Function first

user/src/bin/sync_sem.rs:16–21

()

const SEM_SYNC: usize = 0;

unsafe fn first() -> ! {
    sleep(10);
    println!("First work and wakeup Second");
    semaphore_up(SEM_SYNC);
    exit(0)
}

unsafe fn second() -> ! {
    println!("Second want to continue,but need to wait first");