import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.comm.CommPortIdentifier;
import javax.comm.SerialPort;

public class CricketComm
{
  private static final boolean DEBUG = false;

  private static final String hex(int x)
  {
    return "0x"+Integer.toHexString(x);
  }

  private SerialPort fPort;
  private InputStream fIn;
  private OutputStream fOut;

  CricketComm(String port)
  {
    try {
      CommPortIdentifier id = CommPortIdentifier.getPortIdentifier(port);
      fPort = (SerialPort) id.open("Passing", /*timeout=*/ 0);
      fPort.setSerialPortParams(/*baudrate=*/ 9600,
                                SerialPort.DATABITS_8,
                                SerialPort.STOPBITS_1,
                                SerialPort.PARITY_NONE);
      fIn = fPort.getInputStream();
      fOut = fPort.getOutputStream();
    } catch (Exception e) {
      throw new Problem(e, "Cannot start CricketComm");
    }
  }

  void send(int value)
  {
    try {    
      if (DEBUG) System.out.println("Send "+hex(value));
      fOut.write(value);
      if (DEBUG) System.out.println("Waiting for echo");
      int echo = fIn.read();
      if (echo != value)
        throw new Problem("Send "+hex(value)+", echo "+hex(echo));
      if (DEBUG) System.out.println("Received echo");
    } catch (IOException e) {
      throw new Problem(e, "Cannot send to Cricket");
    }
  }

  int receive()
  {
    try {
      if (DEBUG) System.out.println("Waiting for receive");
      int value = fIn.read();
      if (DEBUG) System.out.println("Received "+hex(value));
      return value;
    } catch (IOException e) {
      throw new Problem(e, "Cannot receive from Cricket");
    }
  }

  void close()
  {
    fPort.close();
  }
}