/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2022 The Stockfish developers (see AUTHORS file)
+ Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
Score scores[TERM_NB][COLOR_NB];
- double to_cp(Value v) { return double(v) / PawnValueEg; }
+ double to_cp(Value v) { return double(v) / UCI::NormalizeToPawnValue; }
void add(int idx, Color c, Score s) {
scores[idx][c] = s;
// Initialize score by reading the incrementally updated scores included in
// the position object (material + piece square tables) and the material
// imbalance. Score is computed internally from the white point of view.
- Score score = pos.psq_score() + me->imbalance() + pos.this_thread()->trend;
+ Score score = pos.psq_score() + me->imbalance();
// Probe the pawn hash table
pe = Pawns::probe(pos);
return v;
}
-
- /// Fisher Random Chess: correction for cornered bishops, to fix chess960 play with NNUE
-
- Value fix_FRC(const Position& pos) {
-
- constexpr Bitboard Corners = 1ULL << SQ_A1 | 1ULL << SQ_H1 | 1ULL << SQ_A8 | 1ULL << SQ_H8;
-
- if (!(pos.pieces(BISHOP) & Corners))
- return VALUE_ZERO;
-
- int correction = 0;
-
- if ( pos.piece_on(SQ_A1) == W_BISHOP
- && pos.piece_on(SQ_B2) == W_PAWN)
- correction -= CorneredBishop;
-
- if ( pos.piece_on(SQ_H1) == W_BISHOP
- && pos.piece_on(SQ_G2) == W_PAWN)
- correction -= CorneredBishop;
-
- if ( pos.piece_on(SQ_A8) == B_BISHOP
- && pos.piece_on(SQ_B7) == B_PAWN)
- correction += CorneredBishop;
-
- if ( pos.piece_on(SQ_H8) == B_BISHOP
- && pos.piece_on(SQ_G7) == B_PAWN)
- correction += CorneredBishop;
-
- return pos.side_to_move() == WHITE ? Value(3 * correction)
- : -Value(3 * correction);
- }
-
} // namespace Eval
Value Eval::evaluate(const Position& pos, int* complexity) {
Value v;
- Color stm = pos.side_to_move();
Value psq = pos.psq_eg_stm();
- // Deciding between classical and NNUE eval (~10 Elo): for high PSQ imbalance we use classical,
- // but we switch to NNUE during long shuffling or with high material on the board.
- bool useClassical = (pos.this_thread()->depth > 9 || pos.count<ALL_PIECES>() > 7)
- && abs(psq) * 5 > (856 + pos.non_pawn_material() / 64) * (10 + pos.rule50_count());
-
- // Deciding between classical and NNUE eval (~10 Elo): for high PSQ imbalance we use classical,
- // but we switch to NNUE during long shuffling or with high material on the board.
- if (!useNNUE || useClassical)
- {
- v = Evaluation<NO_TRACE>(pos).value();
- useClassical = abs(v) >= 297;
- }
- // If result of a classical evaluation is much lower than threshold fall back to NNUE
- if (useNNUE && !useClassical)
+ // We use the much less accurate but faster Classical eval when the NNUE
+ // option is set to false. Otherwise we use the NNUE eval unless the
+ // PSQ advantage is decisive and several pieces remain. (~3 Elo)
+ bool useClassical = !useNNUE || (pos.count<ALL_PIECES>() > 7 && abs(psq) > 1760);
+
+ if (useClassical)
+ v = Evaluation<NO_TRACE>(pos).value();
+ else
{
- int nnueComplexity;
- int scale = 1064 + 106 * pos.non_pawn_material() / 5120;
- Value optimism = pos.this_thread()->optimism[stm];
+ int nnueComplexity;
+ int scale = 1076 + 96 * pos.non_pawn_material() / 5120;
+
+ Color stm = pos.side_to_move();
+ Value optimism = pos.this_thread()->optimism[stm];
+
+ Value nnue = NNUE::evaluate(pos, true, &nnueComplexity);
- Value nnue = NNUE::evaluate(pos, true, &nnueComplexity);
- // Blend nnue complexity with (semi)classical complexity
- nnueComplexity = (104 * nnueComplexity + 131 * abs(nnue - psq)) / 256;
- if (complexity) // Return hybrid NNUE complexity to caller
- *complexity = nnueComplexity;
+ // Blend nnue complexity with (semi)classical complexity
+ nnueComplexity = ( 412 * nnueComplexity
+ + 428 * abs(psq - nnue)
+ + (optimism > 0 ? int(optimism) * int(psq - nnue) : 0)
+ ) / 1024;
- optimism = optimism * (269 + nnueComplexity) / 256;
- v = (nnue * scale + optimism * (scale - 754)) / 1024;
+ // Return hybrid NNUE complexity to caller
+ if (complexity)
+ *complexity = nnueComplexity;
- if (pos.is_chess960())
- v += fix_FRC(pos);
+ optimism = optimism * (278 + nnueComplexity) / 256;
+ v = (nnue * scale + optimism * (scale - 755)) / 1024;
}
// Damp down the evaluation linearly when shuffling
- v = v * (195 - pos.rule50_count()) / 211;
+ v = v * (197 - pos.rule50_count()) / 214;
// Guarantee evaluation does not hit the tablebase range
v = std::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);
// When not using NNUE, return classical complexity to caller
- if (complexity && (!useNNUE || useClassical))
- *complexity = abs(v - psq);
+ if (complexity && useClassical)
+ *complexity = abs(v - psq);
return v;
}
std::memset(scores, 0, sizeof(scores));
// Reset any global variable used in eval
- pos.this_thread()->depth = 0;
- pos.this_thread()->trend = SCORE_ZERO;
pos.this_thread()->bestValue = VALUE_ZERO;
pos.this_thread()->optimism[WHITE] = VALUE_ZERO;
pos.this_thread()->optimism[BLACK] = VALUE_ZERO;
projects / stockfish / blobdiff