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RTEMS 4.6.1 On-Line Library


Semaphore Manager cre_sem - Create Semaphore

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3.4.1: cre_sem - Create Semaphore

CALLING SEQUENCE:

ER cre_sem(
  ID semid,
  T_CSEM *pk_csem
);

STATUS CODES:

E_OK - Normal Completion

E_ID - Invalid ID number (semid was invalid or could not be used)

E_NOMEM - Insufficient memory (Memory for control block cannot be allocated)

E_OACV - Object access violation (A semid less than -4 was specified from a user task.)

E_RSATR - Reserved attribute (sematr was invalid or could not be used)

E_OBJ - Invalid object state (a semaphore of the same ID already exists)

E_PAR - Parameter error (pk_csem is invalid and/or isemcnt or maxsem is negative or invalid)

EN_OBJNO - An object number which could not be accessed on the target node is specified.

EN_CTXID - Specified an object on another node when the system call was issued from a task in dispatch disabled state or from a task- independent portion

EN_PAR - A value outside the range supported by the target node and/or transmission packet format was specified as a parameter (a value outside supported range was specified for exinf, sematr, isemcnt and/or maxsem)

DESCRIPTION:

This routine creates a semaphore that resides on the local node. The semaphore is initialized based on the attributes specified in the pk_csem structure. The initial and maximum counts of the semaphore are set based on the isemcnt and maxsem fields in this structure.

Specifying TA_TPRI in the sematr field of the semaphore attributes structure causes tasks waiting for a semaphore to be serviced according to task priority. When TA_TFIFO is selected, tasks are serviced in First In-First Out order.

NOTES:

Multiprocessing is not supported. Thus none of the "EN_" status codes will be returned.

All memory is preallocated for RTEMS ITRON objects. Thus, no dynamic memory allocation is performed by cre_sem and the E_NOMEM error can not be returned.

This directive will not cause the running task to be preempted.

The following semaphore attribute constants are defined by RTEMS:


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