From 53f882ff1a95d444dd9b3cd0eb39d493d0e6280e Mon Sep 17 00:00:00 2001 From: Tord Romstad Date: Thu, 15 Oct 2009 12:39:55 +0200 Subject: [PATCH] Minor improvement in eval of unstoppable pawns promoting one ply apart. Marco's new code for evaluating two unstoppable passed pawns where one pawn promotes a single ply before the other tried to detect cases where the pawn that promotes first could immediately capture the pawn that promotes a ply later, but didn't work in cases where the two pawns are on the same file. An example of this is the following position: 8/8/3K4/2P5/2p5/3k4/8/8 w - - With the new code, such positions are handled correctly. --- src/evaluate.cpp | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/evaluate.cpp b/src/evaluate.cpp index a03f7ddb..104a0a6b 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -1069,7 +1069,10 @@ namespace { Square winnerQSq = relative_square(winnerSide, make_square(square_file(pawnToGo[winnerSide]), RANK_8)); Square loserQSq = relative_square(loserSide, make_square(square_file(pawnToGo[loserSide]), RANK_8)); - Bitboard b = pos.attacks_from(winnerQSq); + Bitboard b = pos.occupied_squares(); + clear_bit(&b, pawnToGo[winnerSide]); + clear_bit(&b, pawnToGo[loserSide]); + b = queen_attacks_bb(winnerQSq, b); if ( (b & pos.pieces(KING, loserSide)) ||(bit_is_set(b, loserQSq) && !bit_is_set(ei.attacked_by(loserSide), loserQSq))) -- 2.39.2