Creating a new library. Tutorial please

Projects Programming
5

SerialPreset.h

#ifndef SerialPreset_h
#define SerialPreset_h

#include  "Arduino.h"

class SerialPreset
{
  public:
    SerialPreset();
    String SerialRead();
};

extern SerialPreset SerialPreset;

#endif

SerialPreset.cpp

#include "Arduino.h"
#include "SerialPreset.h"

#define SOP  '<'   //Start of packet
#define EOP  '>'   //End of packet

String SOCP = "([";
String EOCP = ")]";
String CPS  = ",|";

bool started = false;
bool ended = false;

char inData[256];
byte index;
boolean Echo;
String HardwareCommands[4] = {"Analog", "Digital", "PWM", "Tx"};


SerialPreset::SerialPreset(){  }

String SerialPreset::SerialRead()  {
 while(Serial.available() > 0)
  {
    //Start serial thingy now!
    
    char inChar = Serial.read();
    if(inChar == SOP)
    {
       index = 0;
       inData[index] = '\0';
       started = true;
       ended = false;
    }
    else if(inChar == EOP)
    {
       ended = true;
       break;
    }
    else
    {
      if(index < 256)
      {
        inData[index] = inChar;
        index++;
        inData[index] = '\0';
      }
    }
  }

  // We are here either because all pending serial
  // data has been read OR because an end of
  // packet marker arrived. Which is it?
  if(started && ended)
  {
    // The end of packet marker arrived. Return the packet
    return inData;
    // Reset for the next packet
    started = false;
    ended = false;
    index = 0;
    inData[index] = '\0';
  }  
}

You'll probably recognize the above code, I found it here on the forum.
I just figured that my sketches would be more organized if I put the code in a serparate library.