String Hex to long converter.

const unsigned int MAX_INPUT = 50;
String Line[10];

void setup() {

  Serial.begin(9600);
}

void loop() {

  //check for terminal input via display.


  while (Serial.available () > 0) {

    processIncomingByte (Serial.read ());

  }


}


void processIncomingByte (const byte inByte)
{
  static char input_line [MAX_INPUT];
  static unsigned int input_pos = 0;

  switch (inByte)
  {

    case '\n':   // end of text
      input_line [input_pos] = 0;  // terminating null byte

      // terminator reached! process input_line here ...
      process_data (input_line);

      // reset buffer for next time
      input_pos = 0;
      break;

    case '\r':   // discard carriage return
      break;

    default:
      // keep adding if not full ... allow for terminating null byte
      if (input_pos < (MAX_INPUT - 1))
        input_line [input_pos++] = inByte;
      break;

  }  // end of switch

}


void process_data(char str[])
{
  char *pch;

  //text parsing
  int counter = 0;
  pch = strtok(str, " ,.-");

  //read through the input and split it into new lines based on where spaces and other symbols are.
  while (pch != NULL)
  {
    //set line to be equal to the split.
    Line[counter] = pch;

    pch = strtok(NULL, "= ,.>");
    counter++;
  }
  Serial.println(Line[0]);
  Serial.println(Line[1]);


  //if the command is the one we are looking for then run the hex command
  if (Line[0] == "HEX") {


    ConvertHex(Line[1]);

  }





}

long ConvertHex(String input)
{

  //how many hex chars there are. (if you change this youll need to redo the math at the bottom.
  int HexValues[4];

  //print how many get recived.
  Serial.println(input.length());
 //for the ammount of hex chars run through them and convert them into their individual base 10 values.
  for (int i = 0; i <= input.length() - 1; i++)
  {

    switch (input.charAt(i))
    {
      case 'A':
        HexValues[i] = 10;
        break;

      case 'B':
        HexValues[i] = 11;
        break;

      case 'C':
        HexValues[i] = 12;
        break;

      case 'D':
        HexValues[i] = 13;
        break;

      case 'E':
        HexValues[i] = 14;
        break;

      case 'F':
        HexValues[i] = 15;
        break;

      default:
        //if value is equal to its base 10 counter part then leave it be and convert it to int.
        HexValues[i] = (input.charAt(i) - '0');
        break;
    }

    //print the value of each hex symbol on its own.
    Serial.print("value:");
    Serial.println(HexValues[i]);
  }


  // add up all of the values and multiply based of their current place and to convert them to base 10.
  Serial.print("Total value:");
  Serial.println(HexValues[0] * 4096 + HexValues[1] * 256 + HexValues[2] * 16 + HexValues[3]);
  return (HexValues[0] * 4096 + HexValues[1] * 256 + HexValues[2] * 16 + HexValues[3]);
  //if you want to change this to do 24 bit hex inputs youll need to redo the math. here is where i got the equation from.
  //https://www.rapidtables.com/convert/number/hex-to-decimal.html?x=1111
}