+/**
+ * Select a Thread. This implementation defaults to round-robin, if a
+ * thread is not already provided.
+ *
+ * @param t Thread to run, if chosen by an external entity (e.g.,
+ * ModelChecker). May be NULL to indicate no external choice.
+ * @return The next Thread to run
+ */
+Thread * Scheduler::next_thread(Thread *t)
+{
+ if ( t == NULL ) {
+ int old_curr_thread = curr_thread_index;
+ while(true) {
+ curr_thread_index = (curr_thread_index+1) % enabled_len;
+ if (is_enabled[curr_thread_index]) {
+ t = model->get_thread(int_to_id(curr_thread_index));
+ break;
+ }
+ if (curr_thread_index == old_curr_thread) {
+ print();
+ return NULL;
+ }
+ }