rt_err_t rt_sem_control(rt_sem_t sem, int cmd, void *arg)
{
    rt_base_t level;

    /* parameter check */
    RT_ASSERT(sem != RT_NULL);
    RT_ASSERT(rt_object_get_type(&sem->parent.parent) == RT_Object_Class_Semaphore);

    if (cmd == RT_IPC_CMD_RESET)
    {
        rt_ubase_t value;

        /* get value */
        value = (rt_ubase_t)arg;
        /* disable interrupt */
        level = rt_hw_interrupt_disable();

        /* resume all waiting thread */
        _ipc_list_resume_all(&sem->parent.suspend_thread);

        /* set new value */
        sem->value = (rt_uint16_t)value;

        /* enable interrupt */
        rt_hw_interrupt_enable(level);

        rt_schedule();

        return RT_EOK;
    }

    return -RT_ERROR;
}
RTM_EXPORT(rt_sem_control);

注意 arg这个参数是void *类型，当需要将信号量复位为0时需要写成如下格式：

rt_sem_control(sys_g.mi.sem_tdat_rf, RT_IPC_CMD_RESET, (void*)0);

不可写为：

rt_sem_control(sys_g.mi.sem_tdat_rf, RT_IPC_CMD_RESET,  0);

否则鬼知道0地址处会有些什么东西去运行。