public static int CalculateSpace(ChessBoard cb)
{
if (!MaterialUtil.HasPawns(cb.MaterialKey))
{
return(0);
}
var score = 0;
score += EvalConstants.OtherScores[EvalConstants.IxSpace]
* BitOperations.PopCount((ulong)(Util.RightTripleShift(cb.Pieces[White][Pawn], 8) &
(cb.Pieces[White][Knight] | cb.Pieces[White][Bishop]) &
Bitboard.Rank234));
score -= EvalConstants.OtherScores[EvalConstants.IxSpace]
* BitOperations.PopCount((ulong)((cb.Pieces[Black][Pawn] << 8) &
(cb.Pieces[Black][Knight] | cb.Pieces[Black][Bishop]) &
Bitboard.Rank567));
// idea taken from Laser
var space = Util.RightTripleShift(cb.Pieces[White][Pawn], 8);
space |= Util.RightTripleShift(space, 8) | Util.RightTripleShift(space, 16);
score += EvalConstants.Space[BitOperations.PopCount((ulong)cb.Pieces[White][All])]
* BitOperations.PopCount((ulong)(space & ~cb.Pieces[White][Pawn] & ~cb.Attacks[Black][Pawn] &
Bitboard.FileCdef));
space = cb.Pieces[Black][Pawn] << 8;
space |= (space << 8) | (space << 16);
score -= EvalConstants.Space[BitOperations.PopCount((ulong)cb.Pieces[Black][All])]
* BitOperations.PopCount((ulong)(space & ~cb.Pieces[Black][Pawn] & ~cb.Attacks[White][Pawn] &
Bitboard.FileCdef));
return(score);
}
public static int CalculatePawnShieldBonus(ChessBoard cb)
{
if (!MaterialUtil.HasPawns(cb.MaterialKey))
{
return(0);
}
int file;
var whiteScore = 0;
var piece = cb.Pieces[White][Pawn] & KingArea[cb.KingIndex[White]] & ~cb.Attacks[Black][Pawn];
while (piece != 0)
{
file = BitOperations.TrailingZeroCount(piece) & 7;
whiteScore +=
EvalConstants.ShieldBonus[Math.Min(7 - file, file)][
Util.RightTripleShift(BitOperations.TrailingZeroCount(piece), 3)];
piece &= ~Bitboard.Files[file];
}
if (cb.Pieces[Black][Queen] == 0)
{
whiteScore /= 2;
}
var blackScore = 0;
piece = cb.Pieces[Black][Pawn] & KingArea[cb.KingIndex[Black]] & ~cb.Attacks[White][Pawn];
while (piece != 0)
{
file = (63 - BitOperations.LeadingZeroCount((ulong)piece)) & 7;
blackScore +=
EvalConstants.ShieldBonus[Math.Min(7 - file, file)]
[7 - (63 - BitOperations.LeadingZeroCount((ulong)piece)) / 8];
piece &= ~Bitboard.Files[file];
}
if (cb.Pieces[White][Queen] == 0)
{
blackScore /= 2;
}
return(whiteScore - blackScore);
}
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);
}