HexCodec.java

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/*
 * This file is part of JXClient, the Fullscreen Java Crossfire Client.
 *
 * JXClient is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * JXClient 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with JXClient; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Copyright (C) 2005-2008 Yann Chachkoff
 * Copyright (C) 2006-2017,2019-2023 Andreas Kirschbaum
 * Copyright (C) 2010-2012,2014-2018,2020-2023 Nicolas Weeger
 */
 
package com.realtime.crossfire.jxclient.util;
 
import org.jetbrains.annotations.NotNull;
 
public class HexCodec {
 
    @NotNull
    private static final CharSequence HEX_CHARS = "0123456789abcdef";
 
    private HexCodec() {
    }
 
    public static void hexEncode2(@NotNull final StringBuilder sb, final int value) {
        sb.append(HEX_CHARS.charAt((value>>4)&15));
        sb.append(HEX_CHARS.charAt(value&15));
    }
 
    private static void hexEncode4(@NotNull final StringBuilder sb, final int value) {
        hexEncode2(sb, value>>8);
        hexEncode2(sb, value);
    }
 
    public static String hexDump(final byte @NotNull [] data, final int start, final int end) {
        final StringBuilder sb = new StringBuilder();
        for (int i = start; i < end; i += 16) {
            hexEncode4(sb, i-start);
            sb.append(':');
            for (int j = i; j < i+16 && j < end; j++) {
                sb.append(' ');
                hexEncode2(sb, data[j]);
            }
            sb.append('\n');
        }
        return sb.toString();
    }
 
}