--- /dev/null
+#include <unistd.h>
+
+#define STRINGIFY(x) #x
+#define TOSTRING(x) STRINGIFY(x)
+
+#define CURRENT_LOCATION __FILE__ ":" TOSTRING(__LINE__)
+
+#define err() \
+{ \
+ _fail("at " CURRENT_LOCATION " "); \
+}
+
+#define mb() asm volatile ("" : : : "memory")
+
+void pass(void);
+void _fail(char *reason);