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Subject: Re: pawn structure, pawn hash, square-of-pawn, pawn-races

Author: Russell Reagan

Date: 00:10:32 08/22/04

Go up one level in this thread


On August 20, 2004 at 14:27:22, Tord Romstad wrote:

>>Without bitboards, the code looks roughly like this:
>>
>>if(pawn_race[(square of white pawn)-(square of black pawn)])
>>   pawn can't run

Did you mean to take the difference of two pawn squares? Bob's code detected
whether a king could stop a pawn. Your code looks like it detects which passed
pawn (white's or black's) promotes first.

I'm also curious how yours works (regardless of what you meant), since it uses
square differences (the 0x88 trick I assume?). Sometimes a pawn can move two
squares. How do you account for that?

Offset of 1 - White can promote
[D]8/8/8/8/8/8/3Pk3/8 w - - 0 1

Offset of 1 - White can not promote
[D]8/8/8/8/8/3Pk3/8/8 w - - 0 1

So you can't depend on the pawn-king offset, can you?



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