我用AT89S52做频率计，谁能帮我把这个程序添加详细的注释

#include unsigned char code Tab[]={ 0xFC，0x60，0xDA，0xF2，0x66，0xB6，0xBE，0xE0，0xFE， 0xF6，0xEE，0x3E，0x9C，0x7A，0x9E，0x8E，0x00，}; unsigned char cfDispPos=0; unsigned long ifTimes=0; unsigned long Freq=0; unsigned long DispNow;... #include unsigned char code Tab[]={ 0xFC，0x60，0xDA，0xF2，0x66，0xB6，0xBE，0xE0，0xFE， 0xF6，0xEE，0x3E，0x9C，0x7A，0x9E，0x8E，0x00，}; unsigned char cfDispPos=0; unsigned long ifTimes=0; unsigned long Freq=0; unsigned long DispNow; bit bfComplete=0; bit bfTesting=0; unsigned char Method=0; unsigned int ifms=0; bit bfShow=1; sbit KEY=P3^7; void Delay(int t) { while(t--); } void StartFreq(unsigned char Method) { switch(Method) { case 0: {EX0=1; //从中断开定时器，测周法
IT0=1;
TMOD=0x11; //Timer0 for precise Time
EA=1;
break;} case 1: {//计数测频法 TH0=0xf8;TL0=0x30; //1ms ifTimes=0; TMOD=0x51; //Time0 for precise Time ，Timer1 for counter TH1=0;TL1=0; EA=1; ET0=1; TR0=1;TR1=1;ET1=1; PT1=1; }default:break; } } void timer0 (void) interrupt 1 { switch(Method) { case 0: //用于计数功能 ifTimes++; break; case 1: //work with T1 TH0=0xf8; TL0=0x30; //1ms ifTimes++; if(ifTimes>2000) //2s { TR1=0; TR0=0; EA=0; ET0=0; ET1=0; Freq+=(TH1*256+TL1); Freq=Freq*10/2; //Keep One bit for '.' if(Freq>900000)Freq=0; bfShow=1; bfComplete=1; } break; default:break; } } void timer1(void) interrupt 3 //测频测周 { switch(Method) { case 0: TH1=0xf8; TL1=0x30; ifms++; if(ifms>1000) { ifms=0;bfShow=1; } case 1: Freq+=65536;break; default:break; } } void EX0_IRQ(void) interrupt 0 //测周法使用 { if(!bfTesting) //first falling edge { TH0=0x0;TL0=0x0; //1ms ifTimes=0; ET0=1; TR0=1; //Timer0 for Time TH1=0xf8;TL1=0x30; TR1=1;ET1=1; bfTesting=1; } else //second falling edge { EA=0;TR0=0; ET0=0; EX0=0; //ET0=0; Freq=(ifTimes*65536+256*TH0+TL0)/2;// us S Freq=10000000/Freq; //Keep one bit for '.' bfComplete=1; } } void SystemInitial(void) { SCON=0X00; //TH0=0xfc;TL0=0x18; //0.5ms StartFreq(Method); } void main(void) { SystemInitial(); while(1) { if(!KEY) { Delay(2000); if(!KEY) { while(!KEY); if(Method) Method=0; else Method=1; DispNow=0; StartFreq(Method); } } if(bfComplete)//开始测量 { if(bfShow) { bfShow=0; DispNow=Freq; } Freq=0; bfComplete=0; bfTesting=0; StartFreq(Method); } {//显示 switch(cfDispPos) { case 0:P2=0x6E; P0=0xFE;break; case 1:P2=Tab[DispNow/1%10]; P0=0xFD;break; case 2:P2=Tab[DispNow/10%10]|(~Tab[8]); P0=0xFB;break; case 3:P2=Tab[DispNow/10]; P0=0xF7;break; case 4:P2=Tab[DispNow/1000%10]; P0=0xEF;break; case 5:P2=Tab[DispNow/10000%10]; P0=0xDF;break; case 6:P2=Tab[DispNow/100000%10]; P0=0xBF;break; case 7:if(Method)P2=0x02;else P2=0; P0=0x7F;break; } Delay(100);cfDispPos++; if(cfDispPos>=8){cfDispPos=0;} } } }