C語言——軟件定時器

都說程序設計 = 算法 + 數據結構。數據結構是挨踢必修課，不過好像學了數據結構之后也沒用來做過啥。不知道做啥，就寫個軟件定時器。

軟件定時器數據結構

typedef struct __software_timer{
    u32 timeout;                                     //初始化時間計數器              
    u32 repeat;                                      //運行間隔：repeat > 0 :周期定時時間  repeat == 0 ：只定時一次
    void (*timeout_callback_handler)(void *para);    //超時回調函數
    struct __software_timer *next;
}software_timer_t;

判斷軟件定時器鏈表是否為空

/**
  * @brief:         Determine if the software timer list is empty
  * @param[in]:     None
  * @retval[out]:   None
  * @note:            
  * @author:        AresXu
  * @github:          
  * @version:       v1.0.0
*/
static u8 is_softtimer_list_empty(void)
{
	if(software_timer_list_head.next == NULL)
		return TRUE;
	else
		return FALSE;
}

插入定時器到軟件定時器鏈表

鏈表使用單向鏈表。

/**
  * @brief:         Insert the software timer node into the linked list
  * @param[in]:     None
  * @retval[out]:   None
  * @note:            
  * @author:        AresXu
  * @github:           
  * @version:       v1.0.0
*/
static void insert_software_timer(software_timer_t *timer_handle)
{
    software_timer_t *tmp;
    software_timer_t *list_head = &software_timer_list_head;

    if(is_softtimer_list_empty())
    {
        list_head->next = timer_handle;
    }
    else
    {
        tmp = list_head->next;
        while(tmp->next)
        {
			if(timer_handle == tmp)    //定時器已經存在
			{
				printf("The timer already exists\r\n");
				return;
			}
            tmp = tmp->next; 
        }
        tmp->next = timer_handle;
    }
}

將定時器從軟件定時器鏈表移除

/**
  * @brief:         Removes the software timer node from the list
  * @param[in]:     None
  * @retval[out]:   None
  * @note:            
  * @author:        AresXu
  * @github:              
  * @version:       v1.0.0
*/
static void remove_software_timer(software_timer_t *timer_handle)
{
    software_timer_t *list_head = &software_timer_list_head;
    software_timer_t *tmp = list_head;
	
	if(is_softtimer_list_empty())
		return;
	
    while(tmp && tmp->next != timer_handle)
    {
        tmp = tmp->next;
    }
	
	if(tmp == NULL)
		return;
	
	tmp->next          = timer_handle->next;
	timer_handle->next = NULL;	
}

初始化軟件定時器

回調函數不能過長，執行時間不能超過定時時間。

/**
  * @brief:         Initializes the software timer
  * @param[in]:     None
  * @retval[out]:   None
  * @note:            
  * @author:        AresXu
  * @github:                    
  * @version:       v1.0.0
*/
void software_timer_init(software_timer_t *timer_handle,u32 timeout,u32 repeat,void (*timerout_cb)(void *))
{
	timer_handle->timeout                  = timeout;
	timer_handle->repeat                   = repeat;
	timer_handle->timeout_callback_handler = timerout_cb;
	timer_handle->next                     = (void *)0;
}

啟動定時器

/**
  * @brief:         Start timer
  * @param[in]:     None
  * @retval[out]:   None
  * @note:            
  * @author:        AresXu
  * @github:              
  * @version:       v1.0.0
*/
void software_timer_start(software_timer_t *timer_handle)
{
	insert_software_timer(timer_handle);         
}

停止定時器

/**
  * @brief:         stop timer
  * @param[in]:     None
  * @retval[out]:   None
  * @note:            
  * @author:        AresXu
  * @github:              
  * @version:       v1.0.0
*/
void software_timer_stop(software_timer_t *timer_handle)
{
	remove_software_timer(timer_handle);        
}

定時器處理函數(主函數調用)

/**
  * @brief:         Timer processing function
  * @param[in]:     None
  * @retval[out]:   None
  * @note:          Must be called by the main function  
  * @author:        AresXu
  * @github:        https://github.com/EmbeddedXGJ       
  * @version:       v1.0.0
*/
void software_timer_main_loop(void)
{
    software_timer_t *tmp = &software_timer_list_head;
	tmp = tmp->next;
	
    while(tmp)
    {
		if(tmp->timeout <= 0)
		{
            tmp->timeout_callback_handler((void *)0);

			if(tmp->repeat > 0)
			{
				tmp->timeout = tmp->repeat;
			}
			else     
			{
				software_timer_stop(tmp);
			}
		}
		tmp = tmp->next;
    } 
}

硬件定時器提供時基

1 ms硬件定時器調用函數。

/**
  * @brief:         Provide a heartbeat to the software timer
  * @param[in]:     void
  * @retval[out]:   void
  * @note:          Must be called by 1ms hardware timer  
  * @author:        AresXu
  * @github:        https://github.com/EmbeddedXGJ      
  * @version:       v1.0.0
*/
void software_timer_ticks(void)
{
    software_timer_t *tmp = &software_timer_list_head;
	tmp = tmp->next;
	
	while(tmp)
	{
		if(tmp->timeout > 0)
		{
			tmp->timeout--;
		}
		tmp = tmp->next;
	}
}

在STM32上測試

• software_timer_test.c:

software_timer_t timer1_t;    
software_timer_t timer2_t;
software_timer_t timer3_t;

void timer1_cb(void *parm)
{
	printf("1000ms >>> dyy\r\n");
}

void timer2_cb(void *parm)
{
	printf("2000ms >>> dyy\r\n");
}

void timer3_cb(void *parm)
{
	printf("500ms  >>> dyy\r\n");
} 

void SoftWareTimer_Init(void)
{
    software_timer_init(&timer1_t,1000,1000,timer1_cb);
    software_timer_init(&timer2_t,2000,2000,timer2_cb);
    software_timer_init(&timer3_t,500,500,timer3_cb);

	software_timer_start(&timer1_t);
	software_timer_start(&timer2_t);
	software_timer_start(&timer3_t);

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