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25
26package javax.sound.midi;
27
28/**
29 * A {@code SysexMessage} object represents a MIDI system exclusive message.
30 * <p>
31 * When a system exclusive message is read from a MIDI file, it always has a
32 * defined length. Data from a system exclusive message from a MIDI file should
33 * be stored in the data array of a {@code SysexMessage} as follows: the system
34 * exclusive message status byte (0xF0 or 0xF7), all message data bytes, and
35 * finally the end-of-exclusive flag (0xF7). The length reported by the
36 * {@code SysexMessage} object is therefore the length of the system exclusive
37 * data plus two: one byte for the status byte and one for the end-of-exclusive
38 * flag.
39 * <p>
40 * As dictated by the Standard MIDI Files specification, two status byte values
41 * are legal for a {@code SysexMessage} read from a MIDI file:
42 * <ul>
43 *   <li>0xF0: System Exclusive message (same as in MIDI wire protocol)
44 *   <li>0xF7: Special System Exclusive message
45 * </ul>
46 * When Java Sound is used to handle system exclusive data that is being
47 * received using MIDI wire protocol, it should place the data in one or more
48 * {@code SysexMessages}. In this case, the length of the system exclusive data
49 * is not known in advance; the end of the system exclusive data is marked by an
50 * end-of-exclusive flag (0xF7) in the MIDI wire byte stream.
51 * <ul>
52 *   <li>0xF0: System Exclusive message (same as in MIDI wire protocol)
53 *   <li>0xF7: End of Exclusive (EOX)
54 * </ul>
55 * The first {@code SysexMessage} object containing data for a particular system
56 * exclusive message should have the status value 0xF0. If this message contains
57 * all the system exclusive data for the message, it should end with the status
58 * byte 0xF7 (EOX). Otherwise, additional system exclusive data should be sent
59 * in one or more {@code SysexMessages} with a status value of 0xF7. The
60 * {@code SysexMessage} containing the last of the data for the system exclusive
61 * message should end with the value 0xF7 (EOX) to mark the end of the system
62 * exclusive message.
63 * <p>
64 * If system exclusive data from {@code SysexMessages} objects is being
65 * transmitted using MIDI wire protocol, only the initial 0xF0 status byte, the
66 * system exclusive data itself, and the final 0xF7 (EOX) byte should be
67 * propagated; any 0xF7 status bytes used to indicate that a
68 * {@code SysexMessage} contains continuing system exclusive data should not be
69 * propagated via MIDI wire protocol.
70 *
71 * @author David Rivas
72 * @author Kara Kytle
73 * @author Florian Bomers
74 */
75public class SysexMessage extends MidiMessage {
76
77    // Status byte defines
78
79    /**
80     * Status byte for System Exclusive message (0xF0, or 240).
81     *
82     * @see MidiMessage#getStatus
83     */
84    public static final int SYSTEM_EXCLUSIVE = 0xF0; // 240
85
86    /**
87     * Status byte for Special System Exclusive message (0xF7, or 247), which is
88     * used in MIDI files. It has the same value as END_OF_EXCLUSIVE, which is
89     * used in the real-time "MIDI wire" protocol.
90     *
91     * @see MidiMessage#getStatus
92     */
93    public static final int SPECIAL_SYSTEM_EXCLUSIVE = 0xF7; // 247
94
95    /**
96     * The data bytes for this system exclusive message. These are initialized
97     * to {@code null} and are set explicitly by
98     * {@link #setMessage(int, byte[], int, long) setMessage}.
99     */
100    //protected byte[] data = null;
101
102    /**
103     * Constructs a new {@code SysexMessage}. The contents of the new message
104     * are guaranteed to specify a valid MIDI message. Subsequently, you may set
105     * the contents of the message using one of the {@code setMessage} methods.
106     *
107     * @see #setMessage
108     */
109    public SysexMessage() {
110        this(new byte[2]);
111        // Default sysex message data: SOX followed by EOX
112        data[0] = (byte) (SYSTEM_EXCLUSIVE & 0xFF);
113        data[1] = (byte) (ShortMessage.END_OF_EXCLUSIVE & 0xFF);
114    }
115
116    /**
117     * Constructs a new {@code SysexMessage} and sets the data for the message.
118     * The first byte of the data array must be a valid system exclusive status
119     * byte (0xF0 or 0xF7). The contents of the message can be changed by using
120     * one of the {@code setMessage} methods.
121     *
122     * @param  data the system exclusive message data including the status byte
123     * @param  length the length of the valid message data in the array,
124     *         including the status byte; it should be non-negative and less
125     *         than or equal to {@code data.length}
126     * @throws InvalidMidiDataException if the parameter values do not specify a
127     *         valid MIDI meta message
128     * @see #setMessage(byte[], int)
129     * @see #setMessage(int, byte[], int)
130     * @see #getData()
131     * @since 1.7
132     */
133    public SysexMessage(byte[] data, int length)
134            throws InvalidMidiDataException {
135        super(null);
136        setMessage(data, length);
137    }
138
139    /**
140     * Constructs a new {@code SysexMessage} and sets the data for the message.
141     * The contents of the message can be changed by using one of the
142     * {@code setMessage} methods.
143     *
144     * @param  status the status byte for the message; it must be a valid system
145     *         exclusive status byte (0xF0 or 0xF7)
146     * @param  data the system exclusive message data (without the status byte)
147     * @param  length the length of the valid message data in the array; it
148     *         should be non-negative and less than or equal to
149     *         {@code data.length}
150     * @throws InvalidMidiDataException if the parameter values do not specify a
151     *         valid MIDI system exclusive message
152     * @see #setMessage(byte[], int)
153     * @see #setMessage(int, byte[], int)
154     * @see #getData()
155     * @since 1.7
156     */
157    public SysexMessage(int status, byte[] data, int length)
158            throws InvalidMidiDataException {
159        super(null);
160        setMessage(status, data, length);
161    }
162
163    /**
164     * Constructs a new {@code SysexMessage}.
165     *
166     * @param  data an array of bytes containing the complete message. The
167     *         message data may be changed using the {@code setMessage} method.
168     * @see #setMessage
169     */
170    protected SysexMessage(byte[] data) {
171        super(data);
172    }
173
174    /**
175     * Sets the data for the system exclusive message. The first byte of the
176     * data array must be a valid system exclusive status byte (0xF0 or 0xF7).
177     *
178     * @param  data the system exclusive message data
179     * @param  length the length of the valid message data in the array,
180     *         including the status byte
181     * @throws InvalidMidiDataException if the parameter values do not specify a
182     *         valid MIDI system exclusive message
183     */
184    @Override
185    public void setMessage(byte[] data, int length) throws InvalidMidiDataException {
186        int status = (data[0] & 0xFF);
187        if ((status != 0xF0) && (status != 0xF7)) {
188            throw new InvalidMidiDataException("Invalid status byte for sysex message: 0x" + Integer.toHexString(status));
189        }
190        super.setMessage(data, length);
191    }
192
193    /**
194     * Sets the data for the system exclusive message.
195     *
196     * @param  status the status byte for the message (0xF0 or 0xF7)
197     * @param  data the system exclusive message data
198     * @param  length the length of the valid message data in the array
199     * @throws InvalidMidiDataException if the status byte is invalid for a
200     *         system exclusive message
201     */
202    public void setMessage(int status, byte[] data, int length) throws InvalidMidiDataException {
203        if ( (status != 0xF0) && (status != 0xF7) ) {
204            throw new InvalidMidiDataException("Invalid status byte for sysex message: 0x" + Integer.toHexString(status));
205        }
206        if (length < 0 || length > data.length) {
207            throw new IndexOutOfBoundsException("length out of bounds: "+length);
208        }
209        this.length = length + 1;
210
211        if (this.data==null || this.data.length < this.length) {
212            this.data = new byte[this.length];
213        }
214
215        this.data[0] = (byte) (status & 0xFF);
216        if (length > 0) {
217            System.arraycopy(data, 0, this.data, 1, length);
218        }
219    }
220
221    /**
222     * Obtains a copy of the data for the system exclusive message. The returned
223     * array of bytes does not include the status byte.
224     *
225     * @return array containing the system exclusive message data
226     */
227    public byte[] getData() {
228        byte[] returnedArray = new byte[length - 1];
229        System.arraycopy(data, 1, returnedArray, 0, (length - 1));
230        return returnedArray;
231    }
232
233    /**
234     * Creates a new object of the same class and with the same contents as this
235     * object.
236     *
237     * @return a clone of this instance
238     */
239    @Override
240    public Object clone() {
241        byte[] newData = new byte[length];
242        System.arraycopy(data, 0, newData, 0, newData.length);
243        SysexMessage event = new SysexMessage(newData);
244        return event;
245    }
246}
247