/*
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
/// Constants and variables
- // Doubled pawn penalty by file, middle game
- const Value DoubledPawnMidgamePenalty[8] = {
- Value(13), Value(20), Value(23), Value(23),
- Value(23), Value(23), Value(20), Value(13)
- };
-
- // Doubled pawn penalty by file, endgame
- const Value DoubledPawnEndgamePenalty[8] = {
- Value(43), Value(48), Value(48), Value(48),
- Value(48), Value(48), Value(48), Value(43)
- };
-
- // Isolated pawn penalty by file, middle game
- const Value IsolatedPawnMidgamePenalty[8] = {
- Value(25), Value(36), Value(40), Value(40),
- Value(40), Value(40), Value(36), Value(25)
- };
-
- // Isolated pawn penalty by file, endgame
- const Value IsolatedPawnEndgamePenalty[8] = {
- Value(30), Value(35), Value(35), Value(35),
- Value(35), Value(35), Value(35), Value(30)
- };
+ #define S(mg, eg) make_score(mg, eg)
- // Backward pawn penalty by file, middle game
- const Value BackwardPawnMidgamePenalty[8] = {
- Value(20), Value(29), Value(33), Value(33),
- Value(33), Value(33), Value(29), Value(20)
+ // Doubled pawn penalty by file
+ const Score DoubledPawnPenalty[8] = {
+ S(13, 43), S(20, 48), S(23, 48), S(23, 48),
+ S(23, 48), S(23, 48), S(20, 48), S(13, 43)
};
- // Backward pawn penalty by file, endgame
- const Value BackwardPawnEndgamePenalty[8] = {
- Value(28), Value(31), Value(31), Value(31),
- Value(31), Value(31), Value(31), Value(28)
+ // Isolated pawn penalty by file
+ const Score IsolatedPawnPenalty[8] = {
+ S(25, 30), S(36, 35), S(40, 35), S(40, 35),
+ S(40, 35), S(40, 35), S(36, 35), S(25, 30)
};
- // Pawn chain membership bonus by file, middle game
- const Value ChainMidgameBonus[8] = {
- Value(11), Value(13), Value(13), Value(14),
- Value(14), Value(13), Value(13), Value(11)
+ // Backward pawn penalty by file
+ const Score BackwardPawnPenalty[8] = {
+ S(20, 28), S(29, 31), S(33, 31), S(33, 31),
+ S(33, 31), S(33, 31), S(29, 31), S(20, 28)
};
- // Pawn chain membership bonus by file, endgame
- const Value ChainEndgameBonus[8] = {
- Value(-1), Value(-1), Value(-1), Value(-1),
- Value(-1), Value(-1), Value(-1), Value(-1)
+ // Pawn chain membership bonus by file
+ const Score ChainBonus[8] = {
+ S(11,-1), S(13,-1), S(13,-1), S(14,-1),
+ S(14,-1), S(13,-1), S(13,-1), S(11,-1)
};
- // Candidate passed pawn bonus by rank, middle game
- const Value CandidateMidgameBonus[8] = {
- Value( 0), Value( 6), Value(6), Value(14),
- Value(34), Value(83), Value(0), Value( 0)
+ // Candidate passed pawn bonus by rank
+ const Score CandidateBonus[8] = {
+ S( 0, 0), S( 6, 13), S(6,13), S(14,29),
+ S(34,68), S(83,166), S(0, 0), S( 0, 0)
};
- // Candidate passed pawn bonus by rank, endgame
- const Value CandidateEndgameBonus[8] = {
- Value( 0), Value( 13), Value(13), Value(29),
- Value(68), Value(166), Value( 0), Value( 0)
- };
-
- // Pawn storm tables for positions with opposite castling
- const int QStormTable[64] = {
- 0, 0, 0, 0, 0, 0, 0, 0,
- -22,-22,-22,-14,-6, 0, 0, 0,
- -6,-10,-10,-10,-6, 0, 0, 0,
- 4, 12, 16, 12, 4, 0, 0, 0,
- 16, 23, 23, 16, 0, 0, 0, 0,
- 23, 31, 31, 23, 0, 0, 0, 0,
- 23, 31, 31, 23, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0
- };
-
- const int KStormTable[64] = {
- 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0,-10,-19,-28,-33,-33,
- 0, 0, 0,-10,-15,-19,-24,-24,
- 0, 0, 0, 0, 1, 1, 1, 1,
- 0, 0, 0, 0, 1, 10, 19, 19,
- 0, 0, 0, 0, 1, 19, 31, 27,
- 0, 0, 0, 0, 0, 22, 31, 22,
- 0, 0, 0, 0, 0, 0, 0, 0
- };
-
- // Pawn storm open file bonuses by file
- const int16_t KStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 };
- const int16_t QStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 };
-
- // Pawn storm lever bonuses by file
- const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 };
-
+ #undef S
}
//// Functions
////
-/// Constructor
+/// PawnInfoTable c'tor and d'tor instantiated one each thread
+
+PawnInfoTable::PawnInfoTable() {
-PawnInfoTable::PawnInfoTable(unsigned numOfEntries) {
+ entries = new PawnInfo[PawnTableSize];
- size = numOfEntries;
- entries = new PawnInfo[size];
if (!entries)
{
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo))
+ std::cerr << "Failed to allocate " << (PawnTableSize * sizeof(PawnInfo))
<< " bytes for pawn hash table." << std::endl;
Application::exit_with_failure();
}
+ memset(entries, 0, PawnTableSize * sizeof(PawnInfo));
}
-/// Destructor
-
PawnInfoTable::~PawnInfoTable() {
- delete [] entries;
-}
-
-
-/// PawnInfo::clear() resets to zero the PawnInfo entry. Note that
-/// kingSquares[] is initialized to SQ_NONE instead.
-void PawnInfo::clear() {
-
- memset(this, 0, sizeof(PawnInfo));
- kingSquares[WHITE] = kingSquares[BLACK] = SQ_NONE;
+ delete [] entries;
}
/// PawnInfoTable::get_pawn_info() takes a position object as input, computes
-/// a PawnInfo object, and returns a pointer to it. The result is also
-/// stored in a hash table, so we don't have to recompute everything when
-/// the same pawn structure occurs again.
+/// a PawnInfo object, and returns a pointer to it. The result is also stored
+/// in a hash table, so we don't have to recompute everything when the same
+/// pawn structure occurs again.
-PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) {
+PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
assert(pos.is_ok());
Key key = pos.get_pawn_key();
- int index = int(key & (size - 1));
+ unsigned index = unsigned(key & (PawnTableSize - 1));
PawnInfo* pi = entries + index;
// If pi->key matches the position's pawn hash key, it means that we
return pi;
// Clear the PawnInfo object, and set the key
- pi->clear();
+ memset(pi, 0, sizeof(PawnInfo));
+ pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE;
pi->key = key;
- Value mgValue[2] = {Value(0), Value(0)};
- Value egValue[2] = {Value(0), Value(0)};
+ // Calculate pawn attacks
+ Bitboard whitePawns = pos.pieces(PAWN, WHITE);
+ Bitboard blackPawns = pos.pieces(PAWN, BLACK);
+ pi->pawnAttacks[WHITE] = ((whitePawns << 9) & ~FileABB) | ((whitePawns << 7) & ~FileHBB);
+ pi->pawnAttacks[BLACK] = ((blackPawns >> 7) & ~FileABB) | ((blackPawns >> 9) & ~FileHBB);
- // Loop through the pawns for both colors
- for (Color us = WHITE; us <= BLACK; us++)
- {
- Color them = opposite_color(us);
- Bitboard ourPawns = pos.pieces<PAWN>(us);
- Bitboard theirPawns = pos.pieces<PAWN>(them);
- Bitboard pawns = ourPawns;
-
- // Initialize pawn storm scores by giving bonuses for open files
- for (File f = FILE_A; f <= FILE_H; f++)
- if (!(pawns & file_bb(f)))
- {
- pi->ksStormValue[us] += KStormOpenFileBonus[f];
- pi->qsStormValue[us] += QStormOpenFileBonus[f];
- pi->halfOpenFiles[us] |= (1 << f);
- }
-
- // Loop through all pawns of the current color and score each pawn
- while (pawns)
- {
- Square s = pop_1st_bit(&pawns);
- File f = square_file(s);
- Rank r = square_rank(s);
-
- assert(pos.piece_on(s) == piece_of_color_and_type(us, PAWN));
-
- // Passed, isolated or doubled pawn?
- bool passed = Position::pawn_is_passed(theirPawns, us, s);
- bool isolated = Position::pawn_is_isolated(ourPawns, s);
- bool doubled = Position::pawn_is_doubled(ourPawns, us, s);
-
- // We calculate kingside and queenside pawn storm
- // scores for both colors. These are used when evaluating
- // middle game positions with opposite side castling.
- //
- // Each pawn is given a base score given by a piece square table
- // (KStormTable[] or QStormTable[]). Pawns which seem to have good
- // chances of creating an open file by exchanging itself against an
- // enemy pawn on an adjacent file gets an additional bonus.
-
- // Kingside pawn storms
- int bonus = KStormTable[relative_square(us, s)];
- if (f >= FILE_F)
- {
- Bitboard b = outpost_mask(us, s) & theirPawns & (FileFBB | FileGBB | FileHBB);
- while (b)
- {
- Square s2 = pop_1st_bit(&b);
- if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- {
- // The enemy pawn has no pawn beside itself, which makes it
- // particularly vulnerable. Big bonus, especially against a
- // weakness on the rook file.
- if (square_file(s2) == FILE_H)
- bonus += 4*StormLeverBonus[f] - 8*square_distance(s, s2);
- else
- bonus += 2*StormLeverBonus[f] - 4*square_distance(s, s2);
- } else
- // There is at least one enemy pawn beside the enemy pawn we look
- // at, which means that the pawn has somewhat better chances of
- // defending itself by advancing. Smaller bonus.
- bonus += StormLeverBonus[f] - 2*square_distance(s, s2);
- }
- }
- pi->ksStormValue[us] += bonus;
-
- // Queenside pawn storms
- bonus = QStormTable[relative_square(us, s)];
- if (f <= FILE_C)
- {
- Bitboard b = outpost_mask(us, s) & theirPawns & (FileABB | FileBBB | FileCBB);
- while (b)
- {
- Square s2 = pop_1st_bit(&b);
- if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- {
- // The enemy pawn has no pawn beside itself, which makes it
- // particularly vulnerable. Big bonus, especially against a
- // weakness on the rook file.
- if (square_file(s2) == FILE_A)
- bonus += 4*StormLeverBonus[f] - 16*square_distance(s, s2);
- else
- bonus += 2*StormLeverBonus[f] - 8*square_distance(s, s2);
- } else
- // There is at least one enemy pawn beside the enemy pawn we look
- // at, which means that the pawn has somewhat better chances of
- // defending itself by advancing. Smaller bonus.
- bonus += StormLeverBonus[f] - 4*square_distance(s, s2);
- }
- }
- pi->qsStormValue[us] += bonus;
-
- // Member of a pawn chain (but not the backward one)? We could speed up
- // the test a little by introducing an array of masks indexed by color
- // and square for doing the test, but because everything is hashed,
- // it probably won't make any noticable difference.
- bool chain = ourPawns
- & neighboring_files_bb(f)
- & (rank_bb(r) | rank_bb(r - (us == WHITE ? 1 : -1)));
-
- // Test for backward pawn
- //
- // If the pawn is passed, isolated, or member of a pawn chain
- // it cannot be backward. If can capture an enemy pawn or if
- // there are friendly pawns behind on neighboring files it cannot
- // be backward either.
- bool backward;
- if ( passed
- || isolated
- || chain
- || (pos.pawn_attacks(us, s) & theirPawns)
- || (ourPawns & behind_bb(us, r) & neighboring_files_bb(f)))
- backward = false;
- else
- {
- // We now know that there are no friendly pawns beside or behind this
- // pawn on neighboring files. We now check whether the pawn is
- // backward by looking in the forward direction on the neighboring
- // files, and seeing whether we meet a friendly or an enemy pawn first.
- Bitboard b = pos.pawn_attacks(us, s);
- if (us == WHITE)
- {
- for ( ; !(b & (ourPawns | theirPawns)); b <<= 8);
- backward = (b | (b << 8)) & theirPawns;
- }
- else
- {
- for ( ; !(b & (ourPawns | theirPawns)); b >>= 8);
- backward = (b | (b >> 8)) & theirPawns;
- }
- }
-
- // Test for candidate passed pawn
- bool candidate;
- candidate = !passed
- && !(theirPawns & file_bb(f))
- && ( count_1s_max_15(neighboring_files_bb(f) & (behind_bb(us, r) | rank_bb(r)) & ourPawns)
- - count_1s_max_15(neighboring_files_bb(f) & in_front_bb(us, r) & theirPawns)
- >= 0);
-
- // In order to prevent doubled passed pawns from receiving a too big
- // bonus, only the frontmost passed pawn on each file is considered as
- // a true passed pawn.
- if (passed && (ourPawns & squares_in_front_of(us, s)))
- passed = false;
-
- // Score this pawn
- if (passed)
- set_bit(&(pi->passedPawns), s);
-
- if (isolated)
- {
- mgValue[us] -= IsolatedPawnMidgamePenalty[f];
- egValue[us] -= IsolatedPawnEndgamePenalty[f];
- if (!(theirPawns & file_bb(f)))
- {
- mgValue[us] -= IsolatedPawnMidgamePenalty[f] / 2;
- egValue[us] -= IsolatedPawnEndgamePenalty[f] / 2;
- }
- }
- if (doubled)
- {
- mgValue[us] -= DoubledPawnMidgamePenalty[f];
- egValue[us] -= DoubledPawnEndgamePenalty[f];
- }
- if (backward)
- {
- mgValue[us] -= BackwardPawnMidgamePenalty[f];
- egValue[us] -= BackwardPawnEndgamePenalty[f];
- if (!(theirPawns & file_bb(f)))
- {
- mgValue[us] -= BackwardPawnMidgamePenalty[f] / 2;
- egValue[us] -= BackwardPawnEndgamePenalty[f] / 2;
- }
- }
- if (chain)
- {
- mgValue[us] += ChainMidgameBonus[f];
- egValue[us] += ChainEndgameBonus[f];
- }
- if (candidate)
- {
- mgValue[us] += CandidateMidgameBonus[relative_rank(us, s)];
- egValue[us] += CandidateEndgameBonus[relative_rank(us, s)];
- }
- } // while(pawns)
- } // for(colors)
-
- pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]);
- pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]);
+ // Evaluate pawns for both colors
+ pi->value = evaluate_pawns<WHITE>(pos, whitePawns, blackPawns, pi)
+ - evaluate_pawns<BLACK>(pos, blackPawns, whitePawns, pi);
return pi;
}
-/// PawnInfo::updateShelter calculates and caches king shelter. It is called
-/// only when king square changes, about 20% of total get_king_shelter() calls.
-int PawnInfo::updateShelter(const Position& pos, Color c, Square ksq) {
+/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color
+
+template<Color Us>
+Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
+ Bitboard theirPawns, PawnInfo* pi) const {
+ Bitboard b;
+ Square s;
+ File f;
+ Rank r;
+ bool passed, isolated, doubled, opposed, chain, backward, candidate;
+ Score value = SCORE_ZERO;
+ const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
+ const Square* ptr = pos.piece_list_begin(Us, PAWN);
- unsigned shelter = 0;
- Bitboard pawns = pos.pieces<PAWN>(c) & this_and_neighboring_files_bb(ksq);
- unsigned r = ksq & (7 << 3);
- for (int i = 1, k = (c ? -8 : 8); i < 4; i++)
+ // Initialize halfOpenFiles[]
+ for (f = FILE_A; f <= FILE_H; f++)
+ if (!(ourPawns & file_bb(f)))
+ pi->halfOpenFiles[Us] |= (1 << f);
+
+ // Loop through all pawns of the current color and score each pawn
+ while ((s = *ptr++) != SQ_NONE)
{
- r += k;
- shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (128 >> i);
+ assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
+
+ f = square_file(s);
+ r = square_rank(s);
+
+ // Our rank plus previous one. Used for chain detection.
+ b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1));
+
+ // Passed, isolated, doubled or member of a pawn
+ // chain (but not the backward one) ?
+ passed = !(theirPawns & passed_pawn_mask(Us, s));
+ doubled = ourPawns & squares_behind(Us, s);
+ opposed = theirPawns & squares_in_front_of(Us, s);
+ isolated = !(ourPawns & neighboring_files_bb(f));
+ chain = ourPawns & neighboring_files_bb(f) & b;
+
+ // Test for backward pawn
+ //
+ backward = false;
+
+ // If the pawn is passed, isolated, or member of a pawn chain
+ // it cannot be backward. If can capture an enemy pawn or if
+ // there are friendly pawns behind on neighboring files it cannot
+ // be backward either.
+ if ( !(passed | isolated | chain)
+ && !(ourPawns & attack_span_mask(opposite_color(Us), s))
+ && !(pos.attacks_from<PAWN>(s, Us) & theirPawns))
+ {
+ // We now know that there are no friendly pawns beside or behind this
+ // pawn on neighboring files. We now check whether the pawn is
+ // backward by looking in the forward direction on the neighboring
+ // files, and seeing whether we meet a friendly or an enemy pawn first.
+ b = pos.attacks_from<PAWN>(s, Us);
+
+ // Note that we are sure to find something because pawn is not passed
+ // nor isolated, so loop is potentially infinite, but it isn't.
+ while (!(b & (ourPawns | theirPawns)))
+ Us == WHITE ? b <<= 8 : b >>= 8;
+
+ // The friendly pawn needs to be at least two ranks closer than the enemy
+ // pawn in order to help the potentially backward pawn advance.
+ backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns;
+ }
+
+ assert(passed | opposed | (attack_span_mask(Us, s) & theirPawns));
+
+ // Test for candidate passed pawn
+ candidate = !(opposed | passed)
+ && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB
+ && count_1s<Max15>(b) >= count_1s<Max15>(attack_span_mask(Us, s) & theirPawns);
+
+ // In order to prevent doubled passed pawns from receiving a too big
+ // bonus, only the frontmost passed pawn on each file is considered as
+ // a true passed pawn.
+ if (passed && (ourPawns & squares_in_front_of(Us, s)))
+ passed = false;
+
+ // Mark the pawn as passed. Pawn will be properly scored in evaluation
+ // because we need full attack info to evaluate passed pawns.
+ if (passed)
+ set_bit(&(pi->passedPawns[Us]), s);
+
+ // Score this pawn
+ if (isolated)
+ {
+ value -= IsolatedPawnPenalty[f];
+ if (!opposed)
+ value -= IsolatedPawnPenalty[f] / 2;
+ }
+ if (doubled)
+ value -= DoubledPawnPenalty[f];
+
+ if (backward)
+ {
+ value -= BackwardPawnPenalty[f];
+ if (!opposed)
+ value -= BackwardPawnPenalty[f] / 2;
+ }
+ if (chain)
+ value += ChainBonus[f];
+
+ if (candidate)
+ value += CandidateBonus[relative_rank(Us, s)];
}
- kingSquares[c] = ksq;
- kingShelters[c] = shelter;
- return shelter;
+
+ return value;
}
+
projects / stockfish / blobdiff