Class LZEncoder

java.lang.Object
org.graalvm.shadowed.org.tukaani.xz.lz.LZEncoder
public abstract class LZEncoder extends Object

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    MF_BT4
     
    static final int
    MF_HC4
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    copyUncompressed(OutputStream out, int backward, int len)
     
    int
    fillWindow(byte[] in, int off, int len)
    Copies new data into the LZEncoder's buffer.
    int
    getAvail()
    Get the number of bytes available, including the current byte.
    int
    getByte(int backward)
    Gets the byte from the given backward offset.
    int
    getByte(int forward, int backward)
    Gets the byte from the given forward minus backward offset.
    static LZEncoder
    getInstance(int dictSize, int extraSizeBefore, int extraSizeAfter, int niceLen, int matchLenMax, int mf, int depthLimit, ArrayCache arrayCache)
    Creates a new LZEncoder.
    abstract Matches
    getMatches()
    Runs match finder for the next byte and returns the matches found.
    int
    getMatchLen(int dist, int lenLimit)
    Get the length of a match at the given distance.
    int
    getMatchLen(int forward, int dist, int lenLimit)
    Get the length of a match at the given distance and forward offset.
    static int
    getMemoryUsage(int dictSize, int extraSizeBefore, int extraSizeAfter, int matchLenMax, int mf)
    Gets approximate memory usage of the LZEncoder base structure and the match finder as kibibytes.
    int
    getPos()
    Gets the lowest four bits of the absolute offset of the current byte.
    boolean
    hasEnoughData(int alreadyReadLen)
    Tests if there is enough input available to let the caller encode at least one more byte.
    boolean
    isStarted()
    Returns true if at least one byte has already been run through the match finder.
    void
    putArraysToCache(ArrayCache arrayCache)
     
    void
    setFinishing()
    Marks that there is no more input remaining.
    void
    setFlushing()
    Marks that all the input needs to be made available in the encoded output.
    void
    setPresetDict(int dictSize, byte[] presetDict)
    Sets a preset dictionary.
    abstract void
    skip(int len)
    Skips the given number of bytes in the match finder.
    boolean
    verifyMatches(Matches matches)
    Verifies that the matches returned by the match finder are valid.

    Methods inherited from class java.lang.Object

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

  • Field Details

  • Method Details

    • getMemoryUsage

      public static int getMemoryUsage(int dictSize, int extraSizeBefore, int extraSizeAfter, int matchLenMax, int mf)
      Gets approximate memory usage of the LZEncoder base structure and the match finder as kibibytes.

    • getInstance

      public static LZEncoder getInstance(int dictSize, int extraSizeBefore, int extraSizeAfter, int niceLen, int matchLenMax, int mf, int depthLimit, ArrayCache arrayCache)
      Creates a new LZEncoder.

      Parameters:
      dictSize - dictionary size
      extraSizeBefore - number of bytes to keep available in the history in addition to dictSize
      extraSizeAfter - number of bytes that must be available after current position + matchLenMax
      niceLen - if a match of at least niceLen bytes is found, be happy with it and stop looking for longer matches
      matchLenMax - don't test for matches longer than matchLenMax bytes
      mf - match finder ID
      depthLimit - match finder search depth limit

    • putArraysToCache

      public void putArraysToCache(ArrayCache arrayCache)

    • setPresetDict

      public void setPresetDict(int dictSize, byte[] presetDict)
      Sets a preset dictionary. If a preset dictionary is wanted, this function must be called immediately after creating the LZEncoder before any data has been encoded.

    • fillWindow

      public int fillWindow(byte[] in, int off, int len)
      Copies new data into the LZEncoder's buffer.

    • isStarted

      public boolean isStarted()
      Returns true if at least one byte has already been run through the match finder.

    • setFlushing

      public void setFlushing()
      Marks that all the input needs to be made available in the encoded output.

    • setFinishing

      public void setFinishing()
      Marks that there is no more input remaining. The read position can be advanced until the end of the data.

    • hasEnoughData

      public boolean hasEnoughData(int alreadyReadLen)
      Tests if there is enough input available to let the caller encode at least one more byte.

    • copyUncompressed

      public void copyUncompressed(OutputStream out, int backward, int len) throws IOException
      Throws:
      IOException

    • getAvail

      public int getAvail()
      Get the number of bytes available, including the current byte.

      Note that the result is undefined if getMatches or skip hasn't been called yet and no preset dictionary is being used.

    • getPos

      public int getPos()
      Gets the lowest four bits of the absolute offset of the current byte. Bits other than the lowest four are undefined.

    • getByte

      public int getByte(int backward)
      Gets the byte from the given backward offset.

      The current byte is at 0, the previous byte at 1 etc. To get a byte at zero-based distance, use getByte(dist + 1).

      This function is equivalent to getByte(0, backward).

    • getByte

      public int getByte(int forward, int backward)
      Gets the byte from the given forward minus backward offset. The forward offset is added to the current position. This lets one read bytes ahead of the current byte.

    • getMatchLen

      public int getMatchLen(int dist, int lenLimit)
      Get the length of a match at the given distance.
      Parameters:
      dist - zero-based distance of the match to test
      lenLimit - don't test for a match longer than this
      Returns:
      length of the match; it is in the range [0, lenLimit]

    • getMatchLen

      public int getMatchLen(int forward, int dist, int lenLimit)
      Get the length of a match at the given distance and forward offset.
      Parameters:
      forward - forward offset
      dist - zero-based distance of the match to test
      lenLimit - don't test for a match longer than this
      Returns:
      length of the match; it is in the range [0, lenLimit]

    • verifyMatches

      public boolean verifyMatches(Matches matches)
      Verifies that the matches returned by the match finder are valid. This is meant to be used in an assert statement. This is totally useless for actual encoding since match finder's results should naturally always be valid if it isn't broken.
      Parameters:
      matches - return value from getMatches
      Returns:
      true if matches are valid, false if match finder is broken

    • getMatches

      public abstract Matches getMatches()
      Runs match finder for the next byte and returns the matches found.

    • skip

      public abstract void skip(int len)
      Skips the given number of bytes in the match finder.