Protocol.java

/*
 * Copyright (c) 2015 "JackWhite20"
 *
 * This file is part of Comix.
 *
 * Comix 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 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package de.jackwhite20.comix.network;

import io.netty.buffer.ByteBuf;

import java.nio.charset.Charset;

/**
 * Created by JackWhite20 on 14.07.2015.
 */
public class Protocol {

    public static final Charset UTF_8 = Charset.forName("UTF-8");

    public static void writeString(String s, ByteBuf buf) {
        byte[] b = s.getBytes( UTF_8 );
        writeVarInt( b.length, buf );
        buf.writeBytes( b );
    }

    public static String readString(ByteBuf buf) {
        int len = readVarInt(buf);
        byte[] b = new byte[len];
        buf.readBytes(b);
        return new String(b, UTF_8);
    }

    public static void writeVarInt(int value, ByteBuf output) {
        int part;
        while ( true ) {
            part = value & 0x7F;

            value >>>= 7;
            if ( value != 0 )
            {
                part |= 0x80;
            }

            output.writeByte( part );

            if ( value == 0 )
            {
                break;
            }
        }
    }

    public static int readVarInt(ByteBuf input) {
        return readVarInt(input, 5);
    }

    public static int readVarInt(ByteBuf input, int maxBytes) {
        int out = 0;
        int bytes = 0;
        byte in;
        while (true) {
            in = input.readByte();

            out |= (in & 0x7F) << (bytes++ * 7);

            if (bytes > maxBytes) {
                throw new RuntimeException("VarInt too big");
            }

            if ((in & 0x80) != 0x80) {
                break;
            }
        }

        return out;
    }

}