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 * BcdPrefixer constructs a prefix storing the length in BCD.
023 * 
024 * @author joconnor
025 * @version $Revision$ $Date$
026 */
027@SuppressWarnings("unused")
028public class BcdPrefixer implements Prefixer
029{
030    /**
031     * A length prefixer for up to 9 chars. The length is encoded with 1 BCD digit.
032     */
033    /**
034     * Pre-built {@link BcdPrefixer} for common BCD length prefix sizes.
035     */
036    public static final BcdPrefixer L = new BcdPrefixer(1);
037    /**
038         * A length prefixer for up to 99 chars. The length is encoded with 2 BCD digits.
039         */
040    public static final BcdPrefixer LL = new BcdPrefixer(2);
041    /**
042         * A length prefixer for up to 999 chars. The length is encoded with 3 BCD digits.
043         */
044    public static final BcdPrefixer LLL = new BcdPrefixer(3);
045    /**
046         * A length prefixer for up to 9999 chars. The length is encoded with 4 BCD digits.
047         */
048    public static final BcdPrefixer LLLL = new BcdPrefixer(4);
049    /**
050     * A length prefixer for up to 99999 chars. The length is encoded with 5 BCD digits.
051     */
052    public static final BcdPrefixer LLLLL = new BcdPrefixer(5);
053    /**
054    * A length prefixer for up to 999999 chars. The length is encoded with 6 BCD digits.
055    */
056    public static final BcdPrefixer LLLLLL = new BcdPrefixer(6);
057
058    /** The number of digits allowed to express the length */
059    private int nDigits;
060
061    /**
062     * Creates a BcdPrefixer with the given number of digits.
063     * @param nDigits the number of BCD digits used for the length prefix
064     */
065    public BcdPrefixer(int nDigits)
066    {
067        this.nDigits = nDigits;
068    }
069
070    @Override
071    public void encodeLength(int length, byte[] b)
072    {
073        for (int i = getPackedLength() - 1; i >= 0; i--) {
074            int twoDigits = length % 100;
075            length /= 100;
076            b[i] = (byte)((twoDigits / 10 << 4) + twoDigits % 10);
077        }
078    }
079
080    @Override
081    public int decodeLength(byte[] b, int offset)
082    {
083        int len = 0;
084        for (int i = 0; i < (nDigits + 1) / 2; i++)
085        {
086            len = 100 * len + ((b[offset + i] & 0xF0) >> 4) * 10 + (b[offset + i] & 0x0F);
087        }
088        return len;
089    }
090
091    @Override
092    public int getPackedLength()
093    {
094        return nDigits + 1 >> 1;
095    }
096}