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) 2015-2019 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] = {
+ constexpr 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
+ {1438 }, // Bishop pair
+ { 40, 38 }, // Pawn
+ { 32, 255, -62 }, // Knight OUR PIECES
+ { 0, 104, 4, 0 }, // Bishop
+ { -26, -2, 47, 105, -208 }, // Rook
+ {-189, 24, 117, 133, -134, -6 } // Queen
};
- const int QuadraticTheirs[][PIECE_TYPE_NB] = {
+ constexpr 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
+ { 97, 100, -42, 137, 268, 0 } // Queen
};
// Endgame evaluation and scaling functions are accessed directly and not through
&& pos.non_pawn_material(us) >= RookValueMg;
}
- bool is_KBPsKs(const Position& pos, Color us) {
+ bool is_KBPsK(const Position& pos, Color us) {
return pos.non_pawn_material(us) == BishopValueMg
&& pos.count<BISHOP>(us) == 1
&& pos.count<PAWN >(us) >= 1;
bool is_KQKRPs(const Position& pos, Color us) {
return !pos.count<PAWN>(us)
&& pos.non_pawn_material(us) == QueenValueMg
- && pos.count<QUEEN>(us) == 1
+ && pos.count<QUEEN>(us) == 1
&& pos.count<ROOK>(~us) == 1
&& pos.count<PAWN>(~us) >= 1;
}
template<Color Us>
int imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
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]
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
// OK, we didn't find any special evaluation function for the current material
// configuration. Is there a suitable specialized scaling function?
- EndgameBase<ScaleFactor>* sf;
+ const EndgameBase<ScaleFactor>* 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;
}
// case we don't return after setting the function.
for (Color c = WHITE; c <= BLACK; ++c)
{
- if (is_KBPsKs(pos, c))
+ if (is_KBPsK(pos, c))
e->scalingFunction[c] = &ScaleKBPsK[c];
else if (is_KQKRPs(pos, c))
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);
-
- 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;
+ npm_w <= BishopValueMg ? 4 : 14);
// Evaluate the material imbalance. We use PIECE_TYPE_NONE as a place holder
// for the bishop pair "extended piece", which allows us to be more flexible
// in defining bishop pair bonuses.
- const int PieceCount[COLOR_NB][PIECE_TYPE_NB] = {
+ const int pieceCount[COLOR_NB][PIECE_TYPE_NB] = {
{ pos.count<BISHOP>(WHITE) > 1, pos.count<PAWN>(WHITE), pos.count<KNIGHT>(WHITE),
pos.count<BISHOP>(WHITE) , pos.count<ROOK>(WHITE), pos.count<QUEEN >(WHITE) },
{ pos.count<BISHOP>(BLACK) > 1, pos.count<PAWN>(BLACK), pos.count<KNIGHT>(BLACK),
pos.count<BISHOP>(BLACK) , pos.count<ROOK>(BLACK), pos.count<QUEEN >(BLACK) } };
- e->value = int16_t((imbalance<WHITE>(PieceCount) - imbalance<BLACK>(PieceCount)) / 16);
+ e->value = int16_t((imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16);
return e;
}