X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmaterial.cpp;h=84d7a4bd0a6331327e96735af16a981ea6ac25c8;hb=f3b296c2e2061951d366edfbd5287f336e865553;hp=995a5b541e185e6a0e772e02fb879ba6c832e09a;hpb=490f67a3f89449e243c3e85feb13679f388d9e22;p=stockfish
diff --git a/src/material.cpp b/src/material.cpp
index 995a5b54..84d7a4bd 100644
--- a/src/material.cpp
+++ b/src/material.cpp
@@ -1,7 +1,6 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -17,226 +16,179 @@
along with this program. If not, see .
*/
-#include // For std::min
#include
-#include
+#include // For std::memset
#include "material.h"
+#include "thread.h"
using namespace std;
-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
- const Value RedundantQueen = Value(320);
- const Value RedundantRook = Value(554);
+namespace Stockfish {
- // pair pawn knight bishop rook queen
- const int LinearCoefficients[6] = { 1617, -162, -1172, -190, 105, 26 };
-
- const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = {
- // pair pawn knight bishop rook queen
- { 7 }, // Bishop pair
- { 39, 2 }, // Pawn
- { 35, 271, -4 }, // Knight
- { 7, 105, 4, 7 }, // Bishop
- { -27, -2, 46, 100, 56 }, // Rook
- { 58, 29, 83, 148, -3, -25 } // Queen
+namespace {
+ #define S(mg, eg) make_score(mg, eg)
+
+ // Polynomial material imbalance parameters
+
+ // One Score parameter for each pair (our piece, another of our pieces)
+ constexpr Score QuadraticOurs[][PIECE_TYPE_NB] = {
+ // OUR PIECE 2
+ // bishop pair pawn knight bishop rook queen
+ {S(1419, 1455) }, // Bishop pair
+ {S( 101, 28), S( 37, 39) }, // Pawn
+ {S( 57, 64), S(249, 187), S(-49, -62) }, // Knight OUR PIECE 1
+ {S( 0, 0), S(118, 137), S( 10, 27), S( 0, 0) }, // Bishop
+ {S( -63, -68), S( -5, 3), S(100, 81), S(132, 118), S(-246, -244) }, // Rook
+ {S(-210, -211), S( 37, 14), S(147, 141), S(161, 105), S(-158, -174), S(-9,-31) } // Queen
};
- const int QuadraticCoefficientsOppositeColor[][PIECE_TYPE_NB] = {
- // THEIR PIECES
- // pair pawn knight bishop rook queen
- { 41 }, // Bishop pair
- { 37, 41 }, // Pawn
- { 10, 62, 41 }, // Knight OUR PIECES
- { 57, 64, 39, 41 }, // Bishop
- { 50, 40, 23, -22, 41 }, // Rook
- { 106, 101, 3, 151, 171, 41 } // Queen
+ // One Score parameter for each pair (our piece, their piece)
+ constexpr Score QuadraticTheirs[][PIECE_TYPE_NB] = {
+ // THEIR PIECE
+ // bishop pair pawn knight bishop rook queen
+ { }, // Bishop pair
+ {S( 33, 30) }, // Pawn
+ {S( 46, 18), S(106, 84) }, // Knight OUR PIECE
+ {S( 75, 35), S( 59, 44), S( 60, 15) }, // Bishop
+ {S( 26, 35), S( 6, 22), S( 38, 39), S(-12, -2) }, // Rook
+ {S( 97, 93), S(100, 163), S(-58, -91), S(112, 192), S(276, 225) } // Queen
};
- // Endgame evaluation and scaling functions accessed direcly and not through
- // the function maps because correspond to more then one material hash key.
- Endgame EvaluateKmmKm[] = { Endgame(WHITE), Endgame(BLACK) };
- Endgame EvaluateKXK[] = { Endgame(WHITE), Endgame(BLACK) };
+ #undef S
+
+ // 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 EvaluateKXK[] = { Endgame(WHITE), Endgame(BLACK) };
Endgame ScaleKBPsK[] = { Endgame(WHITE), Endgame(BLACK) };
Endgame ScaleKQKRPs[] = { Endgame(WHITE), Endgame(BLACK) };
Endgame ScaleKPsK[] = { Endgame(WHITE), Endgame(BLACK) };
Endgame ScaleKPKP[] = { Endgame(WHITE), Endgame(BLACK) };
- // Helper templates used to detect a given material distribution
- template bool is_KXK(const Position& pos) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- return !pos.count(Them)
- && pos.non_pawn_material(Them) == VALUE_ZERO
- && pos.non_pawn_material(Us) >= RookValueMg;
+ // Helper used to detect a given material distribution
+ bool is_KXK(const Position& pos, Color us) {
+ return !more_than_one(pos.pieces(~us))
+ && pos.non_pawn_material(us) >= RookValueMg;
}
- template bool is_KBPsKs(const Position& pos) {
- return pos.non_pawn_material(Us) == BishopValueMg
- && pos.count(Us) == 1
- && pos.count(Us) >= 1;
+ bool is_KBPsK(const Position& pos, Color us) {
+ return pos.non_pawn_material(us) == BishopValueMg
+ && pos.count(us) >= 1;
}
- template bool is_KQKRPs(const Position& pos) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- return !pos.count(Us)
- && pos.non_pawn_material(Us) == QueenValueMg
- && pos.count(Us) == 1
- && pos.count(Them) == 1
- && pos.count(Them) >= 1;
+ bool is_KQKRPs(const Position& pos, Color us) {
+ return !pos.count(us)
+ && pos.non_pawn_material(us) == QueenValueMg
+ && pos.count(~us) == 1
+ && pos.count(~us) >= 1;
}
- /// imbalance() calculates imbalance comparing piece count of each
+
+ /// imbalance() calculates the imbalance by comparing the piece count of each
/// piece type for both colors.
template
- int imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
-
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ Score imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
- int pt1, pt2, pc, v;
- int value = 0;
+ constexpr Color Them = ~Us;
- // Redundancy of major pieces, formula based on Kaufman's paper
- // "The Evaluation of Material Imbalances in Chess"
- if (pieceCount[Us][ROOK] > 0)
- value -= RedundantRook * (pieceCount[Us][ROOK] - 1)
- + RedundantQueen * pieceCount[Us][QUEEN];
+ Score bonus = SCORE_ZERO;
- // Second-degree polynomial material imbalance by Tord Romstad
- for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; pt1++)
+ // Second-degree polynomial material imbalance, by Tord Romstad
+ 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 = QuadraticOurs[pt1][pt1] * pieceCount[Us][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 += QuadraticOurs[pt1][pt2] * pieceCount[Us][pt2]
+ + QuadraticTheirs[pt1][pt2] * pieceCount[Them][pt2];
- value += pc * v;
+ bonus += pieceCount[Us][pt1] * v;
}
- return value;
+
+ return bonus;
}
} // namespace
namespace Material {
-/// Material::probe() takes a position object as input, looks up a MaterialEntry
-/// object, and returns a pointer to it. If the material configuration is not
-/// already present in the table, it is computed and stored there, so we don't
-/// have to recompute everything when the same material configuration occurs again.
-Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
+/// Material::probe() looks up the current position's material configuration in
+/// the material hash table. It returns a pointer to the Entry if the position
+/// is found. Otherwise a new Entry is computed and stored there, so we don't
+/// have to recompute all when the same material configuration occurs again.
+
+Entry* probe(const Position& pos) {
Key key = pos.material_key();
- Entry* e = entries[key];
+ Entry* e = pos.this_thread()->materialTable[key];
- // If e->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 e;
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);
-
- // 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 (endgames.probe(key, e->evaluationFunction))
- return e;
- if (is_KXK(pos))
- {
- e->evaluationFunction = &EvaluateKXK[WHITE];
- return e;
- }
+ Value npm_w = pos.non_pawn_material(WHITE);
+ Value npm_b = pos.non_pawn_material(BLACK);
+ Value npm = std::clamp(npm_w + npm_b, EndgameLimit, MidgameLimit);
- if (is_KXK(pos))
- {
- e->evaluationFunction = &EvaluateKXK[BLACK];
- return e;
- }
+ // Map total non-pawn material into [PHASE_ENDGAME, PHASE_MIDGAME]
+ e->gamePhase = Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit));
- // Draw by insufficient material (trivial draws like KK, KBK and KNK)
- if ( !pos.pieces(PAWN)
- && pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) <= BishopValueMg)
- {
- e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()];
+ // 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 ((e->evaluationFunction = Endgames::probe(key)) != nullptr)
return e;
- }
-
- // Minor piece endgame with at least one minor piece per side and
- // no pawns. Note that the case KmmK is already handled by KXK.
- if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN))
- {
- assert((pos.pieces(WHITE, KNIGHT) | pos.pieces(WHITE, BISHOP)));
- assert((pos.pieces(BLACK, KNIGHT) | pos.pieces(BLACK, BISHOP)));
- if ( pos.count(WHITE) + pos.count(WHITE) <= 2
- && pos.count(BLACK) + pos.count(BLACK) <= 2)
+ for (Color c : { WHITE, BLACK })
+ if (is_KXK(pos, c))
{
- e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()];
+ e->evaluationFunction = &EvaluateKXK[c];
return e;
}
- }
- // 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.
- EndgameBase* sf;
+ // OK, we didn't find any special evaluation function for the current material
+ // configuration. Is there a suitable specialized scaling function?
+ const auto* sf = Endgames::probe(key);
- if (endgames.probe(key, sf))
+ if (sf)
{
- e->scalingFunction[sf->color()] = sf;
+ e->scalingFunction[sf->strongSide] = sf; // Only strong color assigned
return e;
}
- // 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(pos))
- e->scalingFunction[WHITE] = &ScaleKBPsK[WHITE];
-
- if (is_KBPsKs(pos))
- e->scalingFunction[BLACK] = &ScaleKBPsK[BLACK];
-
- if (is_KQKRPs(pos))
- e->scalingFunction[WHITE] = &ScaleKQKRPs[WHITE];
-
- else if (is_KQKRPs(pos))
- e->scalingFunction[BLACK] = &ScaleKQKRPs[BLACK];
+ // We didn't find any specialized scaling function, so fall back on generic
+ // ones that refer to more than one material distribution. Note that in this
+ // case we don't return after setting the function.
+ for (Color c : { WHITE, BLACK })
+ {
+ if (is_KBPsK(pos, c))
+ e->scalingFunction[c] = &ScaleKBPsK[c];
- Value npm_w = pos.non_pawn_material(WHITE);
- Value npm_b = pos.non_pawn_material(BLACK);
+ else if (is_KQKRPs(pos, c))
+ e->scalingFunction[c] = &ScaleKQKRPs[c];
+ }
- if (npm_w + npm_b == VALUE_ZERO)
+ if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN)) // Only pawns on the board
{
if (!pos.count(BLACK))
{
assert(pos.count(WHITE) >= 2);
+
e->scalingFunction[WHITE] = &ScaleKPsK[WHITE];
}
else if (!pos.count(WHITE))
{
assert(pos.count(BLACK) >= 2);
+
e->scalingFunction[BLACK] = &ScaleKPsK[BLACK];
}
else if (pos.count(WHITE) == 1 && pos.count(BLACK) == 1)
@@ -248,30 +200,19 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
}
}
- // No pawns makes it difficult to win, even with a material advantage
+ // Zero or just one pawn makes it difficult to win, even with a small material
+ // advantage. This catches some trivial draws like KK, KBK and KNK and gives a
+ // drawish scale factor for cases such as KRKBP and KmmKm (except for KBBKN).
if (!pos.count(WHITE) && npm_w - npm_b <= BishopValueMg)
- {
- e->factor[WHITE] = (uint8_t)
- (npm_w == npm_b || npm_w < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count(WHITE), 2)]);
- }
+ e->factor[WHITE] = uint8_t(npm_w < RookValueMg ? SCALE_FACTOR_DRAW :
+ npm_b <= BishopValueMg ? 4 : 14);
if (!pos.count(BLACK) && npm_b - npm_w <= BishopValueMg)
- {
- e->factor[BLACK] = (uint8_t)
- (npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count(BLACK), 2)]);
- }
-
- // Compute the space weight
- if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg)
- {
- int minorPieceCount = pos.count(WHITE) + pos.count(WHITE)
- + pos.count(BLACK) + pos.count(BLACK);
-
- e->spaceWeight = make_score(minorPieceCount * minorPieceCount, 0);
- }
+ e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW :
+ npm_w <= BishopValueMg ? 4 : 14);
// 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
+ // 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] = {
{ pos.count(WHITE) > 1, pos.count(WHITE), pos.count(WHITE),
@@ -279,22 +220,10 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
{ pos.count(BLACK) > 1, pos.count(BLACK), pos.count(BLACK),
pos.count(BLACK) , pos.count(BLACK), pos.count(BLACK) } };
- e->value = (int16_t)((imbalance(pieceCount) - imbalance(pieceCount)) / 16);
+ e->score = (imbalance(pieceCount) - imbalance(pieceCount)) / 16;
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
+
+} // namespace Stockfish