一个简易的调度器
单片机源程序如下:
- #include <stc89c51.h>
- /****小小调度器开始**********************************************/
- #define MAXTASKS 3
- volatile unsigned char timers[MAXTASKS];
- #define _SS static unsigned char _lc=0; switch(_lc){default:
- #define _EE ;}; _lc=0; return 255;
- #define WaitX(tickets)??do {_lc=(__LINE__+((__LINE__%256)==0))%256; return tickets ;} while(0); case (__LINE__+((__LINE__%256)==0))%256:
- #define RunTask(TaskName,TaskID) do { if (timers[TaskID]==0) timers[TaskID]=TaskName(); }??while(0);
- #define RunTaskA(TaskName,TaskID) { if (timers[TaskID]==0) {timers[TaskID]=TaskName(); continue;} }? ?//前面的任务优先保证执行
- #define CallSub(SubTaskName) do {unsigned char currdt; _lc=(__LINE__+((__LINE__%256)==0))%256; return 0; case (__LINE__+((__LINE__%256)==0))%256:??currdt=SubTaskName(); if(currdt!=255) return currdt;} while(0);
- #define InitTasks() {unsigned char i; for(i=MAXTASKS;i>0 ;i--) timers[i]=0; }
- #define UpdateTimers() {unsigned char i; for(i=MAXTASKS;i>0 ;i--){if((timers[i-1]!=0)&&(timers[i-1]!=255)) timers[i-1]--;}}
- #define SEM unsigned int
- //初始化信号量
- #define InitSem(sem) sem=0;
- //等待信号量
- #define WaitSem(sem) do{ sem=1; WaitX(0); if (sem>0) return 1;} while(0);
- //等待信号量或定时器溢出， 定时器tickets 最大为0xFFFE
- #define WaitSemX(sem,tickets)??do { sem=tickets+1; WaitX(0); if(sem>1){ sem--;??return 1;} } while(0);
- //发送信号量
- #define SendSem(sem)??do {sem=0;} while(0);
- /*****小小调度器结束*******************************************************/
- sbit LED1 = P2^1;
- sbit LED2 = P2^2;
- sbit LED0 = P2^5;
- unsigned char task0(){
- _SS
- while(1){
- WaitX(50);
- LED0=!LED0;
- }
- _EE
- }
- unsigned char??task1(){
- _SS
- while(1){
- WaitX(100);
- LED1=!LED1;
- }
- _EE
- }
- unsigned char??task2(){
- _SS
- while(1){
- WaitX(100);
- LED2=!LED2;
- }
- _EE
- }
- void InitT0()
- {
- TMOD = 0x21;
- IE |= 0x82;??// 12t
- TL0=0Xff;
- TH0=0XDB;
- TR0 = 1;
- }
- void INTT0(void) interrupt 1 using 1
- {
- TL0=0Xff;? ? //10ms 重装
- TH0=0XDB;//b7;
- UpdateTimers();
- RunTask(task0,0);//任务0具有精确按时获得执行的权限，要求：task0每次执行消耗时间<0.5个 ticket
- }
- void main()
- {
- InitT0();
- InitTasks(); //初始化任务，实际上是给timers清零
- while(1){
- //? ?? ?? ???RunTask(task0,0);
- RunTaskA(task1,1);//任务1具有比任务2高的运行权限
- RunTaskA(task2,2);//任务2具有低的运行权限
- }
- }
所有资料51hei提供下载:
小小调度器.zip
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