1 /* 2 * Copyright 2006, Haiku, Inc. All Rights Reserved. 3 * Distributed under the terms of the MIT License. 4 * 5 * Authors: 6 * Axel Dörfler, axeld@pinc-software.de 7 */ 8 #ifndef LOCK_H 9 #define LOCK_H 10 11 12 #include <OS.h> 13 14 15 typedef struct lock { 16 sem_id sem; 17 vint32 count; 18 } lock; 19 20 21 static inline status_t 22 init_lock(struct lock *lock, const char *name) 23 { 24 lock->sem = create_sem(0, name); 25 lock->count = 0; 26 27 return lock->sem < B_OK ? lock->sem : B_OK; 28 } 29 30 31 static inline void 32 uninit_lock(struct lock *lock) 33 { 34 delete_sem(lock->sem); 35 } 36 37 38 static inline status_t 39 acquire_lock(struct lock *lock) 40 { 41 if (atomic_add(&lock->count, 1) > 0) 42 return acquire_sem(lock->sem); 43 44 return B_OK; 45 } 46 47 48 static inline status_t 49 release_lock(struct lock *lock) 50 { 51 if (atomic_add(&lock->count, -1) > 1) 52 return release_sem(lock->sem); 53 54 return B_OK; 55 } 56 57 #endif /* LOCK_H */ 58