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 * Implements Hex Interpreter. The Hex digits are stored in EBCDIC.
023 * 
024 * @author ayakovlev
025 * @version $Revision:$ $Date:$
026 */
027public class EbcdicHexInterpreter implements BinaryInterpreter
028{
029    /** Public constructor; prefer {@link #INSTANCE} for repeated use. */
030    public EbcdicHexInterpreter() {}
031    /** An instance of this Interpreter. Only one needed for the whole system */
032    public static final EbcdicHexInterpreter INSTANCE = new EbcdicHexInterpreter();
033
034    /** 0-15 to EBCDIC hex digit lookup table. */
035    private static final byte[] HEX_EBCDIC = new byte[] {
036              (byte)0xF0, (byte)0xF1, (byte)0xF2, (byte)0xF3, 
037              (byte)0xF4, (byte)0xF5, (byte)0xF6, (byte)0xF7,
038              (byte)0xF8, (byte)0xF9, (byte)0xC1, (byte)0xC2, 
039              (byte)0xC3, (byte)0xC4, (byte)0xC5, (byte)0xC6
040    };
041
042    /**
043     * Converts the binary data into EBCDIC hex digits.
044     */
045    public void interpret(byte[] data, byte[] b, int offset)
046    {
047        for (int i = 0; i < data.length; i++) {
048            b[offset + i * 2] = HEX_EBCDIC[(data[i] & 0xF0) >> 4];
049            b[offset + i * 2 + 1] = HEX_EBCDIC[data[i] & 0x0F];
050        }
051    }
052
053    /**
054     * Converts the EBCDIC hex digits into binary data.
055     */
056    public byte[] uninterpret(byte[] rawData, int offset, int length)
057    {
058        byte[] ret = new byte[length];
059        for (int i = 0; i < length; i++)
060        {
061            byte hi = rawData[offset + i * 2];
062            byte lo = rawData[offset + i * 2 + 1];
063            int h = hi < (byte) 0xF0 ? 10 + hi - 0xC0 : hi - 0xF0;
064            int l = lo < (byte) 0xF0 ? 10 + lo - 0xC0 : lo - 0xF0;
065            ret[i] = (byte)(h << 4 | l);
066        }
067        return ret;
068    }
069
070    /**
071     * Returns double nBytes because the hex representation of 1 byte needs 2 hex digits.
072     *
073     */
074    public int getPackedLength(int nBytes)
075    {
076        return nBytes * 2;
077    }
078}