/* 
 * Copyright 1998 Sun Microsystems, Inc.  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.
 *
 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

/*
 */

import java.io.*;

class CompressInputStream extends FilterInputStream
    implements CompressConstants
{

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

    // buffer of unpacked 6-bit codes from last 32-word read
    int buf[] = new int[5];

    // position of next code to read in buffer (5 == end of buffer)
    int bufPos = 5;

    public int read() throws IOException {
	try {
	    int code;
	    do {
		code = readCode();
	    } while (code == NOP);	// ignore NOP codes

	    if (code >= BASE)
		return codeTable.charAt(code - BASE);
	    else if (code == RAW) {
		int high = readCode();
		int low = readCode();
		return (high << 4) | low;
	    } else
		throw new IOException("unknown compression code: " + code);
	} catch (EOFException e) {
	    return -1;
	}
    }

    public int read(byte b[], int off, int len) throws IOException {
	if (len <= 0) {
	    return 0;
	}

	int c = read();
	if (c == -1) {
	    return -1;
	}
	b[off] = (byte)c;

	int i = 1;
/*****
	try {
	    for (; i < len ; i++) {
		c = read();
		if (c == -1) {
		    break;
		}
		if (b != null) {
		    b[off + i] = (byte)c;
		}
	    }
	} catch (IOException ee) {
	}
 *****/
	return i;
    }

    private int readCode() throws IOException {
	if (bufPos == 5) {
	    int b1 = in.read();
	    int b2 = in.read();
	    int b3 = in.read();
	    int b4 = in.read();
	    if ((b1 | b2 | b3 | b4) < 0)
		throw new EOFException();
	    int pack = (b1 << 24) | (b2 << 16) | (b3 << 8) | b4;
	    buf[0] = (pack >>> 24) & 0x3F;
	    buf[1] = (pack >>> 18) & 0x3F;
	    buf[2] = (pack >>> 12) & 0x3F;
	    buf[3] = (pack >>>  6) & 0x3F;
	    buf[4] = (pack >>>  0) & 0x3F;
	    bufPos = 0;
	}
	return buf[bufPos++];
    }
}