de.serosystems.lib1090.msgs.bds.ACASActiveResolutionAdvisoryReport Maven / Gradle / Ivy

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package de.serosystems.lib1090.msgs.bds;

import de.serosystems.lib1090.exceptions.BadFormatException;
import de.serosystems.lib1090.msgs.adsb.TCASResolutionAdvisoryMsg;

import java.io.Serializable;

import static de.serosystems.lib1090.msgs.adsb.TCASResolutionAdvisoryMsg.*;

/*
 *  This file is part of de.serosystems.lib1090.
 *
 *  de.serosystems.lib1090 is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  de.serosystems.lib1090 is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with de.serosystems.lib1090.  If not, see .
 */

/**
 * Decoder for ACAS active resolution advisory report (BDS 3,0)
 * See Annex 10 V4 4.3.8.4.2.2
 */
@SuppressWarnings("unused")
public class ACASActiveResolutionAdvisoryReport extends BDSRegister implements Serializable {

    private byte racRecord;
    private boolean raTerminated;
    private boolean multiThreatEncounter;
    private byte threatType;
    private short bdsCode;
    private short activeRa;
    private int threatIdentity;
    private ThreatIdentityData threatIdentityData;

    /** protected no-arg constructor e.g. for serialization with Kryo **/
    protected ACASActiveResolutionAdvisoryReport() {}

    /**
     * @param msg the 7-byte comm-b message (BDS register) as byte array
     * @throws BadFormatException if message has wrong format
     */
    public ACASActiveResolutionAdvisoryReport(byte[] msg) throws BadFormatException {

        super(msg);
        setBds(BDSRegister.bdsCode.ACAS_ACTIVE_RESOLUTION_ADVISORY);

        this.bdsCode = extractBdsCode(msg);

        activeRa = decodeActiveRa(msg);
        racRecord = decodeRacRecord(msg);
        raTerminated = decodeRaTerminated(msg);
        multiThreatEncounter = decodeMultiThreatEncounter(msg);
        threatType = decodeThreatType(msg);
        threatIdentity = decodeThreatIdentity(msg);

        threatIdentityData = TCASResolutionAdvisoryMsg.extractThreatIdentityData(threatType, msg);
    }

    /**
     * Although TCAS 7 is mandated in European and US airspaces, we could still see aircraft using TCAS 6.
     * In this case, the active RA needs to be interpreted differently and the threat identity is not present.
     *
     * @return whether the message should be assumed to originate from a TSO-C119A compatible system
     * 		   (version 6.04 Enhanced).
     */
    public boolean isTCAS6() {
        // bits 59-88 == 0
        return threatIdentity == 0
                && threatType == 0
                && !multiThreatEncounter
                && !raTerminated;
    }

    /**
     * @return 14 bits which indicate the characteristics of the resolution advisory
     *         (Annex 10 V4, 4.3.8.4.2.2.1.1)
     *         For TCAS 6 to be interpreted according to ED-143 V1 2.2.3.9.3.2.3.1.2
     */
    public short getActiveRA() {
        return activeRa;
    }

    /**
     * @return 4 bits which indicate all currently active RACs
     *         (Annex 10 V4, 4.3.8.4.2.2.1.2)
     */
    public byte getRACRecord() {
        return racRecord;
    }

    /**
     * @return whether RA previously generated by ACAS has ceased being generated
     *         (Annex 10 V4, 4.3.8.4.2.2.1.3); not present for TCAS 6 systems
     */
    public Boolean hasRATerminated() {
        if (isTCAS6()) return null;
        return raTerminated;
    }

    /**
     * @return whether two or more simultaneous threats are currently being processed
     *         (Annex 10 V4, 4.3.8.4.2.2.1.4); not present for TCAS 6 systems
     */
    public Boolean hasMultiThreatEncounter() {
        if (isTCAS6()) return null;
        return multiThreatEncounter;
    }

    /**
     * @return the threat type indicator:
     *            0) no identity data in TID
     *            1) TID contains Mode S transponder address
     *            2) TID contains altitude, range, bearing
     *            3) not assigned
     *         (Annex 10 V4, 4.3.8.4.2.2.1.5);
     *         not present for TCAS 6 systems
     */
    public Byte getThreatType() {
        if (isTCAS6()) return null;
        return threatType;
    }

    /**
     * @return the threat's identity. Check getThreatType() before.
     *         (Annex 10 V4, 4.3.8.4.2.2.1.6); not present for TCAS 6 systems
     */
    public Integer getThreatIdentity() {
        if (isTCAS6()) return null;
        return threatIdentity;
    }

    /**
     * A convenient representation of the bit array provided by {@link #getActiveRA()}.
     *
     * Further interpretation of the bits are subject to the caller which needs to handle differences between
     * TCAS 6 and 7 systems (see {@link #isTCAS6()}.
     *
     * A value set to true indicates that the condition is active.
     *
     * @return the currently active resolution advisories (if any) generated by own ACAS unit against one or more threat
     * aircraft.
     */
    public boolean[] getActiveResolutionAdvisories() {
        return TCASResolutionAdvisoryMsg.extractActiveResolutionAdvisories(getMessage());
    }

    /**
     * A convenient representation of the bit array provided by {@link #getRACRecord()}.
     *
     * The active RA complement bits have the following meaning:
     * 
     *     index 0: Do not pass below
     *     index 1: Do not pass above
     *     index 2: Do not turn left
     *     index 3: Do not turn right
     * 
     * The value set to true indicates that the condition is active.
     * 
     * @return the currently active resolution advisory complements (if any) received from other ACAS aircraft equipped
     * with on-board resolution capability.
     */
    public boolean[] getResolutionAdvisoriesComplementsRecord() {
        return TCASResolutionAdvisoryMsg.extractResolutionAdvisoriesComplementsRecord(getMessage());
    }

    /**
     * @return the ICAO 24-bit aircraft address of the threat or the altitude, range, and bearing if the threat is not
     * Mode S equipped; not present for TCAS 6 systems
     */
    public ThreatIdentityData getThreatIdentityData() {
        if (isTCAS6()) return null;

        return threatIdentityData;
    }

    @Override
    public String toString() {
        return "ACASActiveResolutionAdvisoryReport{" +
                "racRecord=" + racRecord +
                ", raTerminated=" + raTerminated +
                ", multiThreatEncounter=" + multiThreatEncounter +
                ", threatType=" + threatType +
                ", bdsCode=" + bdsCode +
                ", activeRa=" + activeRa +
                ", threatIdentity=" + threatIdentity +
                ", threatIdentityData=" + threatIdentityData +
                '}';
    }
}