/*
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) 2008-2010 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
#include <cassert>
-#include <map>
+#include <cstring>
+#include <algorithm>
-#include "lock.h"
#include "material.h"
-
-////
-//// Local definitions
-////
+using namespace std;
namespace {
- const Value BishopPairMidgameBonus = Value(100);
- const Value BishopPairEndgameBonus = Value(100);
+ // Values modified by Joona Kiiski
+ const Value MidgameLimit = Value(15581);
+ const Value EndgameLimit = Value(3998);
- Key KNNKMaterialKey, KKNNMaterialKey;
+ // Scale factors used when one side has no more pawns
+ const int NoPawnsSF[4] = { 6, 12, 32 };
- struct ScalingInfo
- {
- Color col;
- ScalingFunction* fun;
- };
+ // Polynomial material balance parameters
+ const Value RedundantQueenPenalty = Value(320);
+ const Value RedundantRookPenalty = Value(554);
- std::map<Key, EndgameEvaluationFunction*> EEFmap;
- std::map<Key, ScalingInfo> ESFmap;
+ const int LinearCoefficients[6] = { 1617, -162, -1172, -190, 105, 26 };
- Lock EEFmapLock;
- Lock ESFmapLock;
+ const int QuadraticCoefficientsSameColor[][8] = {
+ { 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 } };
- void add(Key k, EndgameEvaluationFunction* f) {
+ const int QuadraticCoefficientsOppositeColor[][8] = {
+ { 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 } };
- EEFmap.insert(std::pair<Key, EndgameEvaluationFunction*>(k, f));
- }
+ // Endgame evaluation and scaling functions accessed direcly and not through
+ // the function maps because correspond to more then one material hash key.
+ Endgame<KmmKm> EvaluateKmmKm[] = { Endgame<KmmKm>(WHITE), Endgame<KmmKm>(BLACK) };
+ Endgame<KXK> EvaluateKXK[] = { Endgame<KXK>(WHITE), Endgame<KXK>(BLACK) };
- void add(Key k, Color c, ScalingFunction* f) {
+ Endgame<KBPsK> ScaleKBPsK[] = { Endgame<KBPsK>(WHITE), Endgame<KBPsK>(BLACK) };
+ Endgame<KQKRPs> ScaleKQKRPs[] = { Endgame<KQKRPs>(WHITE), Endgame<KQKRPs>(BLACK) };
+ Endgame<KPsK> ScaleKPsK[] = { Endgame<KPsK>(WHITE), Endgame<KPsK>(BLACK) };
+ Endgame<KPKP> ScaleKPKP[] = { Endgame<KPKP>(WHITE), Endgame<KPKP>(BLACK) };
- ScalingInfo s = {c, f};
- ESFmap.insert(std::pair<Key, ScalingInfo>(k, s));
+ // Helper templates used to detect a given material distribution
+ template<Color Us> bool is_KXK(const Position& pos) {
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ return pos.non_pawn_material(Them) == VALUE_ZERO
+ && pos.piece_count(Them, PAWN) == 0
+ && pos.non_pawn_material(Us) >= RookValueMidgame;
}
- // 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) {
-
- EndgameEvaluationFunction* f = NULL;
-
- lock_grab(&EEFmapLock);
-
- std::map<Key, EndgameEvaluationFunction*>::iterator it(EEFmap.find(key));
- if (it != EEFmap.end())
- f = it->second;
-
- lock_release(&EEFmapLock);
- return f;
+ template<Color Us> bool is_KBPsKs(const Position& pos) {
+ return pos.non_pawn_material(Us) == BishopValueMidgame
+ && pos.piece_count(Us, BISHOP) == 1
+ && pos.piece_count(Us, PAWN) >= 1;
}
- ScalingInfo getESF(Key key) {
-
- ScalingInfo si = {WHITE, NULL};
-
- lock_grab(&ESFmapLock);
-
- std::map<Key, ScalingInfo>::iterator it(ESFmap.find(key));
- if (it != ESFmap.end())
- si = it->second;
-
- lock_release(&ESFmapLock);
- return si;
- }
-
-}
-
-
-////
-//// Functions
-////
-
-/// 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.
-
-void MaterialInfo::init() {
-
- // Initialize std::map access locks
- lock_init(&EEFmapLock, NULL);
- lock_init(&ESFmapLock, NULL);
-
- typedef Key ZM[2][8][16];
- const ZM& z = Position::zobMaterial;
-
- static const Color W = WHITE;
- static const Color B = BLACK;
-
- KNNKMaterialKey = z[W][KNIGHT][1] ^ z[W][KNIGHT][2];
- KKNNMaterialKey = z[B][KNIGHT][1] ^ z[B][KNIGHT][2];
-
- add(z[W][PAWN][1], &EvaluateKPK);
- add(z[B][PAWN][1], &EvaluateKKP);
-
- 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);
-
- add(z[W][KNIGHT][1] ^ z[W][PAWN][1], W, &ScaleKNPK);
- add(z[B][KNIGHT][1] ^ z[B][PAWN][1], B, &ScaleKKNP);
-
- 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);
-}
-
-
-/// Constructor for the MaterialInfoTable class
-
-MaterialInfoTable::MaterialInfoTable(unsigned int numOfEntries) {
-
- size = numOfEntries;
- entries = new MaterialInfo[size];
- if (!entries)
- {
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo))
- << " bytes for material hash table." << std::endl;
- exit(EXIT_FAILURE);
+ template<Color Us> bool is_KQKRPs(const Position& pos) {
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ return pos.piece_count(Us, PAWN) == 0
+ && pos.non_pawn_material(Us) == QueenValueMidgame
+ && pos.piece_count(Us, QUEEN) == 1
+ && pos.piece_count(Them, ROOK) == 1
+ && pos.piece_count(Them, PAWN) >= 1;
}
- clear();
-}
-
-/// Destructor for the MaterialInfoTable class
+} // namespace
-MaterialInfoTable::~MaterialInfoTable() {
- delete [] entries;
-}
-
-
-/// MaterialInfoTable::clear() clears a material hash table by setting
-/// all entries to 0.
+/// MaterialInfoTable c'tor and d'tor allocate and free the space for Endgames
-void MaterialInfoTable::clear() {
-
- memset(entries, 0, size * sizeof(MaterialInfo));
-}
+void MaterialInfoTable::init() { Base::init(); if (!funcs) funcs = new Endgames(); }
+MaterialInfoTable::~MaterialInfoTable() { delete funcs; }
-/// MaterialInfoTable::get_material_info() takes a position object as input,
+/// MaterialInfoTable::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::material_info(const Position& pos) const {
- Key key = pos.get_material_key();
- int index = key & (size - 1);
- MaterialInfo* mi = entries + index;
+ Key key = pos.material_key();
+ MaterialInfo* mi = probe(key);
// If mi->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 (mi->key == key)
- return mi;
+ return mi;
- // Clear the MaterialInfo object, and set its key
- mi->clear();
+ // Initialize MaterialInfo entry
+ memset(mi, 0, sizeof(MaterialInfo));
mi->key = key;
+ mi->factor[WHITE] = mi->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL;
- // 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.
- 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<Value>(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)
+ if (is_KXK<WHITE>(pos))
{
- mi->evaluationFunction = &EvaluateKXK;
+ mi->evaluationFunction = &EvaluateKXK[WHITE];
return mi;
}
- else if ( pos.non_pawn_material(WHITE) == Value(0)
- && pos.piece_count(WHITE, PAWN) == 0
- && pos.non_pawn_material(BLACK) >= RookValueEndgame)
+
+ if (is_KXK<BLACK>(pos))
{
- mi->evaluationFunction = &EvaluateKKX;
+ mi->evaluationFunction = &EvaluateKXK[BLACK];
return mi;
}
+ if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN))
+ {
+ // 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)
+ {
+ mi->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()];
+ 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
- // are several conflicting applicable scaling functions and we need to
- // decide which one to use.
- ScalingInfo si = getESF(key);
- if (si.fun != NULL)
+ // We face problems when there are several conflicting applicable
+ // scaling functions and we need to decide which one to use.
+ EndgameBase<ScaleFactor>* sf;
+
+ if ((sf = funcs->get<ScaleFactor>(key)) != NULL)
{
- mi->scalingFunction[si.col] = si.fun;
+ mi->scalingFunction[sf->color()] = sf;
return mi;
}
- if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
- && pos.piece_count(WHITE, BISHOP) == 1
- && pos.piece_count(WHITE, PAWN) >= 1)
- mi->scalingFunction[WHITE] = &ScaleKBPK;
-
- if ( pos.non_pawn_material(BLACK) == BishopValueMidgame
- && pos.piece_count(BLACK, BISHOP) == 1
- && pos.piece_count(BLACK, PAWN) >= 1)
- mi->scalingFunction[BLACK] = &ScaleKKBP;
-
- 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;
-
- 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;
-
- if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) == Value(0))
+ // 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<WHITE>(pos))
+ mi->scalingFunction[WHITE] = &ScaleKBPsK[WHITE];
+
+ if (is_KBPsKs<BLACK>(pos))
+ mi->scalingFunction[BLACK] = &ScaleKBPsK[BLACK];
+
+ if (is_KQKRPs<WHITE>(pos))
+ mi->scalingFunction[WHITE] = &ScaleKQKRPs[WHITE];
+
+ else if (is_KQKRPs<BLACK>(pos))
+ mi->scalingFunction[BLACK] = &ScaleKQKRPs[BLACK];
+
+ Value npm_w = pos.non_pawn_material(WHITE);
+ Value npm_b = pos.non_pawn_material(BLACK);
+
+ if (npm_w + npm_b == VALUE_ZERO)
{
if (pos.piece_count(BLACK, PAWN) == 0)
{
assert(pos.piece_count(WHITE, PAWN) >= 2);
- mi->scalingFunction[WHITE] = &ScaleKPsK;
+ mi->scalingFunction[WHITE] = &ScaleKPsK[WHITE];
}
else if (pos.piece_count(WHITE, PAWN) == 0)
{
assert(pos.piece_count(BLACK, PAWN) >= 2);
- mi->scalingFunction[BLACK] = &ScaleKKPs;
+ mi->scalingFunction[BLACK] = &ScaleKPsK[BLACK];
}
else if (pos.piece_count(WHITE, PAWN) == 1 && pos.piece_count(BLACK, PAWN) == 1)
{
- mi->scalingFunction[WHITE] = &ScaleKPKPw;
- mi->scalingFunction[BLACK] = &ScaleKPKPb;
+ // This is a special case because we set scaling functions
+ // for both colors instead of only one.
+ mi->scalingFunction[WHITE] = &ScaleKPKP[WHITE];
+ mi->scalingFunction[BLACK] = &ScaleKPKP[BLACK];
}
}
- // Evaluate the material balance
+ // No pawns makes it difficult to win, even with a material advantage
+ if (pos.piece_count(WHITE, PAWN) == 0 && npm_w - npm_b <= BishopValueMidgame)
+ {
+ mi->factor[WHITE] = uint8_t
+ (npm_w == npm_b || npm_w < RookValueMidgame ? 0 : NoPawnsSF[std::min(pos.piece_count(WHITE, BISHOP), 2)]);
+ }
- Color c;
- int sign;
- Value egValue = Value(0);
- Value mgValue = Value(0);
+ if (pos.piece_count(BLACK, PAWN) == 0 && npm_b - npm_w <= BishopValueMidgame)
+ {
+ mi->factor[BLACK] = uint8_t
+ (npm_w == npm_b || npm_b < RookValueMidgame ? 0 : NoPawnsSF[std::min(pos.piece_count(BLACK, BISHOP), 2)]);
+ }
- for (c = WHITE, sign = 1; c <= BLACK; c++, sign = -sign)
+ // Compute the space weight
+ if (npm_w + npm_b >= 2 * QueenValueMidgame + 4 * RookValueMidgame + 2 * KnightValueMidgame)
{
- // No pawns makes it difficult to win, even with a material advantage
- if ( pos.piece_count(c, PAWN) == 0
- && pos.non_pawn_material(c) - pos.non_pawn_material(opposite_color(c)) <= BishopValueMidgame)
- {
- if ( pos.non_pawn_material(c) == pos.non_pawn_material(opposite_color(c))
- || pos.non_pawn_material(c) < RookValueMidgame)
- mi->factor[c] = 0;
- else
- {
- switch (pos.piece_count(c, BISHOP)) {
- case 2:
- mi->factor[c] = 32;
- break;
- case 1:
- mi->factor[c] = 12;
- break;
- case 0:
- mi->factor[c] = 6;
- break;
- }
- }
- }
-
- // 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":
- // 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)
- {
- Value v = Value((pos.piece_count(c, ROOK) - 1) * 32 + pos.piece_count(c, QUEEN) * 16);
- mgValue -= sign * v;
- egValue -= sign * v;
- }
+ int minorPieceCount = pos.piece_count(WHITE, KNIGHT) + pos.piece_count(WHITE, BISHOP)
+ + pos.piece_count(BLACK, KNIGHT) + pos.piece_count(BLACK, BISHOP);
+
+ mi->spaceWeight = minorPieceCount * minorPieceCount;
}
- mi->mgValue = int16_t(mgValue);
- mi->egValue = int16_t(egValue);
+ // 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
+ // in defining bishop pair bonuses.
+ const int pieceCount[2][8] = {
+ { 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) } };
+
+ mi->value = int16_t((imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16);
return mi;
}
+
+
+/// MaterialInfoTable::imbalance() calculates imbalance comparing piece count of each
+/// piece type for both colors.
+
+template<Color Us>
+int MaterialInfoTable::imbalance(const int pieceCount[][8]) {
+
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+
+ int pt1, pt2, pc, v;
+ int value = 0;
+
+ // Redundancy of major pieces, formula based on Kaufman's paper
+ // "The Evaluation of Material Imbalances in Chess"
+ if (pieceCount[Us][ROOK] > 0)
+ value -= RedundantRookPenalty * (pieceCount[Us][ROOK] - 1)
+ + RedundantQueenPenalty * pieceCount[Us][QUEEN];
+
+ // Second-degree polynomial material imbalance by Tord Romstad
+ for (pt1 = PIECE_TYPE_NONE; pt1 <= QUEEN; pt1++)
+ {
+ pc = pieceCount[Us][pt1];
+ if (!pc)
+ continue;
+
+ v = LinearCoefficients[pt1];
+
+ for (pt2 = PIECE_TYPE_NONE; pt2 <= pt1; pt2++)
+ v += QuadraticCoefficientsSameColor[pt1][pt2] * pieceCount[Us][pt2]
+ + QuadraticCoefficientsOppositeColor[pt1][pt2] * pieceCount[Them][pt2];
+
+ value += pc * v;
+ }
+ return value;
+}
+
+
+/// 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);
+
+ return npm >= MidgameLimit ? PHASE_MIDGAME
+ : npm <= EndgameLimit ? PHASE_ENDGAME
+ : Phase(((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit));
+}
projects / stockfish / blobdiff