/// Bitboards::init() initializes various bitboard tables. It is called at
/// startup and relies on global objects to be already zero-initialized.
public static void init()
{
for (Square s = SquareS.SQ_A1; s <= SquareS.SQ_H8; ++s)
{
BSFTable[bsf_index(SquareBB[s] = 1UL << s)] = s;
}
for (Bitboard b = 1; b < 256; ++b)
{
MS1BTable[b] = more_than_one(b) ? MS1BTable[b - 1] : lsb(b);
}
for (File f = FileS.FILE_A; f <= FileS.FILE_H; ++f)
{
FileBB[f] = f > FileS.FILE_A ? FileBB[f - 1] << 1 : FileABB;
}
for (Rank r = RankS.RANK_1; r <= RankS.RANK_8; ++r)
{
RankBB[r] = r > RankS.RANK_1 ? RankBB[r - 1] << 8 : Rank1BB;
}
for (File f = FileS.FILE_A; f <= FileS.FILE_H; ++f)
{
AdjacentFilesBB[f] = (f > FileS.FILE_A ? FileBB[f - 1] : 0) | (f < FileS.FILE_H ? FileBB[f + 1] : 0);
}
for (int c = ColorS.WHITE; c <= ColorS.BLACK; c++)
{
InFrontBB[c] = new Bitboard[RankS.RANK_NB];
}
for (Rank r = RankS.RANK_1; r < RankS.RANK_8; ++r)
{
InFrontBB[ColorS.WHITE][r] = ~(InFrontBB[ColorS.BLACK][r + 1] = InFrontBB[ColorS.BLACK][r] | RankBB[r]);
}
for (int c = ColorS.WHITE; c <= ColorS.BLACK; c++)
{
ForwardBB[c] = new Bitboard[SquareS.SQUARE_NB];
PawnAttackSpan[c] = new Bitboard[SquareS.SQUARE_NB];
PassedPawnMask[c] = new Bitboard[SquareS.SQUARE_NB];
}
for (Color c = ColorS.WHITE; c <= ColorS.BLACK; ++c)
{
for (Square s = SquareS.SQ_A1; s <= SquareS.SQ_H8; ++s)
{
ForwardBB[c][s] = InFrontBB[c][Types.rank_of(s)] & FileBB[Types.file_of(s)];
PawnAttackSpan[c][s] = InFrontBB[c][Types.rank_of(s)] & AdjacentFilesBB[Types.file_of(s)];
PassedPawnMask[c][s] = ForwardBB[c][s] | PawnAttackSpan[c][s];
}
}
for (Square c = 0; c < SquareS.SQUARE_NB; c++)
{
SquareDistance[c] = new int[SquareS.SQUARE_NB];
DistanceRingsBB[c] = new Bitboard[8];
}
for (Square s1 = SquareS.SQ_A1; s1 <= SquareS.SQ_H8; ++s1)
{
for (Square s2 = SquareS.SQ_A1; s2 <= SquareS.SQ_H8; ++s2)
{
if (s1 != s2)
{
SquareDistance[s1][s2] = Math.Max(file_distance(s1, s2), rank_distance(s1, s2));
DistanceRingsBB[s1][SquareDistance[s1][s2] - 1] |= SquareBB[s2];
}
}
}
int[][] steps = new int[7][];
steps[0] = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
steps[1] = new int[] { 7, 9, 0, 0, 0, 0, 0, 0, 0 };
steps[2] = new int[] { 17, 15, 10, 6, -6, -10, -15, -17, 0 };
steps[3] = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
steps[4] = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
steps[5] = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
steps[6] = new int[] { 9, 7, -7, -9, 8, 1, -1, -8, 0 };
for (Piece p = PieceS.NO_PIECE; p < PieceS.PIECE_NB; p++)
{
StepAttacksBB[p] = new Bitboard[SquareS.SQUARE_NB];
}
for (Color c = ColorS.WHITE; c <= ColorS.BLACK; ++c)
{
for (PieceType pt = PieceTypeS.PAWN; pt <= PieceTypeS.KING; ++pt)
{
for (Square s = SquareS.SQ_A1; s <= SquareS.SQ_H8; ++s)
{
for (int i = 0; steps[pt][i] != 0; ++i)
{
Square to = s + (Square)(c == ColorS.WHITE ? steps[pt][i] : -steps[pt][i]);
if (Types.is_ok_square(to) && BitBoard.square_distance(s, to) < 3)
{
StepAttacksBB[Types.make_piece(c, pt)][s] |= SquareBB[to];
}
}
}
}
}
Square[] RDeltas = new Square[] { SquareS.DELTA_N, SquareS.DELTA_E, SquareS.DELTA_S, SquareS.DELTA_W };
Square[] BDeltas = new Square[] { SquareS.DELTA_NE, SquareS.DELTA_SE, SquareS.DELTA_SW, SquareS.DELTA_NW };
init_magics(PieceTypeS.ROOK, RAttacks, RMagics, RMasks, RShifts, RDeltas, magic_index);
init_magics(PieceTypeS.BISHOP, BAttacks, BMagics, BMasks, BShifts, BDeltas, magic_index);
for (PieceType pt = PieceTypeS.NO_PIECE_TYPE; pt < PieceTypeS.PIECE_TYPE_NB; pt++)
{
PseudoAttacks[pt] = new Bitboard[SquareS.SQUARE_NB];
}
for (Square s = SquareS.SQ_A1; s <= SquareS.SQ_H8; s++)
{
BetweenBB[s] = new Bitboard[SquareS.SQUARE_NB];
LineBB[s] = new Bitboard[SquareS.SQUARE_NB];
}
for (Square s1 = SquareS.SQ_A1; s1 <= SquareS.SQ_H8; ++s1)
{
PseudoAttacks[PieceTypeS.QUEEN][s1] = PseudoAttacks[PieceTypeS.BISHOP][s1] = attacks_bb_SBBPT(s1, 0, PieceTypeS.BISHOP);
PseudoAttacks[PieceTypeS.QUEEN][s1] |= PseudoAttacks[PieceTypeS.ROOK][s1] = attacks_bb_SBBPT(s1, 0, PieceTypeS.ROOK);
for (Square s2 = SquareS.SQ_A1; s2 <= SquareS.SQ_H8; ++s2)
{
Piece pc = (PseudoAttacks[PieceTypeS.BISHOP][s1] & SquareBB[s2]) != 0 ? PieceS.W_BISHOP :
(PseudoAttacks[PieceTypeS.ROOK][s1] & SquareBB[s2]) != 0 ? PieceS.W_ROOK : PieceS.NO_PIECE;
if (pc == PieceS.NO_PIECE)
{
continue;
}
LineBB[s1][s2] = (attacks_bb_PSBB(pc, s1, 0) & attacks_bb_PSBB(pc, s2, 0)) | SquareBB[s1] | SquareBB[s2];
BetweenBB[s1][s2] = attacks_bb_PSBB(pc, s1, SquareBB[s2]) & attacks_bb_PSBB(pc, s2, SquareBB[s1]);
}
}
}
public static Score evaluate(Position pos, Pawns.Entry e, Color Us)
{
Color Them = (Us == ColorS.WHITE ? ColorS.BLACK : ColorS.WHITE);
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 b, p, doubled;
Square s;
File f;
Rank r;
bool passed, isolated, opposed, connected, backward, candidate, unsupported;
Score value = ScoreS.SCORE_ZERO;
Square[] pl = pos.list(Us, PieceTypeS.PAWN);
int plPos = 0;
Bitboard ourPawns = pos.pieces_color_piecetype(Us, PieceTypeS.PAWN);
Bitboard theirPawns = pos.pieces_color_piecetype(Them, PieceTypeS.PAWN);
e.passedPawns[Us] = e.candidatePawns[Us] = 0;
e.kingSquares[Us] = SquareS.SQ_NONE;
e.semiopenFiles[Us] = 0xFF;
e.pawnAttacks[Us] = BitBoard.shift_bb(ourPawns, Right) | BitBoard.shift_bb(ourPawns, Left);
e.pawnsOnSquares[Us][ColorS.BLACK] = Bitcount.popcount_Max15(ourPawns & BitBoard.DarkSquares);
e.pawnsOnSquares[Us][ColorS.WHITE] = pos.count(Us, PieceTypeS.PAWN) - e.pawnsOnSquares[Us][ColorS.BLACK];
// Loop through all pawns of the current color and score each pawn
while ((s = pl[plPos++]) != SquareS.SQ_NONE)
{
Debug.Assert(pos.piece_on(s) == Types.make_piece(Us, PieceTypeS.PAWN));
f = Types.file_of(s);
// This file cannot be semi-open
e.semiopenFiles[Us] &= ~(1 << f);
// Previous rank
p = BitBoard.rank_bb_square(s - Types.pawn_push(Us));
// Our rank plus previous one
b = BitBoard.rank_bb_square(s) | p;
// Flag the pawn as passed, isolated, doubled,
// unsupported or connected (but not the backward one).
connected = (ourPawns & BitBoard.adjacent_files_bb(f) & b) != 0;
unsupported = (0 == (ourPawns & BitBoard.adjacent_files_bb(f) & p));
isolated = (0 == (ourPawns & BitBoard.adjacent_files_bb(f)));
doubled = ourPawns & BitBoard.forward_bb(Us, s);
opposed = (theirPawns & BitBoard.forward_bb(Us, s)) != 0;
passed = (0 == (theirPawns & BitBoard.passed_pawn_mask(Us, s)));
// Test for backward pawn.
// If the pawn is passed, isolated, or connected it cannot be
// backward. If there are friendly pawns behind on adjacent files
// or if it can capture an enemy pawn it cannot be backward either.
if ((passed | isolated | connected) ||
(ourPawns & BitBoard.pawn_attack_span(Them, s)) != 0 ||
(pos.attacks_from_pawn(s, Us) & theirPawns) != 0)
{
backward = false;
}
else
{
// We now know that there are no friendly pawns beside or behind this
// pawn on adjacent files. We now check whether the pawn is
// backward by looking in the forward direction on the adjacent
// files, and picking the closest pawn there.
b = BitBoard.pawn_attack_span(Us, s) & (ourPawns | theirPawns);
b = BitBoard.pawn_attack_span(Us, s) & BitBoard.rank_bb_square(BitBoard.backmost_sq(Us, b));
// If we have an enemy pawn in the same or next rank, the pawn is
// backward because it cannot advance without being captured.
backward = ((b | BitBoard.shift_bb(b, Up)) & theirPawns) != 0;
}
Debug.Assert(opposed | passed | (BitBoard.pawn_attack_span(Us, s) & theirPawns) != 0);
// A not-passed pawn is a candidate to become passed, if it is free to
// advance and if the number of friendly pawns beside or behind this
// pawn on adjacent files is higher than or equal to the number of
// enemy pawns in the forward direction on the adjacent files.
candidate = !(opposed | passed | backward | isolated) &&
(b = BitBoard.pawn_attack_span(Them, s + Types.pawn_push(Us)) & ourPawns) != 0 &&
Bitcount.popcount_Max15(b) >= Bitcount.popcount_Max15(BitBoard.pawn_attack_span(Us, s) & theirPawns);
// Passed pawns will be properly scored in evaluation because we need
// full attack info to evaluate passed pawns. Only the frontmost passed
// pawn on each file is considered a true passed pawn.
if (passed && 0 == doubled)
{
e.passedPawns[Us] |= BitBoard.SquareBB[s];
}
// Score this pawn
if (isolated)
{
value -= Isolated[opposed ? 1 : 0][f];
}
if (unsupported && !isolated)
{
value -= UnsupportedPawnPenalty;
}
if (doubled != 0)
{
value -= Types.divScore(Doubled[f], BitBoard.rank_distance(s, BitBoard.lsb(doubled)));
}
if (backward)
{
value -= Backward[opposed ? 1 : 0][f];
}
if (connected)
{
value += Connected[f][Types.relative_rank_square(Us, s)];
}
if (candidate)
{
value += CandidatePassed[Types.relative_rank_square(Us, s)];
if (0 == doubled)
{
e.candidatePawns[Us] |= BitBoard.SquareBB[s];
}
}
}
// In endgame it's better to have pawns on both wings. So give a bonus according
// to file distance between left and right outermost pawns.
if (pos.count(Us, PieceTypeS.PAWN) > 1)
{
b = (Bitboard)(e.semiopenFiles[Us] ^ 0xFF);
value += PawnsFileSpan * (BitBoard.msb(b) - BitBoard.lsb(b));
}
return(value);
}
// evaluate_pieces() assigns bonuses and penalties to the pieces of a given color
public static Score evaluate_pieces(Position pos, EvalInfo ei, Score[] mobility, Bitboard[] mobilityArea, PieceType Pt, Color Us, bool Trace)
{
if (Us == ColorS.WHITE && Pt == PieceTypeS.KING)
{
return(ScoreS.SCORE_ZERO);
}
Bitboard b;
Square s;
Score score = ScoreS.SCORE_ZERO;
PieceType NextPt = (Us == ColorS.WHITE ? Pt : (Pt + 1));
Color Them = (Us == ColorS.WHITE ? ColorS.BLACK : ColorS.WHITE);
Square[] pl = pos.list(Us, Pt);
int plPos = 0;
ei.attackedBy[Us][Pt] = 0;
while ((s = pl[plPos++]) != SquareS.SQ_NONE)
{
// Find attacked squares, including x-ray attacks for bishops and rooks
b = Pt == PieceTypeS.BISHOP ? BitBoard.attacks_bb_SBBPT(s, pos.pieces() ^ pos.pieces_color_piecetype(Us, PieceTypeS.QUEEN), PieceTypeS.BISHOP)
: Pt == PieceTypeS.ROOK ? BitBoard.attacks_bb_SBBPT(s, pos.pieces() ^ pos.pieces_color_piecetype(Us, PieceTypeS.ROOK, PieceTypeS.QUEEN), PieceTypeS.ROOK)
: pos.attacks_from_square_piecetype(s, Pt);
if ((ei.pinnedPieces[Us] & BitBoard.SquareBB[s]) != 0)
{
b &= BitBoard.LineBB[pos.king_square(Us)][s];
}
ei.attackedBy[Us][PieceTypeS.ALL_PIECES] |= ei.attackedBy[Us][Pt] |= b;
if ((b & ei.kingRing[Them]) != 0)
{
ei.kingAttackersCount[Us]++;
ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
Bitboard bb = (b & ei.attackedBy[Them][PieceTypeS.KING]);
if (bb != 0)
{
ei.kingAdjacentZoneAttacksCount[Us] += Bitcount.popcount_Max15(bb);
}
}
if (Pt == PieceTypeS.QUEEN)
{
b &= ~(ei.attackedBy[Them][PieceTypeS.KNIGHT]
| ei.attackedBy[Them][PieceTypeS.BISHOP]
| ei.attackedBy[Them][PieceTypeS.ROOK]);
}
int mob = (Pt != PieceTypeS.QUEEN ? Bitcount.popcount_Max15(b & mobilityArea[Us])
: Bitcount.popcount(b & mobilityArea[Us]));
mobility[Us] += MobilityBonus[Pt][mob];
// Decrease score if we are attacked by an enemy pawn. The remaining part
// of threat evaluation must be done later when we have full attack info.
if ((ei.attackedBy[Them][PieceTypeS.PAWN] & BitBoard.SquareBB[s]) != 0)
{
score -= ThreatenedByPawn[Pt];
}
if (Pt == PieceTypeS.BISHOP || Pt == PieceTypeS.KNIGHT)
{
// Penalty for bishop with same coloured pawns
if (Pt == PieceTypeS.BISHOP)
{
score -= BishopPawns * ei.pi.pawns_on_same_color_squares(Us, s);
}
// Bishop and knight outposts squares
if (0 == (pos.pieces_color_piecetype(Them, PieceTypeS.PAWN) & BitBoard.pawn_attack_span(Us, s)))
{
score += evaluate_outposts(pos, ei, s, Pt, Us);
}
// Bishop or knight behind a pawn
if (Types.relative_rank_square(Us, s) < RankS.RANK_5 &&
(pos.pieces_piecetype(PieceTypeS.PAWN) & BitBoard.SquareBB[(s + Types.pawn_push(Us))]) != 0)
{
score += MinorBehindPawn;
}
}
if (Pt == PieceTypeS.ROOK)
{
// Rook piece attacking enemy pawns on the same rank/file
if (Types.relative_rank_square(Us, s) >= RankS.RANK_5)
{
Bitboard pawns = pos.pieces_color_piecetype(Them, PieceTypeS.PAWN) & BitBoard.PseudoAttacks[PieceTypeS.ROOK][s];
if (pawns != 0)
{
score += Bitcount.popcount_Max15(pawns) * RookOnPawn;
}
}
// Give a bonus for a rook on a open or semi-open file
if (ei.pi.semiopen_file(Us, Types.file_of(s)) != 0)
{
score += ei.pi.semiopen_file(Them, Types.file_of(s)) != 0 ? RookOpenFile : RookSemiopenFile;
}
if (mob > 3 || ei.pi.semiopen_file(Us, Types.file_of(s)) != 0)
{
continue;
}
Square ksq = pos.king_square(Us);
// Penalize rooks which are trapped by a king. Penalize more if the
// king has lost its castling capability.
if (((Types.file_of(ksq) < FileS.FILE_E) == (Types.file_of(s) < Types.file_of(ksq))) &&
(Types.rank_of(ksq) == Types.rank_of(s) || Types.relative_rank_square(Us, ksq) == RankS.RANK_1) &&
0 == ei.pi.semiopen_side(Us, Types.file_of(ksq), Types.file_of(s) < Types.file_of(ksq)))
{
score -= (TrappedRook - Types.make_score(mob * 8, 0)) * (1 + (pos.can_castle_color(Us) == 0 ? 1 : 0));
}
}
// An important Chess960 pattern: A cornered bishop blocked by a friendly
// pawn diagonally in front of it is a very serious problem, especially
// when that pawn is also blocked.
if (Pt == PieceTypeS.BISHOP &&
pos.is_chess960() != 0 &&
(s == Types.relative_square(Us, SquareS.SQ_A1) || s == Types.relative_square(Us, SquareS.SQ_H1)))
{
Square d = Types.pawn_push(Us) + (Types.file_of(s) == FileS.FILE_A ? SquareS.DELTA_E : SquareS.DELTA_W);
if (pos.piece_on(s + d) == Types.make_piece(Us, PieceTypeS.PAWN))
{
score -= !pos.empty(s + d + Types.pawn_push(Us)) ? TrappedBishopA1H1 * 4
: pos.piece_on(s + d + d) == Types.make_piece(Us, PieceTypeS.PAWN) ? TrappedBishopA1H1 * 2
: TrappedBishopA1H1;
}
}
}
if (Trace)
{
Tracing.terms[Us][Pt] = score;
}
return(score - evaluate_pieces(pos, ei, mobility, mobilityArea, NextPt, Them, Trace));
}
