1 /*
2 * Copyright 1998-2002 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package javax.sound.midi;
27
28 /**
29 * A <code>SysexMessage</code> object represents a MIDI system exclusive message.
30 * <p>
31 * When a system exclusive message is read from a MIDI file, it always has
32 * a defined length. Data from a system exclusive message from a MIDI file
33 * should be stored in the data array of a <code>SysexMessage</code> as
34 * follows: the system exclusive message status byte (0xF0 or 0xF7), all
35 * message data bytes, and finally the end-of-exclusive flag (0xF7).
36 * The length reported by the <code>SysexMessage</code> object is therefore
37 * the length of the system exclusive data plus two: one byte for the status
38 * byte and one for the end-of-exclusive flag.
39 * <p>
40 * As dictated by the Standard MIDI Files specification, two status byte values are legal
41 * for a <code>SysexMessage</code> read from a MIDI file:
42 * <ul>
43 * <li>0xF0: System Exclusive message (same as in MIDI wire protocol)</li>
44 * <li>0xF7: Special System Exclusive message</li>
45 * </ul>
46 * <p>
47 * When Java Sound is used to handle system exclusive data that is being received
48 * using MIDI wire protocol, it should place the data in one or more
49 * <code>SysexMessages</code>. In this case, the length of the system exclusive data
50 * is not known in advance; the end of the system exclusive data is marked by an
51 * end-of-exclusive flag (0xF7) in the MIDI wire byte stream.
52 * <ul>
53 * <li>0xF0: System Exclusive message (same as in MIDI wire protocol)</li>
54 * <li>0xF7: End of Exclusive (EOX)</li>
55 * </ul>
56 * The first <code>SysexMessage</code> object containing data for a particular system
57 * exclusive message should have the status value 0xF0. If this message contains all
58 * the system exclusive data
59 * for the message, it should end with the status byte 0xF7 (EOX).
60 * Otherwise, additional system exclusive data should be sent in one or more
61 * <code>SysexMessages</code> with a status value of 0xF7. The <code>SysexMessage</code>
62 * containing the last of the data for the system exclusive message should end with the
63 * value 0xF7 (EOX) to mark the end of the system exclusive message.
64 * <p>
65 * If system exclusive data from <code>SysexMessages</code> objects is being transmitted
66 * using MIDI wire protocol, only the initial 0xF0 status byte, the system exclusive
67 * data itself, and the final 0xF7 (EOX) byte should be propagated; any 0xF7 status
68 * bytes used to indicate that a <code>SysexMessage</code> contains continuing system
69 * exclusive data should not be propagated via MIDI wire protocol.
70 *
71 * @author David Rivas
72 * @author Kara Kytle
73 * @author Florian Bomers
74 */
75 public class SysexMessage extends MidiMessage {
76
77
78 // Status byte defines
79
80
81 /**
82 * Status byte for System Exclusive message (0xF0, or 240).
83 * @see MidiMessage#getStatus
84 */
85 public static final int SYSTEM_EXCLUSIVE = 0xF0; // 240
86
87
88 /**
89 * Status byte for Special System Exclusive message (0xF7, or 247), which is used
90 * in MIDI files. It has the same value as END_OF_EXCLUSIVE, which
91 * is used in the real-time "MIDI wire" protocol.
92 * @see MidiMessage#getStatus
93 */
94 public static final int SPECIAL_SYSTEM_EXCLUSIVE = 0xF7; // 247
95
96
97 // Instance variables
98
99
100 /*
101 * The data bytes for this system exclusive message. These are
102 * initialized to <code>null</code> and are set explicitly
103 * by {@link #setMessage(int, byte[], int, long) setMessage}.
104 */
105 //protected byte[] data = null;
106
107
108 /**
109 * Constructs a new <code>SysexMessage</code>. The
110 * contents of the new message are guaranteed to specify
111 * a valid MIDI message. Subsequently, you may set the
112 * contents of the message using one of the <code>setMessage</code>
113 * methods.
114 * @see #setMessage
115 */
116 public SysexMessage() {
117 this(new byte[2]);
118 // Default sysex message data: SOX followed by EOX
119 data[0] = (byte) (SYSTEM_EXCLUSIVE & 0xFF);
120 data[1] = (byte) (ShortMessage.END_OF_EXCLUSIVE & 0xFF);
121 }
122
123
124 /**
125 * Constructs a new <code>SysexMessage</code>.
126 * @param data an array of bytes containing the complete message.
127 * The message data may be changed using the <code>setMessage</code>
128 * method.
129 * @see #setMessage
130 */
131 protected SysexMessage(byte[] data) {
132 super(data);
133 }
134
135
136 /**
137 * Sets the data for the system exclusive message. The
138 * first byte of the data array must be a valid system
139 * exclusive status byte (0xF0 or 0xF7).
140 * @param data the system exclusive message data
141 * @param length the length of the valid message data in
142 * the array, including the status byte.
143 */
144 public void setMessage(byte[] data, int length) throws InvalidMidiDataException {
145 int status = (data[0] & 0xFF);
146 if ((status != 0xF0) && (status != 0xF7)) {
147 throw new InvalidMidiDataException("Invalid status byte for sysex message: 0x" + Integer.toHexString(status));
148 }
149 super.setMessage(data, length);
150 }
151
152
153 /**
154 * Sets the data for the system exclusive message.
155 * @param status the status byte for the message (0xF0 or 0xF7)
156 * @param data the system exclusive message data
157 * @param length the length of the valid message data in
158 * the array
159 */
160 public void setMessage(int status, byte[] data, int length) throws InvalidMidiDataException {
161 if ( (status != 0xF0) && (status != 0xF7) ) {
162 throw new InvalidMidiDataException("Invalid status byte for sysex message: 0x" + Integer.toHexString(status));
163 }
164 if (length < 0 || length > data.length) {
165 throw new IndexOutOfBoundsException("length out of bounds: "+length);
166 }
167 this.length = length + 1;
168
169 if (this.data==null || this.data.length < this.length) {
170 this.data = new byte[this.length];
171 }
172
173 this.data[0] = (byte) (status & 0xFF);
174 if (length > 0) {
175 System.arraycopy(data, 0, this.data, 1, length);
176 }
177 }
178
179
180 /**
181 * Obtains a copy of the data for the system exclusive message.
182 * The returned array of bytes does not include the status byte.
183 * @return array containing the system exclusive message data.
184 */
185 public byte[] getData() {
186 byte[] returnedArray = new byte[length - 1];
187 System.arraycopy(data, 1, returnedArray, 0, (length - 1));
188 return returnedArray;
189 }
190
191
192 /**
193 * Creates a new object of the same class and with the same contents
194 * as this object.
195 * @return a clone of this instance
196 */
197 public Object clone() {
198 byte[] newData = new byte[length];
199 System.arraycopy(data, 0, newData, 0, newData.length);
200 SysexMessage event = new SysexMessage(newData);
201 return event;
202 }
203 }
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