/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
+ Copyright (C) 2004-2021 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
#include "half_kp.h"
#include "index_list.h"
-namespace Eval::NNUE::Features {
+namespace Stockfish::Eval::NNUE::Features {
- // Find the index of the feature quantity from the king position and PieceSquare
- template <Side AssociatedKing>
- inline IndexType HalfKP<AssociatedKing>::MakeIndex(Square sq_k, PieceSquare p) {
- return static_cast<IndexType>(PS_END) * static_cast<IndexType>(sq_k) + p;
+ // Orient a square according to perspective (rotates by 180 for black)
+ inline Square orient(Color perspective, Square s) {
+ return Square(int(s) ^ (bool(perspective) * 63));
}
- // Get pieces information
- template <Side AssociatedKing>
- inline void HalfKP<AssociatedKing>::GetPieces(
- const Position& pos, Color perspective,
- PieceSquare** pieces, Square* sq_target_k) {
-
- *pieces = (perspective == BLACK) ?
- pos.eval_list()->piece_list_fb() :
- pos.eval_list()->piece_list_fw();
- const PieceId target = (AssociatedKing == Side::kFriend) ?
- static_cast<PieceId>(PIECE_ID_KING + perspective) :
- static_cast<PieceId>(PIECE_ID_KING + ~perspective);
- *sq_target_k = static_cast<Square>(((*pieces)[target] - PS_W_KING) % SQUARE_NB);
+ // Index of a feature for a given king position and another piece on some square
+ inline IndexType make_index(Color perspective, Square s, Piece pc, Square ksq) {
+ return IndexType(orient(perspective, s) + PieceSquareIndex[perspective][pc] + PS_NB * ksq);
}
// Get a list of indices for active features
template <Side AssociatedKing>
- void HalfKP<AssociatedKing>::AppendActiveIndices(
+ void HalfKP<AssociatedKing>::append_active_indices(
const Position& pos, Color perspective, IndexList* active) {
- // Do nothing if array size is small to avoid compiler warning
- if (RawFeatures::kMaxActiveDimensions < kMaxActiveDimensions) return;
-
- PieceSquare* pieces;
- Square sq_target_k;
- GetPieces(pos, perspective, &pieces, &sq_target_k);
- for (PieceId i = PIECE_ID_ZERO; i < PIECE_ID_KING; ++i) {
- if (pieces[i] != PS_NONE) {
- active->push_back(MakeIndex(sq_target_k, pieces[i]));
- }
+ Square ksq = orient(perspective, pos.square<KING>(perspective));
+ Bitboard bb = pos.pieces() & ~pos.pieces(KING);
+ while (bb)
+ {
+ Square s = pop_lsb(bb);
+ active->push_back(make_index(perspective, s, pos.piece_on(s), ksq));
}
}
- // Get a list of indices for recently changed features
+
+ // append_changed_indices() : get a list of indices for recently changed features
+
+ // IMPORTANT: The `pos` in this function is pretty much useless as it
+ // is not always the position the features are updated to. The feature
+ // transformer code right now can update multiple accumulators per move,
+ // but since Stockfish only keeps the full state of the current leaf
+ // search position it is not possible to always pass here the position for
+ // which the accumulator is being updated. Therefore the only thing that
+ // can be reliably extracted from `pos` is the king square for the king
+ // of the `perspective` color (note: not even the other king's square will
+ // match reality in all cases, this is also the reason why `dp` is passed
+ // as a parameter and not extracted from pos.state()). This is of particular
+ // problem for future nets with other feature sets, where updating the active
+ // feature might require more information from the intermediate positions. In
+ // this case the only easy solution is to remove the multiple updates from
+ // the feature transformer update code and only update the accumulator for
+ // the current leaf position (the position after the move).
+
template <Side AssociatedKing>
- void HalfKP<AssociatedKing>::AppendChangedIndices(
- const Position& pos, Color perspective,
+ void HalfKP<AssociatedKing>::append_changed_indices(
+ const Position& pos, const DirtyPiece& dp, Color perspective,
IndexList* removed, IndexList* added) {
- PieceSquare* pieces;
- Square sq_target_k;
- GetPieces(pos, perspective, &pieces, &sq_target_k);
- const auto& dp = pos.state()->dirtyPiece;
+ Square ksq = orient(perspective, pos.square<KING>(perspective));
for (int i = 0; i < dp.dirty_num; ++i) {
- if (dp.pieceId[i] >= PIECE_ID_KING) continue;
- const auto old_p = static_cast<PieceSquare>(
- dp.old_piece[i].from[perspective]);
- if (old_p != PS_NONE) {
- removed->push_back(MakeIndex(sq_target_k, old_p));
- }
- const auto new_p = static_cast<PieceSquare>(
- dp.new_piece[i].from[perspective]);
- if (new_p != PS_NONE) {
- added->push_back(MakeIndex(sq_target_k, new_p));
- }
+ Piece pc = dp.piece[i];
+ if (type_of(pc) == KING) continue;
+ if (dp.from[i] != SQ_NONE)
+ removed->push_back(make_index(perspective, dp.from[i], pc, ksq));
+ if (dp.to[i] != SQ_NONE)
+ added->push_back(make_index(perspective, dp.to[i], pc, ksq));
}
}
- template class HalfKP<Side::kFriend>;
+ template class HalfKP<Side::Friend>;
-} // namespace Eval::NNUE::Features
+} // namespace Stockfish::Eval::NNUE::Features
projects / stockfish / blobdiff