.pop_front().unwrap();
+                    wake_publishers = true;
+                } else {
+                    break;
+                }
+            }
+
+            if wake_publishers {
+                self.publisher_wakers.wake();
+            }
+        }
+    }
+
+    fn unregister_publisher(&mut self) {
+        self.publisher_count -= 1;
+    }
+}
+
+/// Error type for the [PubSubChannel]
+#[derive(Debug, PartialEq, Eq, Clone)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum Error {
+    /// All subscriber slots are used. To add another subscriber, first another subscriber must be dropped or
+    /// the capacity of the channels must be increased.
+    MaximumSubscribersReached,
+    /// All publisher slots are used. To add another publisher, first another publisher must be dropped or
+    /// the capacity of the channels must be increased.
+    MaximumPublishersReached,
+}
+
+/// 'Middle level' behaviour of the pubsub channel.
+/// This trait is used so that Sub and Pub can be generic over the channel.
+pub trait PubSubBehavior<T> {
+    /// Try to get a message from the queue with the given message id.
+    ///
+    /// If the message is not yet present and a context is given, then its waker is registered in the subsriber wakers.
+    fn get_message_with_context(&self, next_message_id: &mut u64, cx: Option<&mut Context<'_>>) -> Poll<WaitResult<T>>;
+
+    /// Get the amount of messages that are between the given the next_message_id and the most recent message.
+    /// This is not necessarily the amount of messages a subscriber can still received as it may have lagged.
+    fn available(&self, next_message_id: u64) -> u64;
+
+    /// Try to publish a message to the queue.
+    ///
+    /// If the queue is full and a context is given, then its waker is registered in the publisher wakers.
+    fn publish_with_context(&self, message: T, cx: Option<&mut Context<'_>>) -> Result<(), T>;
+
+    /// Publish a message immediately
+    fn publish_immediate(&self, message: T);
+
+    /// The amount of messages that can still be published without having to wait or without having to lag the subscribers
+    fn space(&self) -> usize;
+
+    /// Let the channel know that a subscriber has dropped
+    fn unregister_subscriber(&self, subscriber_next_message_id: u64);
+
+    /// Let the channel know that a publisher has dropped
+    fn unregister_publisher(&self);
+}
+
+/// The result of the subscriber wait procedure
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum WaitResult<T> {
+    /// The subscriber did not receive all messages and lagged by the given amount of messages.
+    /// (This is the amount of messages that were missed)
+    Lagged(u64),
+    /// A message was received
+    Message(T),
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::blocking_mutex::raw::NoopRawMutex;
+
+    #[futures_test::test]
+    async fn dyn_pub_sub_works() {
+        let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
+
+        let mut sub0 = channel.dyn_subscriber().unwrap();
+        let mut sub1 = channel.dyn_subscriber().unwrap();
+        let pub0 = channel.dyn_publisher().unwrap();
+
+        pub0.publish(42).await;
+
+        assert_eq!(sub0.next_message().await, WaitResult::Message(42));
+        assert_eq!(sub1.next_message().await, WaitResult::Message(42));
+
+        assert_eq!(sub0.try_next_message(), None);
+        assert_eq!(sub1.try_next_message(), None);
+    }
+
+    #[futures_test::test]
+    async fn all_subscribers_receive() {
+        let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
+
+        let mut sub0 = channel.subscriber().unwrap();
+        let mut sub1 = channel.subscriber().unwrap();
+        let pub0 = channel.publisher().unwrap();
+
+        pub0.publish(42).await;
+
+        assert_eq!(sub0.next_message().await, WaitResult::Message(42));
+        assert_eq!(sub1.next_message().await, WaitResult::Message(42));
+
+        assert_eq!(sub0.try_next_message(), None);
+        assert_eq!(sub1.try_next_message(), None);
+    }
+
+    #[futures_test::test]
+    async fn lag_when_queue_full_on_immediate_publish() {
+        let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
+
+        let mut sub0 = channel.subscriber().unwrap();
+        let pub0 = channel.publisher().unwrap();
+
+        pub0.publish_immediate(42);
+        pub0.publish_immediate(43);
+        pub0.publish_immediate(44);
+        pub0.publish_immediate(45);
+        pub0.publish_immediate(46);
+        pub0.publish_immediate(47);
+
+        assert_eq!(sub0.try_next_message(), Some(WaitResult::Lagged(2)));
+        assert_eq!(sub0.next_message().await, WaitResult::Message(44));
+        assert_eq!(sub0.next_message().await, WaitResult::Message(45));
+        assert_eq!(sub0.next_message().await, WaitResult::Message(46));
+        assert_eq!(sub0.next_message().await, WaitResult::Message(47));
+        assert_eq!(sub0.try_next_message(), None);
+    }
+
+    #[test]
+    fn limited_subs_and_pubs() {
+        let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
+
+        let sub0 = channel.subscriber();
+        let sub1 = channel.subscriber();
+        let sub2 = channel.subscriber();
+        let sub3 = channel.subscriber();
+        let sub4 = channel.subscriber();
+
+        assert!(sub0.is_ok());
+        assert!(sub1.is_ok());
+        assert!(sub2.is_ok());
+        assert!(sub3.is_ok());
+        assert_eq!(sub4.err().unwrap(), Error::MaximumSubscribersReached);
+
+        drop(sub0);
+
+        let sub5 = channel.subscriber();
+        assert!(sub5.is_ok());
+
+        // publishers
+
+        let pub0 = channel.publisher();
+        let pub1 = channel.publisher();
+        let pub2 = channel.publisher();
+        let pub3 = channel.publisher();
+        let pub4 = channel.publisher();
+
+        assert!(pub0.is_ok());
+        assert!(pub1.is_ok());
+        assert!(pub2.is_ok());
+        assert!(pub3.is_ok());
+        assert_eq!(pub4.err().unwrap(), Error::MaximumPublishersReached);
+
+        drop(pub0);
+
+        let pub5 = channel.publisher();
+        assert!(pub5.is_ok());
+    }
+
+    #[test]
+    fn publisher_wait_on_full_queue() {
+        let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
+
+        let pub0 = channel.publisher().unwrap();
+
+        // There are no subscribers, so the queue will never be full
+        assert_eq!(pub0.try_publish(0), Ok(()));
+        assert_eq!(pub0.try_publish(0), Ok(()));
+        assert_eq!(pub0.try_publish(0), Ok(()));
+        assert_eq!(pub0.try_publish(0), Ok(()));
+        assert_eq!(pub0.try_publish(0), Ok(()));
+
+        let sub0 = channel.subscriber().unwrap();
+
+        assert_eq!(pub0.try_publish(0), Ok(()));
+        assert_eq!(pub0.try_publish(0), Ok(()));
+        assert_eq!(pub0.try_publish(0), Ok(()));
+        assert_eq!(pub0.try_publish(0), Ok(()));
+        assert_eq!(pub0.try_publish(0), Err(0));
+
+        drop(sub0);
+    }
+
+    #[futures_test::test]
+    async fn correct_available() {
+        let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
+
+        let sub0 = channel.subscriber().unwrap();
+        let mut sub1 = channel.subscriber().unwrap();
+        let pub0 = channel.publisher().unwrap();
+
+        assert_eq!(sub0.available(), 0);
+        assert_eq!(sub1.available(), 0);
+
+        pub0.publish(42).await;
+
+        assert_eq!(sub0.available(), 1);
+        assert_eq!(sub1.available(), 1);
+
+        sub1.next_message().await;
+
+        assert_eq!(sub1.available(), 0);
+
+        pub0.publish(42).await;
+
+        assert_eq!(sub0.available(), 2);
+        assert_eq!(sub1.available(), 1);
+    }
+
+    #[futures_test::test]
+    async fn correct_space() {
+        let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
+
+        let mut sub0 = channel.subscriber().unwrap();
+        let mut sub1 = channel.subscriber().unwrap();
+        let pub0 = channel.publisher().unwrap();
+
+        assert_eq!(pub0.space(), 4);
+
+        pub0.publish(42).await;
+
+        assert_eq!(pub0.space(), 3);
+
+        pub0.publish(42).await;
+
+        assert_eq!(pub0.space(), 2);
+
+        sub0.next_message().await;
+        sub0.next_message().await;
+
+        assert_eq!(pub0.space(), 2);
+
+        sub1.next_message().await;
+        assert_eq!(pub0.space(), 3);
+        sub1.next_message().await;
+        assert_eq!(pub0.space(), 4);
+    }
+
+    #[futures_test::test]
+    async fn empty_channel_when_last_subscriber_is_dropped() {
+        let channel = PubSubChannel::<NoopRawMutex, u32, 4, 4, 4>::new();
+
+        let pub0 = channel.publisher().unwrap();
+        let mut sub0 = channel.subscriber().unwrap();
+        let mut sub1 = channel.subscriber().unwrap();
+
+        assert_eq!(4, pub0.space());
+
+        pub0.publish(1).await;
+        pub0.publish(2).await;
+
+        assert_eq!(2, channel.space());
+
+        assert_eq!(1, sub0.try_next_message_pure().unwrap());
+        assert_eq!(2, sub0.try_next_message_pure().unwrap());
+
+        assert_eq!(2, channel.space());
+
+        drop(sub0);
+
+        assert_eq!(2, channel.space());
+
+        assert_eq!(1, sub1.try_next_message_pure().unwrap());
+
+        assert_eq!(3, channel.space());
+
+        drop(sub1);
+
+        assert_eq!(4, channel.space());
+    }
+
+    struct CloneCallCounter(usize);
+
+    impl Clone for CloneCallCounter {
+        fn clone(&self) -> Self {
+            Self(self.0 + 1)
+        }
+    }
+
+    #[futures_test::test]
+    async fn skip_clone_for_last_message() {
+        let channel = PubSubChannel::<NoopRawMutex, CloneCallCounter, 1, 2, 1>::new();
+        let pub0 = channel.publisher().unwrap();
+        let mut sub0 = channel.subscriber().unwrap();
+        let mut sub1 = channel.subscriber().unwrap();
+
+        pub0.publish(CloneCallCounter(0)).await;
+
+        assert_eq!(1, sub0.try_next_message_pure().unwrap().0);
+        assert_eq!(0, sub1.try_next_message_pure().unwrap().0);
+    }
+}

vendor/embassy-sync-0.5.0/src/pubsub/publisher.rs

@@ -0,0 +1,199 @@
+//! Implementation of anything directly publisher related
+
+use core::future::Future;
+use core::marker::PhantomData;
+use core::ops::{Deref, DerefMut};
+use core::pin::Pin;
+use core::task::{Context, Poll};
+
+use super::{PubSubBehavior, PubSubChannel};
+use crate::blocking_mutex::raw::RawMutex;
+
+/// A publisher to a channel
+pub struct Pub<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> {
+    /// The channel we are a publisher for
+    channel: &'a PSB,
+    _phantom: PhantomData<T>,
+}
+
+impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Pub<'a, PSB, T> {
+    pub(super) fn new(channel: &'a PSB) -> Self {
+        Self {
+            channel,
+            _phantom: Default::default(),
+        }
+    }
+
+    /// Publish a message right now even when the queue is full.
+    /// This may cause a subscriber to miss an older message.
+    pub fn publish_immediate(&self, message: T) {
+        self.channel.publish_immediate(message)
+    }
+
+    /// Publish a message. But if the message queue is full, wait for all subscribers to have read the last message
+    pub fn publish<'s>(&'s self, message: T) -> PublisherWaitFuture<'s, 'a, PSB, T> {
+        PublisherWaitFuture {
+            message: Some(message),
+            publisher: self,
+        }
+    }
+
+    /// Publish a message if there is space in the message queue
+    pub fn try_publish(&self, message: T) -> Result<(), T> {
+        self.channel.publish_with_context(message, None)
+    }
+
+    /// The amount of messages that can still be published without having to wait or without having to lag the subscribers
+    ///
+    /// *Note: In the time between checking this and a publish action, other publishers may have had time to publish something.
+    /// So checking doesn't give any guarantees.*
+    pub fn space(&self) -> usize {
+        self.channel.space()
+    }
+}
+
+impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Drop for Pub<'a, PSB, T> {
+    fn drop(&mut self) {
+        self.channel.unregister_publisher()
+    }
+}
+
+/// A publisher that holds a dynamic reference to the channel
+pub struct DynPublisher<'a, T: Clone>(pub(super) Pub<'a, dyn PubSubBehavior<T> + 'a, T>);
+
+impl<'a, T: Clone> Deref for DynPublisher<'a, T> {
+    type Target = Pub<'a, dyn PubSubBehavior<T> + 'a, T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a, T: Clone> DerefMut for DynPublisher<'a, T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+/// A publisher that holds a generic reference to the channel
+pub struct Publisher<'a, M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize>(
+    pub(super) Pub<'a, PubSubChannel<M, T, CAP, SUBS, PUBS>, T>,
+);
+
+impl<'a, M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> Deref
+    for Publisher<'a, M, T, CAP, SUBS, PUBS>
+{
+    type Target = Pub<'a, PubSubChannel<M, T, CAP, SUBS, PUBS>, T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a, M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> DerefMut
+    for Publisher<'a, M, T, CAP, SUBS, PUBS>
+{
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+/// A publisher that can only use the `publish_immediate` function, but it doesn't have to be registered with the channel.
+/// (So an infinite amount is possible)
+pub struct ImmediatePub<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> {
+    /// The channel we are a publisher for
+    channel: &'a PSB,
+    _phantom: PhantomData<T>,
+}
+
+impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> ImmediatePub<'a, PSB, T> {
+    pub(super) fn new(channel: &'a PSB) -> Self {
+        Self {
+            channel,
+            _phantom: Default::default(),
+        }
+    }
+    /// Publish the message right now even when the queue is full.
+    /// This may cause a subscriber to miss an older message.
+    pub fn publish_immediate(&self, message: T) {
+        self.channel.publish_immediate(message)
+    }
+
+    /// Publish a message if there is space in the message queue
+    pub fn try_publish(&self, message: T) -> Result<(), T> {
+        self.channel.publish_with_context(message, None)
+    }
+
+    /// The amount of messages that can still be published without having to wait or without having to lag the subscribers
+    ///
+    /// *Note: In the time between checking this and a publish action, other publishers may have had time to publish something.
+    /// So checking doesn't give any guarantees.*
+    pub fn space(&self) -> usize {
+        self.channel.space()
+    }
+}
+
+/// An immediate publisher that holds a dynamic reference to the channel
+pub struct DynImmediatePublisher<'a, T: Clone>(pub(super) ImmediatePub<'a, dyn PubSubBehavior<T> + 'a, T>);
+
+impl<'a, T: Clone> Deref for DynImmediatePublisher<'a, T> {
+    type Target = ImmediatePub<'a, dyn PubSubBehavior<T> + 'a, T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a, T: Clone> DerefMut for DynImmediatePublisher<'a, T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+/// An immediate publisher that holds a generic reference to the channel
+pub struct ImmediatePublisher<'a, M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize>(
+    pub(super) ImmediatePub<'a, PubSubChannel<M, T, CAP, SUBS, PUBS>, T>,
+);
+
+impl<'a, M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> Deref
+    for ImmediatePublisher<'a, M, T, CAP, SUBS, PUBS>
+{
+    type Target = ImmediatePub<'a, PubSubChannel<M, T, CAP, SUBS, PUBS>, T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a, M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> DerefMut
+    for ImmediatePublisher<'a, M, T, CAP, SUBS, PUBS>
+{
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+/// Future for the publisher wait action
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct PublisherWaitFuture<'s, 'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> {
+    /// The message we need to publish
+    message: Option<T>,
+    publisher: &'s Pub<'a, PSB, T>,
+}
+
+impl<'s, 'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Future for PublisherWaitFuture<'s, 'a, PSB, T> {
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let message = self.message.take().unwrap();
+        match self.publisher.channel.publish_with_context(message, Some(cx)) {
+            Ok(()) => Poll::Ready(()),
+            Err(message) => {
+                self.message = Some(message);
+                Poll::Pending
+            }
+        }
+    }
+}
+
+impl<'s, 'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Unpin for PublisherWaitFuture<'s, 'a, PSB, T> {}

vendor/embassy-sync-0.5.0/src/pubsub/subscriber.rs

@@ -0,0 +1,158 @@
+//! Implementation of anything directly subscriber related
+
+use core::future::Future;
+use core::marker::PhantomData;
+use core::ops::{Deref, DerefMut};
+use core::pin::Pin;
+use core::task::{Context, Poll};
+
+use super::{PubSubBehavior, PubSubChannel, WaitResult};
+use crate::blocking_mutex::raw::RawMutex;
+
+/// A subscriber to a channel
+pub struct Sub<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> {
+    /// The message id of the next message we are yet to receive
+    next_message_id: u64,
+    /// The channel we are a subscriber to
+    channel: &'a PSB,
+    _phantom: PhantomData<T>,
+}
+
+impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Sub<'a, PSB, T> {
+    pub(super) fn new(next_message_id: u64, channel: &'a PSB) -> Self {
+        Self {
+            next_message_id,
+            channel,
+            _phantom: Default::default(),
+        }
+    }
+
+    /// Wait for a published message
+    pub fn next_message<'s>(&'s mut self) -> SubscriberWaitFuture<'s, 'a, PSB, T> {
+        SubscriberWaitFuture { subscriber: self }
+    }
+
+    /// Wait for a published message (ignoring lag results)
+    pub async fn next_message_pure(&mut self) -> T {
+        loop {
+            match self.next_message().await {
+                WaitResult::Lagged(_) => continue,
+                WaitResult::Message(message) => break message,
+            }
+        }
+    }
+
+    /// Try to see if there's a published message we haven't received yet.
+    ///
+    /// This function does not peek. The message is received if there is one.
+    pub fn try_next_message(&mut self) -> Option<WaitResult<T>> {
+        match self.channel.get_message_with_context(&mut self.next_message_id, None) {
+            Poll::Ready(result) => Some(result),
+            Poll::Pending => None,
+        }
+    }
+
+    /// Try to see if there's a published message we haven't received yet (ignoring lag results).
+    ///
+    /// This function does not peek. The message is received if there is one.
+    pub fn try_next_message_pure(&mut self) -> Option<T> {
+        loop {
+            match self.try_next_message() {
+                Some(WaitResult::Lagged(_)) => continue,
+                Some(WaitResult::Message(message)) => break Some(message),
+                None => break None,
+            }
+        }
+    }
+
+    /// The amount of messages this subscriber hasn't received yet
+    pub fn available(&self) -> u64 {
+        self.channel.available(self.next_message_id)
+    }
+}
+
+impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Drop for Sub<'a, PSB, T> {
+    fn drop(&mut self) {
+        self.channel.unregister_subscriber(self.next_message_id)
+    }
+}
+
+impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Unpin for Sub<'a, PSB, T> {}
+
+/// Warning: The stream implementation ignores lag results and returns all messages.
+/// This might miss some messages without you knowing it.
+impl<'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> futures_util::Stream for Sub<'a, PSB, T> {
+    type Item = T;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        match self
+            .channel
+            .get_message_with_context(&mut self.next_message_id, Some(cx))
+        {
+            Poll::Ready(WaitResult::Message(message)) => Poll::Ready(Some(message)),
+            Poll::Ready(WaitResult::Lagged(_)) => {
+                cx.waker().wake_by_ref();
+                Poll::Pending
+            }
+            Poll::Pending => Poll::Pending,
+        }
+    }
+}
+
+/// A subscriber that holds a dynamic reference to the channel
+pub struct DynSubscriber<'a, T: Clone>(pub(super) Sub<'a, dyn PubSubBehavior<T> + 'a, T>);
+
+impl<'a, T: Clone> Deref for DynSubscriber<'a, T> {
+    type Target = Sub<'a, dyn PubSubBehavior<T> + 'a, T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a, T: Clone> DerefMut for DynSubscriber<'a, T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+/// A subscriber that holds a generic reference to the channel
+pub struct Subscriber<'a, M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize>(
+    pub(super) Sub<'a, PubSubChannel<M, T, CAP, SUBS, PUBS>, T>,
+);
+
+impl<'a, M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> Deref
+    for Subscriber<'a, M, T, CAP, SUBS, PUBS>
+{
+    type Target = Sub<'a, PubSubChannel<M, T, CAP, SUBS, PUBS>, T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'a, M: RawMutex, T: Clone, const CAP: usize, const SUBS: usize, const PUBS: usize> DerefMut
+    for Subscriber<'a, M, T, CAP, SUBS, PUBS>
+{
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+/// Future for the subscriber wait action
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct SubscriberWaitFuture<'s, 'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> {
+    subscriber: &'s mut Sub<'a, PSB, T>,
+}
+
+impl<'s, 'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Future for SubscriberWaitFuture<'s, 'a, PSB, T> {
+    type Output = WaitResult<T>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        self.subscriber
+            .channel
+            .get_message_with_context(&mut self.subscriber.next_message_id, Some(cx))
+    }
+}
+
+impl<'s, 'a, PSB: PubSubBehavior<T> + ?Sized, T: Clone> Unpin for SubscriberWaitFuture<'s, 'a, PSB, T> {}

vendor/embassy-sync-0.5.0/src/ring_buffer.rs

@@ -0,0 +1,138 @@
+use core::ops::Range;
+
+pub struct RingBuffer<const N: usize> {
+    start: usize,
+    end: usize,
+    empty: bool,
+}
+
+impl<const N: usize> RingBuffer<N> {
+    pub const fn new() -> Self {
+        Self {
+            start: 0,
+            end: 0,
+            empty: true,
+        }
+    }
+
+    pub fn push_buf(&mut self) -> Range<usize> {
+        if self.start == self.end && !self.empty {
+            trace!("  ringbuf: push_buf empty");
+            return 0..0;
+        }
+
+        let n = if self.start <= self.end {
+            N - self.end
+        } else {
+            self.start - self.end
+        };
+
+        trace!("  ringbuf: push_buf {:?}..{:?}", self.end, self.end + n);
+        self.end..self.end + n
+    }
+
+    pub fn push(&mut self, n: usize) {
+        trace!("  ringbuf: push {:?}", n);
+        if n == 0 {
+            return;
+        }
+
+        self.end = self.wrap(self.end + n);
+        self.empty = false;
+    }
+
+    pub fn pop_buf(&mut self) -> Range<usize> {
+        if self.empty {
+            trace!("  ringbuf: pop_buf empty");
+            return 0..0;
+        }
+
+        let n = if self.end <= self.start {
+            N - self.start
+        } else {
+            self.end - self.start
+        };
+
+        trace!("  ringbuf: pop_buf {:?}..{:?}", self.start, self.start + n);
+        self.start..self.start + n
+    }
+
+    pub fn pop(&mut self, n: usize) {
+        trace!("  ringbuf: pop {:?}", n);
+        if n == 0 {
+            return;
+        }
+
+        self.start = self.wrap(self.start + n);
+        self.empty = self.start == self.end;
+    }
+
+    pub fn is_full(&self) -> bool {
+        self.start == self.end && !self.empty
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.empty
+    }
+
+    #[allow(unused)]
+    pub fn len(&self) -> usize {
+        if self.empty {
+            0
+        } else if self.start < self.end {
+            self.end - self.start
+        } else {
+            N + self.end - self.start
+        }
+    }
+
+    pub fn clear(&mut self) {
+        self.start = 0;
+        self.end = 0;
+        self.empty = true;
+    }
+
+    fn wrap(&self, n: usize) -> usize {
+        assert!(n <= N);
+        if n == N {
+            0
+        } else {
+            n
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn push_pop() {
+        let mut rb: RingBuffer<4> = RingBuffer::new();
+        let buf = rb.push_buf();
+        assert_eq!(0..4, buf);
+        rb.push(4);
+
+        let buf = rb.pop_buf();
+        assert_eq!(0..4, buf);
+        rb.pop(1);
+
+        let buf = rb.pop_buf();
+        assert_eq!(1..4, buf);
+        rb.pop(1);
+
+        let buf = rb.pop_buf();
+        assert_eq!(2..4, buf);
+        rb.pop(1);
+
+        let buf = rb.pop_buf();
+        assert_eq!(3..4, buf);
+        rb.pop(1);
+
+        let buf = rb.pop_buf();
+        assert_eq!(0..0, buf);
+
+        let buf = rb.push_buf();
+        assert_eq!(0..4, buf);
+    }
+}

vendor/embassy-sync-0.5.0/src/signal.rs

@@ -0,0 +1,126 @@
+//! A synchronization primitive for passing the latest value to a task.
+use core::cell::Cell;
+use core::future::{poll_fn, Future};
+use core::task::{Context, Poll, Waker};
+
+use crate::blocking_mutex::raw::RawMutex;
+use crate::blocking_mutex::Mutex;
+
+/// Single-slot signaling primitive.
+///
+/// This is similar to a [`Channel`](crate::channel::Channel) with a buffer size of 1, except
+/// "sending" to it (calling [`Signal::signal`]) when full will overwrite the previous value instead
+/// of waiting for the receiver to pop the previous value.
+///
+/// It is useful for sending data between tasks when the receiver only cares about
+/// the latest data, and therefore it's fine to "lose" messages. This is often the case for "state"
+/// updates.
+///
+/// For more advanced use cases, you might want to use [`Channel`](crate::channel::Channel) instead.
+///
+/// Signals are generally declared as `static`s and then borrowed as required.
+///
+/// ```
+/// use embassy_sync::signal::Signal;
+/// use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+///
+/// enum SomeCommand {
+///   On,
+///   Off,
+/// }
+///
+/// static SOME_SIGNAL: Signal<CriticalSectionRawMutex, SomeCommand> = Signal::new();
+/// ```
+pub struct Signal<M, T>
+where
+    M: RawMutex,
+{
+    state: Mutex<M, Cell<State<T>>>,
+}
+
+enum State<T> {
+    None,
+    Waiting(Waker),
+    Signaled(T),
+}
+
+impl<M, T> Signal<M, T>
+where
+    M: RawMutex,
+{
+    /// Create a new `Signal`.
+    pub const fn new() -> Self {
+        Self {
+            state: Mutex::new(Cell::new(State::None)),
+        }
+    }
+}
+
+impl<M, T> Default for Signal<M, T>
+where
+    M: RawMutex,
+{
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<M, T: Send> Signal<M, T>
+where
+    M: RawMutex,
+{
+    /// Mark this Signal as signaled.
+    pub fn signal(&self, val: T) {
+        self.state.lock(|cell| {
+            let state = cell.replace(State::Signaled(val));
+            if let State::Waiting(waker) = state {
+                waker.wake();
+            }
+        })
+    }
+
+    /// Remove the queued value in this `Signal`, if any.
+    pub fn reset(&self) {
+        self.state.lock(|cell| cell.set(State::None));
+    }
+
+    fn poll_wait(&self, cx: &mut Context<'_>) -> Poll<T> {
+        self.state.lock(|cell| {
+            let state = cell.replace(State::None);
+            match state {
+                State::None => {
+                    cell.set(State::Waiting(cx.waker().clone()));
+                    Poll::Pending
+                }
+                State::Waiting(w) if w.will_wake(cx.waker()) => {
+                    cell.set(State::Waiting(w));
+                    Poll::Pending
+                }
+                State::Waiting(w) => {
+                    cell.set(State::Waiting(cx.waker().clone()));
+                    w.wake();
+                    Poll::Pending
+                }
+                State::Signaled(res) => Poll::Ready(res),
+            }
+        })
+    }
+
+    /// Future that completes when this Signal has been signaled.
+    pub fn wait(&self) -> impl Future<Output = T> + '_ {
+        poll_fn(move |cx| self.poll_wait(cx))
+    }
+
+    /// non-blocking method to check whether this signal has been signaled.
+    pub fn signaled(&self) -> bool {
+        self.state.lock(|cell| {
+            let state = cell.replace(State::None);
+
+            let res = matches!(state, State::Signaled(_));
+
+            cell.set(state);
+
+            res
+        })
+    }
+}

vendor/embassy-sync-0.5.0/src/waitqueue/atomic_waker.rs

@@ -0,0 +1,41 @@
+use core::cell::Cell;
+use core::task::Waker;
+
+use crate::blocking_mutex::raw::CriticalSectionRawMutex;
+use crate::blocking_mutex::Mutex;
+
+/// Utility struct to register and wake a waker.
+pub struct AtomicWaker {
+    waker: Mutex<CriticalSectionRawMutex, Cell<Option<Waker>>>,
+}
+
+impl AtomicWaker {
+    /// Create a new `AtomicWaker`.
+    pub const fn new() -> Self {
+        Self {
+            waker: Mutex::const_new(CriticalSectionRawMutex::new(), Cell::new(None)),
+        }
+    }
+
+    /// Register a waker. Overwrites the previous waker, if any.
+    pub fn register(&self, w: &Waker) {
+        critical_section::with(|cs| {
+            let cell = self.waker.borrow(cs);
+            cell.set(match cell.replace(None) {
+                Some(w2) if (w2.will_wake(w)) => Some(w2),
+                _ => Some(w.clone()),
+            })
+        })
+    }
+
+    /// Wake the registered waker, if any.
+    pub fn wake(&self) {
+        critical_section::with(|cs| {
+            let cell = self.waker.borrow(cs);
+            if let Some(w) = cell.replace(None) {
+                w.wake_by_ref();
+                cell.set(Some(w));
+            }
+        })
+    }
+}

vendor/embassy-sync-0.5.0/src/waitqueue/atomic_waker_turbo.rs

@@ -0,0 +1,30 @@
+use core::ptr;
+use core::ptr::NonNull;
+use core::sync::atomic::{AtomicPtr, Ordering};
+use core::task::Waker;
+
+/// Utility struct to register and wake a waker.
+pub struct AtomicWaker {
+    waker: AtomicPtr<()>,
+}
+
+impl AtomicWaker {
+    /// Create a new `AtomicWaker`.
+    pub const fn new() -> Self {
+        Self {
+            waker: AtomicPtr::new(ptr::null_mut()),
+        }
+    }
+
+    /// Register a waker. Overwrites the previous waker, if any.
+    pub fn register(&self, w: &Waker) {
+        self.waker.store(w.as_turbo_ptr().as_ptr() as _, Ordering::Release);
+    }
+
+    /// Wake the registered waker, if any.
+    pub fn wake(&self) {
+        if let Some(ptr) = NonNull::new(self.waker.load(Ordering::Acquire)) {
+            unsafe { Waker::from_turbo_ptr(ptr) }.wake();
+        }
+    }
+}

vendor/embassy-sync-0.5.0/src/waitqueue/mod.rs

@@ -0,0 +1,11 @@
+//! Async low-level wait queues
+
+#[cfg_attr(feature = "turbowakers", path = "atomic_waker_turbo.rs")]
+mod atomic_waker;
+pub use atomic_waker::*;
+
+mod waker_registration;
+pub use waker_registration::*;
+
+mod multi_waker;
+pub use multi_waker::*;

vendor/embassy-sync-0.5.0/src/waitqueue/multi_waker.rs

@@ -0,0 +1,58 @@
+use core::task::Waker;
+
+use heapless::Vec;
+
+/// Utility struct to register and wake multiple wakers.
+pub struct MultiWakerRegistration<const N: usize> {
+    wakers: Vec<Waker, N>,
+}
+
+impl<const N: usize> MultiWakerRegistration<N> {
+    /// Create a new empty instance
+    pub const fn new() -> Self {
+        Self { wakers: Vec::new() }
+    }
+
+    /// Register a waker. If the buffer is full the function returns it in the error
+    pub fn register<'a>(&mut self, w: &'a Waker) {
+        // If we already have some waker that wakes the same task as `w`, do nothing.
+        // This avoids cloning wakers, and avoids unnecessary mass-wakes.
+        for w2 in &self.wakers {
+            if w.will_wake(w2) {
+                return;
+            }
+        }
+
+        if self.wakers.is_full() {
+            // All waker slots were full. It's a bit inefficient, but we can wake everything.
+            // Any future that is still active will simply reregister.
+            // This won't happen a lot, so it's ok.
+            self.wake();
+        }
+
+        if self.wakers.push(w.clone()).is_err() {
+            // This can't happen unless N=0
+            // (Either `wakers` wasn't full, or it was in which case `wake()` empied it)
+            panic!("tried to push a waker to a zero-length MultiWakerRegistration")
+        }
+    }
+
+    /// Wake all registered wakers. This clears the buffer
+    pub fn wake(&mut self) {
+        // heapless::Vec has no `drain()`, do it unsafely ourselves...
+
+        // First set length to 0, without dropping the contents.
+        // This is necessary for soundness: if wake() panics and we're using panic=unwind.
+        // Setting len=0 upfront ensures other code can't observe the vec in an inconsistent state.
+        // (it'll leak wakers, but that's not UB)
+        let len = self.wakers.len();
+        unsafe { self.wakers.set_len(0) }
+
+        for i in 0..len {
+            // Move a waker out of the vec.
+            let waker = unsafe { self.wakers.as_mut_ptr().add(i).read() };
+            // Wake it by value, which consumes (drops) it.
+            waker.wake();
+        }
+    }
+}

vendor/embassy-sync-0.5.0/src/waitqueue/waker_registration.rs

@@ -0,0 +1,52 @@
+use core::mem;
+use core::task::Waker;
+
+/// Utility struct to register and wake a waker.
+#[derive(Debug, Default)]
+pub struct WakerRegistration {
+    waker: Option<Waker>,
+}
+
+impl WakerRegistration {
+    /// Create a new `WakerRegistration`.
+    pub const fn new() -> Self {
+        Self { waker: None }
+    }
+
+    /// Register a waker. Overwrites the previous waker, if any.
+    pub fn register(&mut self, w: &Waker) {
+        match self.waker {
+            // Optimization: If both the old and new Wakers wake the same task, we can simply
+            // keep the old waker, skipping the clone. (In most executor implementations,
+            // cloning a waker is somewhat expensive, comparable to cloning an Arc).
+            Some(ref w2) if (w2.will_wake(w)) => {}
+            _ => {
+                // clone the new waker and store it
+                if let Some(old_waker) = mem::replace(&mut self.waker, Some(w.clone())) {
+                    // We had a waker registered for another task. Wake it, so the other task can
+                    // reregister itself if it's still interested.
+                    //
+                    // If two tasks are waiting on the same thing concurrently, this will cause them
+                    // to wake each other in a loop fighting over this WakerRegistration. This wastes
+                    // CPU but things will still work.
+                    //
+                    // If the user wants to have two tasks waiting on the same thing they should use
+                    // a more appropriate primitive that can store multiple wakers.
+                    old_waker.wake()
+                }
+            }
+        }
+    }
+
+    /// Wake the registered waker, if any.
+    pub fn wake(&mut self) {
+        if let Some(w) = self.waker.take() {
+            w.wake()
+        }
+    }
+
+    /// Returns true if a waker is currently registered
+    pub fn occupied(&self) -> bool {
+        self.waker.is_some()
+    }
+}

vendor/embassy-sync-0.5.0/src/zerocopy_channel.rs

@@ -0,0 +1,260 @@
+//! A zero-copy queue for sending values between asynchronous tasks.
+//!
+//! It can be used concurrently by multiple producers (senders) and multiple
+//! consumers (receivers), i.e. it is an  "MPMC channel".
+//!
+//! Receivers are competing for messages. So a message that is received by
+//! one receiver is not received by any other.
+//!
+//! This queue takes a Mutex type so that various
+//! targets can be attained. For example, a ThreadModeMutex can be used
+//! for single-core Cortex-M targets where messages are only passed
+//! between tasks running in thread mode. Similarly, a CriticalSectionMutex
+//! can also be used for single-core targets where messages are to be
+//! passed from exception mode e.g. out of an interrupt handler.
+//!
+//! This module provides a bounded channel that has a limit on the number of
+//! messages that it can store, and if this limit is reached, trying to send
+//! another message will result in an error being returned.
+
+use core::cell::RefCell;
+use core::future::poll_fn;
+use core::marker::PhantomData;
+use core::task::{Context, Poll};
+
+use crate::blocking_mutex::raw::RawMutex;
+use crate::blocking_mutex::Mutex;
+use crate::waitqueue::WakerRegistration;
+
+/// A bounded zero-copy channel for communicating between asynchronous tasks
+/// with backpressure.
+///
+/// The channel will buffer up to the provided number of messages.  Once the
+/// buffer is full, attempts to `send` new messages will wait until a message is
+/// received from the channel.
+///
+/// All data sent will become available in the same order as it was sent.
+///
+/// The channel requires a buffer of recyclable elements.  Writing to the channel is done through
+/// an `&mut T`.
+pub struct Channel<'a, M: RawMutex, T> {
+    buf: *mut T,
+    phantom: PhantomData<&'a mut T>,
+    state: Mutex<M, RefCell<State>>,
+}
+
+impl<'a, M: RawMutex, T> Channel<'a, M, T> {
+    /// Initialize a new [`Channel`].
+    ///
+    /// The provided buffer will be used and reused by the channel's logic, and thus dictates the
+    /// channel's capacity.
+    pub fn new(buf: &'a mut [T]) -> Self {
+        let len = buf.len();
+        assert!(len != 0);
+
+        Self {
+            buf: buf.as_mut_ptr(),
+            phantom: PhantomData,
+            state: Mutex::new(RefCell::new(State {
+                len,
+                front: 0,
+                back: 0,
+                full: false,
+                send_waker: WakerRegistration::new(),
+                receive_waker: WakerRegistration::new(),
+            })),
+        }
+    }
+
+    /// Creates a [`Sender`] and [`Receiver`] from an existing channel.
+    ///
+    /// Further Senders and Receivers can be created through [`Sender::borrow`] and
+    /// [`Receiver::borrow`] respectively.
+    pub fn split(&mut self) -> (Sender<'_, M, T>, Receiver<'_, M, T>) {
+        (Sender { channel: self }, Receiver { channel: self })
+    }
+}
+
+/// Send-only access to a [`Channel`].
+pub struct Sender<'a, M: RawMutex, T> {
+    channel: &'a Channel<'a, M, T>,
+}
+
+impl<'a, M: RawMutex, T> Sender<'a, M, T> {
+    /// Creates one further [`Sender`] over the same channel.
+    pub fn borrow(&mut self) -> Sender<'_, M, T> {
+        Sender { channel: self.channel }
+    }
+
+    /// Attempts to send a value over the channel.
+    pub fn try_send(&mut self) -> Option<&mut T> {
+        self.channel.state.lock(|s| {
+            let s = &mut *s.borrow_mut();
+            match s.push_index() {
+                Some(i) => Some(unsafe { &mut *self.channel.buf.add(i) }),
+                None => None,
+            }
+        })
+    }
+
+    /// Attempts to send a value over the channel.
+    pub fn poll_send(&mut self, cx: &mut Context) -> Poll<&mut T> {
+        self.channel.state.lock(|s| {
+            let s = &mut *s.borrow_mut();
+            match s.push_index() {
+                Some(i) => Poll::Ready(unsafe { &mut *self.channel.buf.add(i) }),
+                None => {
+                    s.receive_waker.register(cx.waker());
+                    Poll::Pending
+                }
+            }
+        })
+    }
+
+    /// Asynchronously send a value over the channel.
+    pub async fn send(&mut self) -> &mut T {
+        let i = poll_fn(|cx| {
+            self.channel.state.lock(|s| {
+                let s = &mut *s.borrow_mut();
+                match s.push_index() {
+                    Some(i) => Poll::Ready(i),
+                    None => {
+                        s.receive_waker.register(cx.waker());
+                        Poll::Pending
+                    }
+                }
+            })
+        })
+        .await;
+        unsafe { &mut *self.channel.buf.add(i) }
+    }
+
+    /// Notify the channel that the sending of the value has been finalized.
+    pub fn send_done(&mut self) {
+        self.channel.state.lock(|s| s.borrow_mut().push_done())
+    }
+}
+
+/// Receive-only access to a [`Channel`].
+pub struct Receiver<'a, M: RawMutex, T> {
+    channel: &'a Channel<'a, M, T>,
+}
+
+impl<'a, M: RawMutex, T> Receiver<'a, M, T> {
+    /// Creates one further [`Sender`] over the same channel.
+    pub fn borrow(&mut self) -> Receiver<'_, M, T> {
+        Receiver { channel: self.channel }
+    }
+
+    /// Attempts to receive a value over the channel.
+    pub fn try_receive(&mut self) -> Option<&mut T> {
+        self.channel.state.lock(|s| {
+            let s = &mut *s.borrow_mut();
+            match s.pop_index() {
+                Some(i) => Some(unsafe { &mut *self.channel.buf.add(i) }),
+                None => None,
+            }
+        })
+    }
+
+    /// Attempts to asynchronously receive a value over the channel.
+    pub fn poll_receive(&mut self, cx: &mut Context) -> Poll<&mut T> {
+        self.channel.state.lock(|s| {
+            let s = &mut *s.borrow_mut();
+            match s.pop_index() {
+                Some(i) => Poll::Ready(unsafe { &mut *self.channel.buf.add(i) }),
+                None => {
+                    s.send_waker.register(cx.waker());
+                    Poll::Pending
+                }
+            }
+        })
+    }
+
+    /// Asynchronously receive a value over the channel.
+    pub async fn receive(&mut self) -> &mut T {
+        let i = poll_fn(|cx| {
+            self.channel.state.lock(|s| {
+                let s = &mut *s.borrow_mut();
+                match s.pop_index() {
+                    Some(i) => Poll::Ready(i),
+                    None => {
+                        s.send_waker.register(cx.waker());
+                        Poll::Pending
+                    }
+                }
+            })
+        })
+        .await;
+        unsafe { &mut *self.channel.buf.add(i) }
+    }
+
+    /// Notify the channel that the receiving of the value has been finalized.
+    pub fn receive_done(&mut self) {
+        self.channel.state.lock(|s| s.borrow_mut().pop_done())
+    }
+}
+
+struct State {
+    len: usize,
+
+    /// Front index. Always 0..=(N-1)
+    front: usize,
+    /// Back index. Always 0..=(N-1).
+    back: usize,
+
+    /// Used to distinguish "empty" and "full" cases when `front == back`.
+    /// May only be `true` if `front == back`, always `false` otherwise.
+    full: bool,
+
+    send_waker: WakerRegistration,
+    receive_waker: WakerRegistration,
+}
+
+impl State {
+    fn increment(&self, i: usize) -> usize {
+        if i + 1 == self.len {
+            0
+        } else {
+            i + 1
+        }
+    }
+
+    fn is_full(&self) -> bool {
+        self.full
+    }
+
+    fn is_empty(&self) -> bool {
+        self.front == self.back && !self.full
+    }
+
+    fn push_index(&mut self) -> Option<usize> {
+        match self.is_full() {
+            true => None,
+            false => Some(self.back),
+        }
+    }
+
+    fn push_done(&mut self) {
+        assert!(!self.is_full());
+        self.back = self.increment(self.back);
+        if self.back == self.front {
+            self.full = true;
+        }
+        self.send_waker.wake();
+    }
+
+    fn pop_index(&mut self) -> Option<usize> {
+        match self.is_empty() {
+            true => None,
+            false => Some(self.front),
+        }
+    }
+
+    fn pop_done(&mut self) {
+        assert!(!self.is_empty());
+        self.front = self.increment(self.front);
+        self.full = false;
+        self.receive_waker.wake();
+    }
+}