001/*
002 * jPOS Project [http://jpos.org]
003 * Copyright (C) 2000-2026 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     * Encodes the field length into the byte array.
032     * @param length the field length to encode
033     * @param b the byte array to write the length prefix into
034     * @throws ISOException if the length exceeds the prefix capacity
035     */
036    void encodeLength(int length, byte[] b) throws ISOException;
037
038    /**
039     * Decodes an encoded length from the byte array.
040     * @param b the byte array containing the length prefix
041     * @param offset the offset in {@code b} where the prefix starts
042     * @return the length in chars of the field data to follow this prefix
043     * @throws ISOException if the prefix cannot be decoded
044     */
045    int decodeLength(byte[] b, int offset) throws ISOException;
046
047    /**
048     * Returns the number of bytes taken up by the length encoding.
049     * @return the number of bytes used by the length encoding
050     */
051    int getPackedLength();
052}