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 */ getValue()64 long getValue(); 65 66 /** 67 * Resets the data checksum as if no update was ever called. 68 */ reset()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 */ update(int bval)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 */ update(byte[] buf, int off, int len)85 void update (byte[] buf, int off, int len); 86 } 87