Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#include <algorithm>
#include <cassert>
#include "bitboard.h"
constexpr Score Doubled = S(11, 56);
constexpr Score Isolated = S( 5, 15);
- // Connected pawn bonus by opposed, phalanx, #support and rank
- Score Connected[2][2][3][RANK_NB];
+ // Connected pawn bonus
+ constexpr int Connected[RANK_NB] = { 0, 13, 17, 24, 59, 96, 171 };
// Strength of pawn shelter for our king by [distance from edge][rank].
// RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH);
- Bitboard b, neighbours, stoppers, doubled, supported, phalanx;
+ Bitboard b, neighbours, stoppers, doubled, support, phalanx;
Bitboard lever, leverPush;
Square s;
bool opposed, backward;
Bitboard theirPawns = pos.pieces(Them, PAWN);
e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0;
- e->semiopenFiles[Us] = 0xFF;
e->kingSquares[Us] = SQ_NONE;
e->pawnAttacks[Us] = pawn_attacks_bb<Us>(ourPawns);
e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares);
assert(pos.piece_on(s) == make_piece(Us, PAWN));
File f = file_of(s);
+ Rank r = relative_rank(Us, s);
- e->semiopenFiles[Us] &= ~(1 << f);
e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
// Flag the pawn
opposed = theirPawns & forward_file_bb(Us, s);
- stoppers = theirPawns & passed_pawn_mask(Us, s);
+ stoppers = theirPawns & passed_pawn_span(Us, s);
lever = theirPawns & PawnAttacks[Us][s];
leverPush = theirPawns & PawnAttacks[Us][s + Up];
doubled = ourPawns & (s - Up);
neighbours = ourPawns & adjacent_files_bb(f);
phalanx = neighbours & rank_bb(s);
- supported = neighbours & rank_bb(s - Up);
+ support = neighbours & rank_bb(s - Up);
// A pawn is backward when it is behind all pawns of the same color
// on the adjacent files and cannot be safely advanced.
// which could become passed after one or two pawn pushes when are
// not attacked more times than defended.
if ( !(stoppers ^ lever ^ leverPush)
- && popcount(supported) >= popcount(lever) - 1
- && popcount(phalanx) >= popcount(leverPush))
+ && (support || !more_than_one(lever))
+ && popcount(phalanx) >= popcount(leverPush))
e->passedPawns[Us] |= s;
- else if ( stoppers == SquareBB[s + Up]
- && relative_rank(Us, s) >= RANK_5)
+ else if (stoppers == square_bb(s + Up) && r >= RANK_5)
{
- b = shift<Up>(supported) & ~theirPawns;
+ b = shift<Up>(support) & ~theirPawns;
while (b)
if (!more_than_one(theirPawns & PawnAttacks[Us][pop_lsb(&b)]))
e->passedPawns[Us] |= s;
}
// Score this pawn
- if (supported | phalanx)
- score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)];
-
+ if (support | phalanx)
+ {
+ int v = (phalanx ? 3 : 2) * Connected[r];
+ v = 17 * popcount(support) + (v >> (opposed + 1));
+ score += make_score(v, v * (r - 2) / 4);
+ }
else if (!neighbours)
score -= Isolated, e->weakUnopposed[Us] += !opposed;
else if (backward)
score -= Backward, e->weakUnopposed[Us] += !opposed;
- if (doubled && !supported)
+ if (doubled && !support)
score -= Doubled;
}
namespace Pawns {
-/// Pawns::init() initializes some tables needed by evaluation. Instead of using
-/// hard-coded tables, when makes sense, we prefer to calculate them with a formula
-/// to reduce independent parameters and to allow easier tuning and better insight.
-
-void init() {
-
- static constexpr int Seed[RANK_NB] = { 0, 13, 24, 18, 65, 100, 175, 330 };
-
- for (int opposed = 0; opposed <= 1; ++opposed)
- for (int phalanx = 0; phalanx <= 1; ++phalanx)
- for (int support = 0; support <= 2; ++support)
- for (Rank r = RANK_2; r < RANK_8; ++r)
- {
- int v = 17 * support;
- v += (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed;
-
- Connected[opposed][phalanx][support][r] = make_score(v, v * (r - 2) / 4);
- }
-}
-
-
/// Pawns::probe() looks up the current position's pawns configuration in
/// the pawns hash table. It returns a pointer to the Entry if the position
/// is found. Otherwise a new Entry is computed and stored there, so we don't
e->key = key;
e->scores[WHITE] = evaluate<WHITE>(pos, e);
e->scores[BLACK] = evaluate<BLACK>(pos, e);
- e->openFiles = popcount(e->semiopenFiles[WHITE] & e->semiopenFiles[BLACK]);
- e->asymmetry = popcount( (e->passedPawns[WHITE] | e->passedPawns[BLACK])
- | (e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]));
return e;
}
Value safety = (shift<Down>(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) ?
Value(374) : Value(5);
- File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
+ File center = clamp(file_of(ksq), FILE_B, FILE_G);
for (File f = File(center - 1); f <= File(center + 1); ++f)
{
b = ourPawns & file_bb(f);
- int ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : 0;
+ Rank ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
b = theirPawns & file_bb(f);
- int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0;
+ Rank theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
int d = std::min(f, ~f);
safety += ShelterStrength[d][ourRank];
- safety -= (ourRank && (ourRank == theirRank - 1)) ? 66 * (theirRank == RANK_3)
+ safety -= (ourRank && (ourRank == theirRank - 1)) ? 66 * (theirRank == RANK_3)
: UnblockedStorm[d][theirRank];
}
Square ksq = pos.square<KING>(Us);
kingSquares[Us] = ksq;
- castlingRights[Us] = pos.can_castle(Us);
+ castlingRights[Us] = pos.castling_rights(Us);
int minKingPawnDistance = 0;
Bitboard pawns = pos.pieces(Us, PAWN);
projects / stockfish / blobdiff