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// Handler.java - URLStreamHandler for core protocol.

/* Copyright (C) 2001  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the

Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for

details.  */

package gnu.java.net.protocol.core;

import gnu.gcj.Core;

import gnu.gcj.RawData;

import java.io.InputStream;

import java.io.IOException;

public class CoreInputStream extends InputStream

{

  /* A pointer to the object in memory.  */

  protected RawData ptr;

  /* Position of the next byte in core to be read. */

  protected int pos;

  /* The currently marked position in the stream. */

  protected int mark;

  /* The index in core one greater than the last valid character. */

  protected int count;

  private native int unsafeGetByte (long offset);

  private native int copyIntoByteArray (byte[] dest, int offset, int numBytes);

  public CoreInputStream (Core core)

  {

    ptr = core.ptr;

    count = core.length;

  }

  public synchronized int available()

  {

    return count - pos;

  }

  public synchronized void mark(int readAheadLimit)

  {

    // readAheadLimit is ignored per Java Class Lib. book, p.220.

    mark = pos;

  }

  public boolean markSupported()

  {

    return true;

  }

  public synchronized int read()

  {

    if (pos < count)

      return ((int) unsafeGetByte(pos++)) & 0xFF;

    return -1;

  }

  public synchronized int read(byte[] b, int off, int len)

  {

    if (pos >= count)

      return -1;

    int numBytes = Math.min(count - pos, len);

    copyIntoByteArray (b, off, numBytes);

    pos += numBytes;

    return numBytes;

  }

  public synchronized void reset()

  {

    pos = mark;

  }

  public synchronized long skip(long n)

  {

    // Even though the var numBytes is a long, in reality it can never

    // be larger than an int since the result of subtracting 2 positive

    // ints will always fit in an int.  Since we have to return a long

    // anyway, numBytes might as well just be a long.

    long numBytes = Math.min ((long) (count - pos), n < 0 ? 0L : n);

    pos += numBytes;

    return numBytes;

  }

}