Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
// Polynomial material imbalance parameters
- // pair pawn knight bishop rook queen
- const int Linear[6] = { 1852, -162, -1122, -183, 249, -154 };
-
const int QuadraticOurs[][PIECE_TYPE_NB] = {
// OUR PIECES
// pair pawn knight bishop rook queen
- { 0 }, // Bishop pair
- { 39, 2 }, // Pawn
- { 35, 271, -4 }, // Knight OUR PIECES
- { 0, 105, 4, 0 }, // Bishop
- { -27, -2, 46, 100, -141 }, // Rook
- {-177, 25, 129, 142, -137, 0 } // Queen
+ {1667 }, // Bishop pair
+ { 40, 0 }, // Pawn
+ { 32, 255, -3 }, // Knight OUR PIECES
+ { 0, 104, 4, 0 }, // Bishop
+ { -26, -2, 47, 105, -149 }, // Rook
+ {-185, 24, 122, 137, -134, 0 } // Queen
};
const int QuadraticTheirs[][PIECE_TYPE_NB] = {
// THEIR PIECES
// pair pawn knight bishop rook queen
{ 0 }, // Bishop pair
- { 37, 0 }, // Pawn
- { 10, 62, 0 }, // Knight OUR PIECES
- { 57, 64, 39, 0 }, // Bishop
- { 50, 40, 23, -22, 0 }, // Rook
- { 98, 105, -39, 141, 274, 0 } // Queen
+ { 36, 0 }, // Pawn
+ { 9, 63, 0 }, // Knight OUR PIECES
+ { 59, 65, 42, 0 }, // Bishop
+ { 46, 39, 24, -24, 0 }, // Rook
+ { 101, 100, -37, 141, 268, 0 } // Queen
+ };
+
+ // QueenMinorsImbalance[opp_minor_count] is applied when only one side has a queen.
+ // It contains a bonus/malus for the side with the queen.
+ const int QueenMinorsImbalance[13] = {
+ 31, -8, -15, -25, -5
};
// Endgame evaluation and scaling functions are accessed directly and not through
int bonus = 0;
- // Second-degree polynomial material imbalance by Tord Romstad
+ // Second-degree polynomial material imbalance, by Tord Romstad
for (int pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1)
{
if (!pieceCount[Us][pt1])
continue;
- int v = Linear[pt1];
+ int v = 0;
for (int pt2 = NO_PIECE_TYPE; pt2 <= pt1; ++pt2)
v += QuadraticOurs[pt1][pt2] * pieceCount[Us][pt2]
bonus += pieceCount[Us][pt1] * v;
}
+ // Special handling of Queen vs. Minors
+ if (pieceCount[Us][QUEEN] == 1 && pieceCount[Them][QUEEN] == 0)
+ bonus += QueenMinorsImbalance[pieceCount[Them][KNIGHT] + pieceCount[Them][BISHOP]];
+
return bonus;
}
std::memset(e, 0, sizeof(Entry));
e->key = key;
e->factor[WHITE] = e->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL;
- e->gamePhase = pos.game_phase();
+
+ Value npm_w = pos.non_pawn_material(WHITE);
+ Value npm_b = pos.non_pawn_material(BLACK);
+ Value npm = std::max(EndgameLimit, std::min(npm_w + npm_b, MidgameLimit));
+
+ // Map total non-pawn material into [PHASE_ENDGAME, PHASE_MIDGAME]
+ e->gamePhase = Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit));
// Let's look if we have a specialized evaluation function for this particular
// material configuration. Firstly we look for a fixed configuration one, then
// for a generic one if the previous search failed.
- if (pos.this_thread()->endgames.probe(key, e->evaluationFunction))
+ if ((e->evaluationFunction = pos.this_thread()->endgames.probe<Value>(key)) != nullptr)
return e;
for (Color c = WHITE; c <= BLACK; ++c)
// configuration. Is there a suitable specialized scaling function?
EndgameBase<ScaleFactor>* sf;
- if (pos.this_thread()->endgames.probe(key, sf))
+ if ((sf = pos.this_thread()->endgames.probe<ScaleFactor>(key)) != nullptr)
{
- e->scalingFunction[sf->strong_side()] = sf; // Only strong color assigned
+ e->scalingFunction[sf->strongSide] = sf; // Only strong color assigned
return e;
}
e->scalingFunction[c] = &ScaleKQKRPs[c];
}
- Value npm_w = pos.non_pawn_material(WHITE);
- Value npm_b = pos.non_pawn_material(BLACK);
-
if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN)) // Only pawns on the board
{
if (!pos.count<PAWN>(BLACK))
// 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 < RookValueMg ? SCALE_FACTOR_DRAW :
- npm_b <= BishopValueMg ? 4 : 12);
+ npm_b <= BishopValueMg ? 4 : 14);
if (!pos.count<PAWN>(BLACK) && npm_b - npm_w <= BishopValueMg)
e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW :
- npm_w <= BishopValueMg ? 4 : 12);
+ npm_w <= BishopValueMg ? 4 : 14);
if (pos.count<PAWN>(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN;