org.elasticsearch.lz4.LZ4Constants Maven / Gradle / Ivy

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/*
 * @notice
 *
 * Copyright 2020 Adrien Grand and the lz4-java contributors.
 *
 * 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 org.elasticsearch.lz4;

/**
 * This file is forked from https://github.com/lz4/lz4-java. In particular, it forks the following file
 * net.jpountz.lz4.LZ4Constants.
 *
 * There are no modifications. It is copied to this package for reuse as the original implementation is
 * package private.
 */
enum LZ4Constants {
    ;

    static final int DEFAULT_COMPRESSION_LEVEL = 8 + 1;
    static final int MAX_COMPRESSION_LEVEL = 16 + 1;

    static final int MEMORY_USAGE = 14;
    static final int NOT_COMPRESSIBLE_DETECTION_LEVEL = 6;

    static final int MIN_MATCH = 4;

    static final int HASH_LOG = MEMORY_USAGE - 2;
    static final int HASH_TABLE_SIZE = 1 << HASH_LOG;

    static final int SKIP_STRENGTH = Math.max(NOT_COMPRESSIBLE_DETECTION_LEVEL, 2);
    static final int COPY_LENGTH = 8;
    static final int LAST_LITERALS = 5;
    static final int MF_LIMIT = COPY_LENGTH + MIN_MATCH;
    static final int MIN_LENGTH = MF_LIMIT + 1;

    static final int MAX_DISTANCE = 1 << 16;

    static final int ML_BITS = 4;
    static final int ML_MASK = (1 << ML_BITS) - 1;
    static final int RUN_BITS = 8 - ML_BITS;
    static final int RUN_MASK = (1 << RUN_BITS) - 1;

    static final int LZ4_64K_LIMIT = (1 << 16) + (MF_LIMIT - 1);
    static final int HASH_LOG_64K = HASH_LOG + 1;
    static final int HASH_TABLE_SIZE_64K = 1 << HASH_LOG_64K;

    static final int HASH_LOG_HC = 15;
    static final int HASH_TABLE_SIZE_HC = 1 << HASH_LOG_HC;
    static final int OPTIMAL_ML = ML_MASK - 1 + MIN_MATCH;
}