AVR单片机C语言程序设计实例精粹

				//******************************************************************************
				// File Name : Kernel.c
				// Author    : Steaven
				// Created   : 2008-06-09
				// Modified  : 
				// Revision  : V0.0
				//******************************************************************************
				
				#include "app.h"
				
				//Task Control Block structure
				typedef struct
				{
					INT16U wTimerPeriod;
					INT16U wTimerCount;
					INT16U wEvent;
				}OS_TCB;
				
				//structure array definition
				OS_TCB OSTCB[cMaxTask];
				
				//******************************************************************************
				// Function    : OS_Event_Pend
				// Input       : wTaskPrio - priority of task
				// Output      : event of task
				// Description : Inquiry event of task indexed by priority and then clear it
				//******************************************************************************
				INT16U OS_Event_Pend(INT8U bTaskPrio)
				{
					INT16U wTaskEvent;
					wTaskEvent = OSTCB[bTaskPrio].wEvent;
					OSTCB[bTaskPrio].wEvent &= ~wTaskEvent;
					return(wTaskEvent);
				}
				
				//******************************************************************************
				// Function    : OSEventSend
				// Input       : wTaskPrio - priority of task
				//               wTaskEvent - event to be sent                 
				// Output      : none
				// Description : Send an event to task indexed by priority
				//******************************************************************************
				void OS_Event_Post(INT8U bTaskPrio,INT16U wTaskEvent)
				{
					OSTCB[bTaskPrio].wEvent |= (1 				}
				
				//******************************************************************************
				// Function    : OS_Task_Create
				// Input       : wTaskPrio - priority of task
				//               wTimerPeriod - period of task
				// Output      : none
				// Description : Set time period of a task to create it
				//******************************************************************************
				void OS_Task_Create(INT8U bTaskPrio,INT16U wTimerPeriod)
				{
					OSTCB[bTaskPrio].wTimerPeriod = wTimerPeriod;
				}
				
				//******************************************************************************
				// Function    : OS_Task_Start
				// Input       : wTaskPrio - priority of task
				//               wTimerCount - Initial time count of a task
				// Output      : none
				// Description : Set initial time count of a task
				//******************************************************************************
				void OS_Task_Init(INT8U bTaskPrio,INT16U wTimerCount)
				{
					OSTCB[bTaskPrio].wTimerCount = wTimerCount;
				}
				
				//******************************************************************************
				// Function    : OS_Task_Switch
				// Input       : wTaskPrio - priority of task
				// Output      : none
				// Description : inquiry the task in ready status.if there's no ready task with
				//               priority higher than current one,the task would run
				//******************************************************************************
				INT16U OS_Task_Switch(INT8U bTaskPrio)
				{
					INT8U bTemp;
					for(bTemp = 0;bTemp < bTaskPrio;bTemp++)
					{
						if(OSTCB[bTemp].wEvent != 0)
						{
							return(true);
						}
					}
					return(false);
				}
				
				//******************************************************************************
				// Function    : OS_Task_Update
				// Input       : none
				// Output      : none
				// Description : increase timercount of all tasks in each SYS clock ISR.if task
				//               is timeout,Kernel send a timer event to the task
				//******************************************************************************
				void OS_Task_Update(void)
				{
					INT8U bTemp;
					for(bTemp = 0;bTemp < cMaxTask;bTemp++)
					{
						OSTCB[bTemp].wTimerCount++;
						if(OSTCB[bTemp].wTimerCount == OSTCB[bTemp].wTimerPeriod)
						{
							OSTCB[bTemp].wTimerCount = 0;
							OS_Event_Post(bTemp,0);
						}
					}
				}
				
				//******************************************************************************
				// Function    : OS_Init
				// Input       : none
				// Output      : none
				// Description : Initlization of TCBs
				//******************************************************************************
				void OS_Init(void)
				{
					INT8U bTemp;
					for(bTemp = 0;bTemp < cMaxTask;bTemp++)
					{
						OSTCB[bTemp].wTimerPeriod = 0;
						OSTCB[bTemp].wTimerCount = 0;
						OSTCB[bTemp].wEvent = 0;
					}
				}
				
				//******************************************************************************
				// Function    : OS_Start
				// Input       : none
				// Output      : none
				// Description : Initlization of tasks and Start Kernel
				//******************************************************************************
				void OS_Start(void)
				{
					Task_Init();
					Task_Start();
				}
				
				//===============================END OF FILE==================================//