RTEMS 4.5.0 On-Line Library

Semaphore Manager wai_sem - Wait on Semaphore

RTEMS ITRON 3.0 API User's Guide

3.4.4: wai_sem - Wait on Semaphore

CALLING SEQUENCE:

ER wai_sem(
  ID semid
);

STATUS CODES:

E_OK - Normal Completion

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

E_NOEXS - Object does not exist (the semaphore specified by semid does not exist)

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

E_DLT - The object being waited for was deleted (the specified semaphore was deleted while waiting)

E_RLWAI - Wait state was forcibly released (rel_wai was received while waiting)

E_CTX - Context error (issued from task-independent portions or a task in dispatch disabled state)

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

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 tmout)

DESCRIPTION:

This routine attempts to acquire the semaphore specified by semid. If the semaphore is available (i.e. positive semaphore count), then the semaphore count is decremented and the calling task returns immediately. Otherwise the calling tasking is blocked until the semaphore is released by a subsequent invocation of sig_sem.

NOTES:

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

If the semaphore is not available, then the calling task will be blocked.

RTEMS ITRON 3.0 API User's Guide