feat(threads): introduce a declarative macro for autostarting threads (…

…#301)

Cargo.toml

@@ -65,6 +65,7 @@ document-features = "0.2.8"
 heapless = { version = "0.8.0", default-features = false }
 konst = { version = "0.3.8", default-features = false }
 ld-memory = { version = "0.2.9" }
+paste = { version = "1.0" }
 static_cell = { version = "2.0.0", features = ["nightly"] }
 
 [profile.dev]

src/riot-rs-macros/src/thread.rs

@@ -37,7 +37,7 @@ pub fn thread(args: TokenStream, item: TokenStream) -> TokenStream {
     #[allow(clippy::wildcard_imports)]
     use thread::*;
 
-    use quote::{format_ident, quote};
+    use quote::quote;
 
     let mut attrs = Attributes::default();
     let thread_parser = syn::meta::parser(|meta| attrs.parse(&meta));
@@ -57,7 +57,6 @@ pub fn thread(args: TokenStream, item: TokenStream) -> TokenStream {
     };
 
     let fn_name = thread_function.sig.ident.clone();
-    let slice_fn_name_ident = format_ident!("__start_thread_{fn_name}");
     let Parameters {
         stack_size,
         priority,
@@ -69,12 +68,7 @@ pub fn thread(args: TokenStream, item: TokenStream) -> TokenStream {
         #no_mangle_attr
         #thread_function
 
-        #[#riot_rs_crate::linkme::distributed_slice(#riot_rs_crate::thread::THREAD_FNS)]
-        #[linkme(crate = #riot_rs_crate::linkme)]
-        fn #slice_fn_name_ident() {
-            let stack = #riot_rs_crate::static_cell::make_static!([0u8; #stack_size as usize]);
-            #riot_rs_crate::thread::thread_create_noarg(#fn_name, stack, #priority);
-        }
+        #riot_rs_crate::thread::autostart_thread!(#fn_name, stacksize = #stack_size, priority = #priority);
     };
 
     TokenStream::from(expanded)

src/riot-rs-threads/Cargo.toml

@@ -14,7 +14,9 @@ workspace = true
 cfg-if.workspace = true
 critical-section.workspace = true
 linkme = { workspace = true }
+paste.workspace = true
 riot-rs-runqueue.workspace = true
+static_cell.workspace = true
 
 [target.'cfg(context = "esp32c3")'.dependencies]
 esp-hal = { workspace = true, features = ["esp32c3"] }

src/riot-rs-threads/src/autostart_thread.rs

@@ -0,0 +1,16 @@
+/// Starts the `fn_name` function in a dedicated thread at startup.
+///
+/// The thread is given a `stacksize`-byte stack, and has priority `priority`.
+#[macro_export]
+macro_rules! autostart_thread {
+    ($fn_name:ident, stacksize = $stacksize:literal, priority = $priority:literal) => {
+        $crate::macro_reexports::paste::paste! {
+            #[$crate::macro_reexports::linkme::distributed_slice($crate::THREAD_FNS)]
+            #[linkme(crate = $crate::macro_reexports::linkme)]
+            fn [<__start_thread_ $fn_name>] () {
+                let stack = $crate::macro_reexports::static_cell::make_static!([0u8; $stacksize as usize]);
+                $crate::thread_create_noarg($fn_name, stack, $priority);
+            }
+        }
+    };
+}

src/riot-rs-threads/src/lib.rs

@@ -6,6 +6,7 @@
 #![allow(clippy::indexing_slicing)]
 
 mod arch;
+mod autostart_thread;
 mod ensure_once;
 mod thread;
 mod threadlist;
@@ -14,6 +15,14 @@ pub mod channel;
 pub mod lock;
 pub mod thread_flags;
 
+#[doc(hidden)]
+pub mod macro_reexports {
+    // Used by `autostart_thread`
+    pub use linkme;
+    pub use paste;
+    pub use static_cell;
+}
+
 pub use riot_rs_runqueue::{RunqueueId, ThreadId};
 pub use thread_flags as flags;