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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 *  (C) Copyright IBM Corp. 1999 All Rights Reserved.
 *  Copyright 1997 The Open Group Research Institute.  All rights reserved.
 */
// crc32.java

package sun.security.krb5.internal.crypto;

import java.security.MessageDigestSpi;
import java.security.DigestException;

public final class crc32 extends MessageDigestSpi implements Cloneable {
    private static final int CRC32_LENGTH = 4; //32-bit
    private int seed;
    private static boolean DEBUG = sun.security.krb5.internal.Krb5.DEBUG;
    // buffer;
    // private int bufferIndex, bufferLeft;

    public crc32() {
        init();
    }

    public Object clone() {
        try {
            crc32 crc = (crc32)super.clone();
            crc.init();
            return crc;
        }
        catch (CloneNotSupportedException e) {
        }
        return null;
    }

    /**
     * Return the digest length in bytes
     */
    protected int engineGetDigestLength() {
        return (CRC32_LENGTH);
    }

    /**
     */
    protected byte[] engineDigest() {
        byte[] result = new byte[CRC32_LENGTH];
        result = int2quad(seed);
        //processBuffer(buffer, 0, bufferIndex, result, 0);
        init();
        return result;
    }

    /**
     */
    protected int engineDigest(byte[] buf, int offset, int len) throws DigestException {
        byte[] result = new byte[CRC32_LENGTH];
        result = int2quad(seed);
        if (len < CRC32_LENGTH) {
            throw new DigestException("partial digests not returned");
        }
        if (buf.length - offset < CRC32_LENGTH) {
            throw new DigestException("insufficient space in the output " +
                                      "buffer to store the digest");
        }
        System.arraycopy(result, 0, buf, offset, CRC32_LENGTH);
        //processBuffer(buffer, 0, bufferIndex, result, 0);
        /*if (len < CRC32_LENGTH) {
          throw new DigestException("partial digests not returned");
          }
          if (buf.length - offset < CRC32_LENGTH) {
          throw new DigestException("insufficient space in the output " +
          "buffer to store the digest");
          }
          System.arraycopy(result, 0, buf, offset, CRC32_LENGTH);      */
        init();
        return CRC32_LENGTH;
    }
    /**
     * Update adds the passed byte to the digested data.
     */
    protected synchronized void engineUpdate(byte b) {
        byte[] input = new byte[1];
        input[0] = b;
        //engineUpdate(input, 0, 1);
        engineUpdate(input, seed, 1);
    }

    /**
     * Update adds the selected part of an array of bytes to the digest.
     * This version is more efficient than the byte-at-a-time version;
     * it avoids data copies and reduces per-byte call overhead.
     */
    protected synchronized void engineUpdate(byte input[], int offset,
                                             int len) {
        processData(input, offset, len);
    }
    private static int[] crc32Table = {
        0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
        0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
        0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
        0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
        0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
        0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
        0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
        0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
        0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
        0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
        0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
        0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
        0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
        0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
        0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
        0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
        0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
        0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
        0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
        0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
        0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
        0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
        0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
        0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
        0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
        0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
        0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
        0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
        0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
        0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
        0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
        0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
        0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
        0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
        0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
        0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
        0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
        0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
        0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
        0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
        0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
        0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
        0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
        0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
        0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
        0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
        0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
        0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
        0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
        0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
        0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
        0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
        0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
        0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
        0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
        0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
        0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
        0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
        0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
        0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
        0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
        0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
        0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
        0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
    };

    protected void engineReset() {
        init();
    }

    /**
     * Initialize the CRC32 information
     */
    public void init() {
        seed = 0;
    }

    private void processData(byte[] data, int off, int len) {
        int result = seed;
        for (int i = 0; i < len; i++)
            result = (result >>> 8) ^ crc32Table[(result ^ data[i]) & 0xff];
        seed = result;
    }

    public static int int2crc32(int b) {
        int crc = b;

        for (int i = 8; i > 0; i--) {
            if ((crc & 1) != 0)
                crc = (crc >>> 1) ^ 0xedb88320;
            else
                crc = crc >>> 1;
        }
        return crc;
    }

    public static void printcrc32Table() {
        String temp;
        String zerofill = "00000000";

        System.out.print("\tpublic static int[] crc32Table = {");
        for (int i = 0; i < 256; i++) {
            if ((i % 4) == 0)
                System.out.print("\n\t\t");
            temp = Integer.toHexString(int2crc32(i));
            System.out.print("0x" +
                             zerofill.substring(temp.length()) + temp);
            if (i !=  255)
                System.out.print(", ");
        }
        System.out.println("\n\t};");
    }

    public static int byte2crc32sum(int seed, byte[] data, int size) {
        int crc = seed;

        for (int i = 0; i < size; i++)
            crc = (crc >>> 8) ^ crc32Table[(crc ^ data[i]) & 0xff];
        return crc;
    }

    public static int byte2crc32sum(int seed, byte[] data) {
        return byte2crc32sum(seed, data, data.length);
    }


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