优先级反转.c

运行在ucos下的实验用例程序

/***************************************************************
 * 声明：
 *  本程序只具备演示功能，不能保证适用于您的真实应用。如需使用，请根据
 * 您的实际需要修改本程序。
 *******************************************************************
 *                      电子科技大学嵌入式软件工程中心 版权所有
 *
 *                  Copyright (C) 2006 UESTC ESEC
 **************************************************************/

/**************************************************************
 * 模块: init.c
 *
 * 目的:
 *      这个程序演示基本的天花板优先级的解决。程序启动具有三个不同优先
 *      级的任务，每个任务请求，获得，释放互斥信号量，完成一系列动作。
 **************************************************************/
/********************************************************************************************************
*                                                uC/OS-II
*                                          The Real-Time Kernel
*
*
*********************************************************************************************************
*/

#include <stdio.h>
#include "/host/ide/workspace/ucos/src/includes.h"

/*
*********************************************************************************************************
*                                               CONSTANTS
*********************************************************************************************************
*/

#define     TASK_STK_SIZE         1024                  /* Size of each task's stacks (# of WORDs)       */
#define     TASK_START_ID            0                  /* Application tasks                             */
#define     TASK_START_PRIO         17                  /* Application tasks priorities                  */
#define	    N_TASKS			         3                  /* Number of tasks                               */

/*
*********************************************************************************************************
*                                               VARIABLES
*********************************************************************************************************
*/

OS_STK	      TaskStk[N_TASKS][TASK_STK_SIZE/sizeof(OS_STK)];	/*Tasks stacks                        */
OS_STK        TaskStartStk[TASK_STK_SIZE];                      /* Startup    task stack              */
INT8U         TaskData[N_TASKS];                                /* Parameters to pass to each task    */
OS_EVENT      *mutex;                                           /* 1 mutual exclusive semaphore       */


/*
*********************************************************************************************************
*                                           FUNCTION PROTOTYPES
*********************************************************************************************************
*/

static  void  TaskStartCreateTasks(void);             /* Function prototypes of Create tasks           */

        void  Task0(void *pdata);                     /* Function prototypes of tasks                  */
        void  Task1(void *pdata);
        void  Task2(void *pdata);
        void  TaskStart(void *pdata);				  /* Function prototypes of Startup task           */

/*
*********************************************************************************************************
*                                                MAIN
*********************************************************************************************************
*/

extern void main(void);

/*
 *
 * *********************************************************************************************************
 *
 */

void boot_card()
{
	ucBsp_init();                                          /* Initializa ucBsp                          */

    main();
}

extern void OSCpuInit();

extern void OS_Sched(void);

void  main (void)
{
	INT8U err;                                             /* for setting the mutex                     */


	printk("Welcome to ucos-II\n");

	OSCpuInit();                                           /* Install uC/OS-II's context switch vector  */
    OSInit();                                              /* Install uC/OS-II's context switch vector  */

    mutex=OSSemCreate(1);                                  /* Set a mutual semaphore                    */

    OSTaskCreate(TaskStart, (void *)0, &TaskStartStk[TASK_STK_SIZE - 1], 4);

    OSStart();                                             /* Start multitasking                        */
}


/*
*********************************************************************************************************
*                                              STARTUP TASK
*********************************************************************************************************
*/

void  TaskStart (void *pdata)
{
    INT16S     key;
	int i;

	pdata = pdata;                                            /* Prevent compiler warning                 */

    ucos_x86_idt_set_handler(0x20,(void *)OSTickISR,0x8e00);  /* Install uC/OS-II's clock tick ISR        */
    ucos_timer_init();                                        /* Reprogram tick rate                      */

    TaskStartCreateTasks();                                   /* Create all the application tasks         */

 	OSTaskSuspend(OS_PRIO_SELF);                              /* Suspend the TaskStart                    */
}

/*
***************************************************************************************************************
*                                             CREATE TASKS
***************************************************************************************************************
*/

static  void  TaskStartCreateTasks (void)
{
    INT8U  i;


    for (i = 0; i <N_TASKS; i++)
    {                                                         /* Create N_TASKS identical tasks           */
		  TaskData[i] = i;
	}                                                         /* Each task will pass its own id           */
	OSTaskCreate(Task0, (void *)&TaskData[0], &TaskStk[0][TASK_STK_SIZE - 1], 5);
	OSTaskCreate(Task1, (void *)&TaskData[1], &TaskStk[1][TASK_STK_SIZE - 1], 6);
	OSTaskCreate(Task2, (void *)&TaskData[2], &TaskStk[2][TASK_STK_SIZE - 1], 7);
}

/*
****************************************************************************************************************
*                                                  TASKS
****************************************************************************************************************
*/

void  Task0 (void *pdata)
{
    INT8U  err;
    INT8U  id;
    INT16U value;

	id=*(int *)pdata;
    for (;;)
    {

      printk("Task %d is waitting a event.\n",id);
      OSTimeDly(200);                                       /* Delay 200 clock tick       */
        printk("The event of Task %d come.\n",id);
        printk("Task %d is try to get mutex.\n",id);
        OSSemPend(mutex,0,&err);                          /* Acquire mutex */
		switch(err)
		{
			case OS_NO_ERR:
			    printk("Task %d has got the mutex.\n",id);
			    printk("\n");
                break;
			default:
				printk("Task %d is suspended.\n",id);
				printk("\n");
		}

		OSTimeDly(200);                                     /* Delay 200 clock tick       */
		printk("Task %d release mutex.\n",id);
		
	    OSSemPost(mutex);                                /* Release mutex         */

	 }
}

void  Task1 (void *pdata)
{
    INT8U  err;
    INT8U  id;
    int i;
	id=*(int *)pdata;

	 for (;;) {
	   printk("Task %d is waitting a event.\n",id);
       OSTimeDly(100);                                /* Delay 100 clock tick       */

       printk("The event of Task %d come.\n",id);
       OSTimeDly(100);
           
	 }
}

void  Task2 (void *pdata)
{
    INT8U  err;
    INT8U  id;
    INT16U value;
	id=*(int *)pdata;
	int i;

    for (;;)
    {
		      

		printk("Task %d is trying to get mutex.\n",id);
        OSSemPend(mutex,0,&err);                      /* Acquire mutex */
		switch(err)
		{
		    case OS_NO_ERR:
            {
				printk("\n");
				printk("----------------------------------\n");
				printk("Task %d has got the mutex.\n",id);
				
				OSTimeDly(200);                           /* Delay 100 clock tick       */
				break;
			}
			default :
			{
				printk("Task %d  is failed to get mutex.\n",id);
				printk("\n");
				OSTimeDly(200);                           /* Delay 100 clock tick       */
				break;
			}
		}

      
    printk("Task %d release mutex.\n",id);
    printk("\n");
	OSSemPost(mutex);                            /* Release mutex         */
	}
}