src/main/java/org/eclipse/mdm/openatfx/mdf/mdf3/CGBLOCK.java

/********************************************************************************
 * Copyright (c) 2015-2018 Contributors to the Eclipse Foundation
 *
 * See the NOTICE file(s) distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 ********************************************************************************/


package org.eclipse.mdm.openatfx.mdf.mdf3;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.channels.SeekableByteChannel;

/**
 * <p>
 * Channel group block: Description of a channel group, i.e. signals which are
 * always measured jointly
 * </p>
 * This block describes the structure of a channel group. A channel group
 * consists of different channels which are measured jointly at the same rate.
 *
 * @author Christian Rechner
 */
class CGBLOCK extends BLOCK {

	public static String BLOCK_ID = "CG";

	// LINK 1 Pointer to next data Channel group block (CGBLOCK) (NIL allowed)
	private long lnkNextCgBlock;

	// LINK 1 Pointer to first channel block (CNBLOCK) (NIL allowed)
	private long lnkFirstCnBlock;

	// LINK 1 Pointer to channel group comment text (TXBLOCK) (NIL allowed)
	private long lnkChannelGroupComment;

	// UINT16 1 Record ID
	private int recordId;

	// UINT16 1 Number of channels
	private int noOfChannels;

	// UINT16 1 Data record size in bytes (without the record ID), i.e. data
	// size of the channel group for each sample
	private int dataRecordSize;

	// UINT32 1 Number of records
	private long noOfRecords;

	// LINK 1 Pointer to first sample reduction block (SRBLOCK) (NIL allowed)
	private long lnkFirstSrBlock;

	/**
	 * Constructor.
	 *
	 * @param sbc
	 *            The byte channel pointing to the MDF file.
	 * @param pos
	 *            The position of the block within the MDF file.
	 */
	private CGBLOCK(SeekableByteChannel sbc, long pos) {
		super(sbc, pos);
	}

	public long getLnkNextCgBlock() {
		return lnkNextCgBlock;
	}

	private void setLnkNextCgBlock(long lnkNextCgBlock) {
		this.lnkNextCgBlock = lnkNextCgBlock;
	}

	public long getLnkFirstCnBlock() {
		return lnkFirstCnBlock;
	}

	private void setLnkFirstCnBlock(long lnkFirstCnBlock) {
		this.lnkFirstCnBlock = lnkFirstCnBlock;
	}

	public long getLnkChannelGroupComment() {
		return lnkChannelGroupComment;
	}

	private void setLnkChannelGroupComment(long lnkChannelGroupComment) {
		this.lnkChannelGroupComment = lnkChannelGroupComment;
	}

	public int getRecordId() {
		return recordId;
	}

	private void setRecordId(int recordId) {
		this.recordId = recordId;
	}

	public int getNoOfChannels() {
		return noOfChannels;
	}

	private void setNoOfChannels(int noOfChannels) {
		this.noOfChannels = noOfChannels;
	}

	public int getDataRecordSize() {
		return dataRecordSize;
	}

	private void setDataRecordSize(int dataRecordSize) {
		this.dataRecordSize = dataRecordSize;
	}

	public long getNoOfRecords() {
		return noOfRecords;
	}

	private void setNoOfRecords(long noOfRecords) {
		this.noOfRecords = noOfRecords;
	}

	public long getLnkFirstSrBlock() {
		return lnkFirstSrBlock;
	}

	private void setLnkFirstSrBlock(long lnkFirstSrBlock) {
		this.lnkFirstSrBlock = lnkFirstSrBlock;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public String toString() {
		return "CGBLOCK [lnkNextCgBlock=" + lnkNextCgBlock + ", lnkFirstCnBlock=" + lnkFirstCnBlock
				+ ", lnkChannelGroupComment=" + lnkChannelGroupComment + ", recordId=" + recordId + ", noOfChannels="
				+ noOfChannels + ", dataRecordSize=" + dataRecordSize + ", noOfRecords=" + noOfRecords
				+ ", lnkFirstSrBlock=" + lnkFirstSrBlock + "]";
	}

	public CGBLOCK getNextCgBlock() throws IOException {
		if (lnkNextCgBlock > 0) {
			return CGBLOCK.read(sbc, lnkNextCgBlock);
		}
		return null;
	}

	public CNBLOCK getFirstCnBlock() throws IOException {
		if (lnkFirstCnBlock > 0) {
			return CNBLOCK.read(sbc, lnkFirstCnBlock);
		}
		return null;
	}

	public TXBLOCK getChannelGroupComment() throws IOException {
		if (lnkChannelGroupComment > 0) {
			return TXBLOCK.read(sbc, lnkChannelGroupComment);
		}
		return null;
	}

	/**
	 * Reads a CGBLOCK from the channel starting at pos
	 *
	 * @param sbc
	 *            The channel to read from.
	 * @param pos
	 *            The position to start reading.
	 * @return The block data.
	 * @throws IOException
	 *             The exception.
	 */
	public static CGBLOCK read(SeekableByteChannel sbc, long pos) throws IOException {
		CGBLOCK block = new CGBLOCK(sbc, pos);

		// read block header
		ByteBuffer bb = ByteBuffer.allocate(4);
		bb.order(ByteOrder.LITTLE_ENDIAN);
		sbc.position(pos);
		sbc.read(bb);
		bb.rewind();

		// CHAR 2 Block type identifier
		block.setId(Mdf3Util.readChars(bb, 2));
		if (!block.getId().equals(BLOCK_ID)) {
			throw new IOException("Wrong block type - expected '" + BLOCK_ID + "', found '" + block.getId() + "'");
		}

		// UINT16 1 Block size of this block in bytes
		block.setLength(Mdf3Util.readUInt16(bb));

		// read block
		bb = ByteBuffer.allocate(block.getLength() - 4);
		bb.order(ByteOrder.LITTLE_ENDIAN);
		sbc.position(pos + 4);
		sbc.read(bb);
		bb.rewind();

		// LINK 1 Pointer to next data Channel group block (CGBLOCK) (NIL
		// allowed)
		block.setLnkNextCgBlock(Mdf3Util.readLink(bb));

		// LINK 1 Pointer to first channel block (CNBLOCK) (NIL allowed)
		block.setLnkFirstCnBlock(Mdf3Util.readLink(bb));

		// LINK 1 Pointer to channel group comment text (TXBLOCK) (NIL allowed)
		block.setLnkChannelGroupComment(Mdf3Util.readLink(bb));

		// UINT16 1 Record ID
		block.setRecordId(Mdf3Util.readUInt16(bb));

		// UINT16 1 Number of channels
		block.setNoOfChannels(Mdf3Util.readUInt16(bb));

		// UINT16 1 Data record size in bytes (without the record ID), i.e. data
		// size of the channel group for each
		// sample
		block.setDataRecordSize(Mdf3Util.readUInt16(bb));

		// UINT32 1 Number of records
		block.setNoOfRecords(Mdf3Util.readUInt32(bb));

		// LINK 1 Pointer to first sample reduction block (SRBLOCK) (NIL
		// allowed)
		// Valid since version 3.30. Default value: NIL.
		if (block.getLength() > 26) {
			block.setLnkFirstSrBlock(Mdf3Util.readLink(bb));
		}

		return block;
	}

}