FreeRTOS实时操作系统空闲任务的阻塞延时实现

//定义空闲栈
 #define configMINIMAL_STACK_SIZE ( ( unsigned short ) 128 )
 StackType_t IdleTaskStack[configMINIMAL_STACK_SIZE];
 //空闲任务任务控制块
 TCB_t IdleTaskTCB;
 //设置空闲任务的参数
 void vApplicationGetIdleTaskMemory( TCB_t **ppxIdleTaskTCBBuffer,
                                    StackType_t **ppxIdleTaskStackBuffer,
                                    uint32_t *pulIdleTaskStackSize )
{
  *ppxIdleTaskTCBBuffer=&IdleTaskTCB;
  *ppxIdleTaskStackBuffer=IdleTaskStack;
  *pulIdleTaskStackSize=configMINIMAL_STACK_SIZE;
}
void vTaskStartScheduler(void)
{
	TCB_t *pxIdleTaskTCBBuffer = NULL;//空闲任务控制块指针
	StackType_t *pxIdleTaskStackBuffer = NULL;//空闲任务栈指针
	uint32_t ulIdleTaskStackSize;	 //空闲任务栈大小
	
	//设置空闲任务参数
	vApplicationGetIdleTaskMemory(&pxIdleTaskTCBBuffer,
																&pxIdleTaskStackBuffer,
																&ulIdleTaskStackSize);
	//创建空闲任务
	xIdleTaskHandle = xTaskCreateStatic((TaskFunction_t)prvIdleTask,
										(char *)"IDLE",
										(uint32_t)ulIdleTaskStackSize,
										(void*)NULL,
										(StackType_t*)pxIdleTaskStackBuffer,
                    (TCB_t*)pxIdleTaskTCBBuffer);

  //将空闲任务添加到就绪列表
  vListInsertEnd(&(pxReadyTasksLists[0]),&(((TCB_t *)pxIdleTaskTCBBuffer)->xStateListItem));

	//手动指定第一个要运行的任务
	pxCurrentTCB = &Task1TCB;
	//启动调度器
	if(xPortStartScheduler()!=pdfALSE)
	{
		//启动成功则不会运行到这里
	}
}

typedef struct tskTaskControlBlock
{
	volatile StackType_t * pxTopOfStack;
	ListItem_t xStateListItem; 
	StackType_t * pxStack; ·
	char pcTaskName[configMAX_TASK_NAME_LEN];
	TickType_t xTicksToDelay; //用于延时
}tskTCB;

void vTaskDelay(const TickType_t xTicksToDelay)
{
	  TCB_t *pxTCB = NULL;
	  pxTCB = pxCurrentTCB;
	  //设置延时时间
	  pxTCB->xTicksToDelay = xTicksToDelay;
	  //进行一次任务切换
	  taskYIELD();
}

void vTaskSwitchContext( void )
{   //如果当前时空闲任务，尝试去执行任务1或任务2,如果他们延时时间都没到则继续执行空闲任务
	if( pxCurrentTCB == &IdleTaskTCB )
	{
			if(Task1TCB.xTicksToDelay == 0)
			{
				  pxCurrentTCB =&Task1TCB;
			}
      else if(Task2TCB.xTicksToDelay == 0)
		  {
		      pxCurrentTCB =&Task2TCB;
		  }
      else
      {
          return;
      }
  }
 else  //当前任务不是空闲任务会执行到这里
 {    //当前任务时任务1或任务2的话，检查另一个任务
      //如果另外的任务不在延时中，会切换到该任务
      //否则，判断当前任务是否在延时中，是则切换到空闲任务，
      //否则，不进行任何切换
		 if (pxCurrentTCB == &Task1TCB)
		 {
				 if (Task2TCB.xTicksToDelay == 0)
				 {
							pxCurrentTCB =&Task2TCB;
				 }
				 else if (pxCurrentTCB->xTicksToDelay != 0)
				 {
							pxCurrentTCB = &IdleTaskTCB;
				 }
				 else
				 {
							return;
				 }
		 }
		 else if (pxCurrentTCB == &Task2TCB)
		 {
				 if (Task1TCB.xTicksToDelay == 0)
				 {
					 pxCurrentTCB =&Task1TCB;
				 }
				 else if (pxCurrentTCB->xTicksToDelay != 0)
				 {
					 pxCurrentTCB = &IdleTaskTCB;
				 }
				 else
				 {
					 return;
				 }
		 }
 }
}

void xPortSysTickHandler( void )
{
 int x = portSET_INTERRUPT_MASK_FROM_ISR();
 xTaskIncrementTick();
 portCLEAR_INTERRUPT_MASK_FROM_ISR(x);
}
void xTaskIncrementTick( void )
{
	 TCB_t *pxTCB = NULL;
	 BaseType_t i = 0;
	 const TickType_t xConstTickCount = xTickCount + 1;
	 xTickCount = xConstTickCount;
	 for (i=0; i<configMAX_PRIORITIES; i++)
	 {
	 pxTCB = ( TCB_t * ) listGET_OWNER_OF_HEAD_ENTRY( ( &pxReadyTasksLists[i] ) );
	 if (pxTCB->xTicksToDelay > 0)
	 {
	 pxTCB->xTicksToDelay --; //这里递减
	 }
	 }
	 portYIELD();
}

//systick控制寄存器
#define portNVIC_SYSTICK_CTRL_REG (*((volatile uint32_t *) 0xe000e010 ))
//systick重装载寄存器
#define portNVIC_SYSTICK_LOAD_REG (*((volatile uint32_t *) 0xe000e014 ))
//systick时钟源选择
#ifndef configSYSTICK_CLOCK_HZ
	#define configSYSTICK_CLOCK_HZ confiGCPU_CLOCK_HZ
    #define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL )
#else
    #define portNVIC_SYSTICK_CLK_BIT ( 0 )
#endif
#define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL )
#define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL )
void vPortSetupTimerInterrupt( void )
{
    //重装载计数器值
	portNVIC_SYSTICK_LOAD_REG = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;
    //设置systick时钟使用内核时钟
    //使能systick定时器中断
    //使能systick定时器
	portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT |
	portNVIC_SYSTICK_INT_BIT |
	portNVIC_SYSTICK_ENABLE_BIT );
}

#define configCPU_CLOCK_HZ (( unsigned long ) 25000000)
#define configTICK_RATE_HZ (( TickType_t ) 100)

portCHAR flag1;
portCHAR flag2;
TaskHandle_t Task1_Handle;
StackType_t Task1Stack[128];
TCB_t Task1TCB;
TaskHandle_t Task2_Handle;
StackType_t Task2Stack[128];
TCB_t Task2TCB;

void Task1_Fntry(void *arg)
{
	while(1)
	{  
		  flag1=1;
		  vTaskDelay( 2 );
		  flag1=0;
		  vTaskDelay( 2 );
	}
}
void Task2_Fntry(void *arg)
{
	while(1)
	{  
		  flag2=1;
		  vTaskDelay( 2 );
		  flag2=0;
		  vTaskDelay( 2 );
	}
}
	int main(void)
	{
		prvInitialiseTaskLists();
		Task1_Handle = xTaskCreateStatic(Task1_Fntry,"task1",128,NULL,Task1Stack,&Task1TCB);
		vListInsertEnd(&pxReadyTasksLists[1],&((&Task1TCB)->xStateListItem));
		Task2_Handle = xTaskCreateStatic(Task2_Fntry,"task2",128,NULL,Task2Stack,&Task2TCB);
		vListInsertEnd(&pxReadyTasksLists[2],&((&Task2TCB)->xStateListItem));
		vTaskStartScheduler();
		for(;;)
		{}
	}