JXmodem

Introduction

This library is a port of Georges Menie's Xmodem routines to Java, adapted to use Java classes (particularly streams) and with support for XModem-1k.

The original C code can be found here: https://www.menie.org/georges/embedded/

The library is written in pure Java. It supports Xmodem, Xmodem-CRC, and XModem-1k. For Xmodem-1k and Xmodem-CRC, CRC calculation is performed via a pre-calculated lookup table.

The library has been tested for accuracy using the sx and rx programs both on the same machine and over a local area network. Further testing under different conditions is both welcome and encouraged.

Add as a dependency

Add the following dependency to your projects pom.xml file:

<dependency>
    <groupId>io.github.neonSonOfXenon.JXmodem</groupId>
    <artifactId>JXmodem</artifactId>
    <version>0.1a</version>
</dependency>

Usage

Usage is fairly simple. All you need is an InputStream and OutputStream to initialize JXmodem:

JXmodem xm = new JXmodem(someInputStream, someOutputStream);

From there, you have a host of functions for simple sending and receipt of byte arrays, strings, and files.

Sending and receiving byte arrays

Sending a byte array is as easy as

byte[] bs = "this is an example string that will be turned into a byte array".getBytes();
boolean success = xm.send(bs); // returns true if the send succeeded

The method send(byte[] data, int offset, int length) also exists for sending subsets of byte arrays.

To receive a byte array, simply do

byte[] bs = xm.receive();

Sending and receiving strings

Strings may be sent using the sendString() method:

String s = "this is an example string that will remain a string";
boolean success = xm.sendString(s); // returns true if the send succeeded

You also have the option to specify a character set for the string via sendString(String message, String charset).

String receipt can be done like so:

String s = xm.receiveString();

Just like sending, you can specify a charset for encoding the string with recieveString(String charset).

Sending and receiving files

File transfers are possible through sendFile() and receiveFile(). These methods handle reading and writing the files to and from local storage. You just need to provide a valid filepath.

// sending a file
String outFilename = "path/to/file.xyz";
boolean sendSuccess = xm.sendFile(outFilename); // returns true if the send succeeded

// receiving a file
String inFilename = "path/to/newFile.xyz";
boolean receiveSuccess = xm.receiveFile(inFilename); // returns true if the file was received 
                                                     // and saved successfully

Still to do

The following is a list of improvements still needed:

• Clean up debugging printouts
• Generate Javadoc