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 <http://www.gnu.org/licenses/>.
*/
////
#include <cassert>
+#include <cstring>
#include "pawns.h"
+#include "position.h"
////
Value(32), Value(32), Value(32), Value(28)
};
- // Pawn chain membership bonus by file, middle game.
+ // 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.
+ // 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)
+ Value( 0), Value(12), Value(12), Value(20),
+ Value(40), Value(90), Value( 0), Value( 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)
+ 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,
+ 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
+ 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
+ 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
- };
+ // 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 };
- const int QStormOpenFileBonus[8] = {
- 0, 0, 0, 0, 0, 30, 45, 30
- };
+ // Pawn storm lever bonuses by file
+ const int StormLeverBonus[8] = { 20, 20, 10, 0, 0, 10, 20, 20 };
}
/// 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);
+ if (entries == NULL)
+ {
+ std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo))
+ << " bytes for pawn hash table." << std::endl;
+ exit(EXIT_FAILURE);
}
- this->clear();
+ clear();
}
/// PawnInfoTable::get_pawn_info() takes a position object as input, computes
-/// a PawnInfo object, and returns a pointer to it. The result is also
+/// 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
+ // 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;
+ // information we found the last time instead of recomputing it
+ if (pi->key == key)
+ return pi;
- // Clear the PawnInfo object, and set the key:
+ // Clear the PawnInfo object, and set the key
pi->clear();
pi->key = key;
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++) {
+ // 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];
+ int bonus;
+
+ // 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) {
- 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;
+ // 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));
+ assert(pos.piece_on(s) == piece_of_color_and_type(us, PAWN));
- // The file containing the pawn is not half open:
- pi->halfOpenFiles[us] &= ~(1 << f);
+ // 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);
+ // 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
+ // 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;
+ // (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.
- case FILE_H:
- bonus += bonus / 2;
- break;
-
- default:
- break;
- }
+ // 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;
- // Queenside pawn storms:
+ // Queenside pawn storms
bonus = QStormTable[relative_square(us, s)];
- if(bonus > 0 && passed_pawn_mask(us, s) & theirPawns) {
- switch(f) {
+ 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;
- case FILE_A:
- bonus += bonus / 2;
- break;
+ // 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)));
- case FILE_B:
- bonus += bonus / 2 + bonus / 4;
- break;
+ // 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;
+ }
+ }
- case FILE_C:
- bonus += bonus / 2;
- break;
+ // 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;
+ }
- default:
- break;
- }
+ // 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;
+ }
}
- 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;
+ if (doubled)
+ {
+ mv -= DoubledPawnMidgamePenalty[f];
+ ev -= DoubledPawnEndgamePenalty[f];
}
- else {
- for(b=pos.pawn_attacks(us, s); !(b&(ourPawns|theirPawns)); b>>=8);
- backward = (b | (b >> 8)) & theirPawns;
+ if (backward)
+ {
+ mv -= BackwardPawnMidgamePenalty[f];
+ ev -= BackwardPawnEndgamePenalty[f];
+ if (pos.file_is_half_open(them, f))
+ {
+ mv -= BackwardPawnMidgamePenalty[f] / 2;
+ ev -= BackwardPawnEndgamePenalty[f] / 2;
+ }
}
- }
-
- // 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);
-
- // 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 (chain)
+ {
+ mv += ChainMidgameBonus[f];
+ ev += ChainEndgameBonus[f];
}
- }
- 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 (candidate)
+ {
+ mv += CandidateMidgameBonus[relative_rank(us, s)];
+ ev += CandidateEndgameBonus[relative_rank(us, s)];
}
- }
- 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);
- }
- }
+
+ 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;
}
projects / stockfish / blobdiff