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SkippableLongCODEC.java
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SkippableLongCODEC.java
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/**
* This is code is released under the
* Apache License Version 2.0 http://www.apache.org/licenses/.
*
* (c) Daniel Lemire, http://lemire.me/en/
*/
package me.lemire.longcompression;
import me.lemire.integercompression.IntWrapper;
/**
* Interface describing a standard CODEC to compress longs. This is a
* variation on the LongCODEC interface meant to be used for random access
* (i.e., given a large array, you can segment it and decode just the subarray you need).
*
* The main difference is that we must specify the number of longs we wish to
* decode. This information should be stored elsewhere.
*
* This interface was designed by the Terrier team for their search engine.
*
* @author Benoit Lacelle
*
*/
public interface SkippableLongCODEC {
/**
* Compress data from an array to another array.
*
* Both inpos and outpos are modified to represent how much data was read
* and written to. If 12 longs (inlength = 12) are compressed to 3 longs, then
* inpos will be incremented by 12 while outpos will be incremented by 3. We
* use IntWrapper to pass the values by reference.
*
* @param in
* input array
* @param inpos
* where to start reading in the array
* @param inlength
* how many longs to compress
* @param out
* output array
* @param outpos
* where to write in the output array
*/
public void headlessCompress(long[] in, IntWrapper inpos, int inlength, long[] out,
IntWrapper outpos);
/**
* Uncompress data from an array to another array.
*
* Both inpos and outpos parameters are modified to indicate new positions
* after read/write.
*
* @param in
* array containing data in compressed form
* @param inpos
* where to start reading in the array
* @param inlength
* length of the compressed data (ignored by some schemes)
* @param out
* array where to write the uncompressed output
* @param outpos
* where to start writing the uncompressed output in out
* @param num
* number of longs we want to decode, the actual number of longs decoded can be less
*/
public void headlessUncompress(long[] in, IntWrapper inpos, int inlength, long[] out,
IntWrapper outpos, int num);
}