- /*
- * @(#)MetaMessage.java 1.22 03/01/23
- *
- * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
- * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- */
-
- 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
- *
- * @version 1.22, 03/01/23
- * @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
- // $$kk: 09.09.99: need a real event here!!
-
- private static byte[] defaultMessage = { (byte)META, 0 };
-
-
-
- // Instance variables
-
- /**
- * The length of the actual message in the data array.
- * This is used to determine how many bytes of the data array
- * is the message, and how many are the status byte, the
- * type byte, and the variable-length-int describing the
- * length of the message.
- */
- private int dataLength = 0;
-
-
- /**
- * Constructs a new <code>MetaMessage</code>. The contents of
- * the message are not set here; use
- * {@link #setMessage(int, byte[], int) setMessage}
- * to set them subsequently.
- */
- public MetaMessage() {
- //super(defaultMessage);
- this(defaultMessage);
- }
-
-
- /**
- * Constructs a new <code>MetaMessage</code>.
- * @param data an array of bytes containing the complete message.
- * The message data may be changed using the <code>setMessage</code>
- * method.
- * @see #setMessage
- */
- protected MetaMessage(byte[] data) {
- super(data);
- //$$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);
- }
-
- /*
- int oldLength=0;
- int oldDataLength=0;
- byte[] oldData=null;
- try {
- //$$fb 2001-10-06: this is a very inefficient implementation !
- ByteArrayOutputStream bos = new ByteArrayOutputStream();
- DataOutputStream dos = new DataOutputStream(bos);
-
- dos.writeByte(0xFF); // status value for MetaMessages (meta events)
- dos.writeByte(type); // MetaMessage type
-
- writeVarInt( length, dos ); // write the length as a
- // variable int
- dos.write(data, 0, length);
-
- //this.data = bos.toByteArray();
- //this.length = this.data.length;
- //this.dataLength = length;
- oldData = bos.toByteArray();
- oldLength = oldData.length;
- oldDataLength = length;
- } catch (IOException e) {
- }
- */
-
- 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);
- }
-
- /*
- // check equality
- if (this.length != oldLength) {
- System.out.println("length = "+length+" oldLength = "+oldLength);
- } else
- if (this.dataLength != oldDataLength) {
- System.out.println("dataLength = "+dataLength+" oldDataLength = "+oldDataLength);
- } else
- if (this.data.length != oldData.length) {
- System.out.println("this.data.length = "+this.data.length+" oldData.length = "+oldData.length);
- } else {
- boolean succ=true;
- for (int i=0; i<this.data.length; i++) {
- if (this.data[i]!=oldData[i]) {
- succ=false;
- System.out.println(" this.data["+i+"] = "+this.data[i]+" oldData["+i+"] = "+oldData[i]);
- }
- }
- if (succ) {
- System.out.println("Message with length = "+length+" is equal.");
- }
- }
- */
- }
-
-
- /**
- * 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 void writeVarInt(int value, DataOutputStream dos ) throws InvalidMidiDataException, IOException {
-
- int MAX_LENGTH = 6;
- byte bytes[] = new byte[MAX_LENGTH];
- int length = 0;
- int currentByte = 0;
-
- // first make sure our array is zeroed
- for(int i=0; i<MAX_LENGTH; i++) bytes[i] = 0;
-
- // we fill this array up from the end so that bytes will be
- // written to the stream msb first
- for(int i=MAX_LENGTH-1; i >= 0; i--) {
-
- bytes[i] = (byte) (value & 0x7F);
- value = value >>> 7;
- length++;
-
- if( length>1 ) {
- // this is not the last byte to be written to the stream,
- // so change the msb to 1
- bytes[i] |= 0x80;
- }
- if( value==0 ) {
- // we don't need any more bytes to store this integer
- break;
- }
- }
- // make sure we terminated properly
- if ( (bytes[MAX_LENGTH-1] & 0x80) != 0 ) {
-
- throw new InvalidMidiDataException("Unable to create variable-length integer");
- }
-
- // now write our bytes, msb first, to the stream
- dos.write(bytes, (MAX_LENGTH-length), length);
- }
- */
-
- 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);
- }
-
- }