1 /* MetaMessage.java -- A meta message for MIDI files. 2 Copyright (C) 2005 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package javax.sound.midi; 40 41 /** 42 * A system exclusive MIDI message. 43 * 44 * @author Anthony Green (green@redhat.com) 45 * @since 1.3 46 * 47 */ 48 public class MetaMessage extends MidiMessage 49 { 50 /** 51 * The META status code. Only valid for MIDI files, not the wire protocol. 52 */ 53 public static final int META = 0xFF; 54 55 // The length of the variable length data length encoding. 56 private int lengthLength = 0; 57 58 /** 59 * Create a default valid meta message. 60 * 61 * The official specs don't specify what message is to be 62 * created. For now, we create a zero length meta message 63 * with a type code of 0. 64 */ MetaMessage()65 public MetaMessage() 66 { 67 super(new byte[4]); 68 data[0] = (byte) META; 69 data[1] = (byte) 0; // Type 70 data[2] = (byte) 1; // Length length 71 data[3] = (byte) 0; // Length 72 lengthLength = 1; 73 } 74 75 /** 76 * Create a MetaMessage object. 77 * @param data a complete system exclusive message 78 */ MetaMessage(byte[] data)79 public MetaMessage(byte[] data) 80 { 81 super(data); 82 int index = 2; 83 lengthLength = 1; 84 while ((data[index++] & 0x80) > 0) 85 lengthLength++; 86 } 87 88 /** 89 * Set the meta message. 90 * 91 * @param type the meta type byte (< 128) 92 * @param data the message data 93 * @param length the length of the message data 94 * @throws InvalidMidiDataException if this message is invalid 95 */ setMessage(int type, byte[] data, int length)96 public void setMessage(int type, byte[] data, int length) 97 throws InvalidMidiDataException 98 { 99 if (type > 127) 100 throw new InvalidMidiDataException("Meta type 0x" 101 + Integer.toHexString(type) 102 + " must be less than 128"); 103 104 // For a nice description of how variable length values are handled, 105 // see http://www.borg.com/~jglatt/tech/midifile.htm 106 107 // First compute the length of the length value 108 lengthLength = 0; 109 int lengthValue = length; 110 do { 111 lengthValue = lengthValue >> 7; 112 lengthLength++; 113 } while (lengthValue > 0); 114 115 // Now allocate our data array 116 this.length = 2 + lengthLength + length; 117 this.data = new byte[this.length]; 118 this.data[0] = (byte) META; 119 this.data[1] = (byte) type; 120 121 // Now compute the length representation 122 long buffer = length & 0x7F; 123 while ((length >>= 7) > 0) 124 { 125 buffer <<= 8; 126 buffer |= ((length & 0x7F) | 0x80); 127 } 128 129 // Now store the variable length length value 130 int index = 2; 131 do 132 { 133 this.data[index++] = (byte) (buffer & 0xFF); 134 if ((buffer & 0x80) == 0) 135 break; 136 buffer >>= 8; 137 } while (true); 138 139 // Now copy the real data. 140 System.arraycopy(data, 0, this.data, index, length); 141 } 142 143 /** 144 * Get the meta message type. 145 * 146 * @return the meta message type 147 */ getType()148 public int getType() 149 { 150 return data[1]; 151 } 152 153 /** 154 * Get the data for this message, not including the status, 155 * type, or length information. 156 * 157 * @return the message data, not including status, type or lenght info 158 */ getData()159 public byte[] getData() 160 { 161 int dataLength = length - 2 - lengthLength; 162 byte[] result = new byte[dataLength]; 163 System.arraycopy(data, 2 + lengthLength, result, 0, dataLength); 164 return result; 165 } 166 167 /* Create a deep-copy clone of this object. 168 * @see java.lang.Object#clone() 169 */ clone()170 public Object clone() 171 { 172 byte message[] = new byte[length]; 173 System.arraycopy(data, 0, message, 0, length); 174 return new MetaMessage(message); 175 } 176 } 177