001/*
002 * jPOS Project [http://jpos.org]
003 * Copyright (C) 2000-2023 jPOS Software SRL
004 *
005 * This program is free software: you can redistribute it and/or modify
006 * it under the terms of the GNU Affero General Public License as
007 * published by the Free Software Foundation, either version 3 of the
008 * License, or (at your option) any later version.
009 *
010 * This program is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013 * GNU Affero General Public License for more details.
014 *
015 * You should have received a copy of the GNU Affero General Public License
016 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017 */
018
019package org.jpos.iso;
020
021
022/**
023 * This interface is used to encode and decode length prefixes.
024 * 
025 * @author joconnor
026 * @version $Revision$ $Date$
027 */
028public interface Prefixer
029{
030    /**
031         * Fills a byte array with the field length data in raw form.
032         * 
033         * @param length
034         *            The length to be encoded.
035         * @param b
036         *            The byte array to fill with the encoded length.
037         */
038    void encodeLength(int length, byte[] b) throws ISOException;
039
040    /**
041         * Decodes an encoded length.
042         * 
043         * @param b
044         *            The byte array to scan for the length.
045         * @param offset
046         *            The offset to start scanning from.
047         * @return The length in chars of the field data to follow this
048         *         LengthPrefix.
049         */
050    int decodeLength(byte[] b, int offset) throws ISOException;
051
052    /**
053         * Returns the number of bytes taken up by the length encoding.
054         */
055    int getPackedLength();
056}