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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;

import static ai.vespa.airlift.zstd.Constants.MAX_BLOCK_SIZE;

class CompressionContext
{
    public final RepeatedOffsets offsets = new RepeatedOffsets();
    public final BlockCompressionState blockCompressionState;
    public final SequenceStore sequenceStore;

    public final SequenceEncodingContext sequenceEncodingContext = new SequenceEncodingContext();

    public final HuffmanCompressionContext huffmanContext = new HuffmanCompressionContext();

    public CompressionContext(CompressionParameters parameters, long baseAddress, int inputSize)
    {
        int windowSize = Math.max(1, Math.min(1 << parameters.getWindowLog(), inputSize));
        int blockSize = Math.min(MAX_BLOCK_SIZE, windowSize);
        int divider = (parameters.getSearchLength() == 3) ? 3 : 4;

        int maxSequences = blockSize / divider;

        sequenceStore = new SequenceStore(blockSize, maxSequences);

        blockCompressionState = new BlockCompressionState(parameters, baseAddress);
    }

    public void commit()
    {
        offsets.commit();
        huffmanContext.saveChanges();
    }
}