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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

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 * 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,

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 *

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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

     */

    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 final static 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);

    }

}