X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;ds=sidebyside;f=src%2Fpawns.cpp;h=b3c65a0f166268200fb918d4a751f2563f7de378;hb=25b4d0c127af9fe564f7a797460bed4c2837bcc2;hp=a09fe68337d8aa7ab3bbbd5f93dc86023e901fc1;hpb=ab29d8df678adb97e2bc40b04f13e4f17577ada0;p=stockfish
diff --git a/src/pawns.cpp b/src/pawns.cpp
index a09fe683..b3c65a0f 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -1,391 +1,241 @@
/*
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 .
*/
-
-////
-//// Includes
-////
-
#include
-#include
+#include "bitboard.h"
+#include "bitcount.h"
#include "pawns.h"
-
-
-////
-//// Local definitions
-////
+#include "position.h"
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)
+ #define S(mg, eg) make_score(mg, eg)
+
+ // Doubled pawn penalty by opposed flag and file
+ const Score DoubledPawnPenalty[2][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) },
+ { 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 opposed flag and file
+ const Score IsolatedPawnPenalty[2][8] = {
+ { S(37, 45), S(54, 52), S(60, 52), S(60, 52),
+ S(60, 52), S(60, 52), S(54, 52), S(37, 45) },
+ { 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 opposed flag and file
+ const Score BackwardPawnPenalty[2][8] = {
+ { S(30, 42), S(43, 46), S(49, 46), S(49, 46),
+ S(49, 46), S(49, 46), S(43, 46), S(30, 42) },
+ { 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
+ 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)
};
- // 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)
+ // 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)
};
- // 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)
- };
+ const Score PawnStructureWeight = S(233, 201);
- // 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)
- };
-
- // 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)
- };
+ #undef S
- // 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)
- };
-
- // 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)
- };
-
- // 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)
- };
+ inline Score apply_weight(Score v, Score w) {
+ return make_score((int(mg_value(v)) * mg_value(w)) / 0x100,
+ (int(eg_value(v)) * eg_value(w)) / 0x100);
+ }
+}
- // 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
- };
+/// 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 an hash table, so we don't have to recompute everything when the same
+/// pawn structure occurs again.
- // Pawn storm open file bonuses by file:
- const int KStormOpenFileBonus[8] = {
- 45, 45, 30, 0, 0, 0, 0, 0
- };
+PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
- const int QStormOpenFileBonus[8] = {
- 0, 0, 0, 0, 0, 30, 45, 30
- };
+ Key key = pos.get_pawn_key();
+ PawnInfo* pi = probe(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;
+ // Initialize PawnInfo entry
+ pi->key = key;
+ pi->passedPawns[WHITE] = pi->passedPawns[BLACK] = 0;
+ pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE;
+ pi->halfOpenFiles[WHITE] = pi->halfOpenFiles[BLACK] = 0xFF;
-////
-//// Functions
-////
+ // Calculate pawn attacks
+ Bitboard wPawns = pos.pieces(PAWN, WHITE);
+ Bitboard bPawns = pos.pieces(PAWN, BLACK);
+ pi->pawnAttacks[WHITE] = ((wPawns << 9) & ~FileABB) | ((wPawns << 7) & ~FileHBB);
+ pi->pawnAttacks[BLACK] = ((bPawns >> 7) & ~FileABB) | ((bPawns >> 9) & ~FileHBB);
-/// Constructor
+ // Evaluate pawns for both colors and weight the result
+ pi->value = evaluate_pawns(pos, wPawns, bPawns, pi)
+ - evaluate_pawns(pos, bPawns, wPawns, pi);
-PawnInfoTable::PawnInfoTable(unsigned numOfEntries) {
+ pi->value = apply_weight(pi->value, PawnStructureWeight);
- 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);
- }
- clear();
+ return pi;
}
-/// Destructor
+/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color
-PawnInfoTable::~PawnInfoTable() {
- delete [] entries;
-}
+template
+Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
+ Bitboard theirPawns, PawnInfo* pi) {
+ const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
-/// PawnInfoTable::clear() clears the pawn hash table by setting all
-/// entries to 0.
+ Bitboard b;
+ Square s;
+ File f;
+ Rank r;
+ bool passed, isolated, doubled, opposed, chain, backward, candidate;
+ Score value = SCORE_ZERO;
+ const Square* pl = pos.piece_list(Us, PAWN);
-void PawnInfoTable::clear() {
- memset(entries, 0, size * sizeof(PawnInfo));
+ // Loop through all pawns of the current color and score each pawn
+ while ((s = *pl++) != SQ_NONE)
+ {
+ assert(pos.piece_on(s) == make_piece(Us, PAWN));
+
+ f = square_file(s);
+ r = square_rank(s);
+
+ // This file cannot be half open
+ pi->halfOpenFiles[Us] &= ~(1 << f);
+
+ // Our rank plus previous one. Used for chain detection
+ b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1));
+
+ // Flag the pawn as passed, isolated, doubled or member of a pawn
+ // chain (but not the backward one).
+ passed = !(theirPawns & passed_pawn_mask(Us, s));
+ doubled = ourPawns & squares_in_front_of(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 there are friendly pawns behind on neighboring files
+ // or if can capture an enemy pawn it cannot be backward either.
+ if ( !(passed | isolated | chain)
+ && !(ourPawns & attack_span_mask(Them, 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;
+ }
+
+ assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns));
+
+ // A not passed pawn is a candidate to become passed if it is free to
+ // advance and if the number of friendly pawns beside or behind this
+ // pawn on neighboring files is higher or equal than the number of
+ // enemy pawns in the forward direction on the neighboring files.
+ candidate = !(opposed | passed | backward | isolated)
+ && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != EmptyBoardBB
+ && count_1s(b) >= count_1s(attack_span_mask(Us, s) & theirPawns);
+
+ // Passed pawns will be properly scored in evaluation because we need
+ // full attack info to evaluate passed pawns. Only the frontmost passed
+ // pawn on each file is considered a true passed pawn.
+ if (passed && !doubled)
+ set_bit(&(pi->passedPawns[Us]), s);
+
+ // Score this pawn
+ if (isolated)
+ value -= IsolatedPawnPenalty[opposed][f];
+
+ if (doubled)
+ value -= DoubledPawnPenalty[opposed][f];
+
+ if (backward)
+ value -= BackwardPawnPenalty[opposed][f];
+
+ if (chain)
+ value += ChainBonus[f];
+
+ if (candidate)
+ value += CandidateBonus[relative_rank(Us, s)];
+ }
+ return value;
}
-/// 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.
-
-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;
-
- // 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;
+/// PawnInfo::updateShelter() calculates and caches king shelter. It is called
+/// only when king square changes, about 20% of total king_shelter() calls.
+template
+Score PawnInfo::updateShelter(const Position& pos, Square ksq) {
- // Clear the PawnInfo object, and set the key
- pi->clear();
- pi->key = key;
+ const int Shift = (Us == WHITE ? 8 : -8);
- Value mgValue[2] = {Value(0), Value(0)};
- Value egValue[2] = {Value(0), Value(0)};
+ Bitboard pawns;
+ int r, shelter = 0;
- // Loop through the pawns for both colors
- for (Color us = WHITE; us <= BLACK; us++)
+ if (relative_rank(Us, ksq) <= RANK_4)
{
- 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)
- {
- 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);
-
- 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 and queenside pawn storms
- int KBonus = KStormTable[relative_square(us, s)];
- int QBonus = QStormTable[relative_square(us, s)];
- bool outPost = (KBonus > 0 && (outpost_mask(us, s) & theirPawns));
- bool passed = (QBonus > 0 && (passed_pawn_mask(us, s) & theirPawns));
-
- switch (f) {
-
- case FILE_A:
- QBonus += passed * QBonus / 2;
- break;
-
- case FILE_B:
- QBonus += passed * (QBonus / 2 + QBonus / 4);
- break;
-
- case FILE_C:
- QBonus += passed * QBonus / 2;
- break;
-
- case FILE_F:
- KBonus += outPost * KBonus / 4;
- break;
-
- case FILE_G:
- KBonus += outPost * (KBonus / 2 + KBonus / 4);
- break;
-
- case FILE_H:
- KBonus += outPost * 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]);
- return pi;
+ pawns = pos.pieces(PAWN, Us) & this_and_neighboring_files_bb(ksq);
+ r = ksq & (7 << 3);
+ for (int i = 0; i < 3; i++)
+ {
+ r += Shift;
+ shelter += BitCount8Bit[(pawns >> r) & 0xFF] << (6 - i);
+ }
+ }
+ kingSquares[Us] = ksq;
+ kingShelters[Us] = make_score(shelter, 0);
+ return kingShelters[Us];
}
+
+// Explicit template instantiation
+template Score PawnInfo::updateShelter(const Position& pos, Square ksq);
+template Score PawnInfo::updateShelter(const Position& pos, Square ksq);