CcsdsPacket.java

package org.yamcs.utils;

import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;

import org.yamcs.utils.TimeEncoding;



public class CcsdsPacket implements Comparable<CcsdsPacket>{
    static public final int DATA_OFFSET=16;

    static public final int MAX_CCSDS_SIZE=1500;
    protected ByteBuffer bb;

    public CcsdsPacket( byte[] packet) {
        bb = ByteBuffer.wrap(packet);
    }

    public CcsdsPacket(ByteBuffer bb) {
        this.bb=bb;
    }

    public int getSecondaryHeaderFlag() {
        return (bb.getShort(0)>>11)&1;
    }

    public int getSequenceCount() {
        return bb.getShort(2)&0x3FFF;
    }

    public void setSequenceCount(short seqCount) {
        short oldSeqField = bb.getShort(2);
        short seqInd = (short)(oldSeqField&(~0x3FFF));
        bb.putShort(2, (short)((seqCount&0x3FFF) + seqInd));
    }

    public static short getSequenceCount(ByteBuffer bb) {
        return (short) (bb.getShort(2)&0x3FFF);
    }

    public int getAPID() {
        return bb.getShort(0)& 0x07FF;
    }

    public void setAPID(int apid) {
        int tmp=bb.getShort(0) & (~0x07FF);
        tmp=tmp|apid;
        bb.putShort(0,(short)tmp);
    }	
    public static short getAPID(ByteBuffer bb) {
        return (short)(bb.getShort(0)& 0x07FF);
    }

    /*returns the length written in the ccsds header*/
    public static int getCccsdsPacketLength(ByteBuffer bb) {
        return bb.getShort(4)&0xFFFF;
    }


    /*returns the length written in the ccsds header*/
    public int getCccsdsPacketLength() {
        return getCccsdsPacketLength(bb);
    }

    public void setCccsdsPacketLength(short length) {
        //return bb.getShort(4)&0xFFFF;
        bb.putShort(4, length);
    }

    /**returns the length of the packet, normally equals ccsdslength+7*/
    public int getLength() {
        return bb.capacity();
    }

    /**
     * 
     * @return instant
     */
    public long getInstant() {
        return TimeEncoding.fromGpsCcsdsTime(bb.getInt(6), bb.get(10)) ;
    }

    public static long getInstant(ByteBuffer bb) {
        return TimeEncoding.fromGpsCcsdsTime(bb.getInt(6), bb.get(10)) ;
    }

    /**
     * @return time in seconds since 6 Jan 1980
     */
    public long getCoarseTime() {
        return bb.getInt(6)&0xFFFFFFFFL;
    }
    public int getTimeId() {
        return (bb.get(11) &0xFF)>>6;
    }

    public void setCoarseTime(int time) {
        bb.putInt(6, time);
    }

    public static long getCoarseTime(ByteBuffer bb) {
        return bb.getInt(6)&0xFFFFFFFFL;
    }

    public int getFineTime() {
        return bb.get(10)&0xFF;
    }

    public void setFineTime(short fineTime) {
        bb.put(10, (byte)(fineTime&0xFF));
    }

    public static int getFineTime(ByteBuffer bb) {
        return bb.get(10)&0xFF;
    }

    public boolean getChecksumIndicator() {
        return (bb.get(11) & 0x20) == 0x20;
    }

    public int getPacketID() {
        if(getSecondaryHeaderFlag() != 0)
            return bb.getInt(12);
        else
            return 0;
    }

    public void setPacketID(int id) {
        bb.putInt(12, id);
    }



    public byte[] getBytes() {
        return bb.array();
    }

    public ByteBuffer getByteBuffer() {
        return bb;
    }

    public int getPrivateHeaderClass() {
        return bb.get(18);
    }

    public int getPrivateHeaderType() {
        return bb.get(19);
    }


    public int getPrivateHeaderSource() {
        return ((int)bb.get(16))&0xFF;
    }


    public static CcsdsPacket getPacketFromStream(InputStream input) throws IOException {
        byte[] b=new byte[6];
        ByteBuffer bb=ByteBuffer.wrap(b);
        if ( input.read(b) < 6 ) {
            throw new IOException("cannot read CCSDS primary header\n");
        }
        int ccsdslen = bb.getShort(4)&0xFFFF;
        if ( ccsdslen  > MAX_CCSDS_SIZE ) {
            throw new IOException("illegal CCSDS length "+ ccsdslen);
        }
        bb=ByteBuffer.allocate(ccsdslen+7);
        bb.put(b);

        if ( input.read(bb.array(), 6, ccsdslen+1) < ccsdslen+1 ) {
            throw new IOException("cannot read full packet");
        }
        return new CcsdsPacket(bb);
    }


    public static long getInstant(byte[] pkt) {
        return getInstant(ByteBuffer.wrap(pkt));
    }



    public static short getAPID(byte[] packet) {
        return getAPID(ByteBuffer.wrap(packet));
    }

    public static int getCccsdsPacketLength(byte[] buf) {       
        return getCccsdsPacketLength(ByteBuffer.wrap(buf));
    }

    /*comparison based on time*/
    @Override
    public int compareTo(CcsdsPacket p) {
        return Long.signum(this.getInstant()-p.getInstant());
    }

    @Override
    public String toString() {
        StringBuffer sb=new StringBuffer();
        StringBuffer text = new StringBuffer();
        byte c;
        int len = bb.limit();
        sb.append("apid: "+getAPID()+"\n");
        sb.append("packetId: "+getPacketID()+"\n");
        sb.append("time: "+ TimeEncoding.toCombinedFormat(getInstant()));
        sb.append("\n");
        for(int i=0;i<len;++i) {
            if(i%16==0) {
                sb.append(String.format("%04x:",i));
                text.setLength(0);
            }
            c = bb.get(i);
            if ( (i & 1) == 0 ) {
                sb.append(String.format(" %02x",0xFF&c));
            } else {
                sb.append(String.format("%02x",0xFF&c));
            }
            text.append(((c >= ' ') && (c <= 127)) ? String.format("%c",c) : ".");
            if((i+1)%16==0) {
                sb.append(" ");
                sb.append(text);
                sb.append("\n");
            }
        }
        sb.append("\n\n");
        return sb.toString();
    }

}