Function _rt_mb_recv

src/ipc.c:2849–2977

* @brief This function will receive a mail from mailbox object, if there is no mail in mailbox object, * the thread shall wait for a specified time. * * @note Only when there is mail in the mailbox, the receiving thread can get the mail immediately and * return RT_EOK, otherwise the receiving thread will be suspended until the set timeout. If the mail * is

 *           If the return value is any other values, it means that the mailbox release failed.
 */
static rt_err_t _rt_mb_recv(rt_mailbox_t mb, rt_ubase_t *value, rt_int32_t timeout, int suspend_flag)
{
    struct rt_thread *thread;
    rt_base_t level;
    rt_uint32_t tick_delta;
    rt_err_t ret;

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

    /* current context checking */
    RT_DEBUG_SCHEDULER_AVAILABLE(timeout != 0);

    /* initialize delta tick */
    tick_delta = 0;
    /* get current thread */
    thread = rt_thread_self();

    RT_OBJECT_HOOK_CALL(rt_object_trytake_hook, (&(mb->parent.parent)));

    level = rt_spin_lock_irqsave(&(mb->spinlock));

    /* for non-blocking call */
    if (mb->entry == 0 && timeout == 0)
    {
        rt_spin_unlock_irqrestore(&(mb->spinlock), level);

        return -RT_ETIMEOUT;
    }

    /* mailbox is empty */
    while (mb->entry == 0)
    {
        /* reset error number in thread */
        thread->error = -RT_EINTR;

        /* no waiting, return timeout */
        if (timeout == 0)
        {
            rt_spin_unlock_irqrestore(&(mb->spinlock), level);

            thread->error = -RT_ETIMEOUT;

            return -RT_ETIMEOUT;
        }

        /* suspend current thread */
        ret = rt_thread_suspend_to_list(thread, &(mb->parent.suspend_thread),
                                        mb->parent.parent.flag, suspend_flag);
        if (ret != RT_EOK)
        {
            rt_spin_unlock_irqrestore(&(mb->spinlock), level);
            return ret;
        }

        /* has waiting time, start thread timer */
        if (timeout > 0)