DPTXlatorString.java

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/*
    Calimero - A library for KNX network access
    Copyright (C) 2006-2008 B. Malinowsky

    This program 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 2 
    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, write to the Free Software 
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA. 
 
    Linking this library statically or dynamically with other modules is 
    making a combined work based on this library. Thus, the terms and 
    conditions of the GNU General Public License cover the whole 
    combination. 
 
    As a special exception, the copyright holders of this library give you 
    permission to link this library with independent modules to produce an 
    executable, regardless of the license terms of these independent 
    modules, and to copy and distribute the resulting executable under terms 
    of your choice, provided that you also meet, for each linked independent 
    module, the terms and conditions of the license of that module. An 
    independent module is a module which is not derived from or based on 
    this library. If you modify this library, you may extend this exception 
    to your version of the library, but you are not obligated to do so. If 
    you do not wish to do so, delete this exception statement from your 
    version. 
*/

package tuwien.auto.calimero.dptxlator;

import java.util.HashMap;
import java.util.Map;

import tuwien.auto.calimero.exception.KNXFormatException;
import tuwien.auto.calimero.exception.KNXIllegalArgumentException;
import tuwien.auto.calimero.log.LogLevel;

/**
 * Translator for KNX DPTs with main number 16, type <b>string</b>.
 * <p>
 * The KNX data type width is 14 bytes.<br>
 * The default return value after creation is the empty string "" or 14 bytes filled with
 * <i>NULL</i> (ASCII code 0).<br>
 * Characters not supported by the selected character set are silently replaced with the
 * question mark character, '?'.<br>
 * On supplying string items for translation, strings are limited to a maximum length of
 * 14 characters. Exceeding this maximum string length will result in a
 * {@link KNXFormatException}.
 */
public class DPTXlatorString extends DPTXlator
{
	/**
	 * DPT ID 16.000, ASCII string; 7 Bit character set encoding.
	 * <p>
	 */
	public static final DPT DPT_STRING_ASCII = new DPT("16.000", "ASCII string", "", "");

	/**
	 * DPT ID 16.001, ISO-8859-1 string (Latin 1); 8 Bit character set encoding.
	 * <p>
	 */
	public static final DPT DPT_STRING_8859_1 =
		new DPT("16.001", "ISO-8859-1 string (Latin 1)", "", "");

	private static final Map types;

	// default replacement for unsupported characters
	private static final short replacement = '?';

	// standard string length of this type
	private static final int stringLength = 14;

	static {
		types = new HashMap(5);
		types.put(DPT_STRING_ASCII.getID(), DPT_STRING_ASCII);
		types.put(DPT_STRING_8859_1.getID(), DPT_STRING_8859_1);
	}

	/**
	 * Creates a translator for the given datapoint type.
	 * <p>
	 * 
	 * @param dpt the requested datapoint type
	 * @throws KNXFormatException on not supported or not available DPT
	 */
	public DPTXlatorString(DPT dpt) throws KNXFormatException
	{
		this(dpt.getID());
	}

	/**
	 * Creates a translator for the given datapoint type ID.
	 * <p>
	 * 
	 * @param dptID available implemented datapoint type ID
	 * @throws KNXFormatException on wrong formatted or not expected (available)
	 *         <code>dptID</code>
	 */
	public DPTXlatorString(String dptID) throws KNXFormatException
	{
		super(stringLength);
		setTypeID(types, dptID);
		data = new short[stringLength];
	}

	/* (non-Javadoc)
	 * @see tuwien.auto.calimero.dptxlator.DPTXlator#getAllValues()
	 */
	public String[] getAllValues()
	{
		final String[] buf = new String[getItems()];
		for (int i = 0; i < buf.length; ++i)
			buf[i] = fromDPT(i);
		return buf;
	}

	/* (non-Javadoc)
	 * @see tuwien.auto.calimero.dptxlator.DPTXlator#setData(byte[], int)
	 */
	public void setData(byte[] data, int offset)
	{
		if (offset < 0 || offset > data.length)
			throw new KNXIllegalArgumentException("illegal offset " + offset);
		if (data.length - offset > 0)
			toDPT(data, offset);
	}

	/* (non-Javadoc)
	 * @see tuwien.auto.calimero.dptxlator.DPTXlator#getData(byte[], int)
	 */
	public byte[] getData(byte[] dst, int offset)
	{
		final int items = Math.min(data.length, dst.length - offset) / stringLength;
		final int end = items * stringLength;
		if (end == 0)
			logger.error("destination range has to be multiple of 14 bytes "
				+ "for KNX strings");
		for (int i = 0; i < end; ++i)
			dst[offset + i] = (byte) data[i];
		return dst;
	}

	/* (non-Javadoc)
	 * @see tuwien.auto.calimero.dptxlator.DPTXlator#getSubTypes()
	 */
	public final Map getSubTypes()
	{
		return types;
	}

	/**
	 * @return the subtypes of the string translator type
	 * @see DPTXlator#getSubTypesStatic()
	 */
	protected static Map getSubTypesStatic()
	{
		return types;
	}

	private String fromDPT(int index)
	{
		final int offset = index * stringLength;
		final char[] output = new char[stringLength];
		int strlen = 0;
		for (int i = offset; i < (offset + stringLength) && data[i] != 0; ++i) {
			output[strlen] = (char) data[i];
			++strlen;
		}
		return new String(output, 0, strlen);
	}

	private void toDPT(byte[] buf, int offset)
	{
		// check character set, default to ASCII 7 bit encoding
		int rangeMax = 0x7f;
		if (dpt.equals(DPT_STRING_8859_1))
			rangeMax = 0xff;
		final int items = (buf.length - offset) / stringLength;
		if (items == 0) {
			logger.error("source range has to be multiple of 14 bytes for KNX strings");
			return;
		}
		data = new short[items * stringLength];
		// 7 bit encoded characters of ISO-8859-1 are equal to ASCII
		// the lower 256 characters of UCS correspond to ISO-8859-1
		for (int i = 0; i < data.length; ++i) {
			final short c = ubyte(buf[offset + i]);
			data[i] = c <= rangeMax ? c : replacement;
		}
	}

	protected void toDPT(String value, short[] dst, int index) throws KNXFormatException
	{
		if (value.length() > stringLength)
			throw logThrow(LogLevel.WARN, "maximum KNX string length is 14 characters",
				null, value);
		// check character set, default to ASCII 7 bit encoding
		char rangeMax = '\u007f';
		if (dpt.equals(DPT_STRING_8859_1))
			rangeMax = '\u00ff';
		// 7 bit encoded characters of ISO-8859-1 are equal to ASCII
		// the lower 256 characters of UCS correspond to ISO-8859-1
		final int offset = index * stringLength;
		for (int i = 0; i < value.length(); ++i) {
			final char c = value.charAt(i);
			dst[offset + i] = c <= rangeMax ? (short) c : replacement;
		}
	}
}