rtfm-syntax refactor + heterogeneous multi-core support

macros/src/codegen/post_init.rs

@@ -0,0 +1,139 @@
+use proc_macro2::TokenStream as TokenStream2;
+use quote::quote;
+
+use crate::{analyze::Analysis, check::Extra, codegen::util};
+
+/// Generates code that runs after `#[init]` returns
+pub fn codegen(
+    core: u8,
+    analysis: &Analysis,
+    extra: &Extra,
+) -> (Vec<TokenStream2>, Vec<TokenStream2>) {
+    let mut const_app = vec![];
+    let mut stmts = vec![];
+
+    // initialize late resources
+    if let Some(late_resources) = analysis.late_resources.get(&core) {
+        for name in late_resources {
+            // if it's live
+            if analysis.locations.get(name).is_some() {
+                stmts.push(quote!(#name.as_mut_ptr().write(late.#name);));
+            }
+        }
+    }
+
+    if analysis.timer_queues.is_empty() {
+        // cross-initialization barriers -- notify *other* cores that their resources have been
+        // initialized
+        if analysis.initialization_barriers.contains_key(&core) {
+            let ib = util::init_barrier(core);
+
+            const_app.push(quote!(
+                #[rtfm::export::shared]
+                static #ib: rtfm::export::Barrier = rtfm::export::Barrier::new();
+            ));
+
+            stmts.push(quote!(
+                #ib.release();
+            ));
+        }
+
+        // then wait until the other cores have initialized *our* resources
+        for (&initializer, users) in &analysis.initialization_barriers {
+            if users.contains(&core) {
+                let ib = util::init_barrier(initializer);
+
+                stmts.push(quote!(
+                    #ib.wait();
+                ));
+            }
+        }
+
+        // cross-spawn barriers: wait until other cores are ready to receive messages
+        for (&receiver, senders) in &analysis.spawn_barriers {
+            if senders.get(&core) == Some(&false) {
+                let sb = util::spawn_barrier(receiver);
+
+                stmts.push(quote!(
+                    #sb.wait();
+                ));
+            }
+        }
+    } else {
+        // if the `schedule` API is used then we'll synchronize all cores to leave the
+        // `init`-ialization phase at the same time. In this case the rendezvous barrier makes the
+        // cross-initialization and spawn barriers unnecessary
+
+        let m = extra.monotonic();
+
+        if analysis.timer_queues.len() == 1 {
+            // reset the monotonic timer / counter
+            stmts.push(quote!(
+                <#m as rtfm::Monotonic>::reset();
+            ));
+        } else {
+            // in the multi-core case we need a rendezvous (RV) barrier between *all* the cores that
+            // use the `schedule` API; otherwise one of the cores could observe the before-reset
+            // value of the monotonic counter
+            // (this may be easier to implement with `AtomicU8.fetch_sub` but that API is not
+            // available on ARMv6-M)
+
+            // this core will reset the monotonic counter
+            const FIRST: u8 = 0;
+
+            if core == FIRST {
+                for &i in analysis.timer_queues.keys() {
+                    let rv = util::rendezvous_ident(i);
+
+                    const_app.push(quote!(
+                        #[rtfm::export::shared]
+                        static #rv: rtfm::export::Barrier = rtfm::export::Barrier::new();
+                    ));
+
+                    // wait until all the other cores have reached the RV point
+                    if i != FIRST {
+                        stmts.push(quote!(
+                            #rv.wait();
+                        ));
+                    }
+                }
+
+                let rv = util::rendezvous_ident(core);
+                stmts.push(quote!(
+                    // the compiler fences are used to prevent `reset` from being re-ordering wrt to
+                    // the atomic operations -- we don't know if `reset` contains load or store
+                    // operations
+
+                    core::sync::atomic::compiler_fence(core::sync::atomic::Ordering::SeqCst);
+
+                    // reset the counter
+                    <#m as rtfm::Monotonic>::reset();
+
+                    core::sync::atomic::compiler_fence(core::sync::atomic::Ordering::SeqCst);
+
+                    // now unblock all the other cores
+                    #rv.release();
+                ));
+            } else {
+                let rv = util::rendezvous_ident(core);
+
+                // let the first core know that we have reached the RV point
+                stmts.push(quote!(
+                    #rv.release();
+                ));
+
+                let rv = util::rendezvous_ident(FIRST);
+
+                // wait until the first core has reset the monotonic timer
+                stmts.push(quote!(
+                    #rv.wait();
+                ));
+            }
+        }
+    }
+
+    // enable the interrupts -- this completes the `init`-ialization phase
+    stmts.push(quote!(rtfm::export::interrupt::enable();));
+
+    (const_app, stmts)
+}