X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=9a0059dcec379e7e64a3e20ad43525601aaa8f4d;hp=6fdd5c130ea57b372d574ee0cd2b6b744d3c412d;hb=9ca4359f3691305fc5e3306c3084c83557ce09c0;hpb=787d3585548ed7dac06597780a7d0adb64482d41
diff --git a/src/pawns.cpp b/src/pawns.cpp
index 6fdd5c13..9a0059dc 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -1,18 +1,18 @@
/*
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
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
+
Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
-
+
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
@@ -25,7 +25,9 @@
#include
#include
+#include "bitcount.h"
#include "pawns.h"
+#include "position.h"
////
@@ -36,101 +38,39 @@ namespace {
/// 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)
- };
-
- // 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)
- };
+ #define S(mg, eg) make_score(mg, eg)
- // 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)
+ // 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)
};
- // 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)
+ // 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, endgame.
- const Value ChainEndgameBonus[8] = {
- Value(16), Value(16), Value(16), Value(16),
- Value(16), Value(16), Value(16), Value(16)
+ // 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)
};
- // 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)
+ // 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, endgame.
- const Value CandidateEndgameBonus[8] = {
- Value(0), Value(24), Value(24), Value(40),
- Value(80), Value(180), Value(0), Value(0)
- };
-
- // Evaluate pawn storms?
- const bool EvaluatePawnStorms = true;
-
- // 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,
- 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
- };
-
- // Pawn storm open file bonuses by file:
- const int KStormOpenFileBonus[8] = {
- 45, 45, 30, 0, 0, 0, 0, 0
- };
-
- const int QStormOpenFileBonus[8] = {
- 0, 0, 0, 0, 0, 30, 45, 30
+ // 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)
};
+ #undef S
}
@@ -138,250 +78,172 @@ namespace {
//// Functions
////
-/// Constructor
-
-PawnInfoTable::PawnInfoTable(unsigned numOfEntries) {
- size = numOfEntries;
- entries = new PawnInfo[size];
- if(entries == NULL) {
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo))
- << " bytes for pawn hash table." << std::endl;
- exit(EXIT_FAILURE);
- }
- this->clear();
-}
+/// PawnInfoTable c'tor and d'tor instantiated one each thread
+PawnInfoTable::PawnInfoTable() {
-/// Destructor
+ entries = new PawnInfo[PawnTableSize];
-PawnInfoTable::~PawnInfoTable() {
- delete [] entries;
+ if (!entries)
+ {
+ 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));
}
-/// PawnInfoTable::clear() clears the pawn hash table by setting all
-/// entries to 0.
+PawnInfoTable::~PawnInfoTable() {
-void PawnInfoTable::clear() {
- memset(entries, 0, size * sizeof(PawnInfo));
+ 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) const {
-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;
+ unsigned index = unsigned(key & (PawnTableSize - 1));
+ 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.
+ if (pi->key == key)
+ return pi;
+
+ // Clear the PawnInfo object, and set the key
+ memset(pi, 0, sizeof(PawnInfo));
+ pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE;
+ pi->key = key;
- // 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:
- if(pi->key == key)
- return pi;
+ // 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);
- // Clear the PawnInfo object, and set the key:
- pi->clear();
- pi->key = key;
+ // Evaluate pawns for both colors
+ pi->value = evaluate_pawns(pos, whitePawns, blackPawns, pi)
+ - evaluate_pawns(pos, blackPawns, whitePawns, pi);
+ return pi;
+}
- Value mgValue[2] = {Value(0), Value(0)};
- Value egValue[2] = {Value(0), Value(0)};
-
- // 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:
- if(EvaluatePawnStorms)
- 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) {
- Square s = pop_1st_bit(&pawns);
- File f = square_file(s);
- Rank r = square_rank(s);
- bool passed, doubled, isolated, backward, chain, candidate;
- int bonus;
-
- 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);
-
- if(EvaluatePawnStorms) {
- // 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 pawn storms:
- bonus = KStormTable[relative_square(us, s)];
- if(bonus > 0 && outpost_mask(us, s) & theirPawns) {
- switch(f) {
-
- case FILE_F:
- bonus += bonus / 4;
- break;
-
- case FILE_G:
- bonus += bonus / 2 + bonus / 4;
- break;
-
- case FILE_H:
- bonus += bonus / 2;
- break;
-
- default:
- break;
- }
- }
- pi->ksStormValue[us] += bonus;
-
- // Queenside pawn storms:
- bonus = QStormTable[relative_square(us, s)];
- if(bonus > 0 && passed_pawn_mask(us, s) & theirPawns) {
- switch(f) {
-
- case FILE_A:
- bonus += bonus / 2;
- break;
-
- case FILE_B:
- bonus += bonus / 2 + bonus / 4;
- break;
-
- case FILE_C:
- bonus += bonus / 2;
- break;
-
- default:
- break;
- }
- }
- pi->qsStormValue[us] += bonus;
- }
-
- // Member of a pawn chain? 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 = (us == WHITE)?
- (ourPawns & neighboring_files_bb(f) & (rank_bb(r) | rank_bb(r-1))) :
- (ourPawns & neighboring_files_bb(f) & (rank_bb(r) | rank_bb(r+1)));
-
-
- // Test for backward pawn.
-
- // If the pawn is isolated, passed, or member of a pawn chain, it cannot
- // be backward:
- if(passed || isolated || chain)
- backward = false;
- // If the pawn can capture an enemy pawn, it's not backward:
- else if(pos.pawn_attacks(us, s) & theirPawns)
- backward = false;
- // Check for friendly pawns behind on neighboring files:
- else if(ourPawns & in_front_bb(them, r) & neighboring_files_bb(f))
- backward = false;
- else {
- // We now know that there is 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;
- }
+
+/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color
+
+template
+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);
+
+ // 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)
+ {
+ 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(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(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 && pos.file_is_half_open(them, f) &&
- count_1s_max_15(neighboring_files_bb(f)
- & (in_front_bb(them, r) | rank_bb(r))
- & ourPawns)
- - count_1s_max_15(neighboring_files_bb(f) & in_front_bb(us, r)
- & theirPawns)
- >= 0);
+ 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(b) >= count_1s(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))) {
- // 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 (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(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)];
+ if (doubled)
+ value -= DoubledPawnPenalty[f];
+
+ if (backward)
+ {
+ value -= BackwardPawnPenalty[f];
+ if (!opposed)
+ value -= BackwardPawnPenalty[f] / 2;
}
+ if (chain)
+ value += ChainBonus[f];
- 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);
- }
+ if (candidate)
+ value += CandidateBonus[relative_rank(Us, s)];
}
- pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]);
- pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]);
-
- return pi;
+ return value;
}
+