 Volatile-qualified objects in C

Volatile-qualified objects in C are objects whose accesses must follow the implementation's observable-access rules even when the optimizer cannot see an ordinary program dependency. They are commonly used for device registers and state changed by an interrupt handler, under the target compiler's embedded execution model. volatile does not by itself provide atomic multiword access, mutual exclusion or inter-thread synchronization. Protecting a shared snapshot still requires a suitable critical section or another synchronization protocol.^[ref]