X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmaterial.cpp;h=094a13df9156fb2910a4364716a9f67c76bc1d49;hb=ab276357d7dea388a81ea75f9b7d89670cf4fcf0;hp=22953cff6d8d4328706cb1ffe4299d46214d2c05;hpb=4ede49cd850392f28bc9da9537c111d2c3f0b297;p=stockfish
diff --git a/src/material.cpp b/src/material.cpp
index 22953cff..094a13df 100644
--- a/src/material.cpp
+++ b/src/material.cpp
@@ -1,7 +1,7 @@
/*
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) 2008-2015 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
@@ -17,55 +17,47 @@
along with this program. If not, see .
*/
-#include // For std::min
+#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);
+ // Polynomial material imbalance parameters
- // Scale factors used when one side has no more pawns
- const int NoPawnsSF[4] = { 6, 12, 32 };
+ // pair pawn knight bishop rook queen
+ const int Linear[6] = { 1852, -162, -1122, -183, 249, -154 };
- // Polynomial material balance parameters
- const Value RedundantQueen = Value(320);
- const Value RedundantRook = Value(554);
-
- // pair pawn knight bishop rook queen
- const int LinearCoefficients[6] = { 1617, -162, -1172, -190, 105, 26 };
-
- const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = {
+ const int QuadraticOurs[][PIECE_TYPE_NB] = {
+ // OUR PIECES
// pair pawn knight bishop rook queen
- { 7 }, // Bishop pair
+ { 0 }, // 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
+ { 35, 271, -4 }, // Knight OUR PIECES
+ { 0, 105, 4, 0 }, // Bishop
+ { -27, -2, 46, 100, -141 }, // Rook
+ {-177, 25, 129, 142, -137, 0 } // Queen
};
- const int QuadraticCoefficientsOppositeColor[][PIECE_TYPE_NB] = {
+ const int QuadraticTheirs[][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
+ { 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
};
- // 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) };
+ // 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) };
@@ -75,8 +67,7 @@ namespace {
// 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
+ return !more_than_one(pos.pieces(Them))
&& pos.non_pawn_material(Us) >= RookValueMg;
}
@@ -95,7 +86,7 @@ namespace {
&& pos.count(Them) >= 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
@@ -103,62 +94,52 @@ namespace {
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 -= RedundantRook * (pieceCount[Us][ROOK] - 1)
- + RedundantQueen * pieceCount[Us][QUEEN];
+ int bonus = 0;
// Second-degree polynomial material imbalance by Tord Romstad
- for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; pt1++)
+ 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 = Linear[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.
+/// 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, Table& entries, Endgames& endgames) {
+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);
+ e->gamePhase = pos.game_phase();
- // 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))
+ // 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 (pos.this_thread()->endgames.probe(key, e->evaluationFunction))
return e;
if (is_KXK(pos))
@@ -173,37 +154,19 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
return e;
}
- 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(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)
- {
- e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()];
- 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.
+ // OK, we didn't find any special evaluation function for the current material
+ // configuration. Is there a suitable specialized scaling function?
EndgameBase* sf;
- if (endgames.probe(key, sf))
+ if (pos.this_thread()->endgames.probe(key, sf))
{
- e->scalingFunction[sf->color()] = sf;
+ e->scalingFunction[sf->strong_side()] = 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.
+ // 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.
if (is_KBPsKs(pos))
e->scalingFunction[WHITE] = &ScaleKBPsK[WHITE];
@@ -219,16 +182,18 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
Value npm_w = pos.non_pawn_material(WHITE);
Value npm_b = pos.non_pawn_material(BLACK);
- 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)
@@ -240,53 +205,34 @@ 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 : 12);
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)]);
- }
+ e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW :
+ npm_w <= BishopValueMg ? 4 : 12);
- // 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);
+ if (pos.count(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
+ e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN;
- e->spaceWeight = minorPieceCount * minorPieceCount;
- }
+ if (pos.count(BLACK) == 1 && npm_b - npm_w <= BishopValueMg)
+ e->factor[BLACK] = (uint8_t) SCALE_FACTOR_ONEPAWN;
// 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] = {
+ const int PieceCount[COLOR_NB][PIECE_TYPE_NB] = {
{ pos.count(WHITE) > 1, pos.count(WHITE), pos.count(WHITE),
pos.count(WHITE) , pos.count(WHITE), pos.count(WHITE) },
{ 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->value = int16_t((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