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Fork of https://github.com/airlift/aircompressor (zstd only). This module is temporary until we get an official release that includes the ZstdInputStream API (which is already implemented by two different people but neither PR shows any progress).

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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 ai.vespa.airlift.zstd;

class Constants
{
    public static final int SIZE_OF_BYTE = 1;
    public static final int SIZE_OF_SHORT = 2;
    public static final int SIZE_OF_INT = 4;
    public static final int SIZE_OF_LONG = 8;

    public static final int MAGIC_NUMBER = 0xFD2FB528;
    public static final int MAGIC_SKIPFRAME_MIN = 0x184D2A50;
    public static final int MAGIC_SKIPFRAME_MAX = 0x184D2A5F;

    public static final int MIN_WINDOW_LOG = 10;
    public static final int MAX_WINDOW_LOG = 31;

    public static final int SIZE_OF_BLOCK_HEADER = 3;

    public static final int MIN_SEQUENCES_SIZE = 1;
    public static final int MIN_BLOCK_SIZE = 1 // block type tag
            + 1 // min size of raw or rle length header
            + MIN_SEQUENCES_SIZE;
    public static final int MAX_BLOCK_SIZE = 128 * 1024;

    public static final int REPEATED_OFFSET_COUNT = 3;

    // block types
    public static final int RAW_BLOCK = 0;
    public static final int RLE_BLOCK = 1;
    public static final int COMPRESSED_BLOCK = 2;

    // sequence encoding types
    public static final int SEQUENCE_ENCODING_BASIC = 0;
    public static final int SEQUENCE_ENCODING_RLE = 1;
    public static final int SEQUENCE_ENCODING_COMPRESSED = 2;
    public static final int SEQUENCE_ENCODING_REPEAT = 3;

    public static final int MAX_LITERALS_LENGTH_SYMBOL = 35;
    public static final int MAX_MATCH_LENGTH_SYMBOL = 52;
    public static final int MAX_OFFSET_CODE_SYMBOL = 31;
    public static final int DEFAULT_MAX_OFFSET_CODE_SYMBOL = 28;

    public static final int LITERAL_LENGTH_TABLE_LOG = 9;
    public static final int MATCH_LENGTH_TABLE_LOG = 9;
    public static final int OFFSET_TABLE_LOG = 8;

    // literal block types
    public static final int RAW_LITERALS_BLOCK = 0;
    public static final int RLE_LITERALS_BLOCK = 1;
    public static final int COMPRESSED_LITERALS_BLOCK = 2;
    public static final int TREELESS_LITERALS_BLOCK = 3;

    public static final int LONG_NUMBER_OF_SEQUENCES = 0x7F00;

    public static final int[] LITERALS_LENGTH_BITS = {0, 0, 0, 0, 0, 0, 0, 0,
                                                      0, 0, 0, 0, 0, 0, 0, 0,
                                                      1, 1, 1, 1, 2, 2, 3, 3,
                                                      4, 6, 7, 8, 9, 10, 11, 12,
                                                      13, 14, 15, 16};

    public static final int[] MATCH_LENGTH_BITS = {0, 0, 0, 0, 0, 0, 0, 0,
                                                   0, 0, 0, 0, 0, 0, 0, 0,
                                                   0, 0, 0, 0, 0, 0, 0, 0,
                                                   0, 0, 0, 0, 0, 0, 0, 0,
                                                   1, 1, 1, 1, 2, 2, 3, 3,
                                                   4, 4, 5, 7, 8, 9, 10, 11,
                                                   12, 13, 14, 15, 16};

    private Constants()
    {
    }
}