public static int generate_pawn_moves(Position pos, ExtMove[] mlist, int mPos, Bitboard target, CheckInfo ci, Color Us, GenType Type) { // Compute our parametrized parameters at compile time, named according to // the point of view of white side. Color Them = (Us == ColorS.WHITE ? ColorS.BLACK : ColorS.WHITE); Bitboard TRank8BB = (Us == ColorS.WHITE ? BitBoard.Rank8BB : BitBoard.Rank1BB); Bitboard TRank7BB = (Us == ColorS.WHITE ? BitBoard.Rank7BB : BitBoard.Rank2BB); Bitboard TRank3BB = (Us == ColorS.WHITE ? BitBoard.Rank3BB : BitBoard.Rank6BB); Square Up = (Us == ColorS.WHITE ? SquareS.DELTA_N : SquareS.DELTA_S); Square Right = (Us == ColorS.WHITE ? SquareS.DELTA_NE : SquareS.DELTA_SW); Square Left = (Us == ColorS.WHITE ? SquareS.DELTA_NW : SquareS.DELTA_SE); Bitboard b1, b2, dc1, dc2, emptySquares = 0; Bitboard pawnsOn7 = pos.pieces_color_piecetype(Us, PieceTypeS.PAWN) & TRank7BB; Bitboard pawnsNotOn7 = pos.pieces_color_piecetype(Us, PieceTypeS.PAWN) & ~TRank7BB; Bitboard enemies = (Type == GenTypeS.EVASIONS ? pos.pieces_color(Them) & target : Type == GenTypeS.CAPTURES ? target : pos.pieces_color(Them)); // Single and double pawn pushes, no promotions if (Type != GenTypeS.CAPTURES) { emptySquares = (Type == GenTypeS.QUIETS || Type == GenTypeS.QUIET_CHECKS ? target : ~pos.pieces()); b1 = BitBoard.shift_bb(pawnsNotOn7, Up) & emptySquares; b2 = BitBoard.shift_bb(b1 & TRank3BB, Up) & emptySquares; if (Type == GenTypeS.EVASIONS) // Consider only blocking squares { b1 &= target; b2 &= target; } if (Type == GenTypeS.QUIET_CHECKS) { b1 &= pos.attacks_from_pawn(ci.ksq, Them); b2 &= pos.attacks_from_pawn(ci.ksq, Them); // Add pawn pushes which give discovered check. This is possible only // if the pawn is not on the same file as the enemy king, because we // don't generate captures. Note that a possible discovery check // promotion has been already generated among captures. if ((pawnsNotOn7 & ci.dcCandidates) != 0) { dc1 = BitBoard.shift_bb(pawnsNotOn7 & ci.dcCandidates, Up) & emptySquares & ~BitBoard.file_bb_square(ci.ksq); dc2 = BitBoard.shift_bb(dc1 & TRank3BB, Up) & emptySquares; b1 |= dc1; b2 |= dc2; } } while (b1 != 0) { Square to = BitBoard.pop_lsb(ref b1); mlist[mPos++].move = Types.make_move(to - Up, to); } while (b2 != 0) { Square to = BitBoard.pop_lsb(ref b2); mlist[mPos++].move = Types.make_move(to - Up - Up, to); } } // Promotions and underpromotions if (pawnsOn7 != 0 && (Type != GenTypeS.EVASIONS || (target & TRank8BB) != 0)) { if (Type == GenTypeS.CAPTURES) { emptySquares = ~pos.pieces(); } if (Type == GenTypeS.EVASIONS) { emptySquares &= target; } mPos = generate_promotions(mlist, mPos, pawnsOn7, enemies, ci, Type, Right); mPos = generate_promotions(mlist, mPos, pawnsOn7, enemies, ci, Type, Left); mPos = generate_promotions(mlist, mPos, pawnsOn7, emptySquares, ci, Type, Up); } // Standard and en-passant captures if (Type == GenTypeS.CAPTURES || Type == GenTypeS.EVASIONS || Type == GenTypeS.NON_EVASIONS) { b1 = BitBoard.shift_bb(pawnsNotOn7, Right) & enemies; b2 = BitBoard.shift_bb(pawnsNotOn7, Left) & enemies; while (b1 != 0) { Square to = BitBoard.pop_lsb(ref b1); mlist[mPos++].move = Types.make_move(to - Right, to); } while (b2 != 0) { Square to = BitBoard.pop_lsb(ref b2); mlist[mPos++].move = Types.make_move(to - Left, to); } if (pos.ep_square() != SquareS.SQ_NONE) { Debug.Assert(Types.rank_of(pos.ep_square()) == Types.relative_rank_rank(Us, RankS.RANK_6)); // An en passant capture can be an evasion only if the checking piece // is the double pushed pawn and so is in the target. Otherwise this // is a discovery check and we are forced to do otherwise. if (Type == GenTypeS.EVASIONS && (target & BitBoard.SquareBB[(pos.ep_square() - Up)]) == 0) { return(mPos); } b1 = pawnsNotOn7 & pos.attacks_from_pawn(pos.ep_square(), Them); Debug.Assert(b1 != 0); while (b1 != 0) { mlist[mPos++].move = Types.make(BitBoard.pop_lsb(ref b1), pos.ep_square(), MoveTypeS.ENPASSANT); } } } return(mPos); }