namespace {
- // Values modified by Joona Kiiski
- const Value MidgameLimit = Value(15581);
- const Value EndgameLimit = Value(3998);
-
- // Scale factors used when one side has no more pawns
- const int NoPawnsSF[4] = { 6, 12, 32 };
-
// Polynomial material balance parameters
- // pair pawn knight bishop rook queen
- const int LinearCoefficients[6] = { 1852, -162, -1122, -183, 249, -52 };
+ // pair pawn knight bishop rook queen
+ const int Linear[6] = { 1852, -162, -1122, -183, 249, -154 };
- const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = {
+ const int QuadraticSameSide[][PIECE_TYPE_NB] = {
+ // OUR PIECES
// pair pawn knight bishop rook queen
{ 0 }, // Bishop pair
{ 39, 2 }, // Pawn
- { 35, 271, -4 }, // Knight
+ { 35, 271, -4 }, // Knight OUR PIECES
{ 0, 105, 4, 0 }, // Bishop
{ -27, -2, 46, 100, -141 }, // Rook
- { 58, 29, 83, 148, -163, 0 } // Queen
+ {-177, 25, 129, 142, -137, 0 } // Queen
};
- const int QuadraticCoefficientsOppositeColor[][PIECE_TYPE_NB] = {
+ const int QuadraticOppositeSide[][PIECE_TYPE_NB] = {
// THEIR PIECES
// pair pawn knight bishop rook queen
{ 0 }, // Bishop pair
{ 10, 62, 0 }, // Knight OUR PIECES
{ 57, 64, 39, 0 }, // Bishop
{ 50, 40, 23, -22, 0 }, // Rook
- { 106, 101, 3, 151, 171, 0 } // Queen
+ { 98, 105, -39, 141, 274, 0 } // Queen
};
// Endgame evaluation and scaling functions are accessed directly and not through
// the function maps because they correspond to more than one material hash key.
- Endgame<KmmKm> EvaluateKmmKm[] = { Endgame<KmmKm>(WHITE), Endgame<KmmKm>(BLACK) };
Endgame<KXK> EvaluateKXK[] = { Endgame<KXK>(WHITE), Endgame<KXK>(BLACK) };
Endgame<KBPsK> ScaleKBPsK[] = { Endgame<KBPsK>(WHITE), Endgame<KBPsK>(BLACK) };
// Helper templates used to detect a given material distribution
template<Color Us> bool is_KXK(const Position& pos) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
- return !pos.count<PAWN>(Them)
- && pos.non_pawn_material(Them) == VALUE_ZERO
+ return !more_than_one(pos.pieces(Them))
&& pos.non_pawn_material(Us) >= RookValueMg;
}
const Color Them = (Us == WHITE ? BLACK : WHITE);
- int pt1, pt2, pc, v;
- int value = 0;
+ int bonus = 0;
// Second-degree polynomial material imbalance by Tord Romstad
- for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1)
+ for (int pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1)
{
- pc = pieceCount[Us][pt1];
- if (!pc)
+ if (!pieceCount[Us][pt1])
continue;
- v = LinearCoefficients[pt1];
+ int v = Linear[pt1];
- for (pt2 = NO_PIECE_TYPE; pt2 <= pt1; ++pt2)
- v += QuadraticCoefficientsSameColor[pt1][pt2] * pieceCount[Us][pt2]
- + QuadraticCoefficientsOppositeColor[pt1][pt2] * pieceCount[Them][pt2];
+ for (int pt2 = NO_PIECE_TYPE; pt2 <= pt1; ++pt2)
+ v += QuadraticSameSide[pt1][pt2] * pieceCount[Us][pt2]
+ + QuadraticOppositeSide[pt1][pt2] * pieceCount[Them][pt2];
- value += pc * v;
+ bonus += pieceCount[Us][pt1] * v;
}
- return value;
+
+ return bonus;
}
} // namespace
std::memset(e, 0, sizeof(Entry));
e->key = key;
e->factor[WHITE] = e->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL;
- e->gamePhase = game_phase(pos);
+ e->gamePhase = pos.game_phase();
// Let's look if we have a specialized evaluation function for this particular
// material configuration. Firstly we look for a fixed configuration one, then
return e;
}
- if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN))
- {
- // Minor piece endgame with at least one minor piece per side and
- // no pawns. Note that the case KmmK is already handled by KXK.
- assert((pos.pieces(WHITE, KNIGHT) | pos.pieces(WHITE, BISHOP)));
- assert((pos.pieces(BLACK, KNIGHT) | pos.pieces(BLACK, BISHOP)));
-
- if ( pos.count<BISHOP>(WHITE) + pos.count<KNIGHT>(WHITE) <= 2
- && pos.count<BISHOP>(BLACK) + pos.count<KNIGHT>(BLACK) <= 2)
- {
- e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()];
- return e;
- }
- }
-
// OK, we didn't find any special evaluation function for the current
// material configuration. Is there a suitable scaling function?
//
return e;
}
- // Generic scaling functions that refer to more then one material
+ // Generic scaling functions that refer to more than one material
// distribution. They should be probed after the specialized ones.
// Note that these ones don't return after setting the function.
if (is_KBPsKs<WHITE>(pos))
Value npm_w = pos.non_pawn_material(WHITE);
Value npm_b = pos.non_pawn_material(BLACK);
- if (npm_w + npm_b == VALUE_ZERO)
+ if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN))
{
if (!pos.count<PAWN>(BLACK))
{
}
// No pawns makes it difficult to win, even with a material advantage. This
- // catches some trivial draws like KK, KBK and KNK
+ // catches some trivial draws like KK, KBK and KNK and gives a very drawish
+ // scale factor for cases such as KRKBP and KmmKm (except for KBBKN).
if (!pos.count<PAWN>(WHITE) && npm_w - npm_b <= BishopValueMg)
- {
- e->factor[WHITE] = (uint8_t)
- (npm_w == npm_b || npm_w < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(WHITE), 2)]);
- }
+ e->factor[WHITE] = uint8_t(npm_w < RookValueMg ? SCALE_FACTOR_DRAW : npm_b <= BishopValueMg ? 4 : 12);
if (!pos.count<PAWN>(BLACK) && npm_b - npm_w <= BishopValueMg)
- {
- e->factor[BLACK] = (uint8_t)
- (npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(BLACK), 2)]);
- }
+ e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW : npm_w <= BishopValueMg ? 4 : 12);
if (pos.count<PAWN>(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
- {
e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN;
- }
if (pos.count<PAWN>(BLACK) == 1 && npm_b - npm_w <= BishopValueMg)
- {
e->factor[BLACK] = (uint8_t) SCALE_FACTOR_ONEPAWN;
- }
// Compute the space weight
if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg)
return e;
}
-
-/// Material::game_phase() calculates the phase given the current
-/// position. Because the phase is strictly a function of the material, it
-/// is stored in MaterialEntry.
-
-Phase game_phase(const Position& pos) {
-
- Value npm = pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK);
-
- return npm >= MidgameLimit ? PHASE_MIDGAME
- : npm <= EndgameLimit ? PHASE_ENDGAME
- : Phase(((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit));
-}
-
} // namespace Material
projects / stockfish / blobdiff