POC: allow custom executors

1 files changed, 38 insertions, 62 deletions

diff --git a/embassy-executor/src/arch/riscv32.rs b/embassy-executor/src/arch/riscv32.rs
index ff7ec1575..5f766442d 100644
--- a/embassy-executor/src/arch/riscv32.rs
+++ b/embassy-executor/src/arch/riscv32.rs
@@ -1,6 +1,9 @@
 #[cfg(feature = "executor-interrupt")]
 compile_error!("`executor-interrupt` is not supported with `arch-riscv32`.");
 
+#[cfg(feature = "thread-context")]
+compile_error!("`thread-context` is not supported with `arch-riscv32`.");
+
 #[cfg(feature = "executor-thread")]
 pub use thread::*;
 #[cfg(feature = "executor-thread")]
@@ -11,77 +14,50 @@ mod thread {
     #[cfg(feature = "nightly")]
     pub use embassy_macros::main_riscv as main;
 
-    use crate::raw::{Pender, PenderInner};
-    use crate::{raw, Spawner};
-
-    #[derive(Copy, Clone)]
-    pub(crate) struct ThreadPender;
-
-    impl ThreadPender {
-        #[allow(unused)]
-        pub(crate) fn pend(self) {
-            SIGNAL_WORK_THREAD_MODE.store(true, core::sync::atomic::Ordering::SeqCst);
-        }
-    }
+    use crate::raw::OpaqueThreadContext;
+    use crate::thread::ThreadContext;
 
     /// 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 ()>,
+    #[export_name = "__thread_mode_pender"]
+    fn __thread_mode_pender(_core_id: OpaqueThreadContext) {
+        SIGNAL_WORK_THREAD_MODE.store(true, Ordering::SeqCst);
     }
 
-    impl Executor {
-        /// Create a new Executor.
-        pub fn new() -> Self {
-            Self {
-                inner: raw::Executor::new(Pender(PenderInner::Thread(ThreadPender))),
-                not_send: PhantomData,
-            }
-        }
+    /// TODO
+    // Name pending
+    #[derive(Default)] // Default enables Executor::new
+    pub struct RiscVThreadContext {
+        _not_send: PhantomData<*mut ()>,
+    }
 
-        /// 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 ThreadContext for RiscVThreadContext {
+        fn context(&self) -> OpaqueThreadContext {
+            OpaqueThreadContext(())
+        }
 
-            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
+        fn wait(&mut self) {
+            // 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 {
+                    unsafe {
+                        core::arch::asm!("wfi");
+                    }
+                }
+            });
+            // if an interrupt occurred while waiting, it will be serviced here
         }
     }
+
+    /// TODO
+    // Type alias for backwards compatibility
+    pub type Executor = crate::thread::ThreadModeExecutor<RiscVThreadContext>;
 }