Lỗi code dò đường sử dụng 8051

[soluv]

#include <REGX52.H>
#include <stdio.h>
#define roletrai P1^4 
#define rolephai P1^2 
#define dctrai P1^5 
#define dcphai P1^3 

unsigned char dem1=0,dem2=0; 
unsigned char XT,XP ; 
void delayms(int ms) //ham tao tre khoang 1ms 
{ 
int i,j; 
for(i=0;i<ms;i++) 
for(j=0;j<85;j++){} 

} 
void khoitao(void) 
{ 
EA=0; 
TMOD=0x02; 
TL0=0x9B; 
TH0=0x9B; 
ET0=1; 
EA=1; 
TR0=1; 
} 
void timer0(void)interrupt 1 
{ 
	TR0=0; 
	TF0=0; 
	dem1++; 
	dem2++; 
if(dem1<=XP)  
{ 
	dcphai=1;
} 
else  
{ 
	P1^3=0; 
} 
if(dem1>10) dem1=0;
 
if(dem2<=XT)  
{ 
	P1^5=1; 
} 
else  
{ 
	P1^5=0; 
} 
if(dem2>9) dem2=0; 
TR0=1; 
} 
void stop(void) 
 { 
     XP=0; 
	XT=0; 
 } 
void main(void) 
{ 
khoitao(); 
P0=0xB00000000; 
     roletrai=1; 
     rolephai=1; 
     delayms(50); 
   XP=10; 
   XT=9; 
   delayms(500); 
while(1) 
{          
      if (P0==0xB00011000) //lech ph 
          {     
            XP=10; 
            XT=9;
			} 
      if (P0==0xB00010000)
          {    
              XP=10;    
            XT=8; 
           }
      if (P0==0xB00110000)  
           {
		     XP=10; 
             XT=7;
			}
      if ( P0==0xB00100000)
             { 
                 XP=10; 
                XT=6; 
             } 
      if(P0==0xB01100000)
          { 
            XP=10;
			XT=5; 
        } 
      if (P0==0xB01000000)
          { 
            XP=8; 
            XT=5; 
        }
		if(P0==0xB11000000)
		{
			XP=7;
			XT=4;
		}
		 
      if (P0==0xB00001000)//lech tr
          {    
              XP=9;    
            XT=9; 
           }
      if (P0==0xB00001100)  
           {
		     XP=8; 
             XT=9;
			}
      if ( P0==0xB00000100)
             { 
                 XP=7; 
                XT=9; 
             } 
      if(P0==0xB00000110)
          { 
            XP=6;
			XT=9; 
        } 
      if (P0==0xB00000010)
          { 
            XP=5; 
            XT=7; 
        }
		if(P0==0xB00000011)
		{
			XP=4;
			XT=6;
		}	 
  }
  }

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