/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
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; version 2 of the License.
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 com.bigdata.io;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
/**
* Reads bytes from a {@link ByteBuffer}. This class IS NOT thread-safe.
* Caller's MUST {@link ByteBuffer#duplicate()} the {@link ByteBuffer} before
* creating an instance of this class if they wish to avoid side-effects on the
* position and limit of the original {@link ByteBuffer}.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*
* @todo document that this reads the remaining() bytes and has a side effect on
* the position. if that is not the desired behavior then either modify
* this class or invoke {@link ByteBuffer#asReadOnlyBuffer()} and pass the
* result into the constructor instead.
*
* @todo dsiutils now defines its own implementation of this but does not define
* a ByteBufferOutputStream class. if it did, then we might just use its
* implementations instead.
*/
public class ByteBufferInputStream extends InputStream {
private final ByteBuffer buf;
public ByteBufferInputStream(final ByteBuffer buf) {
if (buf == null)
throw new IllegalArgumentException();
this.buf = buf;
}
/**
* Read the next byte from the buffer.
*
* @return The byte as a value in [0:255].
*/
synchronized
public int read() throws IOException {
if (buf.remaining() == 0) {
return -1;
}
// A byte whose value is in [-128:127].
final byte b = buf.get();
return (0xff & b);
// return ((int) b) + 128;
// int v = ((int)b) + 128;
// assert v>=0 && v<=255;
// return v;
// return b;
}
synchronized
public int read(final byte[] a, final int off, final int len)
throws IOException {
if (len == 0)
return 0;
final int remaining = buf.remaining();
if (remaining == 0)
return -1;
final int readLength = Math.min(remaining, len);
// current limit.
final int climit = buf.limit();
// new limit.
buf.limit(buf.position() + readLength);
// bulk copy.
buf.get(a, off, readLength);
// restore the limit (position was updated as a side effect).
buf.limit(climit);
// #of bytes transferred.
return readLength;
}
}