Add Cpu::COUNT and clean up in esp-hal-embassy (#2411)

* Add Cpu::COUNT and simplify

* Avoid a bounds check during pending

Author: bugadani

esp-hal-embassy/src/executor/interrupt.rs

@@ -99,7 +99,7 @@ impl<const SWI: u8> InterruptExecutor<SWI> {
         unsafe {
             (*self.executor.get())
                 .as_mut_ptr()
-                .write(raw::Executor::new(SWI as *mut ()));
+                .write(raw::Executor::new((SWI as usize) as *mut ()));
 
             EXECUTORS[SWI as usize].set((*self.executor.get()).as_mut_ptr());
         }

esp-hal-embassy/src/executor/mod.rs

@@ -7,19 +7,18 @@ mod thread;
 fn __pender(context: *mut ()) {
     use esp_hal::interrupt::software::SoftwareInterrupt;
 
-    let context = (context as usize).to_le_bytes();
-
-    match context[0] {
+    match context as usize {
         // For interrupt executors, the context value is the
         // software interrupt number
         0 => unsafe { SoftwareInterrupt::<0>::steal().raise() },
         1 => unsafe { SoftwareInterrupt::<1>::steal().raise() },
         2 => unsafe { SoftwareInterrupt::<2>::steal().raise() },
+        #[cfg(not(multi_core))]
         3 => unsafe { SoftwareInterrupt::<3>::steal().raise() },
-        other => {
-            assert_eq!(other, THREAD_MODE_CONTEXT);
-            // THREAD_MODE_CONTEXT id is reserved for thread mode executors
-            thread::pend_thread_mode(context[1] as usize)
-        }
+        // THREAD_MODE_CONTEXT + core ID
+        16 => thread::pend_thread_mode(0),
+        #[cfg(multi_core)]
+        17 => thread::pend_thread_mode(1),
+        _ => unreachable!(),
     }
 }

esp-hal-embassy/src/executor/thread.rs

@@ -3,19 +3,17 @@
 use core::marker::PhantomData;
 
 use embassy_executor::{raw, Spawner};
-use esp_hal::get_core;
+use esp_hal::{get_core, Cpu};
 #[cfg(multi_core)]
 use esp_hal::{interrupt::software::SoftwareInterrupt, macros::handler};
 use portable_atomic::{AtomicBool, Ordering};
 
-pub(crate) const THREAD_MODE_CONTEXT: u8 = 16;
+pub(crate) const THREAD_MODE_CONTEXT: usize = 16;
 
 /// global atomic used to keep track of whether there is work to do since sev()
 /// is not available on either Xtensa or RISC-V
-#[cfg(not(multi_core))]
-static SIGNAL_WORK_THREAD_MODE: [AtomicBool; 1] = [AtomicBool::new(false)];
-#[cfg(multi_core)]
-static SIGNAL_WORK_THREAD_MODE: [AtomicBool; 2] = [AtomicBool::new(false), AtomicBool::new(false)];
+static SIGNAL_WORK_THREAD_MODE: [AtomicBool; Cpu::COUNT] =
+    [const { AtomicBool::new(false) }; Cpu::COUNT];
 
 #[cfg(multi_core)]
 #[handler]
@@ -72,12 +70,7 @@ This will use software-interrupt 3 which isn't available for anything else to wa
         }
 
         Self {
-            inner: raw::Executor::new(usize::from_le_bytes([
-                THREAD_MODE_CONTEXT,
-                get_core() as u8,
-                0,
-                0,
-            ]) as *mut ()),
+            inner: raw::Executor::new((THREAD_MODE_CONTEXT + get_core() as usize) as *mut ()),
             not_send: PhantomData,
         }
     }

esp-hal/CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `Pins::steal()` to unsafely obtain GPIO. (#2335)
 - `I2c::with_timeout` (#2361)
 - `Spi::half_duplex_read` and `Spi::half_duplex_write` (#2373)
+- `Cpu::COUNT` and `Cpu::current()` (#?)
 
 ### Changed
 

esp-hal/src/lib.rs

@@ -363,6 +363,17 @@ pub enum Cpu {
     AppCpu = 1,
 }
 
+impl Cpu {
+    /// The number of available cores.
+    pub const COUNT: usize = 1 + cfg!(multi_core) as usize;
+
+    /// Returns the core the application is currently executing on
+    #[inline(always)]
+    pub fn current() -> Self {
+        get_core()
+    }
+}
+
 /// Which core the application is currently executing on
 #[inline(always)]
 pub fn get_core() -> Cpu {