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/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.airlift.compress.bzip2;

// forked from Apache Hadoop
final class Crc32
{
    private static final int[] CRC_32_TABLE = {0x00000000, 0x04c11db7, 0x09823b6e,
            0x0d4326d9, 0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
            0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61, 0x350c9b64,
            0x31cd86d3, 0x3c8ea00a, 0x384fbdbd, 0x4c11db70, 0x48d0c6c7,
            0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2,
            0x52568b75, 0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
            0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd, 0x9823b6e0,
            0x9ce2ab57, 0x91a18d8e, 0x95609039, 0x8b27c03c, 0x8fe6dd8b,
            0x82a5fb52, 0x8664e6e5, 0xbe2b5b58, 0xbaea46ef, 0xb7a96036,
            0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
            0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c,
            0xc3f706fb, 0xceb42022, 0xca753d95, 0xf23a8028, 0xf6fb9d9f,
            0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a,
            0xec7dd02d, 0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
            0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072, 0x128e9dcf,
            0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4,
            0x0808d07d, 0x0cc9cdca, 0x7897ab07, 0x7c56b6b0, 0x71159069,
            0x75d48dde, 0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
            0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066, 0x4d9b3063,
            0x495a2dd4, 0x44190b0d, 0x40d816ba, 0xaca5c697, 0xa864db20,
            0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc, 0xb6238b25,
            0xb2e29692, 0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
            0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a, 0xe0b41de7,
            0xe4750050, 0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c,
            0xfa325055, 0xfef34de2, 0xc6bcf05f, 0xc27dede8, 0xcf3ecb31,
            0xcbffd686, 0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
            0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637, 0x7a089632,
            0x7ec98b85, 0x738aad5c, 0x774bb0eb, 0x4f040d56, 0x4bc510e1,
            0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4,
            0x51435d53, 0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
            0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b, 0x0315d626,
            0x07d4cb91, 0x0a97ed48, 0x0e56f0ff, 0x1011a0fa, 0x14d0bd4d,
            0x19939b94, 0x1d528623, 0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60,
            0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
            0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a,
            0xc0e2d0dd, 0xcda1f604, 0xc960ebb3, 0xbd3e8d7e, 0xb9ff90c9,
            0xb4bcb610, 0xb07daba7, 0xae3afba2, 0xaafbe615, 0xa7b8c0cc,
            0xa379dd7b, 0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
            0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3, 0x5d8a9099,
            0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2,
            0x470cdd2b, 0x43cdc09c, 0x7b827d21, 0x7f436096, 0x7200464f,
            0x76c15bf8, 0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
            0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30, 0x029f3d35,
            0x065e2082, 0x0b1d065b, 0x0fdc1bec, 0x3793a651, 0x3352bbe6,
            0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a, 0x2d15ebe3,
            0x29d4f654, 0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
            0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c, 0xe3a1cbc1,
            0xe760d676, 0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa,
            0xf9278673, 0xfde69bc4, 0x89b8fd09, 0x8d79e0be, 0x803ac667,
            0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
            0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668, 0xbcb4666d,
            0xb8757bda, 0xb5365d03, 0xb1f740b4};

    private int globalCrc;

    Crc32()
    {
        initialiseCRC();
    }

    void initialiseCRC()
    {
        globalCrc = 0xffffffff;
    }

    int getFinalCRC()
    {
        return ~globalCrc;
    }

    void updateCRC(int value)
    {
        int temp = (globalCrc >> 24) ^ value;
        if (temp < 0) {
            temp = 256 + temp;
        }
        globalCrc = (globalCrc << 8) ^ CRC_32_TABLE[temp];
    }

    void updateCRC(int value, int repeat)
    {
        int globalCrcShadow = this.globalCrc;
        while (repeat-- > 0) {
            int temp = (globalCrcShadow >> 24) ^ value;
            globalCrcShadow = (globalCrcShadow << 8) ^ CRC_32_TABLE[(temp >= 0) ? temp : (temp + 256)];
        }
        this.globalCrc = globalCrcShadow;
    }
}