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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Ann: Natools.Chunked_Strings, beta 1
Date: Fri, 2 Dec 2011 14:11:19 +0100
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Date: 2011-12-02T14:11:19+01:00
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On Fri, 02 Dec 2011 10:30:11 +0100, Georg Bauhaus wrote:

> On 02.12.11 09:27, Dmitry A. Kazakov wrote:

>> DNA chain is not a text string. Furthermore it would likely have some
>> specific operations and a representation tailored substring search.
> 
> I have tried this once.  Sequence information is given and is using just
> a handful of characters. I mapped those to some 4bit type, even tried less.
> Added lots of purportedly smart unchecked conversions, some shifting,
> made my head spin by thinking about what combinations of "characters"
> might suggest there could be clever additions, not shifts and the like
> for obtaining info about substrings or single "characters", noted that
> addition is faster than shifting or logical operations on the processor,
> etc. Tried specializing searching. If there is a solution, it seems tricky.
> Perhaps to be found by someone with more than ordinary combinatorial skills.
> In my case this effort has produced only minuscule advantages, sometimes
> the opposite, but the cost was a large number of specialized subprograms.

There is a simple way to do such things efficiently, You tabulate
operations you want. It is just 2**16 combinations for a dyadic operation
taking two arguments of 2**8 states. A 64K array is nothing in these times.
The array can be initialized by an aggregate which text is generated once.

I am using such techniques from time to time, e.g. for character conversion
maps, for small images (icons etc) embedded into the application, etc.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de