Calc average value from given sample size w/ arduino-c

average-sample.ino

// immediate fan speed
int fanRpm = (60000000 / float(pulseIn(tachPin, LOW, 100000))) * 0.5;

// no average yet, use last fan reading
if (avgRpm == 0) {
  avgRpm = fanRpm;
}

// check array vals for first -1
int emptyInd = -1;
for (byte i=0; i<sampleSize; i++) {
  if (rpmSamples[i] == -1) {
    emptyInd = i;
    break;
  }
}

// no -1 founds, calc average
if (emptyInd == -1) {
    long int sumRpm = 0;
    for (byte i=0; i<sampleSize; i++) {
      sumRpm += rpmSamples[i];
      rpmSamples[i] = -1;
    }

    avgRpm = int(sumRpm / float(sampleSize));


// found a -1, so replace it w/ latest fan reading
} else if (emptyInd > -1) {
  rpmSamples[emptyInd] = fanRpm;
}

// send average speed to 4 digi - 7 seggie
displayDigits(avgRpm);

Looks complicated