AT89S52 external clock

I've wrote the following code. I want to output the "Data" bit by bit to Pin1.3,
with the frequency from interrupt (0) pin.

#include <AT89X52.H>
#include <stdio.H>


sbit dataIN = P1^3; //Output Pin

volatile char Data = 0xAA; //Data to be output

void ex0_isr (void) interrupt (0) //Data output bit by bit
{
      if ((Data & 0x80) == 0)
            dataIN = 0;
          else
                dataIN = 1;

          Data<<=1;
}


main()
{
  IT0 = 1;   //  falling edge on /INT0 (P3.2)
  EX0 = 1;   //  Enable EX0 Interrupt
  EA = 1;        // Enable Global Interrupt Flag
}

Here are errors:
interrupt0417.c(15): error C231: 'dataIN': redefinition
interrupt0417.c(17): error C129: missing ';' before '<<='

Anyone can help? Thanks.

This is a wind up. Right?

Yes. I wonder why those codes can't work. Thanks a lot!

I'v fixed my code. There's no error now, but the result isn't right.

NO data has outputed from Pin1.3

Anything wrong here?

#include <AT89X52.H>
#include <stdio.H>


sbit dataIN = P1^3;      //Output


volatile char Data = 0xAA;

void ex0_isr(void) interrupt 0
{
      if ((Data & 0x80) == 0)
            dataIN = 0;
          else
                dataIN = 1;

          Data<<=1;
}



void main()
{
  IT0 = 1;   //  falling edge on /INT0 (P3.2)
  EX0 = 1;   //  Enable EX0 Interrupt
  EA = 1;        // Enable Global Interrupt Flag


}