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This package supports the parsing of AIS messages in Java. AIS, the Automatic Identification System, is a system aiming at improving maritime safety by exchanging messages between ships, other vehicles in particular aircraft involved in search-and-rescue (SAR), and (fixed) base stations. To be precise, this package support the ITU-R M.1371-4 AIS standard. See our extensive javadoc and in particular the class AISParser for more information on how to use this package. The parser was used in the Poseidon project, and is improved in the Metis project to better handle uncertain information. Both projects were led by the Embedded Systems Institute. In both projects Thales Nederlands was the carrying industrial partner, and multiple Dutch universities participated.

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package nl.esi.metis.aisparser.impl;

import nl.esi.metis.aisparser.AISMessage22;
import nl.esi.metis.aisparser.Destination;
import nl.esi.metis.aisparser.DestinationArea;
import nl.esi.metis.aisparser.DestinationIDs;
import nl.esi.metis.aisparser.Sixbit;
import nl.esi.metis.aisparser.UtilsPositionInfo;
import nl.esi.metis.aisparser.UtilsSpare;
import nl.esi.metis.aisparser.annotations.AISIllegalValueAnnotation;
import nl.esi.metis.aisparser.provenance.VDMMessageProvenance;

/** ESI AIS Parser
 * 
 * Copyright 2011/2012 by Pierre van de Laar (Embedded Systems Institute)
 * Copyright 2008 by Brian C. Lane 
 * All Rights Reserved
 * 
 * @author Pierre van de Laar
 * @author Brian C. Lane
 */


/** AIS Message 22 class
 * Channel Management
 * 
 * Field Nr     Field Name                          NrOf Bits   (from, to )
 * ------------------------------------------------------------------------
 *  1	messageID                               	   6	(   1,   6)
 *  2	repeatIndicator                         	   2	(   7,   8)
 *  3	userID                                  	  30	(   9,  38)
 *  4	spare1                                  	   2	(  39,  40)
 *  5	channelA                                	  12	(  41,  52)
 *  6	channelB                                	  12	(  53,  64)
 *  7	txrxMode                                	   4	(  65,  68)
 *  8	power                                   	   1	(  69,  69)
 *  9	destination                             	  70	(  70, 139)
 * 10	addressedMessageIndicator               	   1	( 140, 140)
 * 11	channelABandwidth                       	   1	( 141, 141)
 * 12	channelBBandwidth                       	   1	( 142, 142)
 * 13	transitionalZoneSize                    	   3	( 143, 145)
 * 14	spare2                                  	  23	( 146, 168)
 *                                                      ---- +
 *                           (maximum) number of bits    168
 */
class AISMessage22Impl extends AISMessageImpl implements AISMessage22 {
	public static final int LENGTH = 168;

	public static boolean validLength(int length)
	{
		return (length == LENGTH);
	}

	/**
	 * Return the difference in available and needed bits to parse this sixbit as an AisMessage
	 * A positive difference indicates that there are more bits available than needed by the standard.
	 * @param sb
	 * @return
	 */
	public static int differenceInBits(Sixbit sb)
	{
		return (sb.available() - LENGTH);
	}
	
	private static final int SPARE1_FROM = 39;
	private static final int SPARE1_TO = 40;

	private int spare1;
	/** spare1
	 * @return int value of spare1 (2 bits [39,40])
	 */
	public int getSpare1() { return spare1; }


	private static final int CHANNELA_FROM = 41;
	private static final int CHANNELA_TO = 52;

	private int channelA;
	/** channelA
	 * @return int value of channelA (12 bits [41,52])
	 */
	public int getChannelA() { return channelA; }


	private static final int CHANNELB_FROM = 53;
	private static final int CHANNELB_TO = 64;

	private int channelB;
	/** channelB
	 * @return int value of channelB (12 bits [53,64])
	 */
	public int getChannelB() { return channelB; }


	private static final int TXRXMODE_FROM = 65;
	private static final int TXRXMODE_TO = 68;

	private int txrxMode;
	/** txrxMode
	 * @return int value of txrxMode (4 bits [65,68])
	 */
	public int getTxrxMode() { return txrxMode; }


	private static final int POWER_BITINDEX = 69;

	private boolean power;
	/** power
	 * @return boolean value of power (bit 69)
	 */
	public boolean getPower() { return power; }


	private static final int DESTINATION_FROM = 70;
	//private static final int DESTINATION_TO = 139;

	private Destination destination;
	/** destination
	 * @return Destination value of destination (70 bits [70,139])
	 */
	public Destination getDestination() { return destination; }


	private static final int ADDRESSEDMESSAGEINDICATOR_BITINDEX = 140;

	private boolean addressedMessageIndicator;
	/** addressedMessageIndicator
	 * @return boolean value of addressedMessageIndicator (bit 140)
	 */
	public boolean getAddressedMessageIndicator() { return addressedMessageIndicator; }


	private static final int CHANNELABANDWIDTH_BITINDEX = 141;

	private boolean channelABandwidth;
	/** channelABandwidth
	 * @return boolean value of channelABandwidth (bit 141)
	 */
	public boolean getChannelABandwidth() { return channelABandwidth; }


	private static final int CHANNELBBANDWIDTH_BITINDEX = 142;

	private boolean channelBBandwidth;
	/** channelBBandwidth
	 * @return boolean value of channelBBandwidth (bit 142)
	 */
	public boolean getChannelBBandwidth() { return channelBBandwidth; }


	private static final int TRANSITIONALZONESIZE_FROM = 143;
	private static final int TRANSITIONALZONESIZE_TO = 145;

	private int transitionalZoneSize;
	/** transitionalZoneSize
	 * @return int value of transitionalZoneSize (3 bits [143,145])
	 */
	public int getTransitionalZoneSize() { return transitionalZoneSize; }


	private static final int SPARE2_FROM = 146;
	private static final int SPARE2_TO = 168;

	private int spare2;
	/** spare2
	 * @return int value of spare2 (23 bits [146,168])
	 */
	public int getSpare2() { return spare2; }

	/** AISMessage 22 constructor
	 * @param content AIS content
	 * @param prov the provenance of the message
	 * @precondition validLength(content.length()) && AISMessageBase.getMessageId(content)==22
	 */
	public AISMessage22Impl(Sixbit content, VDMMessageProvenance prov)
	{
		super(content, prov);
		assert(validLength(content.length()));
		assert(getMessageID() == 22);

		spare1 = content.getIntFromTo(SPARE1_FROM,SPARE1_TO);
	    if (!UtilsSpare.isSpareSemanticallyCorrect(spare1))
	    {
	    	annotations.add(new AISIllegalValueAnnotation("getSpare1", spare1, UtilsSpare.range));
	    }
		channelA = content.getIntFromTo(CHANNELA_FROM,CHANNELA_TO);
		channelB = content.getIntFromTo(CHANNELB_FROM,CHANNELB_TO);
		txrxMode = content.getIntFromTo(TXRXMODE_FROM,TXRXMODE_TO);
		power = content.getBoolean(POWER_BITINDEX);
		addressedMessageIndicator = content.getBoolean(ADDRESSEDMESSAGEINDICATOR_BITINDEX);
		if (addressedMessageIndicator)
		{
			destination = new DestinationIDs(DESTINATION_FROM, content);
		}
		else
		{
			destination = new DestinationArea(DESTINATION_FROM, content);
			if (!UtilsPositionInfo.isLongitudeSemanticallyCorrect(((DestinationArea)destination).longitudeUpperRightCornerInDegrees()))
		    {
		    	annotations.add (new AISIllegalValueAnnotation("getDestination.longitudeUpperRightCorner",((DestinationArea)destination).longitudeUpperRightCornerInDegrees(), UtilsPositionInfo.rangeLongitude));
		    }
			if (!UtilsPositionInfo.isLongitudeSemanticallyCorrect(((DestinationArea)destination).longitudeLowerLeftCornerInDegrees()))
		    {
		    	annotations.add (new AISIllegalValueAnnotation("getDestination.longitudeLowerLeftCorner",((DestinationArea)destination).longitudeLowerLeftCornerInDegrees(), UtilsPositionInfo.rangeLongitude));
		    }
	    	if (!UtilsPositionInfo.isLatitudeSemanticallyCorrect(((DestinationArea)destination).latitudeUpperRightCornerInDegrees()))
		    {
		    	annotations.add (new AISIllegalValueAnnotation("getDestination.latitudeUpperRightCorner",((DestinationArea)destination).latitudeUpperRightCornerInDegrees(), UtilsPositionInfo.rangeLatitude));
		    }
	    	if (!UtilsPositionInfo.isLatitudeSemanticallyCorrect(((DestinationArea)destination).latitudeLowerLeftCornerInDegrees()))
		    {
		    	annotations.add (new AISIllegalValueAnnotation("getDestination.latitudeLowerLeftCorner",((DestinationArea)destination).latitudeLowerLeftCornerInDegrees(), UtilsPositionInfo.rangeLatitude));
		    }
		}
		channelABandwidth = content.getBoolean(CHANNELABANDWIDTH_BITINDEX);
		channelBBandwidth = content.getBoolean(CHANNELBBANDWIDTH_BITINDEX);
		transitionalZoneSize = content.getIntFromTo(TRANSITIONALZONESIZE_FROM,TRANSITIONALZONESIZE_TO);
		spare2 = content.getIntFromTo(SPARE2_FROM,SPARE2_TO);
	    if (!UtilsSpare.isSpareSemanticallyCorrect(spare2))
	    {
	    	annotations.add(new AISIllegalValueAnnotation("getSpare2", spare2, UtilsSpare.range));
	    }
	}
}