Create a synchronization object
#include <sys/neutrino.h> int SyncTypeCreate( unsigned type, sync_t * sync, const struct _sync_attr_t * attr ); int SyncTypeCreate_r( unsigned type, sync_t * sync, const struct _sync_attr_t * attr );
If attr is NULL, the default attributes (PTHREAD_PRIO_INHERIT) are assumed.
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The SyncTypeCreate() and SyncTypeCreate_r() kernel calls create a synchronization object in the kernel and initializes sync for use in other synchronization kernel calls. The synchronization object is local to the process. These functions are similar, except for the way they indicate errors. See the Returns section for details.
|You should allocate synchronization objects only in normal memory mappings. On certain processors (e.g. some PPC ones), atomic operations such as calls to pthread_mutex_lock() will cause a fault if the control structure is allocated in uncached memory.|
Synchronization objects can be used for mutexes, semaphores, or condition variables.
The sync_t argument contains at least the following members:
The current state of sync is summarized below:
|0||-1||Statically initialized; auto-created when used|
|count||>0||Recursive counter number of the mutex|
|count||<-1||If the high bit of count is set, it's a flag meaning “others waiting”|
|--||-256||Mutex is dead, waits for revival|
The synchronization object is destroyed by a call to SyncDestroy().
These calls don't block.
The only difference between these functions is the way they indicate errors:
pthread_cond_init(), pthread_mutex_init(), pthread_rwlock_init(), sem_init(), SyncCondvarSignal(), SyncCondvarWait(), SyncDestroy(), SyncMutexLock(), SyncMutexUnlock()
“Synchronization services” in the QNX Neutrino Microkernel chapter of the System Architecture guide