From d3c4e4a20a05085eae8d568c7efdbe09bada9cf5 Mon Sep 17 00:00:00 2001 From: Dario Nieuwenhuis Date: Mon, 3 Apr 2023 01:18:27 +0200 Subject: executor: add Pender, rework Cargo features. This introduces a `Pender` struct with enum cases for thread-mode, interrupt-mode and custom callback executors. This avoids calls through function pointers when using only the thread or interrupt executors. Faster, and friendlier to `cargo-call-stack`. `embassy-executor` now has `arch-xxx` Cargo features to select the arch and to enable the builtin executors (thread and interrupt). --- embassy-executor/src/arch/cortex_m.rs | 238 +++++++++++++++++++++++++++------- embassy-executor/src/arch/riscv32.rs | 133 ++++++++++--------- embassy-executor/src/arch/std.rs | 150 +++++++++++---------- embassy-executor/src/arch/wasm.rs | 134 ++++++++++--------- embassy-executor/src/arch/xtensa.rs | 135 ++++++++++--------- 5 files changed, 496 insertions(+), 294 deletions(-) (limited to 'embassy-executor/src/arch') diff --git a/embassy-executor/src/arch/cortex_m.rs b/embassy-executor/src/arch/cortex_m.rs index 4b27a264e..d6a55c4c7 100644 --- a/embassy-executor/src/arch/cortex_m.rs +++ b/embassy-executor/src/arch/cortex_m.rs @@ -1,59 +1,209 @@ -use core::arch::asm; -use core::marker::PhantomData; -use core::ptr; - -use super::{raw, Spawner}; - -/// Thread mode executor, using WFE/SEV. -/// -/// This is the simplest and most common kind of executor. It runs on -/// thread mode (at the lowest priority level), and uses the `WFE` ARM instruction -/// to sleep when it has no more work to do. When a task is woken, a `SEV` instruction -/// is executed, to make the `WFE` exit from sleep and poll the task. -/// -/// This executor allows for ultra low power consumption for chips where `WFE` -/// triggers low-power sleep without extra steps. If your chip requires extra steps, -/// you may use [`raw::Executor`] directly to program custom behavior. -pub struct Executor { - inner: raw::Executor, - not_send: PhantomData<*mut ()>, +#[cfg(feature = "executor-thread")] +pub use thread::*; +#[cfg(feature = "executor-thread")] +mod thread { + use core::arch::asm; + use core::marker::PhantomData; + + #[cfg(feature = "nightly")] + pub use embassy_macros::main_cortex_m as main; + + use crate::raw::{Pender, PenderInner}; + use crate::{raw, Spawner}; + + #[derive(Copy, Clone)] + pub(crate) struct ThreadPender; + + impl ThreadPender { + pub(crate) fn pend(self) { + unsafe { core::arch::asm!("sev") } + } + } + + /// Thread mode executor, using WFE/SEV. + /// + /// This is the simplest and most common kind of executor. It runs on + /// thread mode (at the lowest priority level), and uses the `WFE` ARM instruction + /// to sleep when it has no more work to do. When a task is woken, a `SEV` instruction + /// is executed, to make the `WFE` exit from sleep and poll the task. + /// + /// This executor allows for ultra low power consumption for chips where `WFE` + /// triggers low-power sleep without extra steps. If your chip requires extra steps, + /// you may use [`raw::Executor`] directly to program custom behavior. + pub struct Executor { + inner: raw::Executor, + not_send: PhantomData<*mut ()>, + } + + impl Executor { + /// Create a new Executor. + pub fn new() -> Self { + Self { + inner: raw::Executor::new(Pender(PenderInner::Thread(ThreadPender))), + not_send: PhantomData, + } + } + + /// Run the executor. + /// + /// The `init` closure is called with a [`Spawner`] that spawns tasks on + /// this executor. Use it to spawn the initial task(s). After `init` returns, + /// the executor starts running the tasks. + /// + /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), + /// for example by passing it as an argument to the initial tasks. + /// + /// This function requires `&'static mut self`. This means you have to store the + /// Executor instance in a place where it'll live forever and grants you mutable + /// access. There's a few ways to do this: + /// + /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) + /// - a `static mut` (unsafe) + /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) + /// + /// This function never returns. + pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! { + init(self.inner.spawner()); + + loop { + unsafe { + self.inner.poll(); + asm!("wfe"); + }; + } + } + } } -impl Executor { - /// Create a new Executor. - pub fn new() -> Self { - Self { - inner: raw::Executor::new(|_| unsafe { asm!("sev") }, ptr::null_mut()), - not_send: PhantomData, +#[cfg(feature = "executor-interrupt")] +pub use interrupt::*; +#[cfg(feature = "executor-interrupt")] +mod interrupt { + use core::cell::UnsafeCell; + use core::mem::MaybeUninit; + + use atomic_polyfill::{AtomicBool, Ordering}; + use cortex_m::interrupt::InterruptNumber; + use cortex_m::peripheral::NVIC; + + use crate::raw::{self, Pender, PenderInner}; + + #[derive(Clone, Copy)] + pub(crate) struct InterruptPender(u16); + + impl InterruptPender { + pub(crate) fn pend(self) { + // STIR is faster, but is only available in v7 and higher. + #[cfg(not(armv6m))] + { + let mut nvic: cortex_m::peripheral::NVIC = unsafe { core::mem::transmute(()) }; + nvic.request(self); + } + + #[cfg(armv6m)] + cortex_m::peripheral::NVIC::pend(self); } } - /// Run the executor. + unsafe impl cortex_m::interrupt::InterruptNumber for InterruptPender { + fn number(self) -> u16 { + self.0 + } + } + + /// Interrupt mode executor. /// - /// The `init` closure is called with a [`Spawner`] that spawns tasks on - /// this executor. Use it to spawn the initial task(s). After `init` returns, - /// the executor starts running the tasks. + /// This executor runs tasks in interrupt mode. The interrupt handler is set up + /// to poll tasks, and when a task is woken the interrupt is pended from software. /// - /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), - /// for example by passing it as an argument to the initial tasks. + /// This allows running async tasks at a priority higher than thread mode. One + /// use case is to leave thread mode free for non-async tasks. Another use case is + /// to run multiple executors: one in thread mode for low priority tasks and another in + /// interrupt mode for higher priority tasks. Higher priority tasks will preempt lower + /// priority ones. /// - /// This function requires `&'static mut self`. This means you have to store the - /// Executor instance in a place where it'll live forever and grants you mutable - /// access. There's a few ways to do this: + /// It is even possible to run multiple interrupt mode executors at different priorities, + /// by assigning different priorities to the interrupts. For an example on how to do this, + /// See the 'multiprio' example for 'embassy-nrf'. /// - /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) - /// - a `static mut` (unsafe) - /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) + /// To use it, you have to pick an interrupt that won't be used by the hardware. + /// Some chips reserve some interrupts for this purpose, sometimes named "software interrupts" (SWI). + /// If this is not the case, you may use an interrupt from any unused peripheral. /// - /// This function never returns. - pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! { - init(self.inner.spawner()); + /// It is somewhat more complex to use, it's recommended to use the thread-mode + /// [`Executor`] instead, if it works for your use case. + pub struct InterruptExecutor { + started: AtomicBool, + executor: UnsafeCell>, + } + + unsafe impl Send for InterruptExecutor {} + unsafe impl Sync for InterruptExecutor {} + + impl InterruptExecutor { + /// Create a new, not started `InterruptExecutor`. + #[inline] + pub const fn new() -> Self { + Self { + started: AtomicBool::new(false), + executor: UnsafeCell::new(MaybeUninit::uninit()), + } + } + + /// Executor interrupt callback. + /// + /// # Safety + /// + /// You MUST call this from the interrupt handler, and from nowhere else. + pub unsafe fn on_interrupt(&'static self) { + let executor = unsafe { (&*self.executor.get()).assume_init_ref() }; + executor.poll(); + } + + /// Start the executor. + /// + /// This initializes the executor, enables the interrupt, and returns. + /// The executor keeps running in the background through the interrupt. + /// + /// This returns a [`SendSpawner`] you can use to spawn tasks on it. A [`SendSpawner`] + /// is returned instead of a [`Spawner`](embassy_executor::Spawner) because the executor effectively runs in a + /// different "thread" (the interrupt), so spawning tasks on it is effectively + /// sending them. + /// + /// To obtain a [`Spawner`](embassy_executor::Spawner) for this executor, use [`Spawner::for_current_executor()`](embassy_executor::Spawner::for_current_executor()) from + /// a task running in it. + /// + /// # Interrupt requirements + /// + /// You must write the interrupt handler yourself, and make it call [`on_interrupt()`](Self::on_interrupt). + /// + /// This method already enables (unmasks) the interrupt, you must NOT do it yourself. + /// + /// You must set the interrupt priority before calling this method. You MUST NOT + /// do it after. + /// + pub fn start(&'static self, irq: impl InterruptNumber) -> crate::SendSpawner { + if self + .started + .compare_exchange(false, true, Ordering::Acquire, Ordering::Relaxed) + .is_err() + { + panic!("InterruptExecutor::start() called multiple times on the same executor."); + } - loop { unsafe { - self.inner.poll(); - asm!("wfe"); - }; + (&mut *self.executor.get()) + .as_mut_ptr() + .write(raw::Executor::new(Pender(PenderInner::Interrupt(InterruptPender( + irq.number(), + ))))) + } + + let executor = unsafe { (&*self.executor.get()).assume_init_ref() }; + + unsafe { NVIC::unmask(irq) } + + executor.spawner().make_send() } } } diff --git a/embassy-executor/src/arch/riscv32.rs b/embassy-executor/src/arch/riscv32.rs index e97a56cda..f66daeae4 100644 --- a/embassy-executor/src/arch/riscv32.rs +++ b/embassy-executor/src/arch/riscv32.rs @@ -1,72 +1,83 @@ -use core::marker::PhantomData; -use core::ptr; -use core::sync::atomic::{AtomicBool, Ordering}; +#[cfg(feature = "executor-interrupt")] +compile_error!("`executor-interrupt` is not supported with `arch-riscv32`."); -use super::{raw, Spawner}; +#[cfg(feature = "executor-thread")] +pub use thread::*; +#[cfg(feature = "executor-thread")] +mod thread { + use core::marker::PhantomData; + use core::sync::atomic::{AtomicBool, Ordering}; -/// global atomic used to keep track of whether there is work to do since sev() is not available on RISCV -/// -static SIGNAL_WORK_THREAD_MODE: AtomicBool = AtomicBool::new(false); + use crate::raw::{Pender, PenderInner}; + use crate::{raw, Spawner}; -/// RISCV32 Executor -pub struct Executor { - inner: raw::Executor, - not_send: PhantomData<*mut ()>, -} + #[derive(Copy, Clone)] + pub(crate) struct ThreadPender; -impl Executor { - /// Create a new Executor. - pub fn new() -> Self { - Self { - // use Signal_Work_Thread_Mode as substitute for local interrupt register - inner: raw::Executor::new( - |_| { - SIGNAL_WORK_THREAD_MODE.store(true, Ordering::SeqCst); - }, - ptr::null_mut(), - ), - not_send: PhantomData, + impl ThreadPender { + #[allow(unused)] + pub(crate) fn pend(self) { + SIGNAL_WORK_THREAD_MODE.store(true, core::sync::atomic::Ordering::SeqCst); } } - /// Run the executor. - /// - /// The `init` closure is called with a [`Spawner`] that spawns tasks on - /// this executor. Use it to spawn the initial task(s). After `init` returns, - /// the executor starts running the tasks. - /// - /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), - /// for example by passing it as an argument to the initial tasks. - /// - /// This function requires `&'static mut self`. This means you have to store the - /// Executor instance in a place where it'll live forever and grants you mutable - /// access. There's a few ways to do this: - /// - /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) - /// - a `static mut` (unsafe) - /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) - /// - /// This function never returns. - pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! { - init(self.inner.spawner()); + /// global atomic used to keep track of whether there is work to do since sev() is not available on RISCV + static SIGNAL_WORK_THREAD_MODE: AtomicBool = AtomicBool::new(false); + + /// RISCV32 Executor + pub struct Executor { + inner: raw::Executor, + not_send: PhantomData<*mut ()>, + } + + impl Executor { + /// Create a new Executor. + pub fn new() -> Self { + Self { + inner: raw::Executor::new(Pender(PenderInner::Thread(ThreadPender))), + not_send: PhantomData, + } + } + + /// Run the executor. + /// + /// The `init` closure is called with a [`Spawner`] that spawns tasks on + /// this executor. Use it to spawn the initial task(s). After `init` returns, + /// the executor starts running the tasks. + /// + /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), + /// for example by passing it as an argument to the initial tasks. + /// + /// This function requires `&'static mut self`. This means you have to store the + /// Executor instance in a place where it'll live forever and grants you mutable + /// access. There's a few ways to do this: + /// + /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) + /// - a `static mut` (unsafe) + /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) + /// + /// This function never returns. + pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! { + init(self.inner.spawner()); - loop { - unsafe { - self.inner.poll(); - // we do not care about race conditions between the load and store operations, interrupts - //will only set this value to true. - critical_section::with(|_| { - // if there is work to do, loop back to polling - // TODO can we relax this? - if SIGNAL_WORK_THREAD_MODE.load(Ordering::SeqCst) { - SIGNAL_WORK_THREAD_MODE.store(false, Ordering::SeqCst); - } - // if not, wait for interrupt - else { - core::arch::asm!("wfi"); - } - }); - // if an interrupt occurred while waiting, it will be serviced here + loop { + unsafe { + self.inner.poll(); + // we do not care about race conditions between the load and store operations, interrupts + //will only set this value to true. + critical_section::with(|_| { + // if there is work to do, loop back to polling + // TODO can we relax this? + if SIGNAL_WORK_THREAD_MODE.load(Ordering::SeqCst) { + SIGNAL_WORK_THREAD_MODE.store(false, Ordering::SeqCst); + } + // if not, wait for interrupt + else { + core::arch::asm!("wfi"); + } + }); + // if an interrupt occurred while waiting, it will be serviced here + } } } } diff --git a/embassy-executor/src/arch/std.rs b/embassy-executor/src/arch/std.rs index 701f0eb18..4e4a178f0 100644 --- a/embassy-executor/src/arch/std.rs +++ b/embassy-executor/src/arch/std.rs @@ -1,84 +1,100 @@ -use std::marker::PhantomData; -use std::sync::{Condvar, Mutex}; +#[cfg(feature = "executor-interrupt")] +compile_error!("`executor-interrupt` is not supported with `arch-std`."); -use super::{raw, Spawner}; +#[cfg(feature = "executor-thread")] +pub use thread::*; +#[cfg(feature = "executor-thread")] +mod thread { + use std::marker::PhantomData; + use std::sync::{Condvar, Mutex}; -/// Single-threaded std-based executor. -pub struct Executor { - inner: raw::Executor, - not_send: PhantomData<*mut ()>, - signaler: &'static Signaler, -} + #[cfg(feature = "nightly")] + pub use embassy_macros::main_std as main; + + use crate::raw::{Pender, PenderInner}; + use crate::{raw, Spawner}; -impl Executor { - /// Create a new Executor. - pub fn new() -> Self { - let signaler = &*Box::leak(Box::new(Signaler::new())); - Self { - inner: raw::Executor::new( - |p| unsafe { - let s = &*(p as *const () as *const Signaler); - s.signal() - }, - signaler as *const _ as _, - ), - not_send: PhantomData, - signaler, + #[derive(Copy, Clone)] + pub(crate) struct ThreadPender(&'static Signaler); + + impl ThreadPender { + #[allow(unused)] + pub(crate) fn pend(self) { + self.0.signal() } } - /// Run the executor. - /// - /// The `init` closure is called with a [`Spawner`] that spawns tasks on - /// this executor. Use it to spawn the initial task(s). After `init` returns, - /// the executor starts running the tasks. - /// - /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), - /// for example by passing it as an argument to the initial tasks. - /// - /// This function requires `&'static mut self`. This means you have to store the - /// Executor instance in a place where it'll live forever and grants you mutable - /// access. There's a few ways to do this: - /// - /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) - /// - a `static mut` (unsafe) - /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) - /// - /// This function never returns. - pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! { - init(self.inner.spawner()); + /// Single-threaded std-based executor. + pub struct Executor { + inner: raw::Executor, + not_send: PhantomData<*mut ()>, + signaler: &'static Signaler, + } - loop { - unsafe { self.inner.poll() }; - self.signaler.wait() + impl Executor { + /// Create a new Executor. + pub fn new() -> Self { + let signaler = &*Box::leak(Box::new(Signaler::new())); + Self { + inner: raw::Executor::new(Pender(PenderInner::Thread(ThreadPender(signaler)))), + not_send: PhantomData, + signaler, + } } - } -} -struct Signaler { - mutex: Mutex, - condvar: Condvar, -} + /// Run the executor. + /// + /// The `init` closure is called with a [`Spawner`] that spawns tasks on + /// this executor. Use it to spawn the initial task(s). After `init` returns, + /// the executor starts running the tasks. + /// + /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), + /// for example by passing it as an argument to the initial tasks. + /// + /// This function requires `&'static mut self`. This means you have to store the + /// Executor instance in a place where it'll live forever and grants you mutable + /// access. There's a few ways to do this: + /// + /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) + /// - a `static mut` (unsafe) + /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) + /// + /// This function never returns. + pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! { + init(self.inner.spawner()); -impl Signaler { - fn new() -> Self { - Self { - mutex: Mutex::new(false), - condvar: Condvar::new(), + loop { + unsafe { self.inner.poll() }; + self.signaler.wait() + } } } - fn wait(&self) { - let mut signaled = self.mutex.lock().unwrap(); - while !*signaled { - signaled = self.condvar.wait(signaled).unwrap(); - } - *signaled = false; + struct Signaler { + mutex: Mutex, + condvar: Condvar, } - fn signal(&self) { - let mut signaled = self.mutex.lock().unwrap(); - *signaled = true; - self.condvar.notify_one(); + impl Signaler { + fn new() -> Self { + Self { + mutex: Mutex::new(false), + condvar: Condvar::new(), + } + } + + fn wait(&self) { + let mut signaled = self.mutex.lock().unwrap(); + while !*signaled { + signaled = self.condvar.wait(signaled).unwrap(); + } + *signaled = false; + } + + fn signal(&self) { + let mut signaled = self.mutex.lock().unwrap(); + *signaled = true; + self.condvar.notify_one(); + } } } diff --git a/embassy-executor/src/arch/wasm.rs b/embassy-executor/src/arch/wasm.rs index 98091cfbb..08ab16b99 100644 --- a/embassy-executor/src/arch/wasm.rs +++ b/embassy-executor/src/arch/wasm.rs @@ -1,74 +1,88 @@ -use core::marker::PhantomData; +#[cfg(feature = "executor-interrupt")] +compile_error!("`executor-interrupt` is not supported with `arch-wasm`."); -use js_sys::Promise; -use wasm_bindgen::prelude::*; +#[cfg(feature = "executor-thread")] +pub use thread::*; +#[cfg(feature = "executor-thread")] +mod thread { -use super::raw::util::UninitCell; -use super::raw::{self}; -use super::Spawner; + use core::marker::PhantomData; -/// WASM executor, wasm_bindgen to schedule tasks on the JS event loop. -pub struct Executor { - inner: raw::Executor, - ctx: &'static WasmContext, - not_send: PhantomData<*mut ()>, -} + #[cfg(feature = "nightly")] + pub use embassy_macros::main_wasm as main; + use js_sys::Promise; + use wasm_bindgen::prelude::*; -pub(crate) struct WasmContext { - promise: Promise, - closure: UninitCell>, -} + use crate::raw::util::UninitCell; + use crate::raw::{Pender, PenderInner}; + use crate::{raw, Spawner}; + + /// WASM executor, wasm_bindgen to schedule tasks on the JS event loop. + pub struct Executor { + inner: raw::Executor, + ctx: &'static WasmContext, + not_send: PhantomData<*mut ()>, + } + + pub(crate) struct WasmContext { + promise: Promise, + closure: UninitCell>, + } + + #[derive(Copy, Clone)] + pub(crate) struct ThreadPender(&'static WasmContext); -impl WasmContext { - pub fn new() -> Self { - Self { - promise: Promise::resolve(&JsValue::undefined()), - closure: UninitCell::uninit(), + impl ThreadPender { + #[allow(unused)] + pub(crate) fn pend(self) { + let _ = self.0.promise.then(unsafe { self.0.closure.as_mut() }); } } -} -impl Executor { - /// Create a new Executor. - pub fn new() -> Self { - let ctx = &*Box::leak(Box::new(WasmContext::new())); - let inner = raw::Executor::new( - |p| unsafe { - let ctx = &*(p as *const () as *const WasmContext); - let _ = ctx.promise.then(ctx.closure.as_mut()); - }, - ctx as *const _ as _, - ); - Self { - inner, - not_send: PhantomData, - ctx, + impl WasmContext { + pub fn new() -> Self { + Self { + promise: Promise::resolve(&JsValue::undefined()), + closure: UninitCell::uninit(), + } } } - /// Run the executor. - /// - /// The `init` closure is called with a [`Spawner`] that spawns tasks on - /// this executor. Use it to spawn the initial task(s). After `init` returns, - /// the executor starts running the tasks. - /// - /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), - /// for example by passing it as an argument to the initial tasks. - /// - /// This function requires `&'static mut self`. This means you have to store the - /// Executor instance in a place where it'll live forever and grants you mutable - /// access. There's a few ways to do this: - /// - /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) - /// - a `static mut` (unsafe) - /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) - pub fn start(&'static mut self, init: impl FnOnce(Spawner)) { - unsafe { - let executor = &self.inner; - self.ctx.closure.write(Closure::new(move |_| { - executor.poll(); - })); - init(self.inner.spawner()); + impl Executor { + /// Create a new Executor. + pub fn new() -> Self { + let ctx = &*Box::leak(Box::new(WasmContext::new())); + Self { + inner: raw::Executor::new(Pender(PenderInner::Thread(ThreadPender(ctx)))), + not_send: PhantomData, + ctx, + } + } + + /// Run the executor. + /// + /// The `init` closure is called with a [`Spawner`] that spawns tasks on + /// this executor. Use it to spawn the initial task(s). After `init` returns, + /// the executor starts running the tasks. + /// + /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), + /// for example by passing it as an argument to the initial tasks. + /// + /// This function requires `&'static mut self`. This means you have to store the + /// Executor instance in a place where it'll live forever and grants you mutable + /// access. There's a few ways to do this: + /// + /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) + /// - a `static mut` (unsafe) + /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) + pub fn start(&'static mut self, init: impl FnOnce(Spawner)) { + unsafe { + let executor = &self.inner; + self.ctx.closure.write(Closure::new(move |_| { + executor.poll(); + })); + init(self.inner.spawner()); + } } } } diff --git a/embassy-executor/src/arch/xtensa.rs b/embassy-executor/src/arch/xtensa.rs index 4ee0d9f78..61ea92c16 100644 --- a/embassy-executor/src/arch/xtensa.rs +++ b/embassy-executor/src/arch/xtensa.rs @@ -1,73 +1,84 @@ -use core::marker::PhantomData; -use core::ptr; -use core::sync::atomic::{AtomicBool, Ordering}; +#[cfg(feature = "executor-interrupt")] +compile_error!("`executor-interrupt` is not supported with `arch-xtensa`."); -use super::{raw, Spawner}; +#[cfg(feature = "executor-thread")] +pub use thread::*; +#[cfg(feature = "executor-thread")] +mod thread { + use core::marker::PhantomData; + use core::sync::atomic::{AtomicBool, Ordering}; -/// global atomic used to keep track of whether there is work to do since sev() is not available on Xtensa -/// -static SIGNAL_WORK_THREAD_MODE: AtomicBool = AtomicBool::new(false); + use crate::raw::{Pender, PenderInner}; + use crate::{raw, Spawner}; -/// Xtensa Executor -pub struct Executor { - inner: raw::Executor, - not_send: PhantomData<*mut ()>, -} + #[derive(Copy, Clone)] + pub(crate) struct ThreadPender; -impl Executor { - /// Create a new Executor. - pub fn new() -> Self { - Self { - // use Signal_Work_Thread_Mode as substitute for local interrupt register - inner: raw::Executor::new( - |_| { - SIGNAL_WORK_THREAD_MODE.store(true, Ordering::SeqCst); - }, - ptr::null_mut(), - ), - not_send: PhantomData, + impl ThreadPender { + #[allow(unused)] + pub(crate) fn pend(self) { + SIGNAL_WORK_THREAD_MODE.store(true, core::sync::atomic::Ordering::SeqCst); } } - /// Run the executor. - /// - /// The `init` closure is called with a [`Spawner`] that spawns tasks on - /// this executor. Use it to spawn the initial task(s). After `init` returns, - /// the executor starts running the tasks. - /// - /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), - /// for example by passing it as an argument to the initial tasks. - /// - /// This function requires `&'static mut self`. This means you have to store the - /// Executor instance in a place where it'll live forever and grants you mutable - /// access. There's a few ways to do this: - /// - /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) - /// - a `static mut` (unsafe) - /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) - /// - /// This function never returns. - pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! { - init(self.inner.spawner()); + /// global atomic used to keep track of whether there is work to do since sev() is not available on Xtensa + static SIGNAL_WORK_THREAD_MODE: AtomicBool = AtomicBool::new(false); + + /// Xtensa Executor + pub struct Executor { + inner: raw::Executor, + not_send: PhantomData<*mut ()>, + } + + impl Executor { + /// Create a new Executor. + pub fn new() -> Self { + Self { + inner: raw::Executor::new(Pender(PenderInner::Thread(ThreadPender))), + not_send: PhantomData, + } + } + + /// Run the executor. + /// + /// The `init` closure is called with a [`Spawner`] that spawns tasks on + /// this executor. Use it to spawn the initial task(s). After `init` returns, + /// the executor starts running the tasks. + /// + /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`), + /// for example by passing it as an argument to the initial tasks. + /// + /// This function requires `&'static mut self`. This means you have to store the + /// Executor instance in a place where it'll live forever and grants you mutable + /// access. There's a few ways to do this: + /// + /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe) + /// - a `static mut` (unsafe) + /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe) + /// + /// This function never returns. + pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! { + init(self.inner.spawner()); - loop { - unsafe { - self.inner.poll(); - // we do not care about race conditions between the load and store operations, interrupts - // will only set this value to true. - // if there is work to do, loop back to polling - // TODO can we relax this? - critical_section::with(|_| { - if SIGNAL_WORK_THREAD_MODE.load(Ordering::SeqCst) { - SIGNAL_WORK_THREAD_MODE.store(false, Ordering::SeqCst); - } else { - // waiti sets the PS.INTLEVEL when slipping into sleep - // because critical sections in Xtensa are implemented via increasing - // PS.INTLEVEL the critical section ends here - // take care not add code after `waiti` if it needs to be inside the CS - core::arch::asm!("waiti 0"); // critical section ends here - } - }); + loop { + unsafe { + self.inner.poll(); + // we do not care about race conditions between the load and store operations, interrupts + // will only set this value to true. + // if there is work to do, loop back to polling + // TODO can we relax this? + critical_section::with(|_| { + if SIGNAL_WORK_THREAD_MODE.load(Ordering::SeqCst) { + SIGNAL_WORK_THREAD_MODE.store(false, Ordering::SeqCst); + } else { + // waiti sets the PS.INTLEVEL when slipping into sleep + // because critical sections in Xtensa are implemented via increasing + // PS.INTLEVEL the critical section ends here + // take care not add code after `waiti` if it needs to be inside the CS + core::arch::asm!("waiti 0"); // critical section ends here + } + }); + } } } } -- cgit