PortSegment.java

package com.digitalpetri.enip.cip.epath;

import io.netty.buffer.ByteBuf;

public final class PortSegment extends EPathSegment {

    private final int portId;
    private final byte[] linkAddress;

    public PortSegment(int portId, byte[] linkAddress) {
        this.portId = portId;
        this.linkAddress = linkAddress;
    }

    public int getPortId() {
        return portId;
    }

    public byte[] getLinkAddress() {
        return linkAddress;
    }

    private static final int EXTENDED_LINKED_ADDRESS_SIZE = 1 << 4;

    public static ByteBuf encode(PortSegment segment, boolean padded, ByteBuf buffer) {
        int writerIndex = buffer.writerIndex();
        int linkAddressLength = segment.getLinkAddress().length;
        boolean needLinkAddressSize = linkAddressLength > 1;
        boolean needExtendedPort = segment.portId > 14;

        int segmentByte = needExtendedPort ? 0x0F : segment.getPortId();
        if (needLinkAddressSize) segmentByte |= EXTENDED_LINKED_ADDRESS_SIZE;
        buffer.writeByte(segmentByte);

        if (needLinkAddressSize) buffer.writeByte(linkAddressLength);
        if (needExtendedPort) buffer.writeShort(segment.getPortId());
        buffer.writeBytes(segment.getLinkAddress());

        int bytesWritten = buffer.writerIndex() - writerIndex;
        if (bytesWritten % 2 != 0) buffer.writeByte(0);

        return buffer;
    }

}