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Thread: The worst case for LZTurbo?

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    Member m^2's Avatar
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    The worst case for LZTurbo?

    While testing how programs perform on a stripped Quake found something interesting...

    "LZTurbo -11" 1227415 0.156
    "LZTurbo -12" 1216635 9.750
    "LZTurbo -13" 1182871 13.641
    "LZTurbo -14" 1164885 27.734
    "LZTurbo -15" 1155096 54.937
    "LZTurbo -16" 1149690 109.625
    "LZTurbo -17" 1146899 209.860
    "LZTurbo -18" 1145159 847.688

    Then I interrupted the compression process. It turned out that the problem is wqpro.exe.
    Any idea why is it a problem? It's just a single 560KB file...
    No other compressor I tested had issues.
    Attached Files Attached Files

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    On older forum,Bulat has proposed that it's "naive binary tree implementation". You can search old forum, but you'll mostly find discussion on GPL violation.

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    Programmer Bulat Ziganshin's Avatar
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    at least cabarc had the same problem on pdf file in some (calgary?) corpus used in ACT. the problem is that with data like this:

    00001
    00002
    00003
    00004
    00005

    you binary tree becomes a list,a ctually. and snce you don't cutoff long searches, speed becomes o(n^2)

    ps: try cabarc on this file

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    Member m^2's Avatar
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    Quote Originally Posted by Bulat Ziganshin View Post
    at least cabarc had the same problem on pdf file in some (calgary?) corpus used in ACT. the problem is that with data like this:

    00001
    00002
    00003
    00004
    00005

    you binary tree becomes a list,a ctually. and snce you don't cutoff long searches, speed becomes o(n^2)

    ps: try cabarc on this file
    I tried like 40 compressors with all supported switches already, cabarc too.
    Only LZTurbo has problems.

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    Programmer Bulat Ziganshin's Avatar
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    if you interested, tru to break file in two parts and then repeat this recursively. at the last end you may find rather small part which makes the problem

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    Member m^2's Avatar
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    This is something strange. Can anybody try the attached file?
    Attached Files Attached Files

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    A new version (0.94) has been released...

    http://lzturbo.web.officelive.com/documents/lzturbo.zip

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    Thanks LovePimple!

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    Hi Bulat!

    Great job for you! Thanks!

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