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package javax.sound.midi;
/**
* A <code>SysexMessage</code> object represents a MIDI system exclusive message.
* <p>
* When a system exclusive message is read from a MIDI file, it always has
* a defined length. Data from a system exclusive message from a MIDI file
* should be stored in the data array of a <code>SysexMessage</code> as
* follows: the system exclusive message status byte (0xF0 or 0xF7), all
* message data bytes, and finally the end-of-exclusive flag (0xF7).
* The length reported by the <code>SysexMessage</code> object is therefore
* the length of the system exclusive data plus two: one byte for the status
* byte and one for the end-of-exclusive flag.
* <p>
* As dictated by the Standard MIDI Files specification, two status byte values are legal
* for a <code>SysexMessage</code> read from a MIDI file:
* <ul>
* <li>0xF0: System Exclusive message (same as in MIDI wire protocol)</li>
* <li>0xF7: Special System Exclusive message</li>
* </ul>
* <p>
* When Java Sound is used to handle system exclusive data that is being received
* using MIDI wire protocol, it should place the data in one or more
* <code>SysexMessages</code>. In this case, the length of the system exclusive data
* is not known in advance; the end of the system exclusive data is marked by an
* end-of-exclusive flag (0xF7) in the MIDI wire byte stream.
* <ul>
* <li>0xF0: System Exclusive message (same as in MIDI wire protocol)</li>
* <li>0xF7: End of Exclusive (EOX)</li>
* </ul>
* The first <code>SysexMessage</code> object containing data for a particular system
* exclusive message should have the status value 0xF0. If this message contains all
* the system exclusive data
* for the message, it should end with the status byte 0xF7 (EOX).
* Otherwise, additional system exclusive data should be sent in one or more
* <code>SysexMessages</code> with a status value of 0xF7. The <code>SysexMessage</code>
* containing the last of the data for the system exclusive message should end with the
* value 0xF7 (EOX) to mark the end of the system exclusive message.
* <p>
* If system exclusive data from <code>SysexMessages</code> objects is being transmitted
* using MIDI wire protocol, only the initial 0xF0 status byte, the system exclusive
* data itself, and the final 0xF7 (EOX) byte should be propagated; any 0xF7 status
* bytes used to indicate that a <code>SysexMessage</code> contains continuing system
* exclusive data should not be propagated via MIDI wire protocol.
*
* @author David Rivas
* @author Kara Kytle
* @author Florian Bomers
*/
public class SysexMessage extends MidiMessage {
// Status byte defines
/**
* Status byte for System Exclusive message (0xF0, or 240).
* @see MidiMessage#getStatus
*/
public static final int SYSTEM_EXCLUSIVE = 0xF0; // 240
/**
* Status byte for Special System Exclusive message (0xF7, or 247), which is used
* in MIDI files. It has the same value as END_OF_EXCLUSIVE, which
* is used in the real-time "MIDI wire" protocol.
* @see MidiMessage#getStatus
*/
public static final int SPECIAL_SYSTEM_EXCLUSIVE = 0xF7; // 247
// Instance variables
/*
* The data bytes for this system exclusive message. These are
* initialized to <code>null</code> and are set explicitly
* by {@link #setMessage(int, byte[], int, long) setMessage}.
*/
//protected byte[] data = null;
/**
* Constructs a new <code>SysexMessage</code>. The
* contents of the new message are guaranteed to specify
* a valid MIDI message. Subsequently, you may set the
* contents of the message using one of the <code>setMessage</code>
* methods.
* @see #setMessage
*/
public SysexMessage() {
this(new byte[2]);
// Default sysex message data: SOX followed by EOX
data[0] = (byte) (SYSTEM_EXCLUSIVE & 0xFF);
data[1] = (byte) (ShortMessage.END_OF_EXCLUSIVE & 0xFF);
}
/**
* Constructs a new <code>SysexMessage</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 SysexMessage(byte[] data) {
super(data);
}
/**
* Sets the data for the system exclusive message. The
* first byte of the data array must be a valid system
* exclusive status byte (0xF0 or 0xF7).
* @param data the system exclusive message data
* @param length the length of the valid message data in
* the array, including the status byte.
*/
public void setMessage(byte[] data, int length) throws InvalidMidiDataException {
int status = (data[0] & 0xFF);
if ((status != 0xF0) && (status != 0xF7)) {
throw new InvalidMidiDataException("Invalid status byte for sysex message: 0x" + Integer.toHexString(status));
}
super.setMessage(data, length);
}
/**
* Sets the data for the system exclusive message.
* @param status the status byte for the message (0xF0 or 0xF7)
* @param data the system exclusive message data
* @param length the length of the valid message data in
* the array
*/
public void setMessage(int status, byte[] data, int length) throws InvalidMidiDataException {
if ( (status != 0xF0) && (status != 0xF7) ) {
throw new InvalidMidiDataException("Invalid status byte for sysex message: 0x" + Integer.toHexString(status));
}
if (length < 0 || length > data.length) {
throw new IndexOutOfBoundsException("length out of bounds: "+length);
}
this.length = length + 1;
if (this.data==null || this.data.length < this.length) {
this.data = new byte[this.length];
}
this.data[0] = (byte) (status & 0xFF);
if (length > 0) {
System.arraycopy(data, 0, this.data, 1, length);
}
}
/**
* Obtains a copy of the data for the system exclusive message.
* The returned array of bytes does not include the status byte.
* @return array containing the system exclusive message data.
*/
public byte[] getData() {
byte[] returnedArray = new byte[length - 1];
System.arraycopy(data, 1, returnedArray, 0, (length - 1));
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);
SysexMessage event = new SysexMessage(newData);
return event;
}
}