RFID door using strike plate + Wiegand interface

/* Crazy People
 * By Mike Cook April 2009
 * Three RFID readers outputing 26 bit Wiegand code to pins:-
 * Reader A (Head) Pins 2 & 3
 * Interrupt service routine gathers Wiegand pulses (zero or one) until 26 have been recieved
 * Then a sting is sent to processing
 */
int validSiteCodes[] = {196, 452};
int validSerialNumbers[] = {15809, 3285};// see if site code and serial number are in the lists...

volatile long reader1 = 0;
volatile int reader1Count = 0;

void reader1One(void) {
  reader1Count++;
  reader1 = reader1 << 1;
  reader1 |= 1;
}

void reader1Zero(void) {
  reader1Count++;
  reader1 = reader1 << 1;
}

void setup()
{
  Serial.begin(9600);
  // Attach pin change interrupt service routines from the Wiegand RFID readers
  attachInterrupt(0, reader1Zero, RISING);//DATA0 to pin 2
  attachInterrupt(1, reader1One, RISING); //DATA1 to pin 3
  delay(10);
  // the interrupt in the Atmel processor mises out the first negitave pulse as the inputs are already high,
  // so this gives a pulse to each reader input line to get the interrupts working properly.
  // Then clear out the reader variables.
  // The readers are open collector sitting normally at a one so this is OK
  for(int i = 2; i<4; i++){
  pinMode(i, OUTPUT);
   digitalWrite(i, HIGH); // enable internal pull up causing a one
  digitalWrite(i, LOW); // disable internal pull up causing zero and thus an interrupt
  pinMode(i, INPUT);
  digitalWrite(i, HIGH); // enable internal pull up
  }
  delay(10);
  // put the reader input variables to zero
  reader1 = 0;
  reader1Count = 0;
  //digitalWrite(13, HIGH);  // show Arduino has finished initilisation
}

void loop()
{
  if(reader1Count >=26){
//Serial.print(" Reader 1 ");
//Serial.println(reader1,HEX);
 // Serial.println("A");
 //Serial.println(reader1& 0xfffffff);
 int serialNumber=(reader1 >> 1) & 0x3fff;
 int siteCode= (reader1 >> 17) & 0x3ff;

 Serial.print(siteCode);
 Serial.print("  ");
 Serial.println(serialNumber);
  reader1 = 0;
  reader1Count = 0;
if(IsTagValid(siteCode, serialNumber)
){
  digitalWrite(13,HIGH);
}
  else
    digitalWrite(13,LOW);
    delay(2000);
    digitalWrite(13,LOW);   // Open the door. It's cold out here!
}
     }

boolean IsTagValid(int siteCode, int serialNumber)
{
   boolean valid = false;

   // Determine how many valid tags there are
   int validTagCount = sizeof(validSiteCodes)/sizeof(int);

   // Loop through the arrays to see if siteCode
   // and serialNumber are present

   for(int t=0; t<validTagCount; t++)
   {
    if(validSiteCodes[t] == siteCode &&
       validSerialNumbers[t] == serialNumber)
    {
        valid = true;
        break;
    }
   }

   return valid;
}