surround routines by far jump across

crsn/src/asm/instr/flatten.rs

@@ -1,5 +1,5 @@
 use std::collections::HashMap;
-use std::sync::atomic::AtomicU32;
+use std::sync::atomic::{AtomicU32, Ordering};
 
 use crate::asm::data::{Rd, RdData};
 use crate::asm::data::literal::{Label, Value};
@@ -63,7 +63,10 @@ impl Flatten for Vec<Box<dyn Flatten>> {
 
 impl Flatten for Routine {
     fn flatten(self: Box<Self>, label_num: &AtomicU32) -> Result<Vec<Op>, CrsnError> {
-        let mut ops = vec![
+        let skip_label = Label::Numbered(label_num.fetch_add(1, Ordering::Relaxed));
+
+        let mut ops : Vec<Op> = vec![
+            BuiltinOp::FarJump(skip_label.clone()).into(),
             BuiltinOp::Barrier(Some(format!("Routine \"{}\" start", self.name).into())).into(),
             BuiltinOp::Routine(self.name.clone()).into(),
         ];
@@ -71,6 +74,7 @@ impl Flatten for Routine {
         ops.extend(self.body.flatten(label_num)?);
 
         ops.push(BuiltinOp::Barrier(Some(format!("Routine \"{}\" end", self.name).into())).into());
+        ops.push(BuiltinOp::FarLabel(skip_label).into());
 
         numbered_labels_to_skips(ops)
     }

crsn/src/runtime/program.rs

@@ -50,7 +50,7 @@ impl Program {
     /// Read a program instruction at address
     pub fn read(&self, addr: Addr) -> &Op {
         if addr.0 >= self.ops.len() as u64 {
-            &Op::BuiltIn(BuiltinOp::Nop)
+            &Op::BuiltIn(BuiltinOp::Halt)
         } else {
             &self.ops[addr.0 as usize]
         }

examples/proc_skip.csn

@@ -0,0 +1,11 @@
+(
+    (ld r0 1)
+
+    ; the procedure is surrounded by a jump and a label
+    (proc foo
+        (nop)
+        (ret)
+    )
+
+    (ld r0 2)
+)

examples/stacks.csn

@@ -11,5 +11,4 @@
     (cmp r1 1 (ne? (fault)))
 
     (drop @r0)
-    (halt)
 )