From 0179a32cf5b22fdeeaf9a14aa88f49eb51f476ed Mon Sep 17 00:00:00 2001 From: Marco Costalba Date: Mon, 21 Sep 2009 18:07:11 +0100 Subject: [PATCH] Code style and subtle fix in move_is_legal() A bunch of trivial code style and comment fixes. Among them there is a real fix for a subtle case involving promotion moves. We currently check that a pawn push to 8/1th rank must be a promotion, but we don't check the contary, i.e. that a pawn push on a different rank must NOT be a promotion. Note that, funny enough, we perform this control for all the other pieces, but not for the pawns! This patch fixes this really corner case. No functional change. Signed-off-by: Marco Costalba --- src/movegen.cpp | 58 ++++++++++++++++++++++++------------------------- 1 file changed, 28 insertions(+), 30 deletions(-) diff --git a/src/movegen.cpp b/src/movegen.cpp index 9cb588a3..c4b43539 100644 --- a/src/movegen.cpp +++ b/src/movegen.cpp @@ -55,19 +55,19 @@ namespace { // Helper templates template - MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist); + MoveStack* generate_castle_moves(const Position&, MoveStack*); template MoveStack* generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*); template - MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist); + MoveStack* generate_pawn_captures(const Position&, MoveStack*); template - MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion); + MoveStack* generate_pawn_captures_diagonal(MoveStack*, Bitboard, Bitboard, bool); template - MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist, Bitboard dc = EmptyBoardBB, Square ksq = SQ_NONE); + MoveStack* generate_pawn_noncaptures(const Position&, MoveStack*, Bitboard = EmptyBoardBB, Square = SQ_NONE); template inline Bitboard move_pawns(Bitboard p) { @@ -95,7 +95,7 @@ namespace { // Template generate_piece_moves() with specializations and overloads template - MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard); + MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard); template<> MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard); @@ -114,7 +114,7 @@ namespace { } template - MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard, Bitboard); + MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard, Bitboard); template<> inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, @@ -131,7 +131,7 @@ namespace { //// -/// generate_captures generates() all pseudo-legal captures and queen +/// generate_captures() generates all pseudo-legal captures and queen /// promotions. Returns a pointer to the end of the move list. MoveStack* generate_captures(const Position& pos, MoveStack* mlist) { @@ -173,8 +173,8 @@ MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist) { } -/// generate_non_capture_checks() generates all pseudo-legal non-capturing, -/// non-promoting checks. Returns a pointer to the end of the move list. +/// generate_non_capture_checks() generates all pseudo-legal non-captures and +/// underpromotions that give check. Returns a pointer to the end of the move list. MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc) { @@ -231,8 +231,8 @@ MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pin Bitboard b_noKing = pos.occupied_squares(); clear_bit(&b_noKing, ksq); - // Find squares attacked by slider checkers, we will - // remove them from king evasions set so to avoid a couple + // Find squares attacked by slider checkers, we will remove + // them from the king evasions set so to avoid a couple // of cycles in the slow king evasions legality check loop // and to be able to use attackers_to(). Bitboard b = checkers & pos.pieces(BISHOP, QUEEN); @@ -249,14 +249,14 @@ MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pin sliderAttacks |= rook_attacks_bb(from, b_noKing); } - // Generate evasions for king, both captures and non captures - Bitboard b1 = pos.attacks_from(ksq) & ~pos.pieces_of_color(us) & ~sliderAttacks; + // Generate evasions for king, capture and non capture moves Bitboard enemy = pos.pieces_of_color(them); + Bitboard b1 = pos.attacks_from(ksq) & ~pos.pieces_of_color(us) & ~sliderAttacks; while (b1) { + // Note that we can use attackers_to() only because we have already + // removed from b1 the squares attacked by slider checkers. to = pop_1st_bit(&b1); - // Note that we can use attackers_to() only because we - // have already removed slider checkers attacked squares. if (!(pos.attackers_to(to) & enemy)) (*mlist++).move = make_move(ksq, to); } @@ -345,9 +345,9 @@ MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pin } -/// generate_moves() computes a complete list of legal or pseudo legal moves in +/// generate_moves() computes a complete list of legal or pseudo-legal moves in /// the current position. This function is not very fast, and should be used -/// only in situations where performance is unimportant. +/// only in non time-critical paths. MoveStack* generate_moves(const Position& pos, MoveStack* mlist, bool pseudoLegal) { @@ -377,7 +377,7 @@ MoveStack* generate_moves(const Position& pos, MoveStack* mlist, bool pseudoLega /// move_is_legal() takes a position and a (not necessarily pseudo-legal) /// move and tests whether the move is legal. This version is not very fast -/// and should be used only for non time-critical paths. +/// and should be used only in non time-critical paths. bool move_is_legal(const Position& pos, const Move m) { @@ -391,8 +391,8 @@ bool move_is_legal(const Position& pos, const Move m) { } -/// Fast version of move_is_legal() that takes a position a move and -/// a pinned pieces bitboard as input, and tests whether the move is legal. +/// Fast version of move_is_legal() that takes a position a move and a +/// bitboard of pinned pieces as input, and tests whether the move is legal. /// This version must only be used when the side to move is not in check. bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) { @@ -407,7 +407,9 @@ bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) { return move_is_legal(pos, m); Color us = pos.side_to_move(); + Color them = opposite_color(us); Square from = move_from(m); + Square to = move_to(m); Piece pc = pos.piece_on(from); // If the from square is not occupied by a piece belonging to the side to @@ -415,14 +417,11 @@ bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) { if (color_of_piece(pc) != us) return false; - Color them = opposite_color(us); - Square to = move_to(m); - // The destination square cannot be occupied by a friendly piece if (pos.color_of_piece_on(to) == us) return false; - // Proceed according to the type of the moving piece. + // Handle the special case of a pawn move if (type_of_piece(pc) == PAWN) { // Move direction must be compatible with pawn color @@ -430,14 +429,13 @@ bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) { if ((us == WHITE) != (direction > 0)) return false; - // If the destination square is on the 8/1th rank, the move must - // be a promotion. - if ( ( (square_rank(to) == RANK_8 && us == WHITE) - ||(square_rank(to) == RANK_1 && us != WHITE)) - && !move_is_promotion(m)) + // A pawn move is a promotion iff the destination square is + // on the 8/1th rank. + if (( (square_rank(to) == RANK_8 && us == WHITE) + ||(square_rank(to) == RANK_1 && us != WHITE)) != bool(move_is_promotion(m))) return false; - // Proceed according to the square delta between the source and + // Proceed according to the square delta between the origin and // destionation squares. switch (direction) { -- 2.39.2