Author: Alessandro Damiani
Date: 02:33:17 08/27/05
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On August 27, 2005 at 03:12:23, Gerd Isenberg wrote: >On August 26, 2005 at 16:11:53, Dan Honeycutt wrote: > >>Run the lowest bits down the a or h file and you can do pawn captures without >>having to mask those files. >> >>Best >>Dan H. > >Hi Dan, > >a very nice idea! Keeping the a-file in least significant byte and the h-file in >the most significant byte (or vice versa) to avoid a-h-wraps for pawn attacks >and further ands. > >eg. with a1 == 0: > >a1 a2 a3 a4 a5 a6 a7 a8 >b1 b2 b3 b4 b5 b6 b7 b8 >c1 c2 c3 c4 c5 c6 c7 c8 >d1 d2 d3 d4 d5 d6 d7 d8 >e1 e2 e3 e4 e5 e6 e7 e8 >f1 f2 f3 f4 f5 f6 f7 f8 >g1 g2 g3 g4 g5 g6 g7 g8 >h1 h2 h3 h4 h5 h6 h7 h8 > >"left" attacks of white pawns ::= white pawns >> 7 ; eg. e4:d5 >"right" attacks of white pawns ::= white pawns << 9 ; eg. e4:f5 >"left" attacks of black pawns ::= black pawns >> 9 ; eg. e4:d3 >"right" attacks of black pawns ::= black pawns << 7 ; eg. e4:f3 > >Gerd A nice idea indeed, but then vertical shifting needs masking, e.g. shiftUp(e8) = f1. So, no real gain in the end, I guess. Or do I miss something? Alessandro
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