Author: Robert Hyatt
Date: 07:37:04 02/01/01
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On February 01, 2001 at 03:40:05, David Rasmussen wrote: >On February 01, 2001 at 00:28:39, Robert Hyatt wrote: >> >>you need one more test. How quickly can you generate _only_ capture >>moves? That is the biggest part of the total move generation process, >>because of the q-search. And that is a place where bitmaps really shines >>brightly. IE I can generate captures _just_ as quickly as I can generate >>non-captures. I don't have to cull non-captures or anything, after the >>fact... I just never generate them in the first place... >> >>0x88 does great at generating everything. It loses its advantage and then >>some when you take generating only captures. I also can generate legal-only >>moves without doing in-check tests... > >How do you do that? Generate legal-only moves without doing in-check tests, that >is. You can look at my code named "GenerateCheckEvasions()" but the idea is this (simplified and maybe wrong): 1. If I am checked by a single piece, capture it. 2. If I am checked by a single sliding piece, interpose. 3. If I am checked by either 1 or two pieces, move the king out of the check. for 3, you might think that I have to check for legality after generating a king move, but it isn't needed. If the checking piece is a slider, I have to move in any direction but +/- the checking direction. Bitmaps handle all of this easily, so that I can produce moves that I _know_ are legal.
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