/*
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
#include <cassert>
#include <cstring>
+#include "bitcount.h"
#include "pawns.h"
+#include "position.h"
////
/// Constants and variables
- // Doubled pawn penalty by file, middle game.
- const Value DoubledPawnMidgamePenalty[8] = {
- Value(20), Value(30), Value(34), Value(34),
- Value(34), Value(34), Value(30), Value(20)
- };
-
- // Doubled pawn penalty by file, endgame.
- const Value DoubledPawnEndgamePenalty[8] = {
- Value(35), Value(40), Value(40), Value(40),
- Value(40), Value(40), Value(40), Value(35)
- };
-
- // Isolated pawn penalty by file, middle game.
- const Value IsolatedPawnMidgamePenalty[8] = {
- Value(20), Value(30), Value(34), Value(34),
- Value(34), Value(34), Value(30), Value(20)
- };
-
- // Isolated pawn penalty by file, endgame.
- const Value IsolatedPawnEndgamePenalty[8] = {
- Value(35), Value(40), Value(40), Value(40),
- Value(40), Value(40), Value(40), Value(35)
- };
+ #define S(mg, eg) make_score(mg, eg)
- // Backward pawn penalty by file, middle game.
- const Value BackwardPawnMidgamePenalty[8] = {
- Value(16), Value(24), Value(27), Value(27),
- Value(27), Value(27), Value(24), Value(16)
+ // 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(32), Value(32), Value(32),
- Value(32), Value(32), Value(32), 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(14), Value(16), Value(17), Value(18),
- Value(18), Value(17), Value(16), Value(14)
+ // 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(16), Value(16), Value(16), Value(16),
- Value(16), Value(16), Value(16), Value(16)
+ // 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(12), Value(12), Value(20),
- Value(40), Value(90), 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(24), Value(24), Value(40),
- Value(80), Value(180), Value(0), Value( 0)
- };
-
- // Pawn storm tables for positions with opposite castling:
+ // Pawn storm tables for positions with opposite castling
const int QStormTable[64] = {
0, 0, 0, 0, 0, 0, 0, 0,
- -22,-22,-22,-13,-4, 0, 0, 0,
- -4, -9, -9, -9,-4, 0, 0, 0,
- 9, 18, 22, 18, 9, 0, 0, 0,
- 22, 31, 31, 22, 0, 0, 0, 0,
- 31, 40, 40, 31, 0, 0, 0, 0,
- 31, 40, 40, 31, 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,-4,-13,-22,-27,-27,
- 0, 0, 0,-4, -9,-13,-18,-18,
- 0, 0, 0, 0, 9, 9, 9, 9,
- 0, 0, 0, 0, 9, 18, 27, 27,
- 0, 0, 0, 0, 9, 27, 40, 36,
- 0, 0, 0, 0, 0, 31, 40, 31,
- 0, 0, 0, 0, 0, 0, 0, 0
+ 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 int KStormOpenFileBonus[8] = {
- 45, 45, 30, 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 };
- const int QStormOpenFileBonus[8] = {
- 0, 0, 0, 0, 0, 30, 45, 30
- };
+ // Pawn storm lever bonuses by file
+ const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 };
}
size = numOfEntries;
entries = new PawnInfo[size];
- if (entries == NULL)
+ if (!entries)
{
std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo))
<< " bytes for pawn hash table." << std::endl;
- exit(EXIT_FAILURE);
+ Application::exit_with_failure();
}
- clear();
}
}
-/// PawnInfoTable::clear() clears the pawn hash table by setting all
-/// entries to 0.
+/// PawnInfo::clear() resets to zero the PawnInfo entry. Note that
+/// kingSquares[] is initialized to SQ_NONE instead.
+
+void PawnInfo::clear() {
-void PawnInfoTable::clear() {
- memset(entries, 0, size * sizeof(PawnInfo));
+ memset(this, 0, sizeof(PawnInfo));
+ kingSquares[WHITE] = kingSquares[BLACK] = SQ_NONE;
}
/// 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) {
assert(pos.is_ok());
Key key = pos.get_pawn_key();
int index = int(key & (size - 1));
- PawnInfo *pi = entries + index;
+ PawnInfo* pi = entries + index;
// If pi->key matches the position's pawn hash key, it means that we
- // have analysed this pawn structure before, and we can simply return the
- // information we found the last time instead of recomputing it
+ // have analysed this pawn structure before, and we can simply return
+ // the information we found the last time instead of recomputing it.
if (pi->key == key)
return pi;
pi->clear();
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.pawns(us);
- Bitboard theirPawns = pos.pawns(them);
- Bitboard pawns = ourPawns;
-
- // Initialize pawn storm scores by giving bonuses for open files
- for (File f = FILE_A; f <= FILE_H; f++)
- if (pos.file_is_half_open(us, f))
- {
- pi->ksStormValue[us] += KStormOpenFileBonus[f];
- pi->qsStormValue[us] += QStormOpenFileBonus[f];
- }
-
- // Loop through all pawns of the current color and score each pawn
- while (pawns)
- {
- bool passed, doubled, isolated, backward, chain, candidate;
- Square s = pop_1st_bit(&pawns);
- File f = square_file(s);
- Rank r = square_rank(s);
-
- assert(pos.piece_on(s) == pawn_of_color(us));
-
- // The file containing the pawn is not half open
- pi->halfOpenFiles[us] &= ~(1 << f);
-
- // Passed, isolated or doubled pawn?
- passed = pos.pawn_is_passed(us, s);
- isolated = pos.pawn_is_isolated(us, s);
- doubled = pos.pawn_is_doubled(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[]). This score is increased if
- // there are enemy pawns on adjacent files in front of the pawn.
- // This is because we want to be able to open files against the
- // enemy king, and to avoid blocking the pawn structure (e.g. white
- // pawns on h6, g5, black pawns on h7, g6, f7).
-
- // Kingside and queenside pawn storms
- int KBonus = KStormTable[relative_square(us, s)];
- int QBonus = QStormTable[relative_square(us, s)];
- bool outPostFlag = (KBonus > 0 && (outpost_mask(us, s) & theirPawns));
- bool passedFlag = (QBonus > 0 && (passed_pawn_mask(us, s) & theirPawns));
-
- switch (f) {
-
- case FILE_A:
- QBonus += passedFlag * QBonus / 2;
- break;
-
- case FILE_B:
- QBonus += passedFlag * (QBonus / 2 + QBonus / 4);
- break;
-
- case FILE_C:
- QBonus += passedFlag * QBonus / 2;
- break;
-
- case FILE_F:
- KBonus += outPostFlag * KBonus / 4;
- break;
-
- case FILE_G:
- KBonus += outPostFlag * (KBonus / 2 + KBonus / 4);
- break;
-
- case FILE_H:
- KBonus += outPostFlag * KBonus / 2;
- break;
-
- default:
- break;
- }
- pi->ksStormValue[us] += KBonus;
- pi->qsStormValue[us] += QBonus;
-
- // 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)));
-
- // 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.
- 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;
- if (us == WHITE)
- {
- for (b = pos.pawn_attacks(us, s); !(b & (ourPawns | theirPawns)); b <<= 8);
- backward = (b | (b << 8)) & theirPawns;
- }
- else
- {
- for (b = pos.pawn_attacks(us, s); !(b & (ourPawns | theirPawns)); b >>= 8);
- backward = (b | (b >> 8)) & theirPawns;
- }
- }
-
- // Test for candidate passed pawn
- candidate = !passed
- && pos.file_is_half_open(them, 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)))
- {
- // candidate = true;
- passed = false;
- }
-
- // Score this pawn
- Value mv = Value(0), ev = Value(0);
- if (isolated)
- {
- mv -= IsolatedPawnMidgamePenalty[f];
- ev -= IsolatedPawnEndgamePenalty[f];
- if (pos.file_is_half_open(them, f))
- {
- mv -= IsolatedPawnMidgamePenalty[f] / 2;
- ev -= IsolatedPawnEndgamePenalty[f] / 2;
- }
- }
- if (doubled)
- {
- mv -= DoubledPawnMidgamePenalty[f];
- ev -= DoubledPawnEndgamePenalty[f];
- }
- if (backward)
- {
- mv -= BackwardPawnMidgamePenalty[f];
- ev -= BackwardPawnEndgamePenalty[f];
- if (pos.file_is_half_open(them, f))
- {
- mv -= BackwardPawnMidgamePenalty[f] / 2;
- ev -= BackwardPawnEndgamePenalty[f] / 2;
- }
- }
- if (chain)
- {
- mv += ChainMidgameBonus[f];
- ev += ChainEndgameBonus[f];
- }
- if (candidate)
- {
- mv += CandidateMidgameBonus[relative_rank(us, s)];
- ev += CandidateEndgameBonus[relative_rank(us, s)];
- }
-
- mgValue[us] += mv;
- egValue[us] += ev;
-
- // If the pawn is passed, set the square of the pawn in the passedPawns
- // bitboard
- if (passed)
- set_bit(&(pi->passedPawns), 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;
}
+
+
+/// 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) {
+ Square s;
+ File f;
+ Rank r;
+ bool passed, isolated, doubled, opposed, chain, backward, candidate;
+ int bonus;
+ 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 (f = FILE_A; f <= FILE_H; f++)
+ if (!(ourPawns & 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 ((s = *ptr++) != SQ_NONE)
+ {
+ f = square_file(s);
+ r = square_rank(s);
+
+ assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
+
+ // Passed, isolated or doubled pawn?
+ passed = !(theirPawns & passed_pawn_mask(Us, s));
+ isolated = !(ourPawns & neighboring_files_bb(s));
+ doubled = ourPawns & squares_behind(Us, s);
+ opposed = theirPawns & squares_in_front_of(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
+ bonus = KStormTable[relative_square(Us, s)];
+ if (f >= FILE_F)
+ {
+ Bitboard b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB);
+ while (b)
+ {
+ // Give a bonus according to the distance of the nearest enemy pawn
+ Square s2 = pop_1st_bit(&b);
+ int v = StormLeverBonus[f] - 2 * square_distance(s, s2);
+
+ // 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) == FILE_H ? 4 : 2);
+
+ bonus += v;
+ }
+ }
+ 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)
+ {
+ // Give a bonus according to the distance of the nearest enemy pawn
+ Square s2 = pop_1st_bit(&b);
+ int v = StormLeverBonus[f] - 4 * square_distance(s, s2);
+
+ // 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) == FILE_A ? 4 : 2);
+
+ bonus += v;
+ }
+ }
+ 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.
+ 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.
+ if ( (passed | isolated | chain)
+ || (ourPawns & behind_bb(Us, r) & neighboring_files_bb(f))
+ || (pos.attacks_from<PAWN>(s, Us) & theirPawns))
+ 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.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;
+ }
+
+ // Test for candidate passed pawn
+ candidate = !passed
+ && !opposed
+ && ( 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)
+ {
+ value -= IsolatedPawnPenalty[f];
+ if (!(theirPawns & file_bb(f)))
+ value -= IsolatedPawnPenalty[f] / 2;
+ }
+ if (doubled)
+ value -= DoubledPawnPenalty[f];
+
+ if (backward)
+ {
+ value -= BackwardPawnPenalty[f];
+ if (!(theirPawns & file_bb(f)))
+ value -= BackwardPawnPenalty[f] / 2;
+ }
+ if (chain)
+ value += ChainBonus[f];
+
+ if (candidate)
+ value += CandidateBonus[relative_rank(Us, s)];
+ }
+
+ return value;
+}
+
+
+/// 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) {
+
+ 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++)
+ {
+ r += k;
+ shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (128 >> i);
+ }
+ kingSquares[c] = ksq;
+ kingShelters[c] = shelter;
+ return shelter;
+}
projects / stockfish / blobdiff