public static int CalculateThreats(ChessBoard cb)
{
var score = 0;
var whites = cb.Pieces[White][All];
var whitePawns = cb.Pieces[White][Pawn];
var blacks = cb.Pieces[Black][All];
var blackPawns = cb.Pieces[Black][Pawn];
var whiteAttacks = cb.Attacks[White][All];
var whitePawnAttacks = cb.Attacks[White][Pawn];
var whiteMinorAttacks = cb.Attacks[White][Knight] | cb.Attacks[White][Bishop];
var blackAttacks = cb.Attacks[Black][All];
var blackPawnAttacks = cb.Attacks[Black][Pawn];
var blackMinorAttacks = cb.Attacks[Black][Knight] | cb.Attacks[Black][Bishop];
// double attacked pieces
var piece = cb.DoubleAttacks[White] & blacks;
while (piece != 0)
{
score += EvalConstants.DoubleAttacked[cb.PieceIndexes[BitOperations.TrailingZeroCount(piece)]];
piece &= piece - 1;
}
piece = cb.DoubleAttacks[Black] & whites;
while (piece != 0)
{
score -= EvalConstants.DoubleAttacked[cb.PieceIndexes[BitOperations.TrailingZeroCount(piece)]];
piece &= piece - 1;
}
if (MaterialUtil.HasPawns(cb.MaterialKey))
{
// unused outposts
score += BitOperations.PopCount((ulong)(cb.PassedPawnsAndOutposts & cb.EmptySpaces &
whiteMinorAttacks & whitePawnAttacks))
* EvalConstants.Threats[EvalConstants.IxUnusedOutpost];
score -= BitOperations.PopCount((ulong)(cb.PassedPawnsAndOutposts & cb.EmptySpaces &
blackMinorAttacks & blackPawnAttacks))
* EvalConstants.Threats[EvalConstants.IxUnusedOutpost];
// pawn push threat
piece = (whitePawns << 8) & cb.EmptySpaces & ~blackAttacks;
score += BitOperations.PopCount((ulong)(Bitboard.GetWhitePawnAttacks(piece) & blacks)) *
EvalConstants.Threats[EvalConstants.IxPawnPushThreat];
piece = Util.RightTripleShift(blackPawns, 8) & cb.EmptySpaces & ~whiteAttacks;
score -= BitOperations.PopCount((ulong)(Bitboard.GetBlackPawnAttacks(piece) & whites)) *
EvalConstants.Threats[EvalConstants.IxPawnPushThreat];
// piece attacked by pawn
score += BitOperations.PopCount((ulong)(whitePawnAttacks & blacks & ~blackPawns)) *
EvalConstants.Threats[EvalConstants.IxPawnAttacks];
score -= BitOperations.PopCount((ulong)(blackPawnAttacks & whites & ~whitePawns)) *
EvalConstants.Threats[EvalConstants.IxPawnAttacks];
// multiple pawn attacks possible
if (BitOperations.PopCount((ulong)(whitePawnAttacks & blacks)) > 1)
{
score += EvalConstants.Threats[EvalConstants.IxMultiplePawnAttacks];
}
if (BitOperations.PopCount((ulong)(blackPawnAttacks & whites)) > 1)
{
score -= EvalConstants.Threats[EvalConstants.IxMultiplePawnAttacks];
}
// pawn attacked
score += BitOperations.PopCount((ulong)(whiteAttacks & blackPawns)) *
EvalConstants.Threats[EvalConstants.IxPawnAttacked];
score -= BitOperations.PopCount((ulong)(blackAttacks & whitePawns)) *
EvalConstants.Threats[EvalConstants.IxPawnAttacked];
}
// minors attacked and not defended by a pawn
score += BitOperations.PopCount((ulong)(whiteAttacks &
(cb.Pieces[Black][Knight] |
(cb.Pieces[Black][Bishop] & ~blackAttacks))))
* EvalConstants.Threats[EvalConstants.IxMajorAttacked];
score -= BitOperations.PopCount((ulong)(blackAttacks &
(cb.Pieces[White][Knight] |
(cb.Pieces[White][Bishop] & ~whiteAttacks))))
* EvalConstants.Threats[EvalConstants.IxMajorAttacked];
if (cb.Pieces[Black][Queen] != 0)
{
// queen attacked by rook
score += BitOperations.PopCount((ulong)(cb.Attacks[White][Rook] & cb.Pieces[Black][Queen])) *
EvalConstants.Threats[EvalConstants.IxQueenAttacked];
// queen attacked by minors
score += BitOperations.PopCount((ulong)(whiteMinorAttacks & cb.Pieces[Black][Queen])) *
EvalConstants.Threats[EvalConstants.IxQueenAttackedMinor];
}
if (cb.Pieces[White][Queen] != 0)
{
// queen attacked by rook
score -= BitOperations.PopCount((ulong)(cb.Attacks[Black][Rook] & cb.Pieces[White][Queen])) *
EvalConstants.Threats[EvalConstants.IxQueenAttacked];
// queen attacked by minors
score -= BitOperations.PopCount((ulong)(blackMinorAttacks & cb.Pieces[White][Queen])) *
EvalConstants.Threats[EvalConstants.IxQueenAttackedMinor];
}
// rook attacked by minors
score += BitOperations.PopCount((ulong)(whiteMinorAttacks & cb.Pieces[Black][Rook])) *
EvalConstants.Threats[EvalConstants.IxRookAttacked];
score -= BitOperations.PopCount((ulong)(blackMinorAttacks & cb.Pieces[White][Rook])) *
EvalConstants.Threats[EvalConstants.IxRookAttacked];
return(score);
}
private static int CalculatePawnScores(ChessBoard cb)
{
var score = 0;
// penalty for doubled pawns
for (var i = 0; i < 8; i++)
{
if (BitOperations.PopCount((ulong)(cb.Pieces[White][Pawn] & Bitboard.Files[i])) > 1)
{
score -= EvalConstants.PawnScores[EvalConstants.IxPawnDouble];
}
if (BitOperations.PopCount((ulong)(cb.Pieces[Black][Pawn] & Bitboard.Files[i])) > 1)
{
score += EvalConstants.PawnScores[EvalConstants.IxPawnDouble];
}
}
// bonus for connected pawns
var pawns = Bitboard.GetWhitePawnAttacks(cb.Pieces[White][Pawn]) & cb.Pieces[White][Pawn];
while (pawns != 0)
{
score += EvalConstants.PawnConnected[BitOperations.TrailingZeroCount(pawns) / 8];
pawns &= pawns - 1;
}
pawns = Bitboard.GetBlackPawnAttacks(cb.Pieces[Black][Pawn]) & cb.Pieces[Black][Pawn];
while (pawns != 0)
{
score -= EvalConstants.PawnConnected[7 - BitOperations.TrailingZeroCount(pawns) / 8];
pawns &= pawns - 1;
}
// bonus for neighbour pawns
pawns = Bitboard.GetPawnNeighbours(cb.Pieces[White][Pawn]) & cb.Pieces[White][Pawn];
while (pawns != 0)
{
score += EvalConstants.PawnNeighbour[BitOperations.TrailingZeroCount(pawns) / 8];
pawns &= pawns - 1;
}
pawns = Bitboard.GetPawnNeighbours(cb.Pieces[Black][Pawn]) & cb.Pieces[Black][Pawn];
while (pawns != 0)
{
score -= EvalConstants.PawnNeighbour[7 - BitOperations.TrailingZeroCount(pawns) / 8];
pawns &= pawns - 1;
}
// set outposts
cb.PassedPawnsAndOutposts = 0;
pawns = Bitboard.GetWhitePawnAttacks(cb.Pieces[White][Pawn]) & ~cb.Pieces[White][Pawn] &
~cb.Pieces[Black][Pawn];
while (pawns != 0)
{
if ((Bitboard.GetWhiteAdjacentMask(BitOperations.TrailingZeroCount(pawns)) & cb.Pieces[Black][Pawn]) ==
0)
{
cb.PassedPawnsAndOutposts |= pawns & -pawns;
}
pawns &= pawns - 1;
}
pawns = Bitboard.GetBlackPawnAttacks(cb.Pieces[Black][Pawn]) & ~cb.Pieces[White][Pawn] &
~cb.Pieces[Black][Pawn];
while (pawns != 0)
{
if ((Bitboard.GetBlackAdjacentMask(BitOperations.TrailingZeroCount(pawns)) & cb.Pieces[White][Pawn]) ==
0)
{
cb.PassedPawnsAndOutposts |= pawns & -pawns;
}
pawns &= pawns - 1;
}
int index;
// white
pawns = cb.Pieces[White][Pawn];
while (pawns != 0)
{
index = BitOperations.TrailingZeroCount(pawns);
// isolated pawns
if ((Bitboard.FilesAdjacent[index & 7] & cb.Pieces[White][Pawn]) == 0)
{
score -= EvalConstants.PawnScores[EvalConstants.IxPawnIsolated];
}
// backward pawns
else if ((Bitboard.GetBlackAdjacentMask(index + 8) & cb.Pieces[White][Pawn]) == 0)
{
if ((StaticMoves.PawnAttacks[White][index + 8] & cb.Pieces[Black][Pawn]) != 0)
{
if ((Bitboard.Files[index & 7] & cb.Pieces[Black][Pawn]) == 0)
{
score -= EvalConstants.PawnScores[EvalConstants.IxPawnBackward];
}
}
}
// pawn defending 2 pawns
if (BitOperations.PopCount((ulong)(StaticMoves.PawnAttacks[White][index] & cb.Pieces[White][Pawn])) ==
2)
{
score -= EvalConstants.PawnScores[EvalConstants.IxPawnInverse];
}
// set passed pawns
if ((Bitboard.GetWhitePassedPawnMask(index) & cb.Pieces[Black][Pawn]) == 0)
{
cb.PassedPawnsAndOutposts |= pawns & -pawns;
}
// candidate passed pawns (no pawns in front, more friendly pawns behind and adjacent than enemy pawns)
else if (63 - BitOperations.LeadingZeroCount(
(ulong)((cb.Pieces[White][Pawn] | cb.Pieces[Black][Pawn]) &
Bitboard.Files[index & 7])) == index)
{
if (BitOperations.PopCount((ulong)(cb.Pieces[White][Pawn] &
Bitboard.GetBlackPassedPawnMask(index + 8))) >=
BitOperations.PopCount(
(ulong)(cb.Pieces[Black][Pawn] & Bitboard.GetWhitePassedPawnMask(index))))
{
score += EvalConstants.PassedCandidate[index / 8];
}
}
pawns &= pawns - 1;
}
// black
pawns = cb.Pieces[Black][Pawn];
while (pawns != 0)
{
index = BitOperations.TrailingZeroCount(pawns);
// isolated pawns
if ((Bitboard.FilesAdjacent[index & 7] & cb.Pieces[Black][Pawn]) == 0)
{
score += EvalConstants.PawnScores[EvalConstants.IxPawnIsolated];
}
// backward pawns
else if ((Bitboard.GetWhiteAdjacentMask(index - 8) & cb.Pieces[Black][Pawn]) == 0)
{
if ((StaticMoves.PawnAttacks[Black][index - 8] & cb.Pieces[White][Pawn]) != 0)
{
if ((Bitboard.Files[index & 7] & cb.Pieces[White][Pawn]) == 0)
{
score += EvalConstants.PawnScores[EvalConstants.IxPawnBackward];
}
}
}
// pawn defending 2 pawns
if (BitOperations.PopCount((ulong)(StaticMoves.PawnAttacks[Black][index] & cb.Pieces[Black][Pawn])) ==
2)
{
score += EvalConstants.PawnScores[EvalConstants.IxPawnInverse];
}
// set passed pawns
if ((Bitboard.GetBlackPassedPawnMask(index) & cb.Pieces[White][Pawn]) == 0)
{
cb.PassedPawnsAndOutposts |= pawns & -pawns;
}
// candidate passers
else if (BitOperations.TrailingZeroCount((cb.Pieces[White][Pawn] | cb.Pieces[Black][Pawn]) &
Bitboard.Files[index & 7]) == index)
{
if (BitOperations.PopCount((ulong)(cb.Pieces[Black][Pawn] &
Bitboard.GetWhitePassedPawnMask(index - 8))) >=
BitOperations.PopCount(
(ulong)(cb.Pieces[White][Pawn] & Bitboard.GetBlackPassedPawnMask(index))))
{
score -= EvalConstants.PassedCandidate[7 - index / 8];
}
}
pawns &= pawns - 1;
}
return(score);
}
