| /* |
| * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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| * questions. |
| */ |
| |
| package javax.sound.midi; |
| |
| /** |
| * A {@code MetaMessage} is a {@link MidiMessage} 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} 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 |
| * {@link ShortMessage} with the status value {@code 0xFF} represents a system |
| * reset message. In MIDI files, this same status value denotes a |
| * {@code MetaMessage}. The types of meta-message are distinguished from each |
| * other by the first byte that follows the status byte {@code 0xFF}. 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}. |
| * |
| * @author David Rivas |
| * @author Kara Kytle |
| * @see MetaEventListener |
| */ |
| public class MetaMessage extends MidiMessage { |
| |
| /** |
| * Status byte for {@code MetaMessage} (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 |
| |
| /** |
| * 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}. The contents of the message are not |
| * set here; use {@link #setMessage(int, byte[], int) setMessage} to set |
| * them subsequently. |
| */ |
| public MetaMessage() { |
| // Default meta message data: just the META status byte value |
| this(new byte[]{(byte) META, 0}); |
| } |
| |
| /** |
| * Constructs a new {@code MetaMessage} and sets the message parameters. The |
| * contents of the message can be changed by using the {@code setMessage} |
| * method. |
| * |
| * @param type meta-message type (must be less than 128) |
| * @param data the data bytes in the MIDI message |
| * @param length an amount of bytes in the {@code data} byte array; it |
| * should be non-negative and less than or equal to |
| * {@code data.length} |
| * @throws InvalidMidiDataException if the parameter values do not specify a |
| * valid MIDI meta message |
| * @see #setMessage(int, byte[], int) |
| * @see #getType() |
| * @see #getData() |
| * @since 1.7 |
| */ |
| public MetaMessage(int type, byte[] data, int length) |
| throws InvalidMidiDataException { |
| super(null); |
| setMessage(type, data, length); // can throw InvalidMidiDataException |
| } |
| |
| /** |
| * Constructs a new {@code MetaMessage}. |
| * |
| * @param data an array of bytes containing the complete message. The |
| * message data may be changed using the {@code setMessage} 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}. Since only one |
| * status byte value, {@code 0xFF}, is allowed for meta-messages, it does |
| * not need to be specified here. Calls to |
| * {@link MidiMessage#getStatus getStatus} return {@code 0xFF} for all |
| * meta-messages. |
| * <p> |
| * The {@code type} argument should be a valid value for the byte that |
| * follows the status byte in the {@code MetaMessage}. The {@code data} |
| * argument should contain all the subsequent bytes of the |
| * {@code MetaMessage}. In other words, the byte that specifies the type of |
| * {@code MetaMessage} 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} byte array |
| * @throws InvalidMidiDataException 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); |
| } |
| |
| 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); |
| } |
| } |
| |
| /** |
| * Obtains the type of the {@code MetaMessage}. |
| * |
| * @return an integer representing the {@code MetaMessage} 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 |
| */ |
| @Override |
| 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 int getVarIntLength(long value) { |
| int length = 0; |
| do { |
| value = value >> 7; |
| length++; |
| } while (value > 0); |
| return length; |
| } |
| |
| private static final 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); |
| } |
| } |
