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简介

timeslice是一个时间片轮询框架，他是一个完全解耦的时间片轮询框架，他的使用非常方便，该项目一共有四个文件分别是tieslice的头文件和源文件以及list的头文件和源文件，tieslice是负责轮询任务，list是一个双向链表负责任务的管理，在Linux内核中使用非常广泛也很经典，该框架是参考rtt实时操作系统的侵入式链表实现的，本章文章是将该框架移植到stm32单片机上实验，使用也非常容易，单片机只需要启用一个定时器作为时钟即可；

本章使用环境：

stm32f407vet6
代码工程使用cubemx创建

项目代码

该项目的代码是我在微信公众号上看到的一个文章，代码并没有上传在github上，这里直接贴上源代码；

timeslice.h

#ifndef _TIMESLICE_H
#define _TIMESLICE_H#include "list.h"typedef enum {TASK_STOP,TASK_RUN
} IsTaskRun;typedef struct timesilce
{unsigned int id;void (*task_hdl)(void);IsTaskRun is_run;unsigned int timer;unsigned int timeslice_len;ListObj timeslice_task_list;
} TimesilceTaskObj;void timeslice_exec(void);
void timeslice_tick(void);
void timeslice_task_init(TimesilceTaskObj* obj, void (*task_hdl)(void), unsigned int id, unsigned int timeslice_len);
void timeslice_task_add(TimesilceTaskObj* obj);
void timeslice_task_del(TimesilceTaskObj* obj);
unsigned int timeslice_get_task_timeslice_len(TimesilceTaskObj* obj);
unsigned int timeslice_get_task_num(void);
unsigned char timeslice_task_isexist(TimesilceTaskObj* obj);#endif

timeslice.c

#include "timeslice.h"static LIST_HEAD(timeslice_task_list);void timeslice_exec()
{ListObj* node;TimesilceTaskObj* task;list_for_each(node, &timeslice_task_list){task = list_entry(node, TimesilceTaskObj, timeslice_task_list);if (task->is_run == TASK_RUN){task->task_hdl();task->is_run = TASK_STOP;}}
}void timeslice_tick()
{ListObj* node;TimesilceTaskObj* task;list_for_each(node, &timeslice_task_list){task = list_entry(node, TimesilceTaskObj, timeslice_task_list);if (task->timer != 0){task->timer--;if (task->timer == 0){task->is_run = TASK_RUN;task->timer = task->timeslice_len;}}}
}unsigned int timeslice_get_task_num()
{return list_len(&timeslice_task_list);
}void timeslice_task_init(TimesilceTaskObj* obj, void (*task_hdl)(void), unsigned int id, unsigned int timeslice_len)
{obj->id = id;obj->is_run = TASK_STOP;obj->task_hdl = task_hdl;obj->timer = timeslice_len;obj->timeslice_len = timeslice_len;
}void timeslice_task_add(TimesilceTaskObj* obj)
{list_insert_before(&timeslice_task_list, &obj->timeslice_task_list);
}void timeslice_task_del(TimesilceTaskObj* obj)
{if (timeslice_task_isexist(obj))list_remove(&obj->timeslice_task_list);elsereturn;
}unsigned char timeslice_task_isexist(TimesilceTaskObj* obj)
{unsigned char isexist = 0;ListObj* node;TimesilceTaskObj* task;list_for_each(node, &timeslice_task_list){task = list_entry(node, TimesilceTaskObj, timeslice_task_list);if (obj->id == task->id)isexist = 1;}return isexist;
}unsigned int timeslice_get_task_timeslice_len(TimesilceTaskObj* obj)
{return obj->timeslice_len;
}

list.h

#ifndef _LIST_H
#define _LIST_H#define offset_of(type, member)             (unsigned long) &((type*)0)->member
#define container_of(ptr, type, member)     ((type *)((char *)(ptr) - offset_of(type, member)))typedef struct list_structure
{struct list_structure* next;struct list_structure* prev;
} ListObj;#define LIST_HEAD_INIT(name)    {&(name), &(name)}
#define LIST_HEAD(name)         ListObj name = LIST_HEAD_INIT(name)void list_init(ListObj* list);
void list_insert_after(ListObj* list, ListObj* node);
void list_insert_before(ListObj* list, ListObj* node);
void list_remove(ListObj* node);
int list_isempty(const ListObj* list);
unsigned int list_len(const ListObj* list);#define list_entry(node, type, member) \container_of(node, type, member)#define list_for_each(pos, head) \for (pos = (head)->next; pos != (head); pos = pos->next)#define list_for_each_safe(pos, n, head) \for (pos = (head)->next, n = pos->next; pos != (head); \pos = n, n = pos->next)#endif

list.c

#include "list.h"void list_init(ListObj* list)
{list->next = list->prev = list;
}void list_insert_after(ListObj* list, ListObj* node)
{list->next->prev = node;node->next = list->next;list->next = node;node->prev = list;
}void list_insert_before(ListObj* list, ListObj* node)
{list->prev->next = node;node->prev = list->prev;list->prev = node;node->next = list;
}void list_remove(ListObj* node)
{node->next->prev = node->prev;node->prev->next = node->next;node->next = node->prev = node;
}int list_isempty(const ListObj* list)
{return list->next == list;
}unsigned int list_len(const ListObj* list)
{unsigned int len = 0;const ListObj* p = list;while (p->next != list){p = p->next;len++;}return len;
}

创建工程

配置高速时钟和低速时钟为外部晶振提供

配置调试模式为sw调试模式

配置时钟频率
配置led，这里我的板子是这三个io接入的是led

配置一个10ms的定时器（1000000hz / 1000ms == 1ms = 1khz 就得到10ms需要计数10000重载）记得打开中断

配置工程并生成，工程名设置，单独生成.c.h文件拷贝库文件


下面开始代码的移植工作；

移植代码

首先我们需要将该开源项目的代码添加到工程中
在定时器中断服务函数中添加timeslice轮询函数

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{if(htim->Instance == TIM3){timeslice_tick();}
}

然后我们需要在main函数中启动定时器并在while1中调用exec函数调度时间片

 HAL_TIM_Base_Start_IT(&htim3);/* USER CODE END 2 *//* Infinite loop *//* USER CODE BEGIN WHILE */while (1){/* USER CODE END WHILE *//* USER CODE BEGIN 3 */timeslice_exec();}

到这里我们的移植工作就做完了，该项目的解耦效果真的非常好，移植相当简单，然后我们创建几个任务实验一下效果；

实验

/* USER CODE BEGIN Header */
/********************************************************************************* @file           : main.c* @brief          : Main program body******************************************************************************* @attention** Copyright (c) 2023 STMicroelectronics.* All rights reserved.** This software is licensed under terms that can be found in the LICENSE file* in the root directory of this software component.* If no LICENSE file comes with this software, it is provided AS-IS.********************************************************************************/
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "tim.h"
#include "gpio.h"/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "timeslice.h"
/* USER CODE END Includes *//* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD *//* USER CODE END PTD *//* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD *//* USER CODE END PD *//* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM *//* USER CODE END PM *//* Private variables ---------------------------------------------------------*//* USER CODE BEGIN PV */
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{if(htim->Instance == TIM3){timeslice_tick();}
}// 创建3个任务对象
TimesilceTaskObj task_1, task_2, task_3;// 具体的任务函数
void task1_hdl()
{HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_13);
}void task2_hdl()
{HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_14 );
}void task3_hdl()
{HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_15);
}// 初始化任务对象，并且将任务添加到时间片轮询调度中
void task_init()
{timeslice_task_init(&task_1, task1_hdl, 1, 1);timeslice_task_init(&task_2, task2_hdl, 2, 1);timeslice_task_init(&task_3, task3_hdl, 3, 1);timeslice_task_add(&task_1);timeslice_task_add(&task_2);timeslice_task_add(&task_3);
}
/* USER CODE END PV *//* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP *//* USER CODE END PFP *//* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 *//* USER CODE END 0 *//*** @brief  The application entry point.* @retval int*/
int main(void)
{/* USER CODE BEGIN 1 *//* USER CODE END 1 *//* MCU Configuration--------------------------------------------------------*//* Reset of all peripherals, Initializes the Flash interface and the Systick. */HAL_Init();/* USER CODE BEGIN Init *//* USER CODE END Init *//* Configure the system clock */SystemClock_Config();/* USER CODE BEGIN SysInit *//* USER CODE END SysInit *//* Initialize all configured peripherals */MX_GPIO_Init();MX_TIM3_Init();/* USER CODE BEGIN 2 */HAL_TIM_Base_Start_IT(&htim3);task_init();/* USER CODE END 2 *//* Infinite loop *//* USER CODE BEGIN WHILE */while (1){/* USER CODE END WHILE *//* USER CODE BEGIN 3 */timeslice_exec();}/* USER CODE END 3 */
}/*** @brief System Clock Configuration* @retval None*/
void SystemClock_Config(void)
{RCC_OscInitTypeDef RCC_OscInitStruct = {0};RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};/** Configure the main internal regulator output voltage*/__HAL_RCC_PWR_CLK_ENABLE();__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);/** Initializes the RCC Oscillators according to the specified parameters* in the RCC_OscInitTypeDef structure.*/RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;RCC_OscInitStruct.HSEState = RCC_HSE_ON;RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;RCC_OscInitStruct.PLL.PLLM = 25;RCC_OscInitStruct.PLL.PLLN = 336;RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;RCC_OscInitStruct.PLL.PLLQ = 4;if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK){Error_Handler();}/** Initializes the CPU, AHB and APB buses clocks*/RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK){Error_Handler();}
}/* USER CODE BEGIN 4 *//* USER CODE END 4 *//*** @brief  This function is executed in case of error occurrence.* @retval None*/
void Error_Handler(void)
{/* USER CODE BEGIN Error_Handler_Debug *//* User can add his own implementation to report the HAL error return state */__disable_irq();while (1){}/* USER CODE END Error_Handler_Debug */
}#ifdef  USE_FULL_ASSERT
/*** @brief  Reports the name of the source file and the source line number*         where the assert_param error has occurred.* @param  file: pointer to the source file name* @param  line: assert_param error line source number* @retval None*/
void assert_failed(uint8_t *file, uint32_t line)
{/* USER CODE BEGIN 6 *//* User can add his own implementation to report the file name and line number,ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) *//* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

核心部分

// 创建3个任务对象
TimesilceTaskObj task_1, task_2, task_3;// 具体的任务函数
void task1_hdl()
{HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_13);
}void task2_hdl()
{HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_14 );
}void task3_hdl()
{HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_15);
}// 初始化任务对象，并且将任务添加到时间片轮询调度中
void task_init()
{timeslice_task_init(&task_1, task1_hdl, 1, 1);timeslice_task_init(&task_2, task2_hdl, 2, 2);timeslice_task_init(&task_3, task3_hdl, 3, 3);timeslice_task_add(&task_1);timeslice_task_add(&task_2);timeslice_task_add(&task_3);
}

需要注意的是必须要有一个任务是需要在exec前创建，这样才能保证运行，其他的任务可以在这个任务中再创建，上面的实验是实现三个任务，三个任务分别为一个中断触发一次，第二个任务是每隔两个中断触发一次，第三个任务是每隔三个中断触发一次任务；

函数说明

timeslice_task_init

初始化任务函数

void timeslice_task_init(TimesilceTaskObj* obj, void (*task_hdl)(void), unsigned int id, unsigned int timeslice_len)
{obj->id = id;obj->is_run = TASK_STOP;obj->task_hdl = task_hdl;obj->timer = timeslice_len;obj->timeslice_len = timeslice_len;
}

在这个函数中将任务结构体参数初始化，id类似于任务名称用于区分任务，is_run是一个标志位用于判断该任务在该次中断是否需要执行，task_hd1表示函数指针也就是我们的任务函数，timer表示每多少次中断触发一次计数，timeslice_len 表示没多少次中断触发一次计数初始值，在timeslice_tick中当timer的值减到0任务将触发并会重新复位timer的值为 timeslice_len ；

timeslice_task_add

添加任务到双向链表中

void timeslice_task_add(TimesilceTaskObj* obj)
{list_insert_before(&timeslice_task_list, &obj->timeslice_task_list);
}void list_insert_before(ListObj* list, ListObj* node)
{list->prev->next = node;node->prev = list->prev;list->prev = node;node->next = list;
}

该链表（timeslice_task_list）在timeslice_tick中会轮询进行遍历

timeslice_tak_del

删除正在运行的任务链表

void timeslice_task_del(TimesilceTaskObj* obj)
{if (timeslice_task_isexist(obj))list_remove(&obj->timeslice_task_list);elsereturn;
}

在该函数中会通过timeslice_task_isexist函数去判断链表中是否存在该任务的id，如果存在将返回退出允许，这里涉及到一个Linux中的函数list_entry->container_of,该函数是通过结构体的某个变量获取整个结构体的指针位置，有兴趣可以去学习一下该项目代码的实现；

timeslice_get_task_num

获取当前任务数量，也就是链表的长度

unsigned int timeslice_get_task_num()
{return list_len(&timeslice_task_list);
}unsigned int list_len(const ListObj* list)
{unsigned int len = 0;const ListObj* p = list;while (p->next != list){p = p->next;len++;}return len;
}

结尾

整体的代码不算复杂但是是值得学习的一个项目，我是凉开水白菜祝各位程序员们节日快乐~ 咱们下文见~