roaderosv0.2.c

最简单的51操作系统

/*******************************************************************
	File:				RoaderOS.c 
	Description:	MCS-51 RTOS						
	Autor: 			roader 
	Version:			1.0								
	Date:				2004-07
	Compiler:		Keil
	Emial:			[e-mail]
*********************************************************************/

#include <reg51.h>

/*------------------------------------------------------------------*/

#define uChar 	unsigned char
#define uShort	unsigned short
#define uLong 	unsigned long
#define sChar 	signed 	char
#define sShort	signed 	short
#define sLong 	signed 	long

/*------------------------------------------------------------------*/

#define TASKS_SIZE 	5	 
#define FRAME_SIZE 	20		//frame size
#define REGS_SIZE 	16		//register size	
#define IDLE_TASK 	TASKS_SIZE -1

#define disable()  	EA=0    //close interrupt
#define enable()   	EA=1    //open interrupt

/*------------------------------------------------------------------*/

enum	task_state{READY = 1 ,RUNNING, BLOCKED, SLEEPING, SUSPENDED, DEAD};

uChar	data 	cur_task = IDLE_TASK;
char 	data 	task_id 	= 0;

struct _tasks
{
	enum task_state 	status;
	uChar data 			*sp;
	uChar					frame[FRAME_SIZE];
} tasks[TASKS_SIZE];

/*------------------------------------------------------------------*/

sbit 			P1_0 = P1^0;

/*------------------------------------------------------------------*/

void 	Init_Timer();
void 	Create_Task(void *task, uChar id);
void 	Kill_Task(uChar id);
void 	Idle_Task();
void 	Start_Task();
void 	task1();
void 	task2();

/*------------------------------------------------------------------*/

void 	ContextSwitch() interrupt 3 using 0
{
	/* auto push IE */
	
	*(uChar data *)(++SP) = IE;
	
	disable();

	#pragma asm
		PUSH DPL
		PUSH DPH
		PUSH 0x00
		PUSH 0x01
		PUSH 0x02
		PUSH 0x03
		PUSH 0x04
		PUSH 0x05
		PUSH 0x06
		PUSH 0x07
	#pragma endasm

	tasks[cur_task].sp = (uChar data *)SP;

	//find ready task
	for(task_id = 0; task_id < TASKS_SIZE; task_id++)
	{
		cur_task=(uChar)(cur_task+1)%TASKS_SIZE;
		if(tasks[cur_task].status != READY)
			continue;
		else
			break;
	}

	//if not find,execute idle task
	if (tasks[cur_task].status != READY ) 
		cur_task = TASKS_SIZE-1;

	SP = tasks[cur_task].sp;

	#pragma asm
		POP 0x07
		POP 0x06
		POP 0x05
		POP 0x04
		POP 0x03
		POP 0x02
		POP 0x01
		POP 0x00
		POP DPH
		POP DPL
	#pragma endasm

	// pop IE
	IE = *(uChar data *)(SP--);

}
/*------------------------------------------------------------------*/

void 	Init_Timer()
{
	TMOD 	= (TMOD & 0x0F) | 0x20;
  	TH1 	= 256;
	TL1 	= TH1;
  	TR1 	= 1; 
  	ET1 	= 1;                   
  	EA		= 1;
}

/*------------------------------------------------------------------*/

void 	Create_Task(void *task, uChar id)
{ 
	*(uChar data *)(++SP)=IE;
	disable();

	tasks[id].frame[0] = (uChar)(((uShort)task)&0xff);
	tasks[id].frame[1] = (uChar)(((uShort)task)>>8);
	tasks[id].frame[4] = 0;
	tasks[id].sp 		 = tasks[id].frame - 1 + REGS_SIZE;
	tasks[id].status 	 = READY;

	IE = *(uChar data *)(SP--);
}

/*------------------------------------------------------------------*/

void 	Kill_Task(uChar id)
{
	*(uChar data *)(++SP) = IE;
	disable();
	
	tasks[id].status 		= DEAD;
	tasks[id].frame[0] 	= 0;
	tasks[id].frame[1] 	= 0;

	IE = *(uChar data *)(SP--);
}

/*------------------------------------------------------------------*/

void 	Idle_Task() 
{
	while(1) 
	{ 
		PCON |= 0x01;
	}
}

/*------------------------------------------------------------------*/

void 	Start_Task()
{
	Idle_Task();
}

/*------------------------------------------------------------------*/

void 	task1()
{
	while(1)
	{
		P1_0 = 0;
	}
}
void 	task2()
{
	while(1)
	{
		P1_0 = 0;
	}
}

/*------------------------------------------------------------------*/

void 	main(void) 
{
	Create_Task(task1, 0);	
	Create_Task(task2, 1);
	Create_Task(Idle_Task, IDLE_TASK);	

	Init_Timer(); 	
	
	Start_Task();		
}