20191001（12）RT-Thread 时钟管理源码解读（1）创建部分

2023-08-17 17:35 392阅读 0赞

#### 目的 ####

1.  了解创建和初始化源码

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#### 正文 ####

根据阅读线程源码的经验，我直接开始阅读最核心的函数 \_rt\_timer\_init()

/**
     * timer structure
     */
    struct rt_timer
    {
        struct rt_object parent;                            /**< inherit from rt_object */
    
        rt_list_t        row[RT_TIMER_SKIP_LIST_LEVEL];
    
        void (*timeout_func)(void *parameter);              /**< timeout function */
        void            *parameter;                         /**< timeout function's parameter */
    
        rt_tick_t        init_tick;                         /**< timer timeout tick */
        rt_tick_t        timeout_tick;                      /**< timeout tick */
    };
    typedef struct rt_timer *rt_timer_t;

static void _rt_timer_init(rt_timer_t timer, //静态定时器对象句柄 
                               void (*timeout)(void *parameter), //超时回调函数
                               void      *parameter,//传入参数
                               rt_tick_t  time,//超时时间
                               rt_uint8_t flag)//定时器创建时的参数，支持的值包括单次定时、周期定时、 硬件定时器、软件定时器（可以用 “或” 关系取多个值）
    {
        int i;
    
        /* set flag */
        timer->parent.flag  = flag;
    
        /* set deactivated */
        timer->parent.flag &= ~RT_TIMER_FLAG_ACTIVATED;
    
        timer->timeout_func = timeout;
        timer->parameter    = parameter;
    
        timer->timeout_tick = 0;
        timer->init_tick    = time;
    
        /* initialize timer list */
        for (i = 0; i < RT_TIMER_SKIP_LIST_LEVEL; i++)
        {
            rt_list_init(&(timer->row[i])); //见
        }
    }

/**
     * @brief initialize a list
     *
     * @param l list to be initialized
     */
    rt_inline void rt_list_init(rt_list_t *l)
    {
        l->next = l->prev = l;
    }

总体看来这部内容就是对于 rt\_timer 数据结构进行赋值操作，总体操作与线程部分一致不做细致讲解

--------------------

初始化函数和创建函数

//function: rt_timer_create() 
    /**
     * This function will create a timer
     *
     * @param name the name of timer
     * @param timeout the timeout function
     * @param parameter the parameter of timeout function
     * @param time the tick of timer
     * @param flag the flag of timer
     *
     * @return the created timer object
     */
    rt_timer_t rt_timer_create(const char *name, //定时器名字
                               void (*timeout)(void *parameter),
                               void       *parameter,
                               rt_tick_t   time,
                               rt_uint8_t  flag)
    {
        struct rt_timer *timer;
    
        /* allocate a object */
        //由系统分配一个定时器对象
        timer = (struct rt_timer *)rt_object_allocate(RT_Object_Class_Timer, name);
        if (timer == RT_NULL)
        {
            return RT_NULL;
        }
    
        _rt_timer_init(timer, timeout, parameter, time, flag);
    
        return timer;
    }

//rt_timer_init()
    /**
     * This function will initialize a timer, normally this function is used to
     * initialize a static timer object.
     *
     * @param timer the static timer object
     * @param name the name of timer
     * @param timeout the timeout function
     * @param parameter the parameter of timeout function
     * @param time the tick of timer
     * @param flag the flag of timer
     */
    void rt_timer_init(rt_timer_t  timer, //定时器对象的句柄（指针）
                       const char *name,
                       void (*timeout)(void *parameter),
                       void       *parameter,
                       rt_tick_t   time,
                       rt_uint8_t  flag)
    {
        /* timer check */
        RT_ASSERT(timer != RT_NULL);
    
        /* timer object initialization */
        rt_object_init((rt_object_t)timer, RT_Object_Class_Timer, name);
    
        _rt_timer_init(timer, timeout, parameter, time, flag);
    }