/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2009 Marco Costalba
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 <cassert>
+#include <sstream>
#include <map>
-#include "lock.h"
#include "material.h"
+using namespace std;
////
//// Local definitions
namespace {
- const Value BishopPairMidgameBonus = Value(100);
- const Value BishopPairEndgameBonus = Value(100);
+ // Values modified by Joona Kiiski
+ const Value BishopPairMidgameBonus = Value(109);
+ const Value BishopPairEndgameBonus = Value(97);
- Key KNNKMaterialKey, KKNNMaterialKey;
-
- struct ScalingInfo
- {
- Color col;
- ScalingFunction* fun;
- };
-
- std::map<Key, EndgameEvaluationFunction*> EEFmap;
- std::map<Key, ScalingInfo> ESFmap;
-
- Lock EEFmapLock;
- Lock ESFmapLock;
+ // Polynomial material balance parameters
+ const Value RedundantQueenPenalty = Value(358);
+ const Value RedundantRookPenalty = Value(536);
+ const int LinearCoefficients[6] = { 1740, -146, -1246, -197, 206, -7 };
- void add(Key k, EndgameEvaluationFunction* f) {
-
- EEFmap.insert(std::pair<Key, EndgameEvaluationFunction*>(k, f));
- }
-
- void add(Key k, Color c, ScalingFunction* f) {
-
- ScalingInfo s = {c, f};
- ESFmap.insert(std::pair<Key, ScalingInfo>(k, s));
- }
+ const int QuadraticCoefficientsSameColor[][6] = {
+ { 0, 0, 0, 0, 0, 0 }, { 31, -4, 0, 0, 0, 0 }, { 14, 267, -21, 0, 0, 0 },
+ { 0, 7, -26, 0, 0, 0 }, { -3, -1, 69, 162, 80, 0 }, { 40, 27, 119, 174, -64, -49 } };
- // STL map are not guaranteed to be thread safe even
- // for read-access so we need this two helpers to access them.
- EndgameEvaluationFunction* getEEF(Key key) {
+ const int QuadraticCoefficientsOppositeColor[][6] = {
+ { 0, 0, 0, 0, 0, 0 }, { -9, 0, 0, 0, 0, 0 }, { 49, 32, 0, 0, 0, 0 },
+ { -25, 19, -5, 0, 0, 0 }, { 97, -6, 39, -88, 0, 0 }, { 77, 69, -42, 104, 116, 0 } };
- EndgameEvaluationFunction* f = NULL;
-
- lock_grab(&EEFmapLock);
-
- if (EEFmap.find(key) != EEFmap.end())
- f = EEFmap[key];
-
- lock_release(&EEFmapLock);
- return f;
- }
-
- ScalingInfo getESF(Key key) {
-
- ScalingInfo si = {WHITE, NULL};
-
- lock_grab(&ESFmapLock);
-
- if (ESFmap.find(key) != ESFmap.end())
- si = ESFmap[key];
-
- lock_release(&ESFmapLock);
- return si;
- }
+ // Unmapped 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<KBPK> ScaleKBPK(WHITE), ScaleKKBP(BLACK);
+ ScalingFunction<KQKRP> ScaleKQKRP(WHITE), ScaleKRPKQ(BLACK);
+ ScalingFunction<KPsK> ScaleKPsK(WHITE), ScaleKKPs(BLACK);
+ ScalingFunction<KPKP> ScaleKPKPw(WHITE), ScaleKPKPb(BLACK);
+ Key KNNKMaterialKey, KKNNMaterialKey;
}
////
-//// Functions
+//// Classes
////
-/// MaterialInfo::init() is called during program initialization. It
-/// precomputes material hash keys for a few basic endgames, in order
-/// to make it easy to recognize such endgames when they occur.
+typedef EndgameEvaluationFunctionBase EF;
+typedef EndgameScalingFunctionBase SF;
-void MaterialInfo::init() {
+/// See header for a class description. It is declared here to avoid
+/// to include <map> in the header file.
- // Initialize std::map access locks
- lock_init(&EEFmapLock, NULL);
- lock_init(&ESFmapLock, NULL);
+class EndgameFunctions {
+public:
+ EndgameFunctions();
+ ~EndgameFunctions();
+ template<class T> T* get(Key key) const;
- typedef Key ZM[2][8][16];
- const ZM& z = Position::zobMaterial;
+private:
+ template<class T> void add(const string& keyCode);
- static const Color W = WHITE;
- static const Color B = BLACK;
+ static Key buildKey(const string& keyCode);
+ static const string swapColors(const string& keyCode);
- KNNKMaterialKey = z[W][KNIGHT][1] ^ z[W][KNIGHT][2];
- KKNNMaterialKey = z[B][KNIGHT][1] ^ z[B][KNIGHT][2];
+ // Here we store two maps, one for evaluate and one for scaling
+ pair<map<Key, EF*>, map<Key, SF*> > maps;
- add(z[W][PAWN][1], &EvaluateKPK);
- add(z[B][PAWN][1], &EvaluateKKP);
+ // Maps accessing functions for 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; }
+};
- add(z[W][BISHOP][1] ^ z[W][KNIGHT][1], &EvaluateKBNK);
- add(z[B][BISHOP][1] ^ z[B][KNIGHT][1], &EvaluateKKBN);
- add(z[W][ROOK][1] ^ z[B][PAWN][1], &EvaluateKRKP);
- add(z[W][PAWN][1] ^ z[B][ROOK][1], &EvaluateKPKR);
- add(z[W][ROOK][1] ^ z[B][BISHOP][1], &EvaluateKRKB);
- add(z[W][BISHOP][1] ^ z[B][ROOK][1], &EvaluateKBKR);
- add(z[W][ROOK][1] ^ z[B][KNIGHT][1], &EvaluateKRKN);
- add(z[W][KNIGHT][1] ^ z[B][ROOK][1], &EvaluateKNKR);
- add(z[W][QUEEN][1] ^ z[B][ROOK][1], &EvaluateKQKR);
- add(z[W][ROOK][1] ^ z[B][QUEEN][1], &EvaluateKRKQ);
+// 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; }
- add(z[W][KNIGHT][1] ^ z[W][PAWN][1], W, &ScaleKNPK);
- add(z[B][KNIGHT][1] ^ z[B][PAWN][1], B, &ScaleKKNP);
+template<> map<Key, SF*>&
+EndgameFunctions::get<SF>() { return maps.second; }
- add(z[W][ROOK][1] ^ z[W][PAWN][1] ^ z[B][ROOK][1] , W, &ScaleKRPKR);
- add(z[W][ROOK][1] ^ z[B][ROOK][1] ^ z[B][PAWN][1] , B, &ScaleKRKRP);
- add(z[W][BISHOP][1] ^ z[W][PAWN][1] ^ z[B][BISHOP][1], W, &ScaleKBPKB);
- add(z[W][BISHOP][1] ^ z[B][BISHOP][1] ^ z[B][PAWN][1] , B, &ScaleKBKBP);
- add(z[W][BISHOP][1] ^ z[W][PAWN][1] ^ z[B][KNIGHT][1], W, &ScaleKBPKN);
- add(z[W][KNIGHT][1] ^ z[B][BISHOP][1] ^ z[B][PAWN][1] , B, &ScaleKNKBP);
- add(z[W][ROOK][1] ^ z[W][PAWN][1] ^ z[W][PAWN][2] ^ z[B][ROOK][1] ^ z[B][PAWN][1], W, &ScaleKRPPKRP);
- add(z[W][ROOK][1] ^ z[W][PAWN][1] ^ z[B][ROOK][1] ^ z[B][PAWN][1] ^ z[B][PAWN][2], B, &ScaleKRPKRPP);
-}
+////
+//// Functions
+////
/// Constructor for the MaterialInfoTable class
size = numOfEntries;
entries = new MaterialInfo[size];
- if (!entries)
+ funcs = new EndgameFunctions();
+ if (!entries || !funcs)
{
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo))
- << " bytes for material hash table." << std::endl;
- exit(EXIT_FAILURE);
+ cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo))
+ << " bytes for material hash table." << endl;
+ Application::exit_with_failure();
}
- clear();
}
MaterialInfoTable::~MaterialInfoTable() {
+ delete funcs;
delete [] entries;
}
-/// MaterialInfoTable::clear() clears a material hash table by setting
-/// all entries to 0.
-
-void MaterialInfoTable::clear() {
-
- memset(entries, 0, size * sizeof(MaterialInfo));
-}
-
-
/// 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
/// is stored there, so we don't have to recompute everything when the
/// same material configuration occurs again.
-MaterialInfo *MaterialInfoTable::get_material_info(const Position& pos) {
+MaterialInfo* MaterialInfoTable::get_material_info(const Position& pos) {
Key key = pos.get_material_key();
int index = key & (size - 1);
// have analysed this material configuration before, and we can simply
// return the information we found the last time instead of recomputing it.
if (mi->key == key)
- return mi;
+ return mi;
// Clear the MaterialInfo object, and set its key
mi->clear();
// KNN vs K is a draw.
if (key == KNNKMaterialKey || key == KKNNMaterialKey)
{
- mi->factor[WHITE] = mi->factor[BLACK] = 0;
- return mi;
+ mi->factor[WHITE] = mi->factor[BLACK] = 0;
+ return mi;
}
// Let's look if we have a specialized evaluation function for this
- // particular material configuration.
- if ((mi->evaluationFunction = getEEF(key)) != NULL)
+ // particular material configuration. First we look for a fixed
+ // configuration one, then a generic one if previous search failed.
+ if ((mi->evaluationFunction = funcs->get<EF>(key)) != NULL)
return mi;
else if ( pos.non_pawn_material(BLACK) == Value(0)
&& pos.piece_count(BLACK, PAWN) == 0
- && pos.non_pawn_material(WHITE) >= RookValueEndgame)
+ && pos.non_pawn_material(WHITE) >= RookValueMidgame)
{
mi->evaluationFunction = &EvaluateKXK;
return mi;
}
else if ( pos.non_pawn_material(WHITE) == Value(0)
&& pos.piece_count(WHITE, PAWN) == 0
- && pos.non_pawn_material(BLACK) >= RookValueEndgame)
+ && pos.non_pawn_material(BLACK) >= RookValueMidgame)
{
mi->evaluationFunction = &EvaluateKKX;
return mi;
}
+ else if ( pos.pawns() == EmptyBoardBB
+ && pos.rooks() == EmptyBoardBB
+ && pos.queens() == 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));
+
+ if ( pos.piece_count(WHITE, BISHOP) + pos.piece_count(WHITE, KNIGHT) <= 2
+ && pos.piece_count(BLACK, BISHOP) + pos.piece_count(BLACK, KNIGHT) <= 2)
+ {
+ mi->evaluationFunction = &EvaluateKmmKm;
+ return mi;
+ }
+ }
// OK, we didn't find any special evaluation function for the current
// 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.
- ScalingInfo si = getESF(key);
- if (si.fun != NULL)
+ SF* sf;
+
+ if ((sf = funcs->get<SF>(key)) != NULL)
{
- mi->scalingFunction[si.col] = si.fun;
+ mi->scalingFunction[sf->color()] = sf;
return mi;
}
}
}
+ // Compute the space weight
+ if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >=
+ 2*QueenValueMidgame + 4*RookValueMidgame + 2*KnightValueMidgame)
+ {
+ int minorPieceCount = pos.piece_count(WHITE, KNIGHT)
+ + pos.piece_count(BLACK, KNIGHT)
+ + pos.piece_count(WHITE, BISHOP)
+ + pos.piece_count(BLACK, BISHOP);
+
+ mi->spaceWeight = minorPieceCount * minorPieceCount;
+ }
+
// Evaluate the material balance
- Color c;
+ const int bishopsPair_count[2] = { pos.piece_count(WHITE, BISHOP) > 1, pos.piece_count(BLACK, BISHOP) > 1 };
+ Color c, them;
int sign;
- Value egValue = Value(0);
- Value mgValue = Value(0);
+ int matValue = 0;
for (c = WHITE, sign = 1; c <= BLACK; c++, sign = -sign)
{
}
}
- // 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);
-
- // Redundancy of major pieces, again based on Kaufman's paper:
if (pos.piece_count(c, ROOK) >= 1)
+ matValue -= sign * ((pos.piece_count(c, ROOK) - 1) * RedundantRookPenalty + pos.piece_count(c, QUEEN) * RedundantQueenPenalty);
+
+ // 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.
+ them = opposite_color(c);
+ for (PieceType 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;
+ int c1, c2, c3;
+ c1 = sign * (pt1 != NO_PIECE_TYPE ? pos.piece_count(c, pt1) : bishopsPair_count[c]);
+ if (!c1)
+ continue;
+
+ matValue += c1 * LinearCoefficients[pt1];
+
+ for (PieceType pt2 = NO_PIECE_TYPE; pt2 <= pt1; pt2++)
+ {
+ c2 = (pt2 != NO_PIECE_TYPE ? pos.piece_count(c, pt2) : bishopsPair_count[c]);
+ c3 = (pt2 != NO_PIECE_TYPE ? pos.piece_count(them, pt2) : bishopsPair_count[them]);
+ matValue += c1 * c2 * QuadraticCoefficientsSameColor[pt1][pt2];
+ matValue += c1 * c3 * QuadraticCoefficientsOppositeColor[pt1][pt2];
+ }
}
}
- 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 needed
+/// because std::map is not guaranteed to be thread-safe even if accessed
+/// only for a lookup.
+
+EndgameFunctions::EndgameFunctions() {
+
+ KNNKMaterialKey = buildKey("KNNK");
+ KKNNMaterialKey = buildKey("KKNN");
+
+ 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");
+ 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);
+
+ 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.
+ for (size_t i = 0; i < keyCode.length(); i++)
+ {
+ if (keyCode[i] == 'K')
+ upcase = !upcase;
+
+ s << char(upcase? toupper(keyCode[i]) : tolower(keyCode[i]));
+ }
+ s << 8 - keyCode.length() << "/8/8/8/8/8/8/8 w -";
+ return Position(s.str()).get_material_key();
+}
+
+const string EndgameFunctions::swapColors(const string& keyCode) {
+
+ // Build corresponding key for the opposite color: "KBPKN" -> "KNKBP"
+ size_t idx = keyCode.find("K", 1);
+ return keyCode.substr(idx) + keyCode.substr(0, idx);
+}
+
+template<class T>
+void EndgameFunctions::add(const string& keyCode) {
+
+ typedef typename T::Base F;
+
+ get<F>().insert(pair<Key, F*>(buildKey(keyCode), new T(WHITE)));
+ get<F>().insert(pair<Key, F*>(buildKey(swapColors(keyCode)), new T(BLACK)));
+}
+
+template<class T>
+T* EndgameFunctions::get(Key key) const {
+
+ typename map<Key, T*>::const_iterator it(get<T>().find(key));
+ return (it != get<T>().end() ? it->second : NULL);
+}
projects / stockfish / blobdiff