libjava/java/util/zip/Checksum.java

   1 /* Checksum.java - Interface to compute a data checksum
   2    Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package java.util.zip;
  39
  40 /*
  41  * Written using on-line Java Platform 1.2 API Specification, as well
  42  * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
  43  * Status:  Believed complete and correct.
  44  */
  45
  46 /**
  47  * Interface to compute a data checksum used by checked input/output streams.
  48  * A data checksum can be updated by one byte or with a byte array. After each
  49  * update the value of the current checksum can be returned by calling
  50  * <code>getValue</code>. The complete checksum object can also be reset
  51  * so it can be used again with new data.
  52  *
  53  * @see CheckedInputStream
  54  * @see CheckedOutputStream
  55  *
  56  * @author Per Bothner
  57  * @author Jochen Hoenicke
  58  */
  59 public interface Checksum
  60 {
  61   /**
  62    * Returns the data checksum computed so far.
  63    */
  64   long getValue();
  65
  66   /**
  67    * Resets the data checksum as if no update was ever called.
  68    */
  69   void reset();
  70
  71   /**
  72    * Adds one byte to the data checksum.
  73    *
  74    * @param bval the data value to add. The high byte of the int is ignored.
  75    */
  76   void update (int bval);
  77
  78   /**
  79    * Adds the byte array to the data checksum.
  80    *
  81    * @param buf the buffer which contains the data
  82    * @param off the offset in the buffer where the data starts
  83    * @param len the length of the data
  84    */
  85   void update (byte[] buf, int off, int len);
  86 }