mega buttons

const int LED_PIN = 13;
const int BRAUD_RATE = 9600;

const int PIN_NO = 29; 
const int STATE_PIN_NO = 4;

// Input pin management
int rPins[PIN_NO] = {A3,A4,A11,A12,A13,A14,A15,5,6,7,8,9,10,11,12,22,23,24,25,26,27,34,35,36,37,38,39,40,41};
int rPinsFlags[PIN_NO][2];
int statePins[STATE_PIN_NO] = {28,29,31,32};
int statePinsFlags[STATE_PIN_NO][2];

uint8_t codebuffer[8] = { 0 };  // Global keyboard keycodes buffer
uint8_t keyModifier = 0;

void setup() {
    //Start Serial
  Serial.begin(BRAUD_RATE);
  pinMode(LED_PIN, OUTPUT);//for led status

  pinMode(30, INPUT_PULLUP);
  pinMode(33, INPUT_PULLUP);

  setInputPinsPullup(rPins,PIN_NO);
  setInputPinsPullup(statePins,STATE_PIN_NO);
  delay(200); 
}
  
void loop() {
    keyModifier = 0;
    if(digitalRead(30) == LOW ){
        keyModifier = 0x01;
    }
   if(digitalRead(33) == LOW ){//main power switch
      handleButtonPress(rPins,PIN_NO,rPinsFlags,false);
      handleButtonPress(statePins,STATE_PIN_NO,statePinsFlags,true);
   }
}

void handleButtonPress(int pinsToCheck[], int numPins, int flags[][2],bool statePins){
  for(int Pin = 0; Pin < numPins; Pin++)
    {
      if(digitalRead(pinsToCheck[Pin]) == LOW ) //something is pressed and fires off once only, statePin or not
      {  
        if (flags[Pin][1] == 0){
          flags[Pin][1] = 1;
          codebuffer[0] = keyModifier;//KEY_LEFT_CTRL + KEY_LEFT_ALT + KEY_LEFT_SHIFT;
          codebuffer[2] = Pin + 4;
          outputBuffer();
          releaseKey();
          delay(200);
        }
      }else if(digitalRead(pinsToCheck[Pin]) == HIGH and flags[Pin][1] == 1 and statePins){ //if nothing pressed and is statePin and was previously pressed, send signal: "off state" (ie new keycode)
          flags[Pin][1] = 0;
          codebuffer[0] = keyModifier;//KEY_LEFT_CTRL + KEY_LEFT_ALT + KEY_LEFT_SHIFT;
          codebuffer[2] = PIN_NO + Pin + 4;
          outputBuffer();
          releaseKey();
          delay(200);
      }else{
        flags[Pin][1] = 0;
      }
    } 
}

void outputBuffer(){
  Serial.write(codebuffer,8);
}

void releaseKey(){
   codebuffer[0] = 0;
   codebuffer[2] = 0;
   Serial.write(codebuffer, 8);  // Release key
}

void setInputPinsPullup(int pinsToSet[], int numPins){
   for(int Pin = 0; Pin < numPins; Pin++)
  {
    pinMode(pinsToSet[Pin], INPUT_PULLUP);
  }
}