org.openremote.agent.protocol.velbus.VelbusPacketEncoderDecoder.java Source code

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Here is the source code for org.openremote.agent.protocol.velbus.VelbusPacketEncoderDecoder.java

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/*
 * Copyright 2017, OpenRemote Inc.
 *
 * See the CONTRIBUTORS.txt file in the distribution for a
 * full listing of individual contributors.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.openremote.agent.protocol.velbus;

import io.netty.buffer.ByteBuf;

import java.util.List;

import static org.openremote.agent.protocol.velbus.VelbusPacket.MAX_PACKET_SIZE;

public final class VelbusPacketEncoderDecoder {
    private VelbusPacketEncoderDecoder() {
    }

    public static void decode(ByteBuf buf, List<VelbusPacket> messages) {
        int startIndex = buf.indexOf(0, buf.capacity() - 1, VelbusPacket.STX);

        if (startIndex < 0) {
            return;
        }

        if (startIndex > 0) {
            buf.readerIndex(startIndex);
            buf.discardReadBytes();
        }

        if (buf.readableBytes() < 4) {
            return;
        }

        int dataSize = buf.getByte(3);

        if (buf.readableBytes() < 6 + dataSize) {
            return;
        }

        // Find end of packet
        int endIndex = buf.indexOf(4 + dataSize, MAX_PACKET_SIZE, VelbusPacket.ETX);

        if (endIndex < 0) {
            if (buf.readableBytes() > MAX_PACKET_SIZE) {
                buf.readerIndex(MAX_PACKET_SIZE);
                buf.discardReadBytes();
            }
            return;
        }

        byte[] packetBytes = new byte[endIndex + 1];
        buf.readBytes(packetBytes);
        buf.discardReadBytes();
        VelbusPacket packet = new VelbusPacket(packetBytes);

        if (packet.isValid()) {
            messages.add(packet);
        }
    }

    public static void encode(VelbusPacket message, ByteBuf buf) {
        buf.writeBytes(message.pack());
    }
}