11 /* A simple spinlock. Yield the thread while the given integer is set by
12 * another. Could probably be improved... */
13 #define LOCK(l) do { \
14 while(ATOMIC_EXCHANGE(int, &(l), true, almemory_order_acq_rel) == true) \
17 #define UNLOCK(l) ATOMIC_STORE(&(l), false, almemory_order_release)
20 void RWLockInit(RWLock
*lock
)
22 InitRef(&lock
->read_count
, 0);
23 InitRef(&lock
->write_count
, 0);
24 ATOMIC_INIT(&lock
->read_lock
, false);
25 ATOMIC_INIT(&lock
->read_entry_lock
, false);
26 ATOMIC_INIT(&lock
->write_lock
, false);
29 void ReadLock(RWLock
*lock
)
31 LOCK(lock
->read_entry_lock
);
32 LOCK(lock
->read_lock
);
33 /* NOTE: ATOMIC_ADD returns the *old* value! */
34 if(ATOMIC_ADD(&lock
->read_count
, 1, almemory_order_acq_rel
) == 0)
35 LOCK(lock
->write_lock
);
36 UNLOCK(lock
->read_lock
);
37 UNLOCK(lock
->read_entry_lock
);
40 void ReadUnlock(RWLock
*lock
)
42 /* NOTE: ATOMIC_SUB returns the *old* value! */
43 if(ATOMIC_SUB(&lock
->read_count
, 1, almemory_order_acq_rel
) == 1)
44 UNLOCK(lock
->write_lock
);
47 void WriteLock(RWLock
*lock
)
49 if(ATOMIC_ADD(&lock
->write_count
, 1, almemory_order_acq_rel
) == 0)
50 LOCK(lock
->read_lock
);
51 LOCK(lock
->write_lock
);
54 void WriteUnlock(RWLock
*lock
)
56 UNLOCK(lock
->write_lock
);
57 if(ATOMIC_SUB(&lock
->write_count
, 1, almemory_order_acq_rel
) == 1)
58 UNLOCK(lock
->read_lock
);