- Move generic implementation of atomic_set_return to core/atomic.c
- Generic implementation of atomic compare and swap in core/atomic.c
- atomic_cas is used to implement atomic counters in core/include/atomic.h
- atomic_int_t is an atomic integer type
- ATOMIC_INIT can be used as an initializer for atomic_int_t
- ATOMIC_VALUE gets a reference to the value of an atomic integer