com.digitalpetri.modbus.ModbusTcpCodec Maven / Gradle / Ivy

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There is a newer version: 2.0.0-RC3

package com.digitalpetri.modbus;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageCodec;
import java.nio.ByteBuffer;
import java.util.List;

public class ModbusTcpCodec extends ByteToMessageCodec {

  public static final int MBAP_TOTAL_LENGTH = 7;
  public static final int MBAP_LENGTH_FIELD_OFFSET = 4;

  @Override
  protected void encode(ChannelHandlerContext ctx, ModbusTcpFrame msg, ByteBuf out) {
    var buffer = ByteBuffer.allocate(MBAP_TOTAL_LENGTH + msg.pdu().limit() - msg.pdu().position());
    MbapHeader.Serializer.encode(msg.header(), buffer);
    buffer.put(msg.pdu());

    buffer.flip();
    out.writeBytes(buffer);
  }

  @Override
  protected void decode(ChannelHandlerContext ctx, ByteBuf in, List