Make interrupt module more standard.

- Move typelevel interrupts to a special-purpose mod: `embassy_xx::interrupt::typelevel`.
- Reexport the PAC interrupt enum in `embassy_xx::interrupt`.

This has a few advantages:
- The `embassy_xx::interrupt` module is now more "standard".
  - It works with `cortex-m` functions for manipulating interrupts, for example.
  - It works with RTIC.
- the interrupt enum allows holding value that can be "any interrupt at runtime", this can't be done with typelevel irqs.
- When "const-generics on enums" is stable, we can remove the typelevel interrupts without disruptive changes to `embassy_xx::interrupt`.

embassy-macros/src/lib.rs

@@ -156,16 +156,3 @@ pub fn main_wasm(args: TokenStream, item: TokenStream) -> TokenStream {
     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]
-pub fn cortex_m_interrupt(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);
-    cortex_m_interrupt::run(args, f).unwrap_or_else(|x| x).into()
-}
-
-#[proc_macro]
-pub fn cortex_m_interrupt_declare(item: TokenStream) -> TokenStream {
-    let name = syn::parse_macro_input!(item as syn::Ident);
-    cortex_m_interrupt_declare::run(name).unwrap_or_else(|x| x).into()
-}

embassy-macros/src/macros/cortex_m_interrupt.rs

@@ -1,66 +0,0 @@
-use std::iter;
-
-use darling::FromMeta;
-use proc_macro2::TokenStream;
-use quote::quote;
-use syn::{ReturnType, Type, Visibility};
-
-use crate::util::ctxt::Ctxt;
-
-#[derive(Debug, FromMeta)]
-struct Args {}
-
-pub fn run(args: syn::AttributeArgs, mut f: syn::ItemFn) -> Result<TokenStream, TokenStream> {
-    let _args = Args::from_list(&args).map_err(|e| e.write_errors())?;
-
-    let ident = f.sig.ident.clone();
-    let ident_s = ident.to_string();
-
-    // XXX should we blacklist other attributes?
-
-    let valid_signature = f.sig.constness.is_none()
-        && f.vis == Visibility::Inherited
-        && f.sig.abi.is_none()
-        && f.sig.inputs.is_empty()
-        && f.sig.generics.params.is_empty()
-        && f.sig.generics.where_clause.is_none()
-        && f.sig.variadic.is_none()
-        && match f.sig.output {
-            ReturnType::Default => true,
-            ReturnType::Type(_, ref ty) => match **ty {
-                Type::Tuple(ref tuple) => tuple.elems.is_empty(),
-                Type::Never(..) => true,
-                _ => false,
-            },
-        };
-
-    let ctxt = Ctxt::new();
-
-    if !valid_signature {
-        ctxt.error_spanned_by(
-            &f.sig,
-            "`#[interrupt]` handlers must have signature `[unsafe] fn() [-> !]`",
-        );
-    }
-
-    ctxt.check()?;
-
-    f.block.stmts = iter::once(
-        syn::parse2(quote! {{
-            // Check that this interrupt actually exists
-            let __irq_exists_check: interrupt::#ident;
-        }})
-        .unwrap(),
-    )
-    .chain(f.block.stmts)
-    .collect();
-
-    let result = quote!(
-        #[doc(hidden)]
-        #[export_name = #ident_s]
-        #[allow(non_snake_case)]
-        #f
-    );
-
-    Ok(result)
-}

embassy-macros/src/macros/cortex_m_interrupt_declare.rs

@@ -1,21 +0,0 @@
-use proc_macro2::TokenStream;
-use quote::{format_ident, quote};
-
-pub fn run(name: syn::Ident) -> Result<TokenStream, TokenStream> {
-    let name = format_ident!("{}", name);
-    let doc = format!("{} interrupt.", name);
-
-    let result = quote! {
-        #[doc = #doc]
-        #[allow(non_camel_case_types)]
-        pub enum #name{}
-        unsafe impl ::embassy_cortex_m::interrupt::Interrupt for #name {
-            fn number() -> u16 {
-                use cortex_m::interrupt::InterruptNumber;
-                let irq = InterruptEnum::#name;
-                irq.number() as u16
-            }
-        }
-    };
-    Ok(result)
-}

embassy-macros/src/macros/mod.rs

@@ -1,4 +1,2 @@
-pub mod cortex_m_interrupt;
-pub mod cortex_m_interrupt_declare;
 pub mod main;
 pub mod task;