net.jpountz.lz4.LZ4DecompressorWithLength Maven / Gradle / Ivy
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package net.jpountz.lz4;
/*
* 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.
*/
import java.nio.ByteBuffer;
/**
* Convenience class to decompress data compressed by {@link LZ4CompressorWithLength}.
* This decompressor is NOT compatible with any other compressors in lz4-java
* or any other lz4 tools.
* The user does not need to specify the length of the compressed data or
* original data because the length of the original decompressed data is
* included in the compressed data.
*/
public class LZ4DecompressorWithLength {
private final LZ4FastDecompressor decompressor;
/**
* Returns the decompressed length of compressed data in src.
*
* @param src the compressed data
* @return the decompressed length
*/
public static int getDecompressedLength(byte[] src) {
return getDecompressedLength(src, 0);
}
/**
* Returns the decompressed length of compressed data in src[srcOff:].
*
* @param src the compressed data
* @param srcOff the start offset in src
* @return the decompressed length
*/
public static int getDecompressedLength(byte[] src, int srcOff) {
return (src[srcOff] & 0xFF) | (src[srcOff + 1] & 0xFF) << 8 | (src[srcOff + 2] & 0xFF) << 16 | src[srcOff + 3] << 24;
}
/**
* Returns the decompressed length of compressed data in src.
*
* @param src the compressed data
* @return the decompressed length
*/
public static int getDecompressedLength(ByteBuffer src) {
return getDecompressedLength(src, src.position());
}
/**
* Returns the decompressed length of compressed data in src[srcOff:].
*
* @param src the compressed data
* @param srcOff the start offset in src
* @return the decompressed length
*/
public static int getDecompressedLength(ByteBuffer src, int srcOff) {
return (src.get(srcOff) & 0xFF) | (src.get(srcOff + 1) & 0xFF) << 8 | (src.get(srcOff + 2) & 0xFF) << 16 | src.get(srcOff + 3) << 24;
}
/**
* Creates a new decompressor to decompress data compressed by {@link LZ4CompressorWithLength}.
*
* @param decompressor decompressor to use
*/
public LZ4DecompressorWithLength(LZ4FastDecompressor decompressor) {
this.decompressor = decompressor;
}
/**
* Convenience method, equivalent to calling
* {@link #decompress(byte[], int, byte[], int) decompress(src, 0, dest, 0)}.
*
* @param src the compressed data
* @param dest the destination buffer to store the decompressed data
* @return the number of bytes read to restore the original input
*/
public int decompress(byte[] src, byte[] dest) {
return decompress(src, 0, dest, 0);
}
/**
* Decompresses src[srcOff:] into dest[destOff:]
* and returns the number of bytes read from src.
*
* @param src the compressed data
* @param srcOff the start offset in src
* @param dest the destination buffer to store the decompressed data
* @param destOff the start offset in dest
* @return the number of bytes read to restore the original input
*/
public int decompress(byte[] src, int srcOff, byte[] dest, int destOff) {
final int destLen = getDecompressedLength(src, srcOff);
return decompressor.decompress(src, srcOff + 4, dest, destOff, destLen) + 4;
}
/**
* Convenience method, equivalent to calling
* {@link #decompress(byte[], int) decompress(src, 0)}.
*
* @param src the compressed data
* @return the decompressed data
*/
public byte[] decompress(byte[] src) {
return decompress(src, 0);
}
/**
* Convenience method which returns src[srcOff:]
* decompressed.
* Warning: this method has an
* important overhead due to the fact that it needs to allocate a buffer to
* decompress into.
*
* @param src the compressed data
* @param srcOff the start offset in src
* @return the decompressed data
*/
public byte[] decompress(byte[] src, int srcOff) {
final int destLen = getDecompressedLength(src, srcOff);
return decompressor.decompress(src, srcOff + 4, destLen);
}
/**
* Decompresses src into dest. This method moves the positions of the buffers.
*
* @param src the compressed data
* @param dest the destination buffer to store the decompressed data
*/
public void decompress(ByteBuffer src, ByteBuffer dest) {
final int destLen = getDecompressedLength(src, src.position());
final int read = decompressor.decompress(src, src.position() + 4, dest, dest.position(), destLen);
src.position(src.position() + 4 + read);
dest.position(dest.position() + destLen);
}
/** Decompresses src[srcOff:] into dest[destOff:]
* and returns the number of bytes read from src.
* The positions and limits of the {@link ByteBuffer}s remain unchanged.
*
* @param src the compressed data
* @param srcOff the start offset in src
* @param dest the destination buffer to store the decompressed data
* @param destOff the start offset in dest
* @return the number of bytes read to restore the original input
*/
public int decompress(ByteBuffer src, int srcOff, ByteBuffer dest, int destOff) {
final int destLen = getDecompressedLength(src, srcOff);
return decompressor.decompress(src, srcOff + 4, dest, destOff, destLen) + 4;
}
}