rf_decode_intr_based_v3

volatile byte isrFlag;
byte loopFlag;

// and many other variables

void setup()
{
  pinModeFast(2, INPUT);    // LA.ch#0
  pinModeFast(12, OUTPUT);  // LA.ch#1
  pinModeFast(13, OUTPUT);  // LA.ch#2

  lastTrig = micros();

  isrFlag = LOW;
  loopFlag = LOW;

  digitalWriteFast(12, isrFlag);
  digitalWriteFast (13, loopFlag);

  noInterrupts();
  lastState = digitalReadFast(2);
  attachInterrupt(0, myISR, CHANGE);
  interrupts();
}

void loop()
{
  loopFlag = ~loopFlag;
  digitalWriteFast(13, loopFlag);

}

void myISR()
{
  thisTrig = micros();
  slab = thisTrig - lastTrig;

  isrFlag = ~isrFlag;
  digitalWriteFast(12, isrFlag);

  // code that checks lastState (HIGH/LOW) and slab (duration of lastState)
  // to identify SHORT-LOW, SHORT-HIGH, LONG-LOW, LONG-HIGH, VERYLONG-LOW and INVALID
  // sequence. INVALID sequence is ignored and decoder FSM is reset, others are
  // accumulated via a circular-queue until codeword-length is reached, at which point
  // codeword is processed i.e. matched with previous codeword to compare address bits
  // and if matched, data bits returned
}