/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, 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
#include "material.h"
-using std::string;
+using namespace std;
+
////
//// Local definitions
namespace {
// Values modified by Joona Kiiski
- const Value BishopPairMidgameBonus = Value(109);
- const Value BishopPairEndgameBonus = Value(97);
-
- Key KNNKMaterialKey, KKNNMaterialKey;
-
+ const Value MidgameLimit = Value(15581);
+ const Value EndgameLimit = Value(3998);
+
+ // Polynomial material balance parameters
+ const Value RedundantQueenPenalty = Value(320);
+ const Value RedundantRookPenalty = Value(554);
+
+ const int LinearCoefficients[6] = { 1617, -162, -1172, -190, 105, 26 };
+
+ const int QuadraticCoefficientsSameColor[][6] = {
+ { 7, 7, 7, 7, 7, 7 }, { 39, 2, 7, 7, 7, 7 }, { 35, 271, -4, 7, 7, 7 },
+ { 7, 25, 4, 7, 7, 7 }, { -27, -2, 46, 100, 56, 7 }, { 58, 29, 83, 148, -3, -25 } };
+
+ const int QuadraticCoefficientsOppositeColor[][6] = {
+ { 41, 41, 41, 41, 41, 41 }, { 37, 41, 41, 41, 41, 41 }, { 10, 62, 41, 41, 41, 41 },
+ { 57, 64, 39, 41, 41, 41 }, { 50, 40, 23, -22, 41, 41 }, { 106, 101, 3, 151, 171, 41 } };
+
+ // Named endgame evaluation and scaling functions, these
+ // are accessed direcly and not through the function maps.
+ EvaluationFunction<KmmKm> EvaluateKmmKm(WHITE);
+ EvaluationFunction<KXK> EvaluateKXK(WHITE), EvaluateKKX(BLACK);
+ ScalingFunction<KBPsK> ScaleKBPsK(WHITE), ScaleKKBPs(BLACK);
+ ScalingFunction<KQKRPs> ScaleKQKRPs(WHITE), ScaleKRPsKQ(BLACK);
+ ScalingFunction<KPsK> ScaleKPsK(WHITE), ScaleKKPs(BLACK);
+ ScalingFunction<KPKP> ScaleKPKPw(WHITE), ScaleKPKPb(BLACK);
+
+ typedef EndgameEvaluationFunctionBase EF;
+ typedef EndgameScalingFunctionBase SF;
}
+
////
//// Classes
////
-
-/// See header for a class description. It is declared here to avoid
-/// to include <map> in the header file.
+/// EndgameFunctions class stores endgame evaluation and scaling functions
+/// in two std::map. Because STL library is not guaranteed to be thread
+/// safe even for read access, the maps, although with identical content,
+/// are replicated for each thread. This is faster then using locks.
class EndgameFunctions {
-
public:
EndgameFunctions();
- EndgameEvaluationFunctionBase* getEEF(Key key) const;
- EndgameScalingFunctionBase* getESF(Key key, Color* c) const;
+ ~EndgameFunctions();
+ template<class T> T* get(Key key) const;
private:
- void add(const string& keyCode, EndgameEvaluationFunctionBase* f);
- void add(const string& keyCode, Color c, EndgameScalingFunctionBase* f);
- Key buildKey(const string& keyCode);
+ template<class T> void add(const string& keyCode);
- struct ScalingInfo
- {
- Color col;
- EndgameScalingFunctionBase* fun;
- };
+ static Key buildKey(const string& keyCode);
+ static const string swapColors(const string& keyCode);
+
+ // Here we store two maps, for evaluate and scaling functions
+ pair<map<Key, EF*>, map<Key, SF*> > maps;
- std::map<Key, EndgameEvaluationFunctionBase*> EEFmap;
- std::map<Key, ScalingInfo> ESFmap;
+ // Maps accessing functions returning const and non-const references
+ template<typename T> const map<Key, T*>& get() const { return maps.first; }
+ template<typename T> map<Key, T*>& get() { return maps.first; }
};
+// Explicit specializations of a member function shall be declared in
+// the namespace of which the class template is a member.
+template<> const map<Key, SF*>&
+EndgameFunctions::get<SF>() const { return maps.second; }
+
+template<> map<Key, SF*>&
+EndgameFunctions::get<SF>() { return maps.second; }
+
////
//// Functions
////
-
-/// Constructor for the MaterialInfoTable class
+/// MaterialInfoTable c'tor and d'tor, called once by each thread
MaterialInfoTable::MaterialInfoTable(unsigned int numOfEntries) {
size = numOfEntries;
entries = new MaterialInfo[size];
funcs = new EndgameFunctions();
+
if (!entries || !funcs)
{
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo))
- << " bytes for material hash table." << std::endl;
+ cerr << "Failed to allocate " << numOfEntries * sizeof(MaterialInfo)
+ << " bytes for material hash table." << endl;
Application::exit_with_failure();
}
}
-
-/// Destructor for the MaterialInfoTable class
-
MaterialInfoTable::~MaterialInfoTable() {
delete funcs;
}
+/// MaterialInfoTable::game_phase() calculates the phase given the current
+/// position. Because the phase is strictly a function of the material, it
+/// is stored in MaterialInfo.
+
+Phase MaterialInfoTable::game_phase(const Position& pos) {
+
+ Value npm = pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK);
+
+ if (npm >= MidgameLimit)
+ return PHASE_MIDGAME;
+ else if (npm <= EndgameLimit)
+ return PHASE_ENDGAME;
+
+ return Phase(((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit));
+}
+
/// MaterialInfoTable::get_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
mi->clear();
mi->key = key;
- // A special case before looking for a specialized evaluation function
- // KNN vs K is a draw.
- if (key == KNNKMaterialKey || key == KKNNMaterialKey)
- {
- mi->factor[WHITE] = mi->factor[BLACK] = 0;
- return mi;
- }
+ // Store game phase
+ mi->gamePhase = MaterialInfoTable::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 ((mi->evaluationFunction = funcs->getEEF(key)) != NULL)
+ if ((mi->evaluationFunction = funcs->get<EF>(key)) != NULL)
return mi;
else if ( pos.non_pawn_material(BLACK) == Value(0)
mi->evaluationFunction = &EvaluateKKX;
return mi;
}
- else if ( pos.pawns() == EmptyBoardBB
- && pos.rooks() == EmptyBoardBB
- && pos.queens() == EmptyBoardBB)
+ else if ( pos.pieces(PAWN) == EmptyBoardBB
+ && pos.pieces(ROOK) == EmptyBoardBB
+ && pos.pieces(QUEEN) == EmptyBoardBB)
{
- // Minor piece endgame with at least one minor piece per side,
- // and no pawns.
- assert(pos.knights(WHITE) | pos.bishops(WHITE));
- assert(pos.knights(BLACK) | pos.bishops(BLACK));
+ // 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(KNIGHT, WHITE) | pos.pieces(BISHOP, WHITE)));
+ assert((pos.pieces(KNIGHT, BLACK) | pos.pieces(BISHOP, BLACK)));
if ( pos.piece_count(WHITE, BISHOP) + pos.piece_count(WHITE, KNIGHT) <= 2
&& pos.piece_count(BLACK, BISHOP) + pos.piece_count(BLACK, KNIGHT) <= 2)
// material configuration. Is there a suitable scaling function?
//
// The code below is rather messy, and it could easily get worse later,
- // if we decide to add more special cases. We face problems when there
+ // if we decide to add more special cases. We face problems when there
// are several conflicting applicable scaling functions and we need to
// decide which one to use.
- Color c;
- EndgameScalingFunctionBase* sf;
+ SF* sf;
- if ((sf = funcs->getESF(key, &c)) != NULL)
+ if ((sf = funcs->get<SF>(key)) != NULL)
{
- mi->scalingFunction[c] = sf;
+ mi->scalingFunction[sf->color()] = sf;
return mi;
}
+ // 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 ( pos.non_pawn_material(WHITE) == BishopValueMidgame
&& pos.piece_count(WHITE, BISHOP) == 1
&& pos.piece_count(WHITE, PAWN) >= 1)
- mi->scalingFunction[WHITE] = &ScaleKBPK;
+ mi->scalingFunction[WHITE] = &ScaleKBPsK;
if ( pos.non_pawn_material(BLACK) == BishopValueMidgame
&& pos.piece_count(BLACK, BISHOP) == 1
&& pos.piece_count(BLACK, PAWN) >= 1)
- mi->scalingFunction[BLACK] = &ScaleKKBP;
+ mi->scalingFunction[BLACK] = &ScaleKKBPs;
if ( pos.piece_count(WHITE, PAWN) == 0
&& pos.non_pawn_material(WHITE) == QueenValueMidgame
&& pos.piece_count(WHITE, QUEEN) == 1
&& pos.piece_count(BLACK, ROOK) == 1
&& pos.piece_count(BLACK, PAWN) >= 1)
- mi->scalingFunction[WHITE] = &ScaleKQKRP;
+ mi->scalingFunction[WHITE] = &ScaleKQKRPs;
else if ( pos.piece_count(BLACK, PAWN) == 0
&& pos.non_pawn_material(BLACK) == QueenValueMidgame
&& pos.piece_count(BLACK, QUEEN) == 1
&& pos.piece_count(WHITE, ROOK) == 1
&& pos.piece_count(WHITE, PAWN) >= 1)
- mi->scalingFunction[BLACK] = &ScaleKRPKQ;
+ mi->scalingFunction[BLACK] = &ScaleKRPsKQ;
if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) == Value(0))
{
}
else if (pos.piece_count(WHITE, PAWN) == 1 && pos.piece_count(BLACK, PAWN) == 1)
{
+ // This is a special case because we set scaling functions
+ // for both colors instead of only one.
mi->scalingFunction[WHITE] = &ScaleKPKPw;
mi->scalingFunction[BLACK] = &ScaleKPKPb;
}
}
// Evaluate the material balance
-
- int sign;
- Value egValue = Value(0);
- Value mgValue = Value(0);
+ const int pieceCount[2][6] = { { pos.piece_count(WHITE, BISHOP) > 1, pos.piece_count(WHITE, PAWN), pos.piece_count(WHITE, KNIGHT),
+ pos.piece_count(WHITE, BISHOP), pos.piece_count(WHITE, ROOK), pos.piece_count(WHITE, QUEEN) },
+ { pos.piece_count(BLACK, BISHOP) > 1, pos.piece_count(BLACK, PAWN), pos.piece_count(BLACK, KNIGHT),
+ pos.piece_count(BLACK, BISHOP), pos.piece_count(BLACK, ROOK), pos.piece_count(BLACK, QUEEN) } };
+ Color c, them;
+ int sign, pt1, pt2, pc;
+ int v, vv, matValue = 0;
for (c = WHITE, sign = 1; c <= BLACK; c++, sign = -sign)
{
{
if ( pos.non_pawn_material(c) == pos.non_pawn_material(opposite_color(c))
|| pos.non_pawn_material(c) < RookValueMidgame)
- mi->factor[c] = 0;
+ mi->factor[c] = SCALE_FACTOR_ZERO;
else
{
switch (pos.piece_count(c, BISHOP)) {
}
}
- // Bishop pair
- if (pos.piece_count(c, BISHOP) >= 2)
- {
- mgValue += sign * BishopPairMidgameBonus;
- egValue += sign * BishopPairEndgameBonus;
- }
-
- // Knights are stronger when there are many pawns on the board. The
- // formula is taken from Larry Kaufman's paper "The Evaluation of Material
- // Imbalances in Chess":
+ // Redundancy of major pieces, formula based on Kaufman's paper
+ // "The Evaluation of Material Imbalances in Chess"
// http://mywebpages.comcast.net/danheisman/Articles/evaluation_of_material_imbalance.htm
- mgValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16);
- egValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16);
+ if (pieceCount[c][ROOK] >= 1)
+ matValue -= sign * ((pieceCount[c][ROOK] - 1) * RedundantRookPenalty + pieceCount[c][QUEEN] * RedundantQueenPenalty);
- // Redundancy of major pieces, again based on Kaufman's paper:
- if (pos.piece_count(c, ROOK) >= 1)
+ them = opposite_color(c);
+ v = 0;
+
+ // Second-degree polynomial material imbalance by Tord Romstad
+ //
+ // We use NO_PIECE_TYPE as a place holder for the bishop pair "extended piece",
+ // this allow us to be more flexible in defining bishop pair bonuses.
+ for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; pt1++)
{
- Value v = Value((pos.piece_count(c, ROOK) - 1) * 32 + pos.piece_count(c, QUEEN) * 16);
- mgValue -= sign * v;
- egValue -= sign * v;
+ pc = pieceCount[c][pt1];
+ if (!pc)
+ continue;
+
+ vv = LinearCoefficients[pt1];
+
+ for (pt2 = NO_PIECE_TYPE; pt2 <= pt1; pt2++)
+ vv += pieceCount[c][pt2] * QuadraticCoefficientsSameColor[pt1][pt2]
+ + pieceCount[them][pt2] * QuadraticCoefficientsOppositeColor[pt1][pt2];
+
+ v += pc * vv;
}
+ matValue += sign * v;
}
- mi->mgValue = int16_t(mgValue);
- mi->egValue = int16_t(egValue);
+ mi->value = int16_t(matValue / 16);
return mi;
}
-/// EndgameFunctions member definitions. This class is used to store the maps
-/// of end game and scaling functions that MaterialInfoTable will query for
-/// each key. The maps are constant and are populated only at construction,
-/// but are per-thread instead of globals to avoid expensive locks.
+/// EndgameFunctions member definitions.
EndgameFunctions::EndgameFunctions() {
- KNNKMaterialKey = buildKey("KNNK");
- KKNNMaterialKey = buildKey("KKNN");
-
- add("KPK", &EvaluateKPK);
- add("KKP", &EvaluateKKP);
- add("KBNK", &EvaluateKBNK);
- add("KKBN", &EvaluateKKBN);
- add("KRKP", &EvaluateKRKP);
- add("KPKR", &EvaluateKPKR);
- add("KRKB", &EvaluateKRKB);
- add("KBKR", &EvaluateKBKR);
- add("KRKN", &EvaluateKRKN);
- add("KNKR", &EvaluateKNKR);
- add("KQKR", &EvaluateKQKR);
- add("KRKQ", &EvaluateKRKQ);
- add("KBBKN", &EvaluateKBBKN);
- add("KNKBB", &EvaluateKNKBB);
-
- add("KNPK", WHITE, &ScaleKNPK);
- add("KKNP", BLACK, &ScaleKKNP);
- add("KRPKR", WHITE, &ScaleKRPKR);
- add("KRKRP", BLACK, &ScaleKRKRP);
- add("KBPKB", WHITE, &ScaleKBPKB);
- add("KBKBP", BLACK, &ScaleKBKBP);
- add("KBPPKB", WHITE, &ScaleKBPPKB);
- add("KBKBPP", BLACK, &ScaleKBKBPP);
- add("KBPKN", WHITE, &ScaleKBPKN);
- add("KNKBP", BLACK, &ScaleKNKBP);
- add("KRPPKRP", WHITE, &ScaleKRPPKRP);
- add("KRPKRPP", BLACK, &ScaleKRPKRPP);
- add("KRPPKRP", WHITE, &ScaleKRPPKRP);
- add("KRPKRPP", BLACK, &ScaleKRPKRPP);
+ add<EvaluationFunction<KNNK> >("KNNK");
+ add<EvaluationFunction<KPK> >("KPK");
+ add<EvaluationFunction<KBNK> >("KBNK");
+ add<EvaluationFunction<KRKP> >("KRKP");
+ add<EvaluationFunction<KRKB> >("KRKB");
+ add<EvaluationFunction<KRKN> >("KRKN");
+ add<EvaluationFunction<KQKR> >("KQKR");
+ add<EvaluationFunction<KBBKN> >("KBBKN");
+
+ add<ScalingFunction<KNPK> >("KNPK");
+ add<ScalingFunction<KRPKR> >("KRPKR");
+ add<ScalingFunction<KBPKB> >("KBPKB");
+ add<ScalingFunction<KBPPKB> >("KBPPKB");
+ add<ScalingFunction<KBPKN> >("KBPKN");
+ add<ScalingFunction<KRPPKRP> >("KRPPKRP");
+}
+
+EndgameFunctions::~EndgameFunctions() {
+
+ for (map<Key, EF*>::iterator it = maps.first.begin(); it != maps.first.end(); ++it)
+ delete (*it).second;
+
+ for (map<Key, SF*>::iterator it = maps.second.begin(); it != maps.second.end(); ++it)
+ delete (*it).second;
}
Key EndgameFunctions::buildKey(const string& keyCode) {
assert(keyCode.length() > 0 && keyCode[0] == 'K');
assert(keyCode.length() < 8);
- std::stringstream s;
+ stringstream s;
bool upcase = false;
- // Build up a fen substring with the given pieces, note
- // that the fen string could be of an illegal position.
+ // Build up a fen string with the given pieces, note that
+ // the fen string could be of an illegal position.
for (size_t i = 0; i < keyCode.length(); i++)
{
if (keyCode[i] == 'K')
return Position(s.str()).get_material_key();
}
-void EndgameFunctions::add(const string& keyCode, EndgameEvaluationFunctionBase* f) {
+const string EndgameFunctions::swapColors(const string& keyCode) {
- EEFmap.insert(std::pair<Key, EndgameEvaluationFunctionBase*>(buildKey(keyCode), f));
+ // Build corresponding key for the opposite color: "KBPKN" -> "KNKBP"
+ size_t idx = keyCode.find("K", 1);
+ return keyCode.substr(idx) + keyCode.substr(0, idx);
}
-void EndgameFunctions::add(const string& keyCode, Color c, EndgameScalingFunctionBase* f) {
-
- ScalingInfo s = {c, f};
- ESFmap.insert(std::pair<Key, ScalingInfo>(buildKey(keyCode), s));
-}
+template<class T>
+void EndgameFunctions::add(const string& keyCode) {
-EndgameEvaluationFunctionBase* EndgameFunctions::getEEF(Key key) const {
+ typedef typename T::Base F;
- std::map<Key, EndgameEvaluationFunctionBase*>::const_iterator it(EEFmap.find(key));
- return (it != EEFmap.end() ? it->second : NULL);
+ get<F>().insert(pair<Key, F*>(buildKey(keyCode), new T(WHITE)));
+ get<F>().insert(pair<Key, F*>(buildKey(swapColors(keyCode)), new T(BLACK)));
}
-EndgameScalingFunctionBase* EndgameFunctions::getESF(Key key, Color* c) const {
-
- std::map<Key, ScalingInfo>::const_iterator it(ESFmap.find(key));
- if (it == ESFmap.end())
- return NULL;
+template<class T>
+T* EndgameFunctions::get(Key key) const {
- *c = it->second.col;
- return it->second.fun;
+ typename map<Key, T*>::const_iterator it(get<T>().find(key));
+ return (it != get<T>().end() ? it->second : NULL);
}
projects / stockfish / blobdiff