/*
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)
- };
+ #define S(mg, eg) make_score(mg, eg)
- // 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)
+ // 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)
};
- // 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)
+ // 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)
};
- // 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)
+ // 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)
};
- // 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)
+ // 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)
};
- // 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)
- };
-
- // 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)
- };
-
- // 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, endgame
- const Value CandidateEndgameBonus[8] = {
- Value( 0), Value( 13), Value(13), Value(29),
- Value(68), Value(166), 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)
};
// Pawn storm tables for positions with opposite castling
};
// 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 };
+ const int16_t QStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 };
+ const int16_t KStormOpenFileBonus[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(unsigned numOfEntries) {
+PawnInfoTable::PawnInfoTable(unsigned numOfEntries) : size(numOfEntries) {
- size = numOfEntries;
entries = new PawnInfo[size];
if (!entries)
{
}
-/// Destructor
-
PawnInfoTable::~PawnInfoTable() {
+
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 & (size - 1));
PawnInfo* pi = entries + index;
// If pi->key matches the position's pawn hash key, it means that we
pi->pawnAttacks[BLACK] = ((blackPawns >> 7) & ~FileABB) | ((blackPawns >> 9) & ~FileHBB);
// Evaluate pawns for both colors
- Values whiteValues = evaluate_pawns<WHITE>(pos, whitePawns, blackPawns, pi);
- Values blackValues = evaluate_pawns<BLACK>(pos, blackPawns, whitePawns, pi);
-
- pi->mgValue = int16_t(whiteValues.first - blackValues.first);
- pi->egValue = int16_t(whiteValues.second - blackValues.second);
+ pi->value = evaluate_pawns<WHITE>(pos, whitePawns, blackPawns, pi)
+ - evaluate_pawns<BLACK>(pos, blackPawns, whitePawns, pi);
return pi;
}
/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color
template<Color Us>
-PawnInfoTable::Values PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
- Bitboard theirPawns, PawnInfo* pi) {
+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, chain, backward, candidate;
int bonus;
- Value mgValue = Value(0);
- Value egValue = Value(0);
+ bool passed, isolated, doubled, opposed, chain, backward, candidate;
+ Score value = make_score(0, 0);
const Square* ptr = pos.piece_list_begin(Us, PAWN);
// Initialize pawn storm scores by giving bonuses for open files
- for (File f = FILE_A; f <= FILE_H; f++)
+ for (f = FILE_A; f <= FILE_H; f++)
if (!(ourPawns & file_bb(f)))
{
pi->ksStormValue[Us] += KStormOpenFileBonus[f];
assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
- // Passed, isolated or doubled pawn?
- passed = Position::pawn_is_passed(theirPawns, Us, s);
- isolated = Position::pawn_is_isolated(ourPawns, s);
- doubled = Position::pawn_is_doubled(ourPawns, Us, s);
+ // Calculate kingside and queenside pawn storm scores for both colors to be
+ // used when evaluating middle game positions with opposite side castling.
+ bonus = (f >= FILE_F ? evaluate_pawn_storm<Us, KingSide>(s, r, f, theirPawns) : 0);
+ pi->ksStormValue[Us] += KStormTable[relative_square(Us, s)] + bonus;
- // 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
- 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;
+ bonus = (f <= FILE_C ? evaluate_pawn_storm<Us, QueenSide>(s, r, f, theirPawns) : 0);
+ pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + 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;
+ // Our rank plus previous one. Used for chain detection.
+ b = rank_bb(r) | rank_bb(r + (Us == WHITE ? -1 : 1));
- // 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.
- chain = ourPawns
- & neighboring_files_bb(f)
- & (rank_bb(r) | rank_bb(r - (Us == WHITE ? 1 : -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
//
// there are friendly pawns behind on neighboring files it cannot
// be backward either.
if ( (passed | isolated | chain)
- || (ourPawns & behind_bb(Us, r) & neighboring_files_bb(f))
+ || (ourPawns & attack_span_mask(opposite_color(Us), s))
|| (pos.attacks_from<PAWN>(s, Us) & theirPawns))
backward = false;
else
// 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.attacks_from<PAWN>(s, Us);
+ 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.
backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns;
}
+ assert(passed | opposed | (attack_span_mask(Us, s) & theirPawns));
+
// Test for candidate passed pawn
- 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);
+ candidate = !(opposed | passed)
+ && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB
+ && count_1s_max_15(b) >= count_1s_max_15(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
if (passed && (ourPawns & squares_in_front_of(Us, s)))
passed = false;
- // Score this pawn
+ // 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), s);
+ // Score this pawn
if (isolated)
{
- mgValue -= IsolatedPawnMidgamePenalty[f];
- egValue -= IsolatedPawnEndgamePenalty[f];
- if (!(theirPawns & file_bb(f)))
- {
- mgValue -= IsolatedPawnMidgamePenalty[f] / 2;
- egValue -= IsolatedPawnEndgamePenalty[f] / 2;
- }
+ value -= IsolatedPawnPenalty[f];
+ if (!opposed)
+ value -= IsolatedPawnPenalty[f] / 2;
}
if (doubled)
- {
- mgValue -= DoubledPawnMidgamePenalty[f];
- egValue -= DoubledPawnEndgamePenalty[f];
- }
+ value -= DoubledPawnPenalty[f];
+
if (backward)
{
- mgValue -= BackwardPawnMidgamePenalty[f];
- egValue -= BackwardPawnEndgamePenalty[f];
- if (!(theirPawns & file_bb(f)))
- {
- mgValue -= BackwardPawnMidgamePenalty[f] / 2;
- egValue -= BackwardPawnEndgamePenalty[f] / 2;
- }
+ value -= BackwardPawnPenalty[f];
+ if (!opposed)
+ value -= BackwardPawnPenalty[f] / 2;
}
if (chain)
- {
- mgValue += ChainMidgameBonus[f];
- egValue += ChainEndgameBonus[f];
- }
+ value += ChainBonus[f];
+
if (candidate)
- {
- mgValue += CandidateMidgameBonus[relative_rank(Us, s)];
- egValue += CandidateEndgameBonus[relative_rank(Us, s)];
- }
+ value += CandidateBonus[relative_rank(Us, s)];
}
- return Values(mgValue, egValue);
+ return value;
+}
+
+
+/// PawnInfoTable::evaluate_pawn_storm() evaluates each pawn which seems
+/// to have good chances of creating an open file by exchanging itself
+/// against an enemy pawn on an adjacent file.
+
+template<Color Us, PawnInfoTable::SideType Side>
+int PawnInfoTable::evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const {
+
+ const Bitboard StormFilesBB = (Side == KingSide ? FileFBB | FileGBB | FileHBB
+ : FileABB | FileBBB | FileCBB);
+ const int K = (Side == KingSide ? 2 : 4);
+ const File RookFile = (Side == KingSide ? FILE_H : FILE_A);
+
+ Bitboard b = attack_span_mask(Us, s) & theirPawns & StormFilesBB;
+ int bonus = 0;
+
+ while (b)
+ {
+ // Give a bonus according to the distance of the nearest enemy pawn
+ Square s2 = pop_1st_bit(&b);
+ Rank r2 = square_rank(s2);
+ int v = StormLeverBonus[f] - K * rank_distance(r, r2);
+
+ // If enemy pawn has no pawn beside itself is particularly vulnerable.
+ // Big bonus, especially against a weakness on the rook file
+ if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
+ v *= (square_file(s2) == RookFile ? 4 : 2);
+
+ bonus += v;
+ }
+ return bonus;
}
/// only when king square changes, about 20% of total get_king_shelter() calls.
int PawnInfo::updateShelter(const Position& pos, Color c, Square ksq) {
- unsigned shelter = 0;
Bitboard pawns = pos.pieces(PAWN, c) & this_and_neighboring_files_bb(ksq);
+ unsigned shelter = 0;
unsigned r = ksq & (7 << 3);
+
for (int i = 1, k = (c ? -8 : 8); i < 4; i++)
{
r += k;
projects / stockfish / blobdiff