headers/private/graphics/intel_extreme/lock.h

   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         int32   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
  58 class Autolock {
  59         public:
  60                 Autolock(struct lock &lock)
  61                         :
  62                         fLock(&lock)
  63                 {
  64                         fStatus = acquire_lock(fLock);
  65                 }
  66
  67                 ~Autolock()
  68                 {
  69                         if (fStatus == B_OK)
  70                                 release_lock(fLock);
  71                 }
  72
  73                 bool
  74                 IsLocked() const
  75                 {
  76                         return fStatus == B_OK;
  77                 }
  78
  79         private:
  80                 status_t        fStatus;
  81                 struct lock     *fLock;
  82 };
  83
  84 #endif  /* LOCK_H */