#include <Arduino.h>
#include <Streaming.h>
Print &cout = Serial;  

//////////////////////////////////////////////////
// Definitions
//////////////////////////////////////////////////

//
// Moving average
//
template <const size_t BUFFERSIZE = 2> class AnalogFilter {
  static_assert(BUFFERSIZE > 0 && BUFFERSIZE < 256, "The buffer size must be between 2 and 255 bytes. ");

public:
  constexpr size_t bufferSize() { return BUFFERSIZE; }

  uint16_t &operator[](size_t idx) { return buffer[idx]; }
  uint16_t average(uint16_t);

private:
  uint16_t buffer[BUFFERSIZE] {0};
  uint8_t bufferIndex {0};
  uint32_t total {0};
};

template <const size_t BUFFERSIZE> uint16_t AnalogFilter<BUFFERSIZE>::average(uint16_t reading) {
  // Perform average on sensor readings
  total = total - buffer[bufferIndex];   // subtract the last reading:
  buffer[bufferIndex] = reading;         // store adc value
  total = total + buffer[bufferIndex];   // add value to total:
  bufferIndex = ((BUFFERSIZE - 1) > bufferIndex) ? bufferIndex + 1 : 0;
  // calculate and return the average (rounded):
  return static_cast<uint16_t>(((total * 10) / BUFFERSIZE + 5) / 10);
}

//////////////////////////////////////////////////
// Global constants and variables
//////////////////////////////////////////////////

constexpr byte ANALOG_READ_PIN {A0};
AnalogFilter<16> aFilter;

//////////////////////////////////////////////////
// Functions forward declaration(s)
//////////////////////////////////////////////////

void setup() {
  Serial.begin(115200);
}

void loop() {
  uint16_t result=  aFilter.average(analogRead(ANALOG_READ_PIN));
  cout << result << F("  Buffer at pos 3 ") << aFilter[2] << endl;
  delay(500);
}