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/* java.util.zip.PendingBuffer

   Copyright (C) 2001 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;

/**

 * This class is general purpose class for writing data to a buffer.

 *

 * It allows you to write bits as well as bytes

 *

 * Based on DeflaterPending.java

 *

 * @author Jochen Hoenicke

 * @date Jan 5, 2000

 */

class PendingBuffer

{

  protected byte[] buf;

  int    start;

  int    end;

  int    bits;

  int    bitCount;

  public PendingBuffer()

  {

    this( 4096 );

  }

  public PendingBuffer(int bufsize)

  {

    buf = new byte[bufsize];

  }

  public final void reset() {

    start = end = bitCount = 0;

  }

  public final void writeByte(int b)

  {

    if (DeflaterConstants.DEBUGGING && start != 0)

      throw new IllegalStateException();

    buf[end++] = (byte) b;

  }

  public final void writeShort(int s)

  {

    if (DeflaterConstants.DEBUGGING && start != 0)

      throw new IllegalStateException();

    buf[end++] = (byte) s;

    buf[end++] = (byte) (s >> 8);

  }

  public final void writeInt(int s)

  {

    if (DeflaterConstants.DEBUGGING && start != 0)

      throw new IllegalStateException();

    buf[end++] = (byte) s;

    buf[end++] = (byte) (s >> 8);

    buf[end++] = (byte) (s >> 16);

    buf[end++] = (byte) (s >> 24);

  }

  public final void writeBlock(byte[] block, int offset, int len)

  {

    if (DeflaterConstants.DEBUGGING && start != 0)

      throw new IllegalStateException();

    System.arraycopy(block, offset, buf, end, len);

    end += len;

  }

  public final int getBitCount() {

    return bitCount;

  }

  public final void alignToByte() {

    if (DeflaterConstants.DEBUGGING && start != 0)

      throw new IllegalStateException();

    if (bitCount > 0)

      {

        buf[end++] = (byte) bits;

        if (bitCount > 8)

          buf[end++] = (byte) (bits >>> 8);

      }

    bits = 0;

    bitCount = 0;

  }

  public final void writeBits(int b, int count)

  {

     if (DeflaterConstants.DEBUGGING && start != 0)

       throw new IllegalStateException();

     if (DeflaterConstants.DEBUGGING)

       System.err.println("writeBits("+Integer.toHexString(b)+","+count+")");

    bits |= b << bitCount;

    bitCount += count;

    if (bitCount >= 16) {

      buf[end++] = (byte) bits;

      buf[end++] = (byte) (bits >>> 8);

      bits >>>= 16;

      bitCount -= 16;

    }

  }

  public final void writeShortMSB(int s) {

    if (DeflaterConstants.DEBUGGING && start != 0)

      throw new IllegalStateException();

    buf[end++] = (byte) (s >> 8);

    buf[end++] = (byte) s;

  }

  public final boolean isFlushed() {

    return end == 0;

  }

  /**

   * Flushes the pending buffer into the given output array.  If the

   * output array is to small, only a partial flush is done.

   *

   * @param output the output array;

   * @param offset the offset into output array;

   * @param length the maximum number of bytes to store;

   * @exception IndexOutOfBoundsException if offset or length are

   * invalid.

   */

  public final int flush(byte[] output, int offset, int length) {

    if (bitCount >= 8)

      {

        buf[end++] = (byte) bits;

        bits >>>= 8;

        bitCount -= 8;

      }

    if (length > end - start)

      {

        length = end - start;

        System.arraycopy(buf, start, output, offset, length);

        start = 0;

        end = 0;

      }

    else

      {

        System.arraycopy(buf, start, output, offset, length);

        start += length;

      }

    return length;

  }

  /**

   * Flushes the pending buffer and returns that data in a new array

   *

   * @return the output stream

   */

  public final byte[] toByteArray()

  {

    byte[] ret = new byte[ end - start ];

    System.arraycopy(buf, start, ret, 0, ret.length);

    start = 0;

    end = 0;

    return ret;

  }

}