Use sema_init(3C) to initialize the semaphore variable pointed to by sp by count amount.
#include <thread.h> int sema_init(sema_t *sp, unsigned int count, int type, void *arg);
type can be one of the following values:
Multiple threads must not initialize the same semaphore simultaneously. A semaphore must not be reinitialized while other threads might be using the semaphore.
#include <thread.h> sema_t sp; int ret; int count; count = 4; /* to be used within this process only */ ret = sema_init(&sp, count, USYNC_THREAD, 0);
#include <thread.h> sema_t sp; int ret; int count; count = 4; /* to be used among all the processes */ ret = sema_init (&sp, count, USYNC_PROCESS, 0);
sp refers to an invalid semaphore.
Either sp or arg point to an illegal address.