Module me.lemire.integercompression
Package me.lemire.integercompression.differential

Class SkippableIntegratedComposition

java.lang.Object
me.lemire.integercompression.differential.SkippableIntegratedComposition
All Implemented Interfaces:
SkippableIntegratedIntegerCODEC
public class SkippableIntegratedComposition extends Object implements SkippableIntegratedIntegerCODEC
Helper class to compose schemes.
Author:
Daniel Lemire

  • Constructor Details

    • SkippableIntegratedComposition

      public SkippableIntegratedComposition(SkippableIntegratedIntegerCODEC f1, SkippableIntegratedIntegerCODEC f2)
      Compose a scheme from a first one (f1) and a second one (f2). The first one is called first and then the second one tries to compress whatever remains from the first run. By convention, the first scheme should be such that if, during decoding, a 32-bit zero is first encountered, then there is no output.
      Parameters:
      f1 - first codec
      f2 - second codec

  • Method Details

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • headlessCompress

      public void headlessCompress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos, IntWrapper initvalue)
      Description copied from interface: SkippableIntegratedIntegerCODEC
      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:
      headlessCompress in interface SkippableIntegratedIntegerCODEC
      Parameters:
      in - input array
      inpos - location in the input array
      inlength - how many integers to compress
      out - output array
      outpos - where to write in the output array
      initvalue - initial value for the purpose of differential coding, the value is automatically updated

    • headlessUncompress

      public void headlessUncompress(int[] in, IntWrapper inpos, int inlength, int[] out, IntWrapper outpos, int num, IntWrapper initvalue)
      Description copied from interface: SkippableIntegratedIntegerCODEC
      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 SkippableIntegratedIntegerCODEC
      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 write the compressed output in out
      num - number of integers we want to decode, the actual number of integers decoded can be less
      initvalue - initial value for the purpose of differential coding, the value is automatically updated

    • maxHeadlessCompressedLength

      public int maxHeadlessCompressedLength(IntWrapper compressedPositions, int inlength)
      Description copied from interface: SkippableIntegratedIntegerCODEC
      Compute the maximum number of integers that might be required to store the compressed form of a given input array segment, without headers.

      This is useful to pre-allocate the output buffer before calling SkippableIntegratedIntegerCODEC.headlessCompress(int[], IntWrapper, int, int[], IntWrapper, IntWrapper).

      Specified by:
      maxHeadlessCompressedLength in interface SkippableIntegratedIntegerCODEC
      Parameters:
      compressedPositions - since not all schemes compress every input integer, this parameter returns how many input integers will actually be compressed. This is useful when composing multiple schemes.
      inlength - number of integers to be compressed
      Returns:
      the maximum number of integers needed in the output array