refactor: autodetect macro variant

Export all main macro per target architecture from embassy-macros,
and select the appropriate macro in embassy-executor.

embassy-macros/src/lib.rs

@@ -45,7 +45,7 @@ pub fn task(args: TokenStream, item: TokenStream) -> TokenStream {
     task::run(args, f).unwrap_or_else(|x| x).into()
 }
 
-/// Creates a new `executor` instance and declares an application entry point spawning the corresponding function body as an async task.
+/// Creates a new `executor` instance and declares an application entry point for Cortex-M spawning the corresponding function body as an async task.
 ///
 /// The following restrictions apply:
 ///
@@ -64,10 +64,85 @@ pub fn task(args: TokenStream, item: TokenStream) -> TokenStream {
 /// }
 /// ```
 #[proc_macro_attribute]
-pub fn main(args: TokenStream, item: TokenStream) -> TokenStream {
+pub fn main_cortex_m(args: TokenStream, item: TokenStream) -> TokenStream {
     let args = syn::parse_macro_input!(args as syn::AttributeArgs);
     let f = syn::parse_macro_input!(item as syn::ItemFn);
-    main::run(args, f).unwrap_or_else(|x| x).into()
+    main::run(args, f, main::cortex_m()).unwrap_or_else(|x| x).into()
+}
+
+/// Creates a new `executor` instance and declares an application entry point for RISC-V spawning the corresponding function body as an async task.
+///
+/// The following restrictions apply:
+///
+/// * The function must accept exactly 1 parameter, an `embassy_executor::Spawner` handle that it can use to spawn additional tasks.
+/// * The function must be declared `async`.
+/// * The function must not use generics.
+/// * Only a single `main` task may be declared.
+///
+/// ## Examples
+/// Spawning a task:
+///
+/// ``` rust
+/// #[embassy_executor::main]
+/// async fn main(_s: embassy_executor::Spawner) {
+///     // Function body
+/// }
+/// ```
+#[proc_macro_attribute]
+pub fn main_riscv(args: TokenStream, item: TokenStream) -> TokenStream {
+    let args = syn::parse_macro_input!(args as syn::AttributeArgs);
+    let f = syn::parse_macro_input!(item as syn::ItemFn);
+    main::run(args, f, main::riscv()).unwrap_or_else(|x| x).into()
+}
+
+/// Creates a new `executor` instance and declares an application entry point for STD spawning the corresponding function body as an async task.
+///
+/// The following restrictions apply:
+///
+/// * The function must accept exactly 1 parameter, an `embassy_executor::Spawner` handle that it can use to spawn additional tasks.
+/// * The function must be declared `async`.
+/// * The function must not use generics.
+/// * Only a single `main` task may be declared.
+///
+/// ## Examples
+/// Spawning a task:
+///
+/// ``` rust
+/// #[embassy_executor::main]
+/// async fn main(_s: embassy_executor::Spawner) {
+///     // Function body
+/// }
+/// ```
+#[proc_macro_attribute]
+pub fn main_std(args: TokenStream, item: TokenStream) -> TokenStream {
+    let args = syn::parse_macro_input!(args as syn::AttributeArgs);
+    let f = syn::parse_macro_input!(item as syn::ItemFn);
+    main::run(args, f, main::std()).unwrap_or_else(|x| x).into()
+}
+
+/// Creates a new `executor` instance and declares an application entry point for WASM spawning the corresponding function body as an async task.
+///
+/// The following restrictions apply:
+///
+/// * The function must accept exactly 1 parameter, an `embassy_executor::Spawner` handle that it can use to spawn additional tasks.
+/// * The function must be declared `async`.
+/// * The function must not use generics.
+/// * Only a single `main` task may be declared.
+///
+/// ## Examples
+/// Spawning a task:
+///
+/// ``` rust
+/// #[embassy_executor::main]
+/// async fn main(_s: embassy_executor::Spawner) {
+///     // Function body
+/// }
+/// ```
+#[proc_macro_attribute]
+pub fn main_wasm(args: TokenStream, item: TokenStream) -> TokenStream {
+    let args = syn::parse_macro_input!(args as syn::AttributeArgs);
+    let f = syn::parse_macro_input!(item as syn::ItemFn);
+    main::run(args, f, main::wasm()).unwrap_or_else(|x| x).into()
 }
 
 #[proc_macro_attribute]