T-Kernel Specification (1.B0.02)

4.4. SYNCHRONIZATION AND COMMUNICATION FUNCTIONS 85
tk ref sem
Reference Semaphore Status
[C Language Interface]
ER ercd = tk_ref_sem ( ID semid, T_RSEM *pk_rsem ) ;
[Parameters]
ID semid Semaphore ID
T RSEM* pk rsem Address of packet for returning status information
pk rsem detail:
VP exinf Extended information
ID wtsk Waiting task information
INT semcnt Semaphore count
(Other implementation-dependent parameters may be added beyond this point.)
[Return Parameters]
ER ercd Error code
[Error Codes]
E OK
E ID
E NOEXS
E PAR
Normal completion
Invalid ID number (semid is invalid or cannot be used)
Object does not exist (the semaphore designated in semid does not exist)
Parameter error (the return parameter packet address cannot be used)
[Description]
References the status of the semaphore designated in semid, passing in the return parameters the
current semaphore count (semcnt), information on tasks waiting for the semaphore (wtsk), and extended
information (exinf).
wtsk indicates the ID of a task waiting for the semaphore. If there are two or more such tasks, the ID
of the task at the head of the queue is returned. If there are no waiting tasks, wtsk = 0 is returned.
If the designated semaphore does not exist, error code E NOEXS is returned.
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02