SEMAPHORE_P
Purpose
semaphore_p issues a P on a semaphore.
Synopsis
#include <types.h>
#include <stub.h>
int semaphore_p(Capability
*semaphore);
Parameters
-
semaphore: a capability for the
semaphore to apply P.
Description
semaphore_p issues a P operation on
the semaphore designated by semaphore. The P operation decrements
the semaphore's value and, if it becomes to 0, blocks the calling thread.
A thread blocked on a semaphore is releases
when the semaphore's value returns to a positive value because some thread
issued a V operation on it.
Return Values
On success, semaphore_p returns 0 and
semaphore's value is decremented.
On fail, semaphore_p returns a negative
value indicating one of the following errors:
See Also
semaphore_create,
semaphore_destroy, semaphore_status,
semaphore_v