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Subject: Re: 0x88 compared to rot BB

Author: Bas Hamstra

Date: 15:22:47 01/12/03

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On January 12, 2003 at 18:07:13, Uri Blass wrote:

>On January 12, 2003 at 17:42:03, Bas Hamstra wrote:
>
>>On January 12, 2003 at 17:18:17, Vincent Diepeveen wrote:
>>>On January 12, 2003 at 17:14:18, Bas Hamstra wrote:
>>>you need indepth processor knowledge if you try to get a concept to work fast
>>>which needs a lot of work to get fast.
>>
>>I have a book about x86 optimation. "Inner loops" I believe it is called. It
>>crushes some well accepted C-myths. It also states that with the later
>>processors it becomes more and more difficult to outsmart the compilers with
>>asm.
>>
>>>this whereas bitboards is all optimized very well for the concept itself.
>>>you work against assembly language stuff in bitboards.
>>>so you better figure out how a processor works before writing a move generator.
>>>
>>>the improtant problems to solve
>>>  - limit the number of branches
>>>  - arrays are allowed to use but try to minimize them
>>>  - do not mix 8 bits with 32 bits. perhaps faster on k6 and even k7, but
>>>    not always. and not at p4.
>>
>>>the square attacked with incremental bitboards is a simple AND.
>>>see gnuchess 4.0 how to do it (not later raped versions of it).
>>
>>But then you imply an incrementally updated attacktable. I doubt that is going
>>to break the nps record, which is what I intended to do :-) I wanted to start
>>with a very fast piece-square searcher, good move sorting, checks in qsearch and
>>extensive pawn strucure analysis (in pawnhash). Now I know you are going to say
>>this won't get me anywhere, I KNOW it, but I just want to try for fun :-) And
>>maybe I will release the source, which I intend to be max 2000 lines. Including
>>UCI (400 lines), not winboard (20000+ lines).
>
>I believe that with a short program you are not going to break the np record.
>speed improvements can come from doing the code longer(for example seperate code
>for white and for black).
>
>Uri

I do not think that is a big factor for reaching that goal. And I have to agree
with Vincent that it's ugly coding (although I do it myself too in Tao).

Bas



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