/*

 * 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);

    }

    //sum from zero, i.e., no pre- or post-conditioning

    public static int byte2crc32sum(byte[] data) {

        return byte2crc32sum(0, data);

    }

    //CCITT ITU-T 3309 CRC-32 w/ standard pre- and post-conditioning

    public static int byte2crc32(byte[] data) {

        return ~byte2crc32sum(0xffffffff, data);

    }

    public static byte[] byte2crc32sum_bytes(byte[] data) {

        int temp = byte2crc32sum(data);

        return int2quad(temp);

    }

    public static byte[] byte2crc32sum_bytes(byte[] data, int size) {

        int temp = byte2crc32sum(0, data, size);

        if (DEBUG) {

            System.out.println(">>>crc32: " + Integer.toHexString(temp));

            System.out.println(">>>crc32: " + Integer.toBinaryString(temp));

        }

        return int2quad(temp);

    }

    public static byte[] int2quad(long input) {

        byte[] output = new byte[4];

        for (int i = 0; i < 4; i++) {

            output[i] = (byte)((input >>> (i * 8)) & 0xff);

        }

        return output;

    }

}