|
| 1 | +//! Expansion of `#[zephyr::task(...)]`. |
| 2 | +
|
| 3 | +use std::{ffi::CString, fmt::Display}; |
| 4 | + |
| 5 | +use darling::FromMeta; |
| 6 | +use darling::export::NestedMeta; |
| 7 | +use proc_macro2::{Literal, Span, TokenStream}; |
| 8 | +use quote::{ToTokens, format_ident, quote}; |
| 9 | +use syn::{ |
| 10 | + Expr, ExprLit, ItemFn, Lit, LitInt, ReturnType, Type, |
| 11 | + visit::{self, Visit}, |
| 12 | +}; |
| 13 | + |
| 14 | +#[derive(Debug, FromMeta, Default)] |
| 15 | +struct Args { |
| 16 | + #[darling(default)] |
| 17 | + pool_size: Option<syn::Expr>, |
| 18 | + #[darling(default)] |
| 19 | + stack_size: Option<syn::Expr>, |
| 20 | +} |
| 21 | + |
| 22 | +pub fn run(args: TokenStream, item: TokenStream) -> TokenStream { |
| 23 | + let mut errors = TokenStream::new(); |
| 24 | + |
| 25 | + // If any of the steps for this macro fail, we still want to expand to an item that is as close |
| 26 | + // to the expected output as possible. This helps out IDEs such that completions and other |
| 27 | + // related features keep working. |
| 28 | + let f: ItemFn = match syn::parse2(item.clone()) { |
| 29 | + Ok(x) => x, |
| 30 | + Err(e) => return token_stream_with_error(item, e), |
| 31 | + }; |
| 32 | + |
| 33 | + let args = match NestedMeta::parse_meta_list(args) { |
| 34 | + Ok(x) => x, |
| 35 | + Err(e) => return token_stream_with_error(item, e), |
| 36 | + }; |
| 37 | + |
| 38 | + let args = match Args::from_list(&args) { |
| 39 | + Ok(x) => x, |
| 40 | + Err(e) => { |
| 41 | + errors.extend(e.write_errors()); |
| 42 | + Args::default() |
| 43 | + } |
| 44 | + }; |
| 45 | + |
| 46 | + let pool_size = args.pool_size.unwrap_or(Expr::Lit(ExprLit { |
| 47 | + attrs: vec![], |
| 48 | + lit: Lit::Int(LitInt::new("1", Span::call_site())), |
| 49 | + })); |
| 50 | + |
| 51 | + let stack_size = args.stack_size.unwrap_or(Expr::Lit(ExprLit { |
| 52 | + attrs: vec![], |
| 53 | + // TODO: Instead of a default, require this. |
| 54 | + lit: Lit::Int(LitInt::new("2048", Span::call_site())), |
| 55 | + })); |
| 56 | + |
| 57 | + if !f.sig.asyncness.is_none() { |
| 58 | + error(&mut errors, &f.sig, "thread function must not be async"); |
| 59 | + } |
| 60 | + |
| 61 | + if !f.sig.generics.params.is_empty() { |
| 62 | + error(&mut errors, &f.sig, "thread function must not be generic"); |
| 63 | + } |
| 64 | + |
| 65 | + if !f.sig.generics.where_clause.is_none() { |
| 66 | + error( |
| 67 | + &mut errors, |
| 68 | + &f.sig, |
| 69 | + "thread function must not have `where` clauses", |
| 70 | + ); |
| 71 | + } |
| 72 | + |
| 73 | + if !f.sig.abi.is_none() { |
| 74 | + error( |
| 75 | + &mut errors, |
| 76 | + &f.sig, |
| 77 | + "thread function must not have an ABI qualifier", |
| 78 | + ); |
| 79 | + } |
| 80 | + |
| 81 | + if !f.sig.variadic.is_none() { |
| 82 | + error(&mut errors, &f.sig, "thread function must not be variadic"); |
| 83 | + } |
| 84 | + |
| 85 | + match &f.sig.output { |
| 86 | + ReturnType::Default => {} |
| 87 | + ReturnType::Type(_, ty) => match &**ty { |
| 88 | + Type::Tuple(tuple) if tuple.elems.is_empty() => {} |
| 89 | + Type::Never(_) => {} |
| 90 | + _ => error( |
| 91 | + &mut errors, |
| 92 | + &f.sig, |
| 93 | + "thread functions must either not return a value, return (), or return `!`", |
| 94 | + ), |
| 95 | + }, |
| 96 | + } |
| 97 | + |
| 98 | + let mut args = Vec::new(); |
| 99 | + let mut fargs = f.sig.inputs.clone(); |
| 100 | + let mut inner_calling = Vec::new(); |
| 101 | + let mut inner_args = Vec::new(); |
| 102 | + |
| 103 | + for arg in fargs.iter_mut() { |
| 104 | + match arg { |
| 105 | + syn::FnArg::Receiver(_) => { |
| 106 | + error( |
| 107 | + &mut errors, |
| 108 | + arg, |
| 109 | + "thread functions must not have `self` arguments", |
| 110 | + ); |
| 111 | + } |
| 112 | + syn::FnArg::Typed(t) => { |
| 113 | + check_arg_ty(&mut errors, &t.ty); |
| 114 | + match t.pat.as_mut() { |
| 115 | + syn::Pat::Ident(id) => { |
| 116 | + id.mutability = None; |
| 117 | + args.push((id.clone(), t.attrs.clone())); |
| 118 | + inner_calling.push(quote! { |
| 119 | + data.#id, |
| 120 | + }); |
| 121 | + inner_args.push(quote! {#id,}); |
| 122 | + } |
| 123 | + _ => { |
| 124 | + error( |
| 125 | + &mut errors, |
| 126 | + arg, |
| 127 | + "pattern matching in task arguments is not yet supported", |
| 128 | + ); |
| 129 | + } |
| 130 | + } |
| 131 | + } |
| 132 | + } |
| 133 | + } |
| 134 | + |
| 135 | + let thread_ident = f.sig.ident.clone(); |
| 136 | + let thread_inner_ident = format_ident!("__{}_thread", thread_ident); |
| 137 | + |
| 138 | + let mut thread_inner = f.clone(); |
| 139 | + let visibility = thread_inner.vis.clone(); |
| 140 | + thread_inner.vis = syn::Visibility::Inherited; |
| 141 | + thread_inner.sig.ident = thread_inner_ident.clone(); |
| 142 | + |
| 143 | + // Assemble the original input arguments. |
| 144 | + let mut full_args = Vec::new(); |
| 145 | + for (arg, cfgs) in &args { |
| 146 | + full_args.push(quote! { |
| 147 | + #(#cfgs)* |
| 148 | + #arg |
| 149 | + }); |
| 150 | + } |
| 151 | + |
| 152 | + let thread_name = Literal::c_string(&CString::new(thread_ident.to_string()).unwrap()); |
| 153 | + |
| 154 | + let mut thread_outer_body = quote! { |
| 155 | + const _ZEPHYR_INTERNAL_STACK_SIZE: usize = zephyr::thread::stack_len(#stack_size); |
| 156 | + const _ZEPHYR_INTERNAL_POOL_SIZE: usize = #pool_size; |
| 157 | + struct _ZephyrInternalArgs { |
| 158 | + // This depends on the argument syntax being valid as a struct definition, which should |
| 159 | + // be the case with the above constraints. |
| 160 | + #fargs |
| 161 | + } |
| 162 | + |
| 163 | + static THREAD: [zephyr::thread::ThreadData<_ZephyrInternalArgs>; _ZEPHYR_INTERNAL_POOL_SIZE] |
| 164 | + = [const { zephyr::thread::ThreadData::new() }; _ZEPHYR_INTERNAL_POOL_SIZE]; |
| 165 | + #[unsafe(link_section = ".noinit.TODO_STACK")] |
| 166 | + static STACK: [zephyr::thread::ThreadStack<_ZEPHYR_INTERNAL_STACK_SIZE>; _ZEPHYR_INTERNAL_POOL_SIZE] |
| 167 | + = [const { zephyr::thread::ThreadStack::new() }; _ZEPHYR_INTERNAL_POOL_SIZE]; |
| 168 | + |
| 169 | + extern "C" fn startup( |
| 170 | + arg0: *mut ::core::ffi::c_void, |
| 171 | + _: *mut ::core::ffi::c_void, |
| 172 | + _: *mut ::core::ffi::c_void, |
| 173 | + ) { |
| 174 | + let init = unsafe { &mut *(arg0 as *mut ::zephyr::thread::InitData<_ZephyrInternalArgs>) }; |
| 175 | + let init = init.0.get(); |
| 176 | + match unsafe { init.replace(None) } { |
| 177 | + None => { |
| 178 | + ::core::panic!("Incorrect thread initialization"); |
| 179 | + } |
| 180 | + Some(data) => { |
| 181 | + #thread_inner_ident(#(#inner_calling)*); |
| 182 | + } |
| 183 | + } |
| 184 | + } |
| 185 | + |
| 186 | + zephyr::thread::ThreadData::acquire( |
| 187 | + &THREAD, |
| 188 | + &STACK, |
| 189 | + _ZephyrInternalArgs { #(#inner_args)* }, |
| 190 | + Some(startup), |
| 191 | + 0, |
| 192 | + #thread_name, |
| 193 | + ) |
| 194 | + }; |
| 195 | + |
| 196 | + let thread_outer_attrs = thread_inner.attrs.clone(); |
| 197 | + |
| 198 | + if !errors.is_empty() { |
| 199 | + thread_outer_body = quote! { |
| 200 | + #[allow(unused_variables, unreachable_code)] |
| 201 | + let _x: ::zephyr::thread::ReadyThread = ::core::todo!(); |
| 202 | + _x |
| 203 | + }; |
| 204 | + } |
| 205 | + |
| 206 | + // Copy the generics + where clause to avoid more spurious errors. |
| 207 | + let generics = &f.sig.generics; |
| 208 | + let where_clause = &f.sig.generics.where_clause; |
| 209 | + |
| 210 | + quote! { |
| 211 | + // This is the user's thread function, renamed. |
| 212 | + #[doc(hidden)] |
| 213 | + #thread_inner |
| 214 | + |
| 215 | + #(#thread_outer_attrs)* |
| 216 | + #visibility fn #thread_ident #generics (#fargs) -> ::zephyr::thread::ReadyThread #where_clause { |
| 217 | + #thread_outer_body |
| 218 | + } |
| 219 | + |
| 220 | + #errors |
| 221 | + } |
| 222 | +} |
| 223 | + |
| 224 | +// Taken from embassy-executor-macros. |
| 225 | +fn check_arg_ty(errors: &mut TokenStream, ty: &Type) { |
| 226 | + struct Visitor<'a> { |
| 227 | + errors: &'a mut TokenStream, |
| 228 | + } |
| 229 | + |
| 230 | + impl<'a, 'ast> Visit<'ast> for Visitor<'a> { |
| 231 | + fn visit_type_reference(&mut self, i: &'ast syn::TypeReference) { |
| 232 | + // only check for elided lifetime here. If not elided, it is checked by |
| 233 | + // `visit_lifetime`. |
| 234 | + if i.lifetime.is_none() { |
| 235 | + error( |
| 236 | + self.errors, |
| 237 | + i.and_token, |
| 238 | + "Arguments for threads must live forever. Try using the `'static` lifetime.", |
| 239 | + ); |
| 240 | + } |
| 241 | + visit::visit_type_reference(self, i); |
| 242 | + } |
| 243 | + |
| 244 | + fn visit_lifetime(&mut self, i: &'ast syn::Lifetime) { |
| 245 | + if i.ident.to_string() != "static" { |
| 246 | + error( |
| 247 | + self.errors, |
| 248 | + i, |
| 249 | + "Arguments for threads must live forever. Try using the `'static` lifetime.", |
| 250 | + ); |
| 251 | + } |
| 252 | + } |
| 253 | + |
| 254 | + fn visit_type_impl_trait(&mut self, i: &'ast syn::TypeImplTrait) { |
| 255 | + error( |
| 256 | + self.errors, |
| 257 | + i, |
| 258 | + "`impl Trait` is not allowed in thread arguments. It is syntax sugar for generics, and threads cannot be generic.", |
| 259 | + ); |
| 260 | + } |
| 261 | + } |
| 262 | + |
| 263 | + Visit::visit_type(&mut Visitor { errors }, ty); |
| 264 | +} |
| 265 | + |
| 266 | +// Utility borrowed from embassy-executor-macros. |
| 267 | +pub fn token_stream_with_error(mut tokens: TokenStream, error: syn::Error) -> TokenStream { |
| 268 | + tokens.extend(error.into_compile_error()); |
| 269 | + tokens |
| 270 | +} |
| 271 | + |
| 272 | +pub fn error<A: ToTokens, T: Display>(s: &mut TokenStream, obj: A, msg: T) { |
| 273 | + s.extend(syn::Error::new_spanned(obj.into_token_stream(), msg).into_compile_error()) |
| 274 | +} |
0 commit comments