+#include <stdlib.h>
+
+#include "libthreads.h"
+#include "schedule.h"
+#include "common.h"
+#include "threads.h"
+
+/* global "model" object */
+#include "model.h"
+
+/*
+ * Return 1 if found next thread, 0 otherwise
+ */
+static int thread_system_next(void)
+{
+ Thread *curr, *next;
+
+ curr = thread_current();
+ if (curr) {
+ if (curr->get_state() == THREAD_READY) {
+ model->check_current_action();
+ model->scheduler->add_thread(curr);
+ } else if (curr->get_state() == THREAD_RUNNING)
+ /* Stopped while running; i.e., completed */
+ curr->complete();
+ else
+ ASSERT(false);
+ }
+ next = model->scheduler->next_thread();
+ if (next)
+ next->set_state(THREAD_RUNNING);
+ DEBUG("(%d, %d)\n", curr ? curr->get_id() : -1, next ? next->get_id() : -1);
+ if (!next)
+ return 1;
+ return Thread::swap(model->get_system_context(), next);
+}
+
+static void thread_wait_finish(void)
+{
+
+ DBG();
+
+ while (!thread_system_next());
+}
+
+/*
+ * Main system function
+ */
+int main()
+{
+ thrd_t user_thread;
+ ucontext_t main_context;
+
+ model = new ModelChecker();
+
+ if (getcontext(&main_context))
+ return 1;
+
+ model->set_system_context(&main_context);
+
+ do {
+ /* Start user program */
+ model->add_thread(new Thread(&user_thread, &user_main, NULL));
+
+ /* Wait for all threads to complete */
+ thread_wait_finish();
+ } while (model->next_execution());
+
+ delete model;
+
+ DEBUG("Exiting\n");
+ return 0;
+}