2008-08-31 23:59:13 -06:00
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/*
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2008-10-19 10:56:28 -06:00
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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2016-01-02 02:43:25 -07:00
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Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
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Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
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2008-08-31 23:59:13 -06:00
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2008-10-19 10:56:28 -06:00
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Stockfish is free software: you can redistribute it and/or modify
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2008-08-31 23:59:13 -06:00
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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2009-01-07 06:26:58 -07:00
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2008-10-19 10:56:28 -06:00
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Stockfish is distributed in the hope that it will be useful,
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2008-08-31 23:59:13 -06:00
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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2009-01-07 06:26:58 -07:00
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2008-08-31 23:59:13 -06:00
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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2013-07-13 05:02:40 -06:00
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#include <algorithm>
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2008-08-31 23:59:13 -06:00
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#include <cassert>
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2011-04-09 12:50:56 -06:00
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#include "bitboard.h"
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2008-08-31 23:59:13 -06:00
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#include "pawns.h"
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2009-03-18 08:36:03 -06:00
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#include "position.h"
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2014-12-30 02:31:50 -07:00
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#include "thread.h"
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2008-08-31 23:59:13 -06:00
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namespace {
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2012-03-28 23:04:44 -06:00
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#define V Value
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2009-11-13 09:23:21 -07:00
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#define S(mg, eg) make_score(mg, eg)
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2008-08-31 23:59:13 -06:00
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2010-10-09 06:20:49 -06:00
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// Isolated pawn penalty by opposed flag and file
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2013-06-01 03:48:38 -06:00
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const Score Isolated[2][FILE_NB] = {
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2016-02-07 13:58:20 -07:00
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{ S(31, 36), S(45, 41), S(50, 41), S(50, 41),
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S(50, 41), S(50, 41), S(45, 41), S(31, 36) },
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{ S(21, 24), S(30, 28), S(33, 28), S(33, 28),
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S(33, 28), S(33, 28), S(30, 28), S(21, 24) } };
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2010-10-09 06:20:49 -06:00
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2015-05-22 04:39:36 -06:00
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// Backward pawn penalty by opposed flag
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2016-02-07 13:58:20 -07:00
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const Score Backward[2] = { S(56, 33), S(41, 19) };
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2016-01-16 14:34:29 -07:00
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2016-01-03 07:15:29 -07:00
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// Unsupported pawn penalty for pawns which are neither isolated or backward,
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// by number of pawns it supports [less than 2 / exactly 2].
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2016-02-07 13:58:20 -07:00
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const Score Unsupported[2] = { S(17, 8), S(21, 12) };
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2008-08-31 23:59:13 -06:00
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2015-02-26 10:56:16 -07:00
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// Connected pawn bonus by opposed, phalanx, twice supported and rank
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Score Connected[2][2][2][RANK_NB];
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2016-01-16 14:34:29 -07:00
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2015-12-30 04:29:25 -07:00
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// Doubled pawn penalty by file
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const Score Doubled[FILE_NB] = {
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2016-02-07 13:58:20 -07:00
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S(11, 34), S(17, 38), S(19, 38), S(19, 38),
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S(19, 38), S(19, 38), S(17, 38), S(11, 34) };
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2008-08-31 23:59:13 -06:00
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2015-12-30 04:29:25 -07:00
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// Lever bonus by rank
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2014-06-11 08:36:46 -06:00
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const Score Lever[RANK_NB] = {
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2015-12-30 04:29:25 -07:00
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S( 0, 0), S( 0, 0), S(0, 0), S(0, 0),
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2016-02-07 13:58:20 -07:00
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S(17, 16), S(33, 32), S(0, 0), S(0, 0) };
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2014-03-23 16:51:25 -06:00
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2014-12-21 02:52:34 -07:00
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// Weakness of our pawn shelter in front of the king by [distance from edge][rank]
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2014-12-20 10:49:56 -07:00
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const Value ShelterWeakness[][RANK_NB] = {
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2015-12-30 04:29:25 -07:00
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{ V( 97), V(21), V(26), V(51), V(87), V( 89), V( 99) },
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{ V(120), V( 0), V(28), V(76), V(88), V(103), V(104) },
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{ V(101), V( 7), V(54), V(78), V(77), V( 92), V(101) },
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{ V( 80), V(11), V(44), V(68), V(87), V( 90), V(119) } };
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2012-03-26 05:52:10 -06:00
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2014-12-21 02:52:34 -07:00
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// Danger of enemy pawns moving toward our king by [type][distance from edge][rank]
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2014-12-20 10:49:56 -07:00
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const Value StormDanger[][4][RANK_NB] = {
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2015-12-30 04:29:25 -07:00
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{ { V( 0), V( 67), V( 134), V(38), V(32) },
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{ V( 0), V( 57), V( 139), V(37), V(22) },
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{ V( 0), V( 43), V( 115), V(43), V(27) },
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{ V( 0), V( 68), V( 124), V(57), V(32) } },
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{ { V(20), V( 43), V( 100), V(56), V(20) },
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{ V(23), V( 20), V( 98), V(40), V(15) },
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{ V(23), V( 39), V( 103), V(36), V(18) },
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{ V(28), V( 19), V( 108), V(42), V(26) } },
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{ { V( 0), V( 0), V( 75), V(14), V( 2) },
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{ V( 0), V( 0), V( 150), V(30), V( 4) },
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{ V( 0), V( 0), V( 160), V(22), V( 5) },
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{ V( 0), V( 0), V( 166), V(24), V(13) } },
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{ { V( 0), V(-283), V(-281), V(57), V(31) },
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{ V( 0), V( 58), V( 141), V(39), V(18) },
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{ V( 0), V( 65), V( 142), V(48), V(32) },
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{ V( 0), V( 60), V( 126), V(51), V(19) } } };
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2012-03-28 04:44:41 -06:00
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// Max bonus for king safety. Corresponds to start position with all the pawns
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2013-11-10 07:24:32 -07:00
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// in front of the king and no enemy pawn on the horizon.
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2015-02-02 13:00:52 -07:00
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const Value MaxSafetyBonus = V(258);
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2012-03-26 05:52:10 -06:00
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2012-03-28 23:04:44 -06:00
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#undef S
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#undef V
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2012-12-22 03:21:06 -07:00
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template<Color Us>
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2013-06-16 02:51:17 -06:00
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Score evaluate(const Position& pos, Pawns::Entry* e) {
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2012-12-22 03:21:06 -07:00
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2013-06-16 02:51:17 -06:00
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const Color Them = (Us == WHITE ? BLACK : WHITE);
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const Square Up = (Us == WHITE ? DELTA_N : DELTA_S);
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const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
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const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE);
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2012-12-22 03:21:06 -07:00
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connected should be bool, not Bitboard
There's no reason to define it as a Bitboard, so for consistency, use bool.
This is even a speedup on my machine: i7-3770k, using gcc 4.9.1 (linux):
stat test master diff
mean 2,341,338 2,327,998 13,134
stdev 15,765 14,717 5,405
speedup 0.56%
P(speedup>0) 100.0%
No functional change.
Resolves #298
2015-03-17 08:01:07 -06:00
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Bitboard b, neighbours, doubled, supported, phalanx;
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2012-12-22 03:21:06 -07:00
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Square s;
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connected should be bool, not Bitboard
There's no reason to define it as a Bitboard, so for consistency, use bool.
This is even a speedup on my machine: i7-3770k, using gcc 4.9.1 (linux):
stat test master diff
mean 2,341,338 2,327,998 13,134
stdev 15,765 14,717 5,405
speedup 0.56%
P(speedup>0) 100.0%
No functional change.
Resolves #298
2015-03-17 08:01:07 -06:00
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bool passed, isolated, opposed, backward, lever, connected;
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2014-12-27 02:47:21 -07:00
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Score score = SCORE_ZERO;
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2015-08-04 01:00:52 -06:00
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const Square* pl = pos.squares<PAWN>(Us);
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2014-06-14 04:16:22 -06:00
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const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)];
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2012-12-22 03:21:06 -07:00
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2014-07-27 08:27:53 -06:00
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Bitboard ourPawns = pos.pieces(Us , PAWN);
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2013-06-16 02:51:17 -06:00
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Bitboard theirPawns = pos.pieces(Them, PAWN);
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2015-11-14 07:30:50 -07:00
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e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0;
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2013-06-16 02:51:17 -06:00
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e->kingSquares[Us] = SQ_NONE;
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e->semiopenFiles[Us] = 0xFF;
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e->pawnAttacks[Us] = shift_bb<Right>(ourPawns) | shift_bb<Left>(ourPawns);
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2016-04-08 11:52:15 -06:00
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e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares);
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2013-06-16 03:59:40 -06:00
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e->pawnsOnSquares[Us][WHITE] = pos.count<PAWN>(Us) - e->pawnsOnSquares[Us][BLACK];
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2013-06-16 02:51:17 -06:00
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2012-12-22 03:21:06 -07:00
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// Loop through all pawns of the current color and score each pawn
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while ((s = *pl++) != SQ_NONE)
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{
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assert(pos.piece_on(s) == make_piece(Us, PAWN));
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2014-10-06 05:26:30 -06:00
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File f = file_of(s);
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2012-12-22 03:21:06 -07:00
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2013-06-01 03:48:38 -06:00
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e->semiopenFiles[Us] &= ~(1 << f);
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2015-11-14 07:30:50 -07:00
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e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
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2015-02-24 03:33:40 -07:00
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// Flag the pawn
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2015-02-28 10:00:52 -07:00
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neighbours = ourPawns & adjacent_files_bb(f);
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2014-03-23 16:51:25 -06:00
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doubled = ourPawns & forward_bb(Us, s);
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opposed = theirPawns & forward_bb(Us, s);
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passed = !(theirPawns & passed_pawn_mask(Us, s));
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2014-06-14 04:16:22 -06:00
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lever = theirPawns & pawnAttacksBB[s];
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2015-02-28 10:00:52 -07:00
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phalanx = neighbours & rank_bb(s);
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supported = neighbours & rank_bb(s - Up);
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connected = supported | phalanx;
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isolated = !neighbours;
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2012-12-22 03:21:06 -07:00
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2013-08-22 06:34:13 -06:00
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// Test for backward pawn.
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2015-02-24 03:33:40 -07:00
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// If the pawn is passed, isolated, lever or connected it cannot be
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2014-01-01 02:50:30 -07:00
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// backward. If there are friendly pawns behind on adjacent files
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2015-06-02 13:06:46 -06:00
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// or if it is sufficiently advanced, it cannot be backward either.
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2015-01-31 02:19:00 -07:00
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if ( (passed | isolated | lever | connected)
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2015-06-02 13:06:46 -06:00
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|| (ourPawns & pawn_attack_span(Them, s))
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|| (relative_rank(Us, s) >= RANK_5))
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2013-08-22 06:34:13 -06:00
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backward = false;
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else
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2012-12-22 03:21:06 -07:00
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{
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2015-02-24 03:33:40 -07:00
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// We now know there are no friendly pawns beside or behind this
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2012-12-22 03:21:06 -07:00
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// pawn on adjacent files. We now check whether the pawn is
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// backward by looking in the forward direction on the adjacent
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2013-09-03 10:05:53 -06:00
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// files, and picking the closest pawn there.
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b = pawn_attack_span(Us, s) & (ourPawns | theirPawns);
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b = pawn_attack_span(Us, s) & rank_bb(backmost_sq(Us, b));
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2012-12-22 03:21:06 -07:00
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2013-09-03 10:05:53 -06:00
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// If we have an enemy pawn in the same or next rank, the pawn is
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// backward because it cannot advance without being captured.
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2013-06-16 02:08:44 -06:00
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backward = (b | shift_bb<Up>(b)) & theirPawns;
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2012-12-22 03:21:06 -07:00
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}
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2013-06-23 02:03:48 -06:00
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assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns));
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2012-12-22 03:21:06 -07:00
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// Passed pawns will be properly scored in evaluation because we need
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2015-12-30 04:29:25 -07:00
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// full attack info to evaluate them. Only the frontmost passed
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2012-12-22 03:21:06 -07:00
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// pawn on each file is considered a true passed pawn.
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if (passed && !doubled)
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e->passedPawns[Us] |= s;
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// Score this pawn
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if (isolated)
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2014-12-27 02:47:21 -07:00
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score -= Isolated[opposed][f];
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2015-03-29 01:24:17 -06:00
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2015-03-28 17:30:46 -06:00
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else if (backward)
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2015-05-22 04:39:36 -06:00
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score -= Backward[opposed];
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2015-03-29 01:24:17 -06:00
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2015-03-28 17:30:46 -06:00
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else if (!supported)
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2016-01-03 07:15:29 -07:00
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score -= Unsupported[more_than_one(neighbours & rank_bb(s + Up))];
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2012-12-22 03:21:06 -07:00
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2014-10-12 13:03:49 -06:00
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if (connected)
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2015-02-28 10:00:52 -07:00
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score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)];
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2015-03-29 01:24:17 -06:00
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2015-03-28 17:30:46 -06:00
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if (doubled)
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score -= Doubled[f] / distance<Rank>(s, frontmost_sq(Us, doubled));
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2015-03-29 01:24:17 -06:00
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2014-06-14 04:16:22 -06:00
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if (lever)
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2014-12-27 02:47:21 -07:00
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score += Lever[relative_rank(Us, s)];
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2012-12-22 03:21:06 -07:00
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}
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2014-06-25 14:01:00 -06:00
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b = e->semiopenFiles[Us] ^ 0xFF;
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e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0;
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2014-12-27 02:47:21 -07:00
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return score;
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2012-12-22 03:21:06 -07:00
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}
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2013-06-16 02:51:17 -06:00
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} // namespace
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2008-08-31 23:59:13 -06:00
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2012-12-22 03:21:06 -07:00
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namespace Pawns {
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2008-08-31 23:59:13 -06:00
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2014-12-30 02:31:50 -07:00
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/// Pawns::init() initializes some tables needed by evaluation. Instead of using
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/// hard-coded tables, when makes sense, we prefer to calculate them with a formula
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/// to reduce independent parameters and to allow easier tuning and better insight.
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2014-10-13 01:23:21 -06:00
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2014-10-12 13:03:49 -06:00
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void init()
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{
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2016-02-07 13:58:20 -07:00
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static const int Seed[RANK_NB] = { 0, 8, 19, 13, 71, 94, 169, 324 };
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2014-10-12 13:03:49 -06:00
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2014-10-13 01:23:21 -06:00
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for (int opposed = 0; opposed <= 1; ++opposed)
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for (int phalanx = 0; phalanx <= 1; ++phalanx)
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2015-02-26 10:56:16 -07:00
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for (int apex = 0; apex <= 1; ++apex)
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for (Rank r = RANK_2; r < RANK_8; ++r)
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{
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int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed;
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v += (apex ? v / 2 : 0);
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2016-02-07 13:58:20 -07:00
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Connected[opposed][phalanx][apex][r] = make_score(v, v * 5 / 8);
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2015-02-26 10:56:16 -07:00
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}
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2014-10-12 13:03:49 -06:00
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}
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2014-10-13 01:23:21 -06:00
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2014-12-30 02:31:50 -07:00
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/// Pawns::probe() looks up the current position's pawns configuration in
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/// the pawns hash table. It returns a pointer to the Entry if the position
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/// is found. Otherwise a new Entry is computed and stored there, so we don't
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/// have to recompute all when the same pawns configuration occurs again.
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2008-08-31 23:59:13 -06:00
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2014-12-30 02:31:50 -07:00
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Entry* probe(const Position& pos) {
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2008-12-09 08:46:10 -07:00
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2011-12-25 03:50:59 -07:00
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Key key = pos.pawn_key();
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2014-12-30 02:31:50 -07:00
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Entry* e = pos.this_thread()->pawnsTable[key];
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2008-08-31 23:59:13 -06:00
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2012-03-31 05:15:57 -06:00
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if (e->key == key)
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return e;
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2008-08-31 23:59:13 -06:00
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2012-03-31 05:15:57 -06:00
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e->key = key;
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2014-12-27 02:47:21 -07:00
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e->score = evaluate<WHITE>(pos, e) - evaluate<BLACK>(pos, e);
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2016-04-08 11:52:15 -06:00
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e->asymmetry = popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]);
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2012-03-31 05:15:57 -06:00
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return e;
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2008-08-31 23:59:13 -06:00
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}
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2009-07-24 04:16:18 -06:00
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2012-12-22 03:21:06 -07:00
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/// Entry::shelter_storm() calculates shelter and storm penalties for the file
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2012-03-28 23:04:44 -06:00
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/// the king is on, as well as the two adjacent files.
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2012-03-26 05:52:10 -06:00
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template<Color Us>
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2012-12-22 03:21:06 -07:00
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Value Entry::shelter_storm(const Position& pos, Square ksq) {
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2012-03-28 04:44:41 -06:00
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const Color Them = (Us == WHITE ? BLACK : WHITE);
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2014-12-21 02:52:34 -07:00
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enum { NoFriendlyPawn, Unblocked, BlockedByPawn, BlockedByKing };
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2013-06-23 02:16:43 -06:00
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Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq));
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2013-07-25 14:23:15 -06:00
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Bitboard ourPawns = b & pos.pieces(Us);
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2012-03-28 04:44:41 -06:00
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Bitboard theirPawns = b & pos.pieces(Them);
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2014-06-21 06:32:11 -06:00
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Value safety = MaxSafetyBonus;
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2014-12-21 02:52:34 -07:00
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File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
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2012-03-28 04:44:41 -06:00
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2014-12-21 02:52:34 -07:00
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for (File f = center - File(1); f <= center + File(1); ++f)
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2012-03-28 04:44:41 -06:00
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|
{
|
2013-10-24 12:34:11 -06:00
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b = ourPawns & file_bb(f);
|
2014-06-21 06:32:11 -06:00
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Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
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2012-03-28 04:44:41 -06:00
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2013-10-24 12:34:11 -06:00
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b = theirPawns & file_bb(f);
|
2014-06-21 06:32:11 -06:00
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|
Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
|
2014-01-10 19:00:17 -07:00
|
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|
2014-12-20 10:49:56 -07:00
|
|
|
safety -= ShelterWeakness[std::min(f, FILE_H - f)][rkUs]
|
2014-12-21 02:52:34 -07:00
|
|
|
+ StormDanger
|
|
|
|
[f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing :
|
|
|
|
rkUs == RANK_1 ? NoFriendlyPawn :
|
|
|
|
rkThem == rkUs + 1 ? BlockedByPawn : Unblocked]
|
|
|
|
[std::min(f, FILE_H - f)][rkThem];
|
2012-03-26 05:52:10 -06:00
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|
|
}
|
2012-03-28 04:44:41 -06:00
|
|
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|
|
return safety;
|
2012-03-26 05:52:10 -06:00
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|
|
}
|
2011-04-09 12:50:56 -06:00
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|
2012-03-28 04:44:41 -06:00
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|
2014-04-13 05:35:58 -06:00
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|
|
/// Entry::do_king_safety() calculates a bonus for king safety. It is called only
|
|
|
|
/// when king square changes, which is about 20% of total king_safety() calls.
|
2012-03-28 04:44:41 -06:00
|
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|
2011-04-09 12:50:56 -06:00
|
|
|
template<Color Us>
|
2014-04-13 05:35:58 -06:00
|
|
|
Score Entry::do_king_safety(const Position& pos, Square ksq) {
|
2012-03-28 04:44:41 -06:00
|
|
|
|
2012-03-28 23:04:44 -06:00
|
|
|
kingSquares[Us] = ksq;
|
2014-03-08 07:08:55 -07:00
|
|
|
castlingRights[Us] = pos.can_castle(Us);
|
2015-03-07 02:03:19 -07:00
|
|
|
int minKingPawnDistance = 0;
|
2012-06-17 02:03:05 -06:00
|
|
|
|
|
|
|
Bitboard pawns = pos.pieces(Us, PAWN);
|
|
|
|
if (pawns)
|
2015-03-07 02:03:19 -07:00
|
|
|
while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {}
|
2011-04-09 12:50:56 -06:00
|
|
|
|
2012-03-28 23:04:44 -06:00
|
|
|
Value bonus = shelter_storm<Us>(pos, ksq);
|
2012-03-28 04:44:41 -06:00
|
|
|
|
2013-12-01 02:25:10 -07:00
|
|
|
// If we can castle use the bonus after the castling if it is bigger
|
2014-03-08 07:08:55 -07:00
|
|
|
if (pos.can_castle(MakeCastling<Us, KING_SIDE>::right))
|
2012-03-28 23:04:44 -06:00
|
|
|
bonus = std::max(bonus, shelter_storm<Us>(pos, relative_square(Us, SQ_G1)));
|
2012-03-28 04:44:41 -06:00
|
|
|
|
2014-03-08 07:08:55 -07:00
|
|
|
if (pos.can_castle(MakeCastling<Us, QUEEN_SIDE>::right))
|
2012-03-28 23:04:44 -06:00
|
|
|
bonus = std::max(bonus, shelter_storm<Us>(pos, relative_square(Us, SQ_C1)));
|
2012-03-26 05:52:10 -06:00
|
|
|
|
2015-03-07 02:03:19 -07:00
|
|
|
return make_score(bonus, -16 * minKingPawnDistance);
|
2011-04-09 12:50:56 -06:00
|
|
|
}
|
|
|
|
|
|
|
|
// Explicit template instantiation
|
2014-04-13 05:35:58 -06:00
|
|
|
template Score Entry::do_king_safety<WHITE>(const Position& pos, Square ksq);
|
|
|
|
template Score Entry::do_king_safety<BLACK>(const Position& pos, Square ksq);
|
2012-12-22 03:21:06 -07:00
|
|
|
|
|
|
|
} // namespace Pawns
|