/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
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/* vim:set softtabstop=3 shiftwidth=3 tabstop=3 expandtab tw=72:
$Id: RollingChecksum.java,v 1.8 2003/05/17 09:48:58 rsdio Exp $
RollingChecksum: interface to a "rolling" checksum.
Copyright (C) 2003 Casey Marshall <rsdio@metastatic.org>
Copyright (C) 2011 Tomas Hlavnicka <hlavntom@fel.cvut.cz>
This file is a part of Jarsync.
Jarsync 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 of the License, or (at
your option) any later version.
Jarsync 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 Jarsync; if not, write to the
Free Software Foundation, Inc.,
59 Temple Place, Suite 330,
Boston, MA 02111-1307
USA
Linking Jarsync statically or dynamically with other modules is
making a combined work based on Jarsync. Thus, the terms and
conditions of the GNU General Public License cover the whole
combination. */
package io.milton.zsync;
/**
* A general interface for 32-bit checksums that have the "rolling"
* property.
*
* @author Casey Marshall
* @version $Revision: 1.8 $
*/
public interface RollingChecksum extends Cloneable, java.io.Serializable {
// Methods.
// -----------------------------------------------------------------------
/**
* Returns the currently-computed 32-bit checksum.
*
* @return The checksum.
*/
int getValue();
/**
* Resets the internal state of the checksum, so it may be re-used
* later.
*/
void reset();
/**
* Update the checksum with a single byte. This is where the
* "rolling" method is used.
*
* @param b The next byte.
*/
void roll(byte b);
/**
* Replaces the current internal state with entirely new data.
*
* @param buf The bytes to checksum.
* @param offset The offset into <code>buf</code> to start reading.
* @param length The number of bytes to update.
*/
void check(byte[] buf, int offset, int length);
/**
* Replaces the current internal state with entirely new data.
* This method is only used to initialize rolling checksum.
*
* @param buf The bytes to checksum.
* @param offset The offset into <code>buf</code> to start reading.
* @param length The number of bytes to update.
*/
void first(byte[] buf, int offset, int length);
/**
* Copies this checksum instance into a new instance. This method
* should be optional, and only implemented if the class implements
* the {@link java.lang.Cloneable} interface.
*
* @return A clone of this instance.
*/
Object clone();
/**
* Tests if a particular checksum is equal to this checksum. This
* means that the other object is an instance of this class, and its
* internal state equals this checksum's internal state.
*
* @param o The object to test.
* @return <code>true</code> if this checksum equals the other
* checksum.
*/
boolean equals(Object o);
}