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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.SIZE_OF_LONG;
import static ai.vespa.airlift.zstd.UnsafeUtil.UNSAFE;
import static sun.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
class SequenceStore
{
public final byte[] literalsBuffer;
public int literalsLength;
public final int[] offsets;
public final int[] literalLengths;
public final int[] matchLengths;
public int sequenceCount;
public final byte[] literalLengthCodes;
public final byte[] matchLengthCodes;
public final byte[] offsetCodes;
public LongField longLengthField;
public int longLengthPosition;
public enum LongField
{
LITERAL, MATCH
}
private static final byte[] LITERAL_LENGTH_CODE = {0, 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15,
16, 16, 17, 17, 18, 18, 19, 19,
20, 20, 20, 20, 21, 21, 21, 21,
22, 22, 22, 22, 22, 22, 22, 22,
23, 23, 23, 23, 23, 23, 23, 23,
24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24};
private static final byte[] MATCH_LENGTH_CODE = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 36, 36, 37, 37, 37, 37,
38, 38, 38, 38, 38, 38, 38, 38, 39, 39, 39, 39, 39, 39, 39, 39,
40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40,
41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42,
42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42};
public SequenceStore(int blockSize, int maxSequences)
{
offsets = new int[maxSequences];
literalLengths = new int[maxSequences];
matchLengths = new int[maxSequences];
literalLengthCodes = new byte[maxSequences];
matchLengthCodes = new byte[maxSequences];
offsetCodes = new byte[maxSequences];
literalsBuffer = new byte[blockSize];
reset();
}
public void appendLiterals(Object inputBase, long inputAddress, int inputSize)
{
UNSAFE.copyMemory(inputBase, inputAddress, literalsBuffer, ARRAY_BYTE_BASE_OFFSET + literalsLength, inputSize);
literalsLength += inputSize;
}
public void storeSequence(Object literalBase, long literalAddress, int literalLength, int offsetCode, int matchLengthBase)
{
long input = literalAddress;
long output = ARRAY_BYTE_BASE_OFFSET + literalsLength;
int copied = 0;
do {
UNSAFE.putLong(literalsBuffer, output, UNSAFE.getLong(literalBase, input));
input += SIZE_OF_LONG;
output += SIZE_OF_LONG;
copied += SIZE_OF_LONG;
}
while (copied < literalLength);
literalsLength += literalLength;
if (literalLength > 65535) {
longLengthField = LongField.LITERAL;
longLengthPosition = sequenceCount;
}
literalLengths[sequenceCount] = literalLength;
offsets[sequenceCount] = offsetCode + 1;
if (matchLengthBase > 65535) {
longLengthField = LongField.MATCH;
longLengthPosition = sequenceCount;
}
matchLengths[sequenceCount] = matchLengthBase;
sequenceCount++;
}
public void reset()
{
literalsLength = 0;
sequenceCount = 0;
longLengthField = null;
}
public void generateCodes()
{
for (int i = 0; i < sequenceCount; ++i) {
literalLengthCodes[i] = (byte) literalLengthToCode(literalLengths[i]);
offsetCodes[i] = (byte) Util.highestBit(offsets[i]);
matchLengthCodes[i] = (byte) matchLengthToCode(matchLengths[i]);
}
if (longLengthField == LongField.LITERAL) {
literalLengthCodes[longLengthPosition] = Constants.MAX_LITERALS_LENGTH_SYMBOL;
}
if (longLengthField == LongField.MATCH) {
matchLengthCodes[longLengthPosition] = Constants.MAX_MATCH_LENGTH_SYMBOL;
}
}
private static int literalLengthToCode(int literalLength)
{
if (literalLength >= 64) {
return Util.highestBit(literalLength) + 19;
}
else {
return LITERAL_LENGTH_CODE[literalLength];
}
}
/*
* matchLengthBase = matchLength - MINMATCH
* (that's how it's stored in SequenceStore)
*/
private static int matchLengthToCode(int matchLengthBase)
{
if (matchLengthBase >= 128) {
return Util.highestBit(matchLengthBase) + 36;
}
else {
return MATCH_LENGTH_CODE[matchLengthBase];
}
}
}
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