/*

 * JBoss, Home of Professional Open Source

 * Copyright 2011, Red Hat, Inc. and individual contributors

 * by the @authors tag. See the copyright.txt in the distribution for a

 * full listing of individual contributors.

 *

 * This is free software; you can redistribute it and/or modify it

 * under the terms of the GNU Lesser General Public License as

 * published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This software 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this software; if not, write to the Free

 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA

 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.

 */



package org.mobicents.protocols.ss7.mtp.util;



/**

 * Small class to define methods of use to o

 * 

 * @author baranowb

 * 

 */

public class MTPUtility {



	/**

	 * Extract routing information from source[], it expects that source is

	 * properly encoded routing label atleast(5bytes long, same as dest). It

	 * copies data to <b>dest</b> and swamp <i>DPC</i> with <i>OPC</i>.

	 * 

	 * @param source

	 * @param dest

	 */

	public static void copyBackRouteHeader(byte[] source, byte[] dest) {

		int thisPointCode = getFromSif_DPC(source, 1);

		int remotePointCode = getFromSif_OPC(source, 1);

		int sls = getFromSif_SLS(source, 1);

		int si = getFromSif_SI(source);

		int ssi = getFromSif_SSI(source);

		writeRoutingLabel(dest, si, ssi, sls, remotePointCode, thisPointCode);

	}



	/**

	 * Retrieves DPC from SIF. SIF starts from byte 1 in MSU. For MSU

	 * [SIO,DPC,OPC,SLS,Data], call would look as following: int dpc =

	 * getFromSif_DPC(MSU,1);

	 * 

	 * @param sif

	 *            - byte[] - either SIF or MSU

	 * @param shift

	 *            - shift in passed byte[]. For MSU its 1. For SIF part of MSU

	 *            it will be 0;

	 * @return

	 */

	public static final int getFromSif_DPC(byte[] sif, int shift) {

		int dpc = (sif[0 + shift] & 0xff | ((sif[1 + shift] & 0x3f) << 8));

		return dpc;

	}



	/**

	 * Retrieves OPC from SIF. SIF starts from byte 1 in MSU. For MSU

	 * [SIO,DPC,OPC,SLS,Data], call would look as following: int opc =

	 * getFromSif_OPC(MSU,1);

	 * 

	 * @param sif

	 *            - byte[] - either SIF or MSU

	 * @param shift

	 *            - shift in passed byte[]. For MSU its 1. For SIF part of MSU

	 *            it will be 0;

	 * @return

	 */

	public static final int getFromSif_OPC(byte[] sif, int shift) {

		int opc = ((sif[1 + shift] & 0xC0) >> 6) | ((sif[2 + shift] & 0xff) << 2) | ((sif[3 + shift] & 0x0f) << 10);

		return opc;

	}



	/**

	 * Retrieves SLS from SIF. SIF starts from byte 1 in MSU. For MSU

	 * [SIO,DPC,OPC,SLS,Data], call would look as following: int opc =

	 * getFromSif_SLS(MSU,1);

	 * 

	 * @param sif

	 *            - byte[] - either SIF or MSU

	 * @param shift

	 *            - shift in passed byte[]. For MSU its 1. For SIF part of MSU

	 *            it will be 0;

	 * @return

	 */

	public static final int getFromSif_SLS(byte[] sif, int shift) {

		int sls = (sif[3 + shift] & 0xf0) >>> 4;

		return sls;

	}



	public static final int getFromSif_SI(byte[] data) {



		int serviceIndicator = data[0] & 0x0f;

		return serviceIndicator;

	}



	public static final int getFromSif_SSI(byte[] data) {

		// see Q.704.14.2

		int subserviceIndicator = (data[0] >> 4) & 0x0F;

		return subserviceIndicator;

	}



	/**

	 * Encodes routing label into passed byte[]. It has to be at least 5 bytes

	 * long!

	 * 

	 * @param destination

	 * @param si

	 * @param ssi

	 * @param sls

	 * @param dpc

	 * @param opc

	 */

	public static void writeRoutingLabel(byte[] destination, int si, int ssi, int sls, int dpc, int opc) {

		// see Q.704.14.2

		destination[0] = (byte) (((ssi & 0x0F) << 4) | (si & 0x0F));

		destination[1] = (byte) dpc;

		destination[2] = (byte) (((dpc >> 8) & 0x3F) | ((opc & 0x03) << 6));

		destination[3] = (byte) (opc >> 2);

		destination[4] = (byte) (((opc >> 10) & 0x0F) | ((sls & 0x0F) << 4));

		// sif[4] = (byte) (((opc>> 10) & 0x0F) | ((0 & 0x0F) << 4));

	}



}