internal MaterialTable()
{
pieceCount[0] = new int[6];
pieceCount[1] = new int[6];
for (int i = 0; i < Constants.MaterialTableSize; i++)
{
entries[i] = new MaterialEntry();
}
}
/// MaterialTable::material_info() takes a position object as input,
/// computes or looks up a MaterialInfo object, and returns a pointer to it.
/// If the material configuration is not already present in the table, it
/// is stored there, so we don't have to recompute everything when the
/// same material configuration occurs again.
internal void probe(Position pos, out MaterialEntry e)
{
Key key = pos.material_key();
e = entries[((UInt32)key) & Constants.MaterialTableMask];
// If mi->key matches the position's material hash key, it means that we
// have analysed this material configuration before, and we can simply
// return the information we found the last time instead of recomputing it.
if (e.key == key)
{
return;
}
// Initialize MaterialInfo entry
Value npm = pos.non_pawn_material(ColorC.WHITE) + pos.non_pawn_material(ColorC.BLACK);
e.value = 0;
e.scalingFunctionWHITE = null; e.scalingFunctionBLACK = null;
e.spaceWeight = 0;
e.key = key;
e.factorWHITE = e.factorBLACK = ScaleFactorC.SCALE_FACTOR_NORMAL;
e.gamePhase = npm >= MidgameLimit ? PhaseC.PHASE_MIDGAME
: npm <= EndgameLimit ? PhaseC.PHASE_ENDGAME
: (((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit));
// Let's look if we have a specialized evaluation function for this
// particular material configuration. First we look for a fixed
// configuration one, then a generic one if previous search failed.
if ((e.evaluationFunction = Endgame.probeValue(key, out e.evaluationFunctionColor)) != null)
{
return;
}
if (is_KXK(ColorC.WHITE, pos))
{
e.evaluationFunction = Endgame.Endgame_KXK;
e.evaluationFunctionColor = ColorC.WHITE;
return;
}
if (is_KXK(ColorC.BLACK, pos))
{
e.evaluationFunction = Endgame.Endgame_KXK;
e.evaluationFunctionColor = ColorC.BLACK;
return;
}
if ((pos.pieces_PT(PieceTypeC.PAWN) == 0) && (pos.pieces_PT(PieceTypeC.ROOK) == 0) && (pos.pieces_PT(PieceTypeC.QUEEN) == 0))
{
// Minor piece endgame with at least one minor piece per side and
// no pawns. Note that the case KmmK is already handled by KXK.
Debug.Assert((pos.pieces_PTC(PieceTypeC.KNIGHT, ColorC.WHITE) | pos.pieces_PTC(PieceTypeC.BISHOP, ColorC.WHITE)) != 0);
Debug.Assert((pos.pieces_PTC(PieceTypeC.KNIGHT, ColorC.BLACK) | pos.pieces_PTC(PieceTypeC.BISHOP, ColorC.BLACK)) != 0);
if (pos.piece_count(ColorC.WHITE, PieceTypeC.BISHOP) + pos.piece_count(ColorC.WHITE, PieceTypeC.KNIGHT) <= 2 &&
pos.piece_count(ColorC.BLACK, PieceTypeC.BISHOP) + pos.piece_count(ColorC.BLACK, PieceTypeC.KNIGHT) <= 2)
{
e.evaluationFunction = Endgame.Endgame_KmmKm;
e.evaluationFunctionColor = pos.sideToMove;
return;
}
}
// OK, we didn't find any special evaluation function for the current
// material configuration. Is there a suitable scaling function?
//
// We face problems when there are several conflicting applicable
// scaling functions and we need to decide which one to use.
EndgameScaleFactor sf;
Color c;
if ((sf = Endgame.probeScaleFactor(key, out c)) != null)
{
if (c == ColorC.WHITE)
{
e.scalingFunctionWHITE = sf;
}
else
{
e.scalingFunctionBLACK = sf;
}
return;
}
// Generic scaling functions that refer to more then one material
// distribution. Should be probed after the specialized ones.
// Note that these ones don't return after setting the function.
if (is_KBPsKs(ColorC.WHITE, pos))
{
e.scalingFunctionWHITE = Endgame.Endgame_KBPsK;
}
if (is_KBPsKs(ColorC.BLACK, pos))
{
e.scalingFunctionBLACK = Endgame.Endgame_KBPsK;
}
if (is_KQKRPs(ColorC.WHITE, pos))
{
e.scalingFunctionWHITE = Endgame.Endgame_KQKRPs;
}
else if (is_KQKRPs(ColorC.BLACK, pos))
{
e.scalingFunctionBLACK = Endgame.Endgame_KQKRPs;
}
Value npm_w = pos.non_pawn_material(ColorC.WHITE);
Value npm_b = pos.non_pawn_material(ColorC.BLACK);
if (npm_w + npm_b == ValueC.VALUE_ZERO)
{
if (pos.piece_count(ColorC.BLACK, PieceTypeC.PAWN) == 0)
{
Debug.Assert(pos.piece_count(ColorC.WHITE, PieceTypeC.PAWN) >= 2);
e.scalingFunctionWHITE = Endgame.Endgame_KPsK;
}
else if (pos.piece_count(ColorC.WHITE, PieceTypeC.PAWN) == 0)
{
Debug.Assert(pos.piece_count(ColorC.BLACK, PieceTypeC.PAWN) >= 2);
e.scalingFunctionBLACK = Endgame.Endgame_KPsK;
}
else if (pos.piece_count(ColorC.WHITE, PieceTypeC.PAWN) == 1 && pos.piece_count(ColorC.BLACK, PieceTypeC.PAWN) == 1)
{
// This is a special case because we set scaling functions
// for both colors instead of only one.
e.scalingFunctionWHITE = Endgame.Endgame_KPKP;
e.scalingFunctionBLACK = Endgame.Endgame_KPKP;
}
}
// No pawns makes it difficult to win, even with a material advantage
if (pos.piece_count(ColorC.WHITE, PieceTypeC.PAWN) == 0 && npm_w - npm_b <= Constants.BishopValueMidgame)
{
e.factorWHITE = (byte)
(npm_w == npm_b || npm_w < Constants.RookValueMidgame ? 0 : NoPawnsSF[Math.Min(pos.piece_count(ColorC.WHITE, PieceTypeC.BISHOP), 2)]);
}
if (pos.piece_count(ColorC.BLACK, PieceTypeC.PAWN) == 0 && npm_b - npm_w <= Constants.BishopValueMidgame)
{
e.factorBLACK = (byte)
(npm_w == npm_b || npm_b < Constants.RookValueMidgame ? 0 : NoPawnsSF[Math.Min(pos.piece_count(ColorC.BLACK, PieceTypeC.BISHOP), 2)]);
}
// Compute the space weight
if (npm_w + npm_b >= 2 * Constants.QueenValueMidgame + 4 * Constants.RookValueMidgame + 2 * Constants.KnightValueMidgame)
{
int minorPieceCount = pos.piece_count(ColorC.WHITE, PieceTypeC.KNIGHT) + pos.piece_count(ColorC.WHITE, PieceTypeC.BISHOP)
+ pos.piece_count(ColorC.BLACK, PieceTypeC.KNIGHT) + pos.piece_count(ColorC.BLACK, PieceTypeC.BISHOP);
e.spaceWeight = minorPieceCount * minorPieceCount;
}
// Evaluate the material imbalance. We use PIECE_TYPE_NONE as a place holder
// for the bishop pair "extended piece", this allow us to be more flexible
// in defining bishop pair bonuses.
pieceCount[0][0] = pos.piece_count(ColorC.WHITE, PieceTypeC.BISHOP) > 1 ? 1 : 0;
pieceCount[0][1] = pos.piece_count(ColorC.WHITE, PieceTypeC.PAWN);
pieceCount[0][2] = pos.piece_count(ColorC.WHITE, PieceTypeC.KNIGHT);
pieceCount[0][3] = pos.piece_count(ColorC.WHITE, PieceTypeC.BISHOP);
pieceCount[0][4] = pos.piece_count(ColorC.WHITE, PieceTypeC.ROOK);
pieceCount[0][5] = pos.piece_count(ColorC.WHITE, PieceTypeC.QUEEN);
pieceCount[1][0] = pos.piece_count(ColorC.BLACK, PieceTypeC.BISHOP) > 1 ? 1 : 0;
pieceCount[1][1] = pos.piece_count(ColorC.BLACK, PieceTypeC.PAWN);
pieceCount[1][2] = pos.piece_count(ColorC.BLACK, PieceTypeC.KNIGHT);
pieceCount[1][3] = pos.piece_count(ColorC.BLACK, PieceTypeC.BISHOP);
pieceCount[1][4] = pos.piece_count(ColorC.BLACK, PieceTypeC.ROOK);
pieceCount[1][5] = pos.piece_count(ColorC.BLACK, PieceTypeC.QUEEN);
e.value = (Int16)((imbalance(ColorC.WHITE) - imbalance(ColorC.BLACK)) / 16);
return;
}