Chris@2: /*
Chris@2: 	Copyright (C) 2001, 2006 by Simon Dixon
Chris@2: 
Chris@2: 	This program is free software; you can redistribute it and/or modify
Chris@2: 	it under the terms of the GNU General Public License as published by
Chris@2: 	the Free Software Foundation; either version 2 of the License, or
Chris@2: 	(at your option) any later version.
Chris@2: 
Chris@2: 	This program is distributed in the hope that it will be useful,
Chris@2: 	but WITHOUT ANY WARRANTY; without even the implied warranty of
Chris@2: 	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Chris@2: 	GNU General Public License for more details.
Chris@2: 
Chris@2: 	You should have received a copy of the GNU General Public License along
Chris@2: 	with this program (the file gpl.txt); if not, download it from
Chris@2: 	http://www.gnu.org/licenses/gpl.txt or write to the
Chris@2: 	Free Software Foundation, Inc.,
Chris@2: 	51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
Chris@2: */
Chris@2: 
Chris@2: package at.ofai.music.util;
Chris@2: import java.io.*;
Chris@2: 
Chris@2: public class RandomAccessInputStream extends InputStream {
Chris@2: 
Chris@2: 	protected RandomAccessFile r;
Chris@2: 	protected long markPosition = 0;
Chris@2: 	
Chris@2: 	public RandomAccessInputStream(String name) throws FileNotFoundException {
Chris@2: 		r = new RandomAccessFile(name, "r");
Chris@2: 	} // constructor
Chris@2: 
Chris@2: 	public RandomAccessInputStream(File f) throws FileNotFoundException {
Chris@2: 		r = new RandomAccessFile(f, "r");
Chris@2: 	} // constructor
Chris@2: 
Chris@2:     /** Returns the number of bytes that can be read (or skipped over) from
Chris@2: 	 *  this input stream without blocking by the next caller of a method for
Chris@2: 	 *  this input stream.
Chris@2: 	 */
Chris@2: 	public int available() throws IOException {
Chris@2: 		long availableBytes = r.length() - r.getFilePointer();
Chris@2: 		if (availableBytes > Integer.MAX_VALUE)
Chris@2: 			return Integer.MAX_VALUE;
Chris@2: 		else
Chris@2: 			return (int)availableBytes;
Chris@2: 	} // available()
Chris@2: 	
Chris@2: 	/** Closes this input stream and releases any system resources associated
Chris@2: 	 *  with the stream.
Chris@2: 	 */
Chris@2: 	public void close() throws IOException {
Chris@2: 		r.close();
Chris@2: 	} // close()
Chris@2: 	
Chris@2: 	/** Marks the current position in this input stream.
Chris@2: 	 *  Warning: Use mark() instead of mark(int).
Chris@2: 	 *  IOExceptions are caught, because InputStream doesn't allow them to be
Chris@2: 	 *  thrown. The exception is printed and the mark position invalidated.
Chris@2: 	 *  @param readlimit Ignored
Chris@2: 	 */
Chris@2: 	public void mark(int readlimit) {
Chris@2: 		try {
Chris@2: 			mark();
Chris@2: 		} catch (IOException e) {
Chris@2: 			e.printStackTrace();
Chris@2: 			markPosition = -1;
Chris@2: 		}
Chris@2: 	} // mark()
Chris@2: 
Chris@2: 	/** Marks the current position in this input stream.
Chris@2: 	 */
Chris@2: 	public void mark() throws IOException {
Chris@2: 		markPosition = r.getFilePointer();
Chris@2: 	} // mark()
Chris@2: 
Chris@2: 	/** This input stream supports the mark and reset methods.
Chris@2: 	 *  @return true
Chris@2: 	 */
Chris@2: 	public boolean markSupported() {
Chris@2: 		return true;
Chris@2: 	} // markSupported()
Chris@2: 
Chris@2: 	/** Reads the next byte of data from the input stream.
Chris@2: 	 */
Chris@2: 	public int read() throws IOException {
Chris@2: 		return r.read();
Chris@2: 	} // read()
Chris@2: 	
Chris@2: 	/** Reads some number of bytes from the input stream and stores them into
Chris@2: 	 *  the buffer array b.
Chris@2: 	 */
Chris@2: 	public int read(byte[] b) throws IOException {
Chris@2: 		return r.read(b);
Chris@2: 	} // read()
Chris@2: 
Chris@2: 	/** Reads up to len bytes of data from the input stream into an array of
Chris@2: 	 *  bytes.
Chris@2: 	 */
Chris@2: 	public int read(byte[] b, int off, int len) throws IOException {
Chris@2: 		return r.read(b, off, len);
Chris@2: 	} // read()
Chris@2: 	
Chris@2: 	/** Repositions this stream to the position at the time the mark method
Chris@2: 	 *  was last called on this input stream. 
Chris@2: 	 */
Chris@2: 	public void reset() throws IOException {
Chris@2: 		if (markPosition < 0)
Chris@2: 			throw new IOException("reset(): invalid mark position");
Chris@2: 		r.seek(markPosition);
Chris@2: 	} // reset()
Chris@2: 	
Chris@2: 	/** Skips over and discards n bytes of data from this input stream.
Chris@2: 	 */
Chris@2: 	public long skip(long n) throws IOException {
Chris@2: 		long pos = r.getFilePointer();
Chris@2: 		r.seek(n + pos);
Chris@2: 		return r.getFilePointer() - pos;
Chris@2: 	} // skip()
Chris@2: 
Chris@2: 	/** Seek to a position n bytes after the mark.
Chris@2: 	 */
Chris@2: 	public long seekFromMark(long n) throws IOException {
Chris@2: 		r.seek(markPosition + n);
Chris@2: 		return r.getFilePointer() - markPosition;
Chris@2: 	} // seekFromMark()
Chris@2: 
Chris@2: } // class RandomAccessInputStream