LEInputStream.java

/**
 * Copyright (C) 2007 Rui Shen (rui.shen@gmail.com) All Right Reserved
 * File     : LEInputStream.java
 * Created	: 2007-3-1
 * ****************************************************************************
 * 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 org.geometerplus.fbreader.formats.chm;

import java.io.EOFException;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * Little Endian Input Stream
 * @author Shufeng
 *
 */
class LEInputStream extends FilterInputStream {

	public LEInputStream(InputStream in) {
		super(in);
	}

	/**
	 * 16-bit little endian unsinged integer
	 */
	public int read16() throws IOException {
        int b1 = read();
        int b2 = read();
        if ((b1 | b2) < 0)
            throw new EOFException();
        return (b1 << 0) + (b2 << 8);
	}
	
	/**
	 * 32-bit little endian integer
	 */
	public int read32() throws IOException {
        int b1 = read();
        int b2 = read();
        int b3 = read();
        int b4 = read();
        if ((b1 | b2 | b3 | b4) < 0)
            throw new EOFException();
        return ((b1 << 0) + (b2 << 8) + (b3 << 16) + (b4 << 24));
	}
	
	/**
	 * Encoded little endian integer
	 */
	public int readENC() throws IOException {
		int r = 0;
		for (;;) {
			int b = read();
			if (b < 0) throw new EOFException();
			r = (r << 7) + (b & 0x7f);
			if ((b & 0x80) == 0)
				return r;
		}
	}

	/**
	 * 64-bit little endian integer
	 */
	public long read64() throws IOException {
        int b1 = read();
        int b2 = read();
        int b3 = read();
        int b4 = read();
        int b5 = read();
        int b6 = read();
        int b7 = read();
        int b8 = read();
        if ((b1 | b2 | b3 | b4 | b5 | b6 | b7 | b8) < 0)
            throw new EOFException();
        return ((b1 << 0) + (b2 << 8) + (b3 << 16) + (b4 << 24) 
        		+ (b5 << 32) + (b6 << 40) + (b7 << 48) + (b8 << 56));
	}
	
	public String readUTF8(int len) throws IOException {
		byte[]buf = new byte[len];
		readFully(buf);
		return new String(buf, 0, len, "UTF-8");
	}
	
	public String readUTF16(int len) throws IOException {
		byte[]buf = new byte[len];
		readFully(buf);
		return new String(buf, 0, len, "UTF-16LE");
	}
			
	public String readGUID() throws IOException {
		return toHexString(read32(), 8) + 
			"-" + toHexString(read16(), 4) + "-" + toHexString(read16(), 4) +
			"-" + toHexString(read(), 2) + toHexString(read(), 2) +
			"-" + toHexString(read(), 2) + toHexString(read(), 2) +
			"-" + toHexString(read(), 2) + toHexString(read(), 2) +
			"-" + toHexString(read(), 2) + toHexString(read(), 2);
	}
	
	private String toHexString(int v, int len) {
		StringBuffer b = new StringBuffer();
		for (int i = 0; i < len; i++)
			b.append('0');
		b.append(Long.toHexString(v));
		return b.substring(b.length() - len).toUpperCase();
	}
	
    public void readFully(byte b[]) throws IOException {
		readFully(b, 0, b.length);
	}

	public void readFully(byte b[], int off, int len)
			throws IOException {
		for (int n = 0; n < len; ) {
			int count = read(b, off + n, len - n);
			if (count < 0)
				throw new EOFException();
			n += count;
		}
	}
}