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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., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 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: }