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Subject: Re: Chess Tiger for Palm!! [Re: hash tables]

Author: José de Jesús García Ruvalcaba

Date: 02:35:52 05/08/01

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On May 07, 2001 at 18:49:27, Christophe Theron wrote:

>
>It is true that you do not have access to flat memory in the Palm. Actually you
>have, but most of the memory is "protected". That is, you can read it with a
>normal pointer (pointers can point anywhere in the Palm address space), but you
>cannot write it directly.
>
>This is a very simple and clever system that prevents a buggy program from
>crashing the entire system and erase your valuable data.
>
>If you want to write somewhere in a block you have allocated (I mean outside
>your data segment), you must ask the system to do it for you. Of course the
>system will first check if the block you are writting into is one of yours.
>
>It is possible to bypass this protection system when you know what you are
>doing.
>
>
>Let me tell you my version about what Richard has said: he wanted to port an
>existing version of his programs without changing a line of assembly. Because of
>the special memory protection scheme of the Palm it was easier for him to pick a
>program that did not use hash tables. The most advanced of his programs which
>does not use hash tables is the Roma (1987), so he ported the Roma and just had
>to write a GUI around it.
>
>
>My way of doing it is different. I have decided that I want only one source code
>for the PC version, the Palm version, the WinCE&PocketPC version and the Linux
>version. And that the Palm and WinCE versions would not be downgraded versions
>of Chess Tiger. So when I find an improvement, all the Tiger engines on all
>platforms benefit from it.
>

I have no idea how difficult it would be, but do you plan to port Chess Tiger to
game consoles like the Playstation 2?
José.

>
>After the release of Chess Tiger 12.0 I have rewritten a lot of things inside
>the engine to achieve this goal. I have rewritten the move format, the move
>generator, the move make/unmake routines and the hash table management. That's
>why I can manage hash tables even on the Palm, that's why Chess Tiger is able to
>perform well on a 16/32 bits processor like the DragonBall (the heart of the
>Palm), and that's why any new version of Chess Tiger for PC will be available
>instantly for the Palm.
>
>
>
>
>    Christophe



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