Function rt_sem_control

src/ipc.c:760–820

* @brief This function will set some extra attributions of a semaphore object. * * @note Currently this function only supports the RT_IPC_CMD_RESET command to reset the semaphore. * * @param sem is a pointer to a semaphore object. * * @param cmd is a command word used to configure some attributions of the semaphore. * * @param arg is the argument of the function to execute

 *           If the return value is any other values, it means that this function failed to execute.
 */
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_uintptr_t)arg;
        level = rt_spin_lock_irqsave(&(sem->spinlock));

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

        /* set new value */
        sem->value = (rt_uint16_t)value;
        rt_spin_unlock_irqrestore(&(sem->spinlock), level);
        rt_schedule();

        return RT_EOK;
    }
    else if (cmd == RT_IPC_CMD_SET_VLIMIT)
    {
        rt_ubase_t max_value;
        rt_bool_t need_schedule = RT_FALSE;

        max_value = (rt_uint16_t)((rt_uintptr_t)arg);
        if (max_value > RT_SEM_VALUE_MAX || max_value < 1)
        {
            return -RT_EINVAL;
        }

        level = rt_spin_lock_irqsave(&(sem->spinlock));
        if (max_value < sem->value)
        {
            if (!rt_list_isempty(&sem->parent.suspend_thread))
            {
                /* resume all waiting thread */
                rt_susp_list_resume_all(&sem->parent.suspend_thread, RT_ERROR);
                need_schedule = RT_TRUE;
            }
        }
        /* set new value */
        sem->max_value = max_value;
        rt_spin_unlock_irqrestore(&(sem->spinlock), level);

        if (need_schedule)
        {
            rt_schedule();
        }

        return RT_EOK;
    }