Example on how to compute Arduino compliant CRC16 checksums in Java.

ArduinoCRC16.java

/**
 * Example on how to compute Arduino compliant CRC16 checksums in Java.
 * 
 * @author info@michaelhoffer.de
 */
public class Main {

    public static void main(String[] args) {
        byte[] data = new byte[]{1,2,3};
        int crc = crc16(data);
        String msg = String.format("CRC16: %x", crc);
        System.out.println(msg);
    }

    /**
     * Computes an Arduino compliant CRC16 checksum for the given data. 
     * 
     * Equivalent code on Arduino:
     * 
     * <pre>
     *   #include <util/crc16.h>
     *   //...
     *   byte data[] = {1,2,3};
     *   uint16_t crc = 0xFFFF;
     *   for (uint32_t i = 0; i < sizeof(data); i++) {
     *     crc = _crc16_update(crc, data[i]);
     *   }
     *   Serial.println(crc,  HEX); // shows 6161
     * </pre>
     * 
     * @param data byte array
     * @return the CRC16 checksum for the specified data
     */
    public static int crc16(final byte[] data) {
        int crc = 0xFFFF;
        for(byte a : data) {
            crc ^= (a & 0xFF); // convert a to unsigned (otherwise, it does not work for a > 127)
            for (int i = 0; i < 8; ++i)
            {
                if ((crc & 1) > 0)
                crc = (crc >> 1) ^ 0xA001;
                else
                crc = (crc >> 1);
            }
        }
        return crc;
    }
}