Semaphore Wait

Syntax

The wait operation of a semaphore is performed by function sema_wait(), which takes a pointer to a semaphore as its only argument.

#include  <synch.h>

sema_t   Semaphore;

int  sema_wait(sema_t *Semaphore);

• The only argument is a pointer to a semaphore.
• If the semaphore counter is zero, the calling thread is blocked.
• If the semaphore counter is greater than zero, the counter is subtracted by 1 and the calling thread continues.
• Returns 0 if successful.