(原创)sem_wait实现毫秒级延时

static int gettimeofday(struct timeval *tp, void *t)
{
    timeb tv;
    
    ftime(&tv);
    tp->tv_sec = tv.time;
    tp->tv_usec = tv.millitm*1000;
    
    return 1;
}


int sem_timedwait_ms(sem_t *sem, int milliseconds)
{
    struct timespec abstime;
    struct timeval now;
    uint64_t tv_nsec;
    
    gettimeofday(&now, NULL);
    
    tv_nsec = now.tv_usec * 1000 + (milliseconds % 1000) * 1000000;
    abstime.tv_sec = now.tv_sec + milliseconds / 1000;
    if(tv_nsec>=1000000000)
    {
        tv_nsec -= 1000000000;
        abstime.tv_sec += 1;
    }
    abstime.tv_nsec = tv_nsec;
    
    return sem_timedwait(sem, &abstime);
}