Package me.lemire.integercompression

Class Simple16

java.lang.Object

me.lemire.integercompression.Simple16

All Implemented Interfaces:

IntegerCODEC, SkippableIntegerCODEC

public final class Simple16
extends Object
implements IntegerCODEC, SkippableIntegerCODEC

This is an implementation of the popular Simple16 scheme. It is limited to 28-bit integers (between 0 and 2^28-1). Note that this does not use differential coding: if you are working on sorted lists, you must compute the deltas separately.

Adapted by D. Lemire from the Apache Lucene project.

Constructor Summary

Constructors

Constructor	Description
Simple16()

Method Summary

Modifier and Type	Method	Description
void	compress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos)	Compress data from an array to another array.
static final int	compressblock(int[] out, int outOffset, int[] in, int inOffset, int n)	Compress an integer array using Simple16
static final int	decompressblock(int[] out, int outOffset, int[] in, int inOffset, int n)	Decompress an integer array using Simple16
void	headlessCompress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos)	Compress data from an array to another array.
void	headlessUncompress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos, int num)	Uncompress data from an array to another array.
String	toString()
static void	uncompress(int[] in, int tmpinpos, int inlength, int[] out, int currentPos, int outlength)	Uncompress data from an array to another array.
void	uncompress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos)	Uncompress data from an array to another array.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

Simple16

public Simple16()

Method Details

headlessCompress

public void headlessCompress(int[] in,
 IntWrapper inpos,
 int inlength,
 int[] out,
 IntWrapper outpos)

Description copied from interface: SkippableIntegerCODEC

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 ints (inlength = 12) are compressed to 3 ints, then inpos will be incremented by 12 while outpos will be incremented by 3. We use IntWrapper to pass the values by reference. Implementation note: contrary to IntegerCODEC.compress(int[], me.lemire.integercompression.IntWrapper, int, int[], me.lemire.integercompression.IntWrapper), this may skip writing information about the number of encoded integers.

Specified by:

headlessCompress in interface SkippableIntegerCODEC

Parameters:

in - input array

inpos - where to start reading in the array

inlength - how many integers to compress

out - output array

outpos - where to write in the output array

compressblock

public static final int compressblock(int[] out,
 int outOffset,
 int[] in,
 int inOffset,
 int n)

Compress an integer array using Simple16

Parameters:

out - the compressed output

outOffset - the offset of the output in the number of integers

in - the integer input array

inOffset - the offset of the input in the number of integers

n - the number of elements to be compressed

Returns:

the number of compressed integers

decompressblock

public static final int decompressblock(int[] out,
 int outOffset,
 int[] in,
 int inOffset,
 int n)

Decompress an integer array using Simple16

Parameters:

out - the decompressed output

outOffset - the offset of the output in the number of integers

in - the compressed input array

inOffset - the offset of the input in the number of integers

n - the number of elements to be compressed

Returns:

the number of processed integers

headlessUncompress

public void headlessUncompress(int[] in,
 IntWrapper inpos,
 int inlength,
 int[] out,
 IntWrapper outpos,
 int num)

Description copied from interface: SkippableIntegerCODEC

Uncompress data from an array to another array. Both inpos and outpos parameters are modified to indicate new positions after read/write.

Specified by:

headlessUncompress in interface SkippableIntegerCODEC

Parameters:

in - array containing data in compressed form

inpos - where to start reading in the array

inlength - length of the compressed data (ignored by some schemes)

out - array where to write the uncompressed output

outpos - where to start writing the uncompressed output in out

num - number of integers we want to decode. May be less than the actual number of compressed integers

uncompress

public static void uncompress(int[] in,
 int tmpinpos,
 int inlength,
 int[] out,
 int currentPos,
 int outlength)

Uncompress data from an array to another array. Both inpos and outpos parameters are modified to indicate new positions after read/write.

Parameters:

in - array containing data in compressed form

tmpinpos - where to start reading in the array

inlength - length of the compressed data (ignored by some schemes)

out - array where to write the compressed output

currentPos - where to write the compressed output in out

outlength - number of integers we want to decode

compress

public void compress(int[] in,
 IntWrapper inpos,
 int inlength,
 int[] out,
 IntWrapper outpos)

Description copied from interface: IntegerCODEC

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 ints (inlength = 12) are compressed to 3 ints, then inpos will be incremented by 12 while outpos will be incremented by 3. We use IntWrapper to pass the values by reference.

Specified by:

compress in interface IntegerCODEC

Parameters:

in - input array

inpos - where to start reading in the array

inlength - how many integers to compress

out - output array

outpos - where to write in the output array

uncompress

public void uncompress(int[] in,
 IntWrapper inpos,
 int inlength,
 int[] out,
 IntWrapper outpos)

Description copied from interface: IntegerCODEC

Uncompress data from an array to another array. Both inpos and outpos parameters are modified to indicate new positions after read/write.

Specified by:

uncompress in interface IntegerCODEC

Parameters:

in - array containing data in compressed form

inpos - where to start reading in the array

inlength - length of the compressed data (ignored by some schemes)

out - array where to write the compressed output

outpos - where to start writing the uncompressed output in out

toString

public String toString()

Overrides:

toString in class Object