ES lift practical code

lift.c

#include<reg51.h>

int floor[] = {0x80,0x40,0x20,0x10,0x08,0x04,0x02};
unsigned int curr = 0;
sbit gd = P1^3;
sbit f = P1^2;
sbit s = P1^1; 
sbit t = P1^0;

void delay()
{
int count=0;
 while(count!=500)
  {
   TMOD=0x01;  //16-bit timer0 selected
   TH0=0xF8;   // Loading high byte in TH
   TL0=0xCC;   // Loaded low byte in TL
   TR0=1;      // Running the timer
    while(!TF0);   //Checking the timer flag register if it is not equal to 1 
   TR0 = 0;      // If TF0=1 stop the timer
   TF0 = 0;      // Clear the Timer Flag bit for next calculation
   count++;
  }
}

void changeFloor(unsigned int dest){
	unsigned int i = curr;
	if(P2<floor[dest]){	 
		while(i>dest){
			i--;
			delay();
			P2 = floor[i];
			
		}
	}
	if(P2>floor[dest]){
		while(i<dest){
			i++;
			delay();
			P2 = floor[i];
		}
	}
	curr = dest;
}

void main(){
P2 = 0x80;
while(1){
	if(gd==0){
		changeFloor(0);
	}
	if(f==0){
		changeFloor(2);
	}
	if(s==0){
		changeFloor(4);
	}
	if(t==0){
		changeFloor(6);
	}
}
}