TagHeader.java

/*
 * JSwiff is an open source Java API for Macromedia Flash file generation
 * and manipulation
 *
 * Copyright (C) 2004-2005 Ralf Terdic (contact@jswiff.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package com.jswiff.swfrecords.tags;

import com.jswiff.io.InputBitStream;

import java.io.IOException;

/**
 * This class represents a SWF tag header.
 */
public final class TagHeader {
	private short code;

	private int length;

	protected boolean isLong;

	/*
	 * Creates a new TagHeader instance.
	 */
	TagHeader() {
		// nothing to do
	}

	TagHeader(InputBitStream stream) throws IOException {
		read(stream);
	}

	/**
	 * Returns the code of the tag which designates its type.
	 * 
	 * @return tag type code
	 * 
	 * @see TagConstants
	 */
	public short getCode() {
		return code;
	}

	/**
	 * Returns the length of the tag.
	 * 
	 * @return tag length
	 */
	public int getLength() {
		return length;
	}

	private void read(InputBitStream stream) throws IOException {
		int codeAndLength = stream.readUI16();
		code = (short) (codeAndLength >> 6); // upper 10 bits
		length = codeAndLength & 0x3F; // 0x3F = 63 = 111111, lower 6 bits
		if (length == 0x3F) {
			isLong = true;
			length = (int) stream.readUI32();
		}
	}

	public boolean isLong() {
		return isLong;
	}

	
	
}