HC-SR04 displaying random stuff after range 9

Im using 8051, LM016L and HC-SR04 for range finder but after range 9 it starts to display random stuff.

unsigned int get_range(void)
{
long int timer_val;
send_pulse();
while(!INT0); //Waiting until echo pulse is detected
while(INT0); //Waiting until echo pulse changes its state
timer_val=(TH0<<8)+TL0;
lcd_cmd(0x81);
lcd_data_string("output:");
lcd_cmd(0x8a);
if(timer_val<38000)
{
cms=timer_val/59;
if (cms!=0)
{
lcd_data(cms+48);

if(cms<15)
{
P1=0xFF;
}
else

{P1=0X00;}


}
}
else
{
lcd_cmd(0x06);
lcd_data_string("Object out of range");
}
return cms;
}

Image

We need to see the rest of your code.
Comments to explain what is supposed to happen would be useful.