/* * Copyright (c) 1999, 2003, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.sound.midi; import java.io.ByteArrayOutputStream;import java.io.DataOutputStream;import java.io.IOException;  /** * A <code>MetaMessage</code> is a <code>{@link MidiMessage}</code> that is not meaningful to synthesizers, but * that can be stored in a MIDI file and interpreted by a sequencer program. * (See the discussion in the <code>MidiMessage</code> * class description.)  The Standard MIDI Files specification defines * various types of meta-events, such as sequence number, lyric, cue point, * and set tempo.  There are also meta-events * for such information as lyrics, copyrights, tempo indications, time and key * signatures, markers, etc.  For more information, see the Standard MIDI Files 1.0 * specification, which is part of the Complete MIDI 1.0 Detailed Specification * published by the MIDI Manufacturer's Association * (<a href = http://www.midi.org>http://www.midi.org</a>). * * <p> * When data is being transported using MIDI wire protocol, * a <code>{@link ShortMessage}</code> with the status value <code>0xFF</code> represents * a system reset message.  In MIDI files, this same status value denotes a <code>MetaMessage</code>. * The types of meta-message are distinguished from each other by the first byte * that follows the status byte <code>0xFF</code>.  The subsequent bytes are data * bytes.  As with system exclusive messages, there are an arbitrary number of * data bytes, depending on the type of <code>MetaMessage</code>. * * @see MetaEventListener * * @author David Rivas * @author Kara Kytle */ public class MetaMessage extends MidiMessage {      // Status byte defines     /**     * Status byte for <code>MetaMessage</code> (0xFF, or 255), which is used     * in MIDI files.  It has the same value as SYSTEM_RESET, which     * is used in the real-time "MIDI wire" protocol.     * @see MidiMessage#getStatus     */    public static final int META                                                = 0xFF; // 255      // Default meta message data: just the META status byte value    // $$kk: 09.09.99: need a real event here!!     private static byte[] defaultMessage                                = { (byte)META, 0 };       // Instance variables     /**     * The length of the actual message in the data array.     * This is used to determine how many bytes of the data array     * is the message, and how many are the status byte, the     * type byte, and the variable-length-int describing the     * length of the message.     */    private int dataLength = 0;      /**     * Constructs a new <code>MetaMessage</code>. The contents of     * the message are not set here; use     * {@link #setMessage(int, byte[], int) setMessage}     * to set them subsequently.     */    public MetaMessage() {        //super(defaultMessage);        this(defaultMessage);    }     /**     * Constructs a new {@code MetaMessage} and sets the message parameters.     * The contents of the message can be changed by using     * the {@code setMessage} method.     *     * @param type   meta-message type (must be less than 128)     * @param data   the data bytes in the MIDI message     * @param length an amount of bytes in the {@code data} byte array;     *     it should be non-negative and less than or equal to     *     {@code data.length}     * @throws InvalidMidiDataException if the parameter values do not specify     *     a valid MIDI meta message     * @see #setMessage(int, byte[], int)     * @see #getType()     * @see #getData()     * @since 1.7     */    public MetaMessage(int type, byte[] data, int length)            throws InvalidMidiDataException {        super(null);        setMessage(type, data, length); // can throw InvalidMidiDataException    }      /**     * Constructs a new <code>MetaMessage</code>.     * @param data an array of bytes containing the complete message.     * The message data may be changed using the <code>setMessage</code>     * method.     * @see #setMessage     */    protected MetaMessage(byte[] data) {        super(data);        //$$fb 2001-10-06: need to calculate dataLength. Fix for bug #4511796        if (data.length>=3) {            dataLength=data.length-3;            int pos=2;            while (pos<data.length && (data[pos] & 0x80)!=0) {                dataLength--; pos++;            }        }    }      /**     * Sets the message parameters for a <code>MetaMessage</code>.     * Since only one status byte value, <code>0xFF</code>, is allowed for meta-messages,     * it does not need to be specified here.  Calls to <code>{@link MidiMessage#getStatus getStatus}</code> return     * <code>0xFF</code> for all meta-messages.     * <p>     * The <code>type</code> argument should be a valid value for the byte that     * follows the status byte in the <code>MetaMessage</code>.  The <code>data</code> argument     * should contain all the subsequent bytes of the <code>MetaMessage</code>.  In other words,     * the byte that specifies the type of <code>MetaMessage</code> is not considered a data byte.     *     * @param type              meta-message type (must be less than 128)     * @param data              the data bytes in the MIDI message     * @param length    the number of bytes in the <code>data</code>     * byte array     * @throws                  <code>InvalidMidiDataException</code>  if the     * parameter values do not specify a valid MIDI meta message     */    public void setMessage(int type, byte[] data, int length) throws InvalidMidiDataException {         if (type >= 128 || type < 0) {            throw new InvalidMidiDataException("Invalid meta event with type " + type);        }        if ((length > 0 && length > data.length) || length < 0) {            throw new InvalidMidiDataException("length out of bounds: "+length);        }         this.length = 2 + getVarIntLength(length) + length;        this.dataLength = length;        this.data = new byte[this.length];        this.data[0] = (byte) META;        // status value for MetaMessages (meta events)        this.data[1] = (byte) type;        // MetaMessage type        writeVarInt(this.data, 2, length); // write the length as a variable int        if (length > 0) {            System.arraycopy(data, 0, this.data, this.length - this.dataLength, this.dataLength);        }    }      /**     * Obtains the type of the <code>MetaMessage</code>.     * @return an integer representing the <code>MetaMessage</code> type     */    public int getType() {        if (length>=2) {            return data[1] & 0xFF;        }        return 0;    }       /**     * Obtains a copy of the data for the meta message.  The returned     * array of bytes does not include the status byte or the message     * length data.  The length of the data for the meta message is     * the length of the array.  Note that the length of the entire     * message includes the status byte and the meta message type     * byte, and therefore may be longer than the returned array.     * @return array containing the meta message data.     * @see MidiMessage#getLength     */    public byte[] getData() {        byte[] returnedArray = new byte[dataLength];        System.arraycopy(data, (length - dataLength), returnedArray, 0, dataLength);        return returnedArray;    }      /**     * Creates a new object of the same class and with the same contents     * as this object.     * @return a clone of this instance     */    public Object clone() {        byte[] newData = new byte[length];        System.arraycopy(data, 0, newData, 0, newData.length);         MetaMessage event = new MetaMessage(newData);        return event;    }     // HELPER METHODS     private int getVarIntLength(long value) {        int length = 0;        do {            value = value >> 7;            length++;        } while (value > 0);        return length;    }     private final static long mask = 0x7F;     private void writeVarInt(byte[] data, int off, long value) {        int shift=63; // number of bitwise left-shifts of mask        // first screen out leading zeros        while ((shift > 0) && ((value & (mask << shift)) == 0)) shift-=7;        // then write actual values        while (shift > 0) {            data[off++]=(byte) (((value & (mask << shift)) >> shift) | 0x80);            shift-=7;        }        data[off] = (byte) (value & mask);    } }