From 0f8bdbdd3f2739e37d788493cb83cf2d9c557f4e Mon Sep 17 00:00:00 2001
From: Emil Fresk <emil.fresk@gmail.com>
Date: Wed, 20 Apr 2022 13:02:55 +0200
Subject: [PATCH] Added check for resource usage and to generate an compile
 error for thumbv6 exceptions

---
 macros/src/codegen/shared_resources.rs | 30 +++++++++++++++++++++++++-
 src/export.rs                          | 10 +++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/macros/src/codegen/shared_resources.rs b/macros/src/codegen/shared_resources.rs
index e3109c8285..f944e3e5ec 100644
--- a/macros/src/codegen/shared_resources.rs
+++ b/macros/src/codegen/shared_resources.rs
@@ -110,12 +110,32 @@ pub fn codegen(
 
     let mut prio_to_masks = HashMap::new();
     let device = &extra.device;
+    let mut uses_exceptions_with_resources = false;
 
     for (&priority, name) in interrupt_ids.chain(app.hardware_tasks.values().flat_map(|task| {
         if !util::is_exception(&task.args.binds) {
             Some((&task.args.priority, &task.args.binds))
         } else {
-            // TODO: exceptions not implemented
+            // If any resource to the exception uses non-lock-free or non-local resources this is
+            // not allwed on thumbv6.
+            uses_exceptions_with_resources = uses_exceptions_with_resources
+                || task
+                    .args
+                    .shared_resources
+                    .iter()
+                    .map(|(ident, access)| {
+                        if access.is_exclusive() {
+                            if let Some(r) = app.shared_resources.get(ident) {
+                                !r.properties.lock_free
+                            } else {
+                                false
+                            }
+                        } else {
+                            false
+                        }
+                    })
+                    .any(|v| v);
+
             None
         }
     })) {
@@ -146,5 +166,13 @@ pub fn codegen(
         const #masks_name: [u32; 3] = [#(#mask_arr),*];
     ));
 
+    if uses_exceptions_with_resources {
+        mod_app.push(quote!(
+            #[doc(hidden)]
+            #[allow(non_camel_case_types)]
+            const __rtic_internal_V6_ERROR: () = rtic::export::v6_panic();
+        ));
+    }
+
     (mod_app, mod_resources)
 }
diff --git a/src/export.rs b/src/export.rs
index 035899180a..42f3fe2e34 100644
--- a/src/export.rs
+++ b/src/export.rs
@@ -339,3 +339,13 @@ pub const fn create_mask<const N: usize>(list_of_shifts: [u32; N]) -> u32 {
 
     mask
 }
+
+#[cfg(not(armv6m))]
+pub const fn v6_panic() {
+    // For non-v6 all is fine
+}
+
+#[cfg(armv6m)]
+pub const fn v6_panic() {
+    panic!("Exceptions with shared resources are not allowed when compiling for thumbv6. Use local resources or `#[lock_free]` shared resources");
+}