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Subject: Re: How are EGTB files accessed so quickly?

Author: gerold daniels

Date: 04:44:15 03/26/05

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On March 26, 2005 at 01:21:08, Dieter Buerssner wrote:

>On March 25, 2005 at 20:00:12, gerold daniels wrote:
>
>>On March 25, 2005 at 09:50:57, Dieter Buerssner wrote:
>
>>>Additionally, the whole database can be compressed.
>
>>i don,t understand that part. if the database is compressed how do can you
>>access it.
>
>The chess engine will have the decompression code included. My little example
>would give a database of 64*64*64 bytes = 256 kbytes. One could compress junks
>of 4 kbytes. one would also store a table, where each compressed part starts.
>Say:
>
>kbyte offset
>0     0
>4     1259
>8     2375
>...
>252   81275
>
>So, when with the formula I gave I calculate an offset of 4759, I know it is in
>the second part. In the above table I look at 4 and see 1259. I decompress the
>bytes between 1259 and 2375. They will decompress exactly to 4096 bytes. I read
>the (4759-4096) = 663th byte of this decompressed block. Instead of reading just
>one byte with uncompressed tables I would need to read about 1 kB (it will
>hardly matter for the time I need) and I would need to run the decompression
>algorithm over this block.
>
>Regards,
>Dieter

good morning Dieter.thanks for the reply.

gerold.



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