Subversion Repositories openrisc

/* OutputWindow.java --

   Copyright (C) 2001, 2004  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath 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, or (at your option)

any later version.

GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package java.util.zip;

/**

 * Contains the output from the Inflation process.

 *

 * We need to have a window so that we can refer backwards into the output stream

 * to repeat stuff.

 *

 * @author John Leuner

 * @since 1.1

 */

class OutputWindow

{

  private static final int WINDOW_SIZE = 1 << 15;

  private static final int WINDOW_MASK = WINDOW_SIZE - 1;

  private byte[] window = new byte[WINDOW_SIZE]; //The window is 2^15 bytes

  private int window_end  = 0;

  private int window_filled = 0;

  public void write(int abyte)

  {

    if (window_filled++ == WINDOW_SIZE)

      throw new IllegalStateException("Window full");

    window[window_end++] = (byte) abyte;

    window_end &= WINDOW_MASK;

  }

  private void slowRepeat(int rep_start, int len, int dist)

  {

    while (len-- > 0)

      {

        window[window_end++] = window[rep_start++];

        window_end &= WINDOW_MASK;

        rep_start &= WINDOW_MASK;

      }

  }

  public void repeat(int len, int dist)

  {

    if ((window_filled += len) > WINDOW_SIZE)

      throw new IllegalStateException("Window full");

    int rep_start = (window_end - dist) & WINDOW_MASK;

    int border = WINDOW_SIZE - len;

    if (rep_start <= border && window_end < border)

      {

        if (len <= dist)

          {

            System.arraycopy(window, rep_start, window, window_end, len);

            window_end += len;

          }

        else

          {

            /* We have to copy manually, since the repeat pattern overlaps.

             */

            while (len-- > 0)

              window[window_end++] = window[rep_start++];

          }

      }

    else

      slowRepeat(rep_start, len, dist);

  }

  public int copyStored(StreamManipulator input, int len)

  {

    len = Math.min(Math.min(len, WINDOW_SIZE - window_filled),

                   input.getAvailableBytes());

    int copied;

    int tailLen = WINDOW_SIZE - window_end;

    if (len > tailLen)

      {

        copied = input.copyBytes(window, window_end, tailLen);

        if (copied == tailLen)

          copied += input.copyBytes(window, 0, len - tailLen);

      }

    else

      copied = input.copyBytes(window, window_end, len);

    window_end = (window_end + copied) & WINDOW_MASK;

    window_filled += copied;

    return copied;

  }

  public void copyDict(byte[] dict, int offset, int len)

  {

    if (window_filled > 0)

      throw new IllegalStateException();

    if (len > WINDOW_SIZE)

      {

        offset += len - WINDOW_SIZE;

        len = WINDOW_SIZE;

      }

    System.arraycopy(dict, offset, window, 0, len);

    window_end = len & WINDOW_MASK;

  }

  public int getFreeSpace()

  {

    return WINDOW_SIZE - window_filled;

  }

  public int getAvailable()

  {

    return window_filled;

  }

  public int copyOutput(byte[] output, int offset, int len)

  {

    int copy_end = window_end;

    if (len > window_filled)

      len = window_filled;

    else

      copy_end = (window_end - window_filled + len) & WINDOW_MASK;

    int copied = len;

    int tailLen = len - copy_end;

    if (tailLen > 0)

      {

        System.arraycopy(window, WINDOW_SIZE - tailLen,

                         output, offset, tailLen);

        offset += tailLen;

        len = copy_end;

      }

    System.arraycopy(window, copy_end - len, output, offset, len);

    window_filled -= copied;

    if (window_filled < 0)

      throw new IllegalStateException();

    return copied;

  }

  public void reset() {

    window_filled = window_end = 0;

  }

}