基于PendSV 双任务时间片切换

1万 · 2020-9-30 16:58

// 定义任务 

um_task task1;      //任务1

um_task task2;      //任务2

um_task task_idle;  //空闲任务



// 定义任务堆栈

um_stack  task1_stack[1024];

um_stack  task2_stack[1024];

um_stack  task_idle_stack[1024];







um_task *CurrentTask,*NextTask;

um_task *TaskTable[3];





void task1_thread(void *param);

void task2_thread(void *param);

void TaskInit(um_task *task,void(*entry)(void*),void *param,unsigned int *task_tack);

void Um_TaskSched();

void ProductPendSV();

1万 · 2020-9-30 16:59

复制

// 任务调度

void Um_TaskSched()

{

  if(CurrentTask == TaskTable[2])

        {

            if(TaskTable[0]->DelayTicks == 0)

                                NextTask = TaskTable[0];

                        else if(TaskTable[1]->DelayTicks == 0)

                                NextTask = TaskTable[1];

                        else  return;

        }

        else

        {

            if(CurrentTask == TaskTable[0])

                        {

                                if(TaskTable[1]->DelayTicks == 0)

                                        NextTask = TaskTable[1];

                                else if(CurrentTask->DelayTicks != 0)

                                        NextTask = TaskTable[2];

                          

                        }

                        else if(CurrentTask == TaskTable[1])

                        {

                          if(TaskTable[0]->DelayTicks == 0)

                                        NextTask = TaskTable[0];

                                else if(CurrentTask->DelayTicks != 0)

                                        NextTask = TaskTable[2];

                        }

        }

                  

        ProductPendSV();

}

1万 · 2020-9-30 16:59

复制

// 设置Systick 中断定时

void SetSysTickPeriod(unsigned int ms)

{

         SysTick->LOAD = ms * SystemCoreClock/1000 -1;

         NVIC_SetPriority(SysTick_IRQn,(1<<__NVIC_PRIO_BITS)-1);

         SysTick->VAL = 0;

         SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk |

                   SysTick_CTRL_TICKINT_Msk   |

                   SysTick_CTRL_ENABLE_Msk; 

        



}

1万 · 2020-9-30 17:01

复制

// Systick 中断函数

void SysTick_Handler()

{

   int i;

   for(i=0;i<2;i++)

   {

      if(TaskTable[i]->DelayTicks >0)

                        {

                           TaskTable[i]->DelayTicks--;

                        }

   }        

         Um_TaskSched();

}

1万 · 2020-9-30 17:02

复制

// 任务延时函数

void TaskDelay(unsigned int delay)

{

  CurrentTask->DelayTicks = delay;

        Um_TaskSched();

}

1万 · 2020-9-30 17:03

复制

// 任务1 任务2 空闲任务 初始化任务

unsigned char flag1,flag2;

void task1_thread(void *param)

{

         SetSysTickPeriod(10);

        while(1)

        {

           flag1 = 1;

           TaskDelay(10);

           flag1 = 0;

           TaskDelay(10);                 

        }        

}

void task2_thread(void *param)

{

        while(1)

        {

           flag2 = 1;

           TaskDelay(10);

           flag2 = 0;

           TaskDelay(10);

        }        

}

void idel_thread(void *param)

{

        

        while(1)

        {

           

        }        

}



void FirstTask()

{

        __set_PSP(0);

  ProductPendSV();

}

1万 · 2020-9-30 17:03

主函数

复制

int main()

{



         

   TaskInit(&task1,task1_thread,(void*)1234,&task1_stack[1024]);

         TaskInit(&task2,task2_thread,(void*)5678,&task2_stack[1024]);

         TaskInit(&task_idle,idel_thread,(void*)0023,&task_idle_stack[1024]);

        

         TaskTable[0] = &task1;

         TaskTable[1] = &task2;

         TaskTable[2] = &task_idle;

        

         NextTask = TaskTable[0];

         FirstTask();

                

}

1万 · 2020-9-30 17:03

//任务初始化函数
void TaskInit(um_task *task,void(*entry)(void*),void *param,um_stack *task_tack)
{
*(--task_tack) = (unsigned long)(1<<24);
   *(--task_tack) = (unsigned long)entry; //pc寄存器
   *(--task_tack) = (unsigned long)0x14;
   *(--task_tack) = (unsigned long)0x12;
   *(--task_tack) = (unsigned long)0x3;
   *(--task_tack) = (unsigned long)0x2;
   *(--task_tack) = (unsigned long)0x1;
   *(--task_tack) = (unsigned long)param;

   *(--task_tack) = (unsigned long)0x11;
   *(--task_tack) = (unsigned long)0x10;
   *(--task_tack) = (unsigned long)0x9;
   *(--task_tack) = (unsigned long)0x8;
   *(--task_tack) = (unsigned long)0x7;
   *(--task_tack) = (unsigned long)0x6;
   *(--task_tack) = (unsigned long)0x5;
   *(--task_tack) = (unsigned long)0x4;
   task->stack_addr = task_tack;
   task->DelayTicks = 0;
}

1万 · 2020-9-30 17:03

// 进入临界区保护
unsigned int TaskEnterCritical()
{
unsigned int primask;

primask = __get_PRIMASK();
__disable_irq();
return primask;
}

// 退出临界区保护
void TaskExitCritical(unsigned int status)
{
__set_PRIMASK(status);
}

1万 · 2020-9-30 17:04

// PendSV异常
void ProductPendSV()
{
*(volatile unsigned long *)NVIC_SYSPRI2 = NVIC_PENDSV_PRI;
*(volatile unsigned long *)NVIC_INT_CTRL = NVIC_PENDSV_SET;
}

// PendSV中断处理函数
__asm__ void PendSV_Handler(void)
{

   IMPORT CurrentTask
   IMPORT NextTask
   MRS R0, PSP                //将PSP寄存器保存到R0中
   CBZ R0,PendSVHander_nosave //判断PSP寄存器的值是否为0 从而判断是否是
                                 //FirstTask任务触发还是umTaskSwitch()触发
   STMDB R0!,{R4-R11}
   LDR R1, = CurrentTask
   LDR R1,[R1]
   STR R0,[R1]

PendSVHander_nosave
LDR R0, = CurrentTask    //完成了nextTask向currentTask赋值操作
LDR R1, = NextTask
LDR R2,[R1]
STR R2,[R0]
LDR R0,[R2]             //从currentTask取出堆栈的地址
LDMIA R0!,{R4-R11}    //批量加载R4-R11寄存器
MSR PSP,R0
ORR LR,LR,#0x04
BX  LR

}