Re: Bidi reordering test results

From: Mark Leisher (
Date: Sat Dec 04 1999 - 10:53:19 EST

I am including all of the message for those who might not be on the Unicode

    Asmus> At 10:08 AM 12/3/99 -0800, Mark Leisher wrote:
>> I have a web page showing the results from tests of two (soon to be
>> three) freely available bidi reordering packages for Unicode text. The
>> text I used for the tests as well as the test programs I wrote for all
>> three are
>> available as well:
>> Please feel free to donate additional tests/code, point out problems,
>> or make comments.

    Asmus> The really interesting question is how do these algorithms compare
    Asmus> with the official bidi reference implementations published by the
    Asmus> Unicode Consortium.

    Asmus> The Unicode sample code is availabe at


    Asmus> The Technical report states:

    Asmus> 1 Reference Code

    Asmus> There are two versions of BIDI reference code available. Both have
    Asmus> been tested to produce identical results. One version is written in
    Asmus> Java, while the other is written in C++. The Java version is
    Asmus> designed to closely follow the steps of the algorithm as described
    Asmus> in this report. The C++ code is designed to show one of the
    Asmus> optimization methods that can be applied to the algorithm, using a
    Asmus> state table for one phase.

    Asmus> It is very important to note that any implementations that don't
    Asmus> match the published algorithm, as evidenced by yielding different
    Asmus> results than the reference implementations, are *not conformant*.

    Asmus> Since the whole purpose of the bidi algorithm is to allow *writers*
    Asmus> to predict the ordering of their text on the *readers'* screen,
    Asmus> adherence to the conformance requirements is crucial.

    Asmus> The published reference implementations were tested exhaustively up
    Asmus> to sequences of length 6 against each other, and stochastically for
    Asmus> much longer sequences, with special prefixes used to force the
    Asmus> implemenations to hit the maximum nesting level during some portion
    Asmus> of the tests.

    Asmus> I would encourage Mark to test his algorithms exhaustively against
    Asmus> the reference code and report his results here.

    Asmus> For more details on bidi and the conformance requirements read the
    Asmus> report at:


Asmus is quite right. I have used the code he pointed out to add a column of
reference results to
Mark Leisher
Computing Research Lab I have never made but one prayer to God,
New Mexico State University a very short one:
Box 30001, Dept. 3CRL "Oh Lord, make my enemies ridiculous."
Las Cruces, NM 88003 And God granted it. -- Voltaire, letter

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