Lock-Free State Transition Using C11 Atomic Compare-Exchange

#include <stdatomic.h>
#include <stdbool.h>
#include <stdio.h>
 
typedef enum { STATE_IDLE, STATE_BUSY, STATE_DONE } MachineState;
 
bool try_transition(_Atomic MachineState *state, MachineState expected, MachineState next) {
    return atomic_compare_exchange_strong(state, &expected, next);
}
 
int main(void) {
    _Atomic MachineState current = STATE_IDLE;
    if (try_transition(&current, STATE_IDLE, STATE_BUSY)) {
        printf("State successfully transitioned to BUSY.\n");
    }
    return 0;
}