51单片机多任务程序例程

#include"reg51.h" extern os_start(); void task1(); void task2(); unsigned char os_state[2]; unsigned char stack1[20]; unsigned char stack2[20]; //char cur_task=0; //void main() void time_init(); //void stack_init(unsigned char *p, // unsigned char adderh,unsigned char adderl); void stack_init(unsigned char *p,unsigned int adder); void start_main() { //unsigned int adderh; //unsigned int adderl; ///adderh=((unsigned int)task1)>>8; //adderl=((unsigned int)task1)&0x00ff; stack_init(stack1,((unsigned int)task1)); stack_init(stack2,((unsigned int)task2)); time_init(); os_state[0]=1; os_start(); } void task2() { int i=5;i=i+7; while(1) { i=i++; } } void task1() {int i=5;i=i+7; while(1) { i=i+10;} } void stack_init(unsigned char *p,unsigned int adder) { //将ACC、B、DPH、DPL、PSW、R0~R7共13个寄存器压栈。 *(p+2)=(unsigned char)(adder>>8); *(p+1)=(unsigned char)(adder%256); *p=(unsigned char)(15+p); *(p+15)=0X88;//R7 *(p+14)=0X77;//R3 *(p+13)=0X66;//R2 *(p+12)=0X55;//R1 *(p+11)=0X44;//R3 *(p+10)=0X33;//R2 *(p+9)=0X22;//R1 *(p+8)=0X11;//R0 *(p+7)=0;//PSW *(p+6)=0;//DPL *(p+5)=0;//DPH *(p+4)=0;//b *(p+3)=0;//ACC //stack1[2]=(unsigned int)task1>>8; //stack1[1]=(unsigned int)task1&0xff; //stack1[0]=(unsigned char)&stack1[15]; } void time_init() { TMOD = 0x01; TH0 = 0xd8; TL0 = 0xf0; TR0 = 1; EA = 1; ET0 = 1; }