Index: src/tests/.expect/coroutine.txt
===================================================================
--- src/tests/.expect/coroutine.txt	(revision d9c44c33df429b559731c041d43b7bee1cfcef97)
+++ src/tests/.expect/coroutine.txt	(revision d9c44c33df429b559731c041d43b7bee1cfcef97)
@@ -0,0 +1,10 @@
+0 0
+1 1
+1 1
+2 2
+3 3
+5 5
+8 8
+13 13
+21 21
+34 34
Index: src/tests/coroutine.c
===================================================================
--- src/tests/coroutine.c	(revision d9c44c33df429b559731c041d43b7bee1cfcef97)
+++ src/tests/coroutine.c	(revision d9c44c33df429b559731c041d43b7bee1cfcef97)
@@ -0,0 +1,75 @@
+#include <fstream>
+#include <threads>
+
+struct Fibonacci {
+      coroutine c;
+      coVtable v;
+      int fn; // used for communication
+};
+
+coroutine* this_coroutine(Fibonacci* this);
+void co_main(Fibonacci* this);
+coVtable* vtable(Fibonacci* this);
+
+void co_main_fib(void* this) {
+      co_main( (Fibonacci*) this );
+}
+
+coroutine* this_coroutine_fib(void* this) {
+      return this_coroutine( (Fibonacci*) this);
+}
+
+void ?{}(Fibonacci* this) {
+      this->fn = 0;
+      this->v.main = co_main_fib;
+      this->v.this_coroutine = this_coroutine_fib;
+      start(this);
+}
+
+void co_main(Fibonacci* this) {
+#ifdef MORE_DEBUG
+      sout | "Starting main of coroutine " | this | endl;
+      sout | "Started from " | this_coroutine(this)->last | endl;
+#endif
+      int fn1, fn2; 		// retained between resumes
+      this->fn = 0;
+      fn1 = this->fn;
+      suspend(); 		// return to last resume
+
+      this->fn = 1;
+      fn2 = fn1;
+      fn1 = this->fn;
+      suspend(); 		// return to last resume
+
+      for ( ;; ) {
+            this->fn = fn1 + fn2;
+            fn2 = fn1;
+            fn1 = this->fn;
+            suspend(); 	// return to last resume
+      }
+}
+
+int next(Fibonacci* this) {
+      resume(this); // transfer to last suspend
+      return this->fn;
+}
+
+coroutine* this_coroutine(Fibonacci* this) {
+      return &this->c;
+}
+
+coVtable* vtable(Fibonacci* this) {
+      return &this->v;
+}
+
+int main() {
+      Fibonacci f1, f2;
+#ifdef MORE_DEBUG      
+      sout | "User coroutines : " | &f1 | ' ' | &f1 | endl;
+#endif
+      for ( int i = 1; i <= 10; i += 1 ) {
+            sout | next(&f1) | ' ' | next(&f2) | endl;
+      }
+
+      return 0;
+}