Small cleanups

[stockfish] / src / position.cpp

diff --git a/src/position.cpp b/src/position.cpp
index 0686d245bc77fe956f3a8e15a7f86360e610c38d..aeac23a33f4c2d631bb3367517d3e20c45911f61 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2021 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
@@ -22,6 +22,7 @@
 #include <cstring> // For std::memset, std::memcmp
 #include <iomanip>
 #include <sstream>
+#include <string_view>
 
 #include "bitboard.h"
 #include "misc.h"
@@ -46,7 +47,7 @@ namespace Zobrist {
 
 namespace {
 
-const string PieceToChar(" PNBRQK  pnbrqk");
+constexpr std::string_view PieceToChar(" PNBRQK  pnbrqk");
 
 constexpr Piece Pieces[] = { W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING,
                              B_PAWN, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING };
@@ -96,7 +97,7 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) {
 
 // Marcel van Kervinck's cuckoo algorithm for fast detection of "upcoming repetition"
 // situations. Description of the algorithm in the following paper:
-// https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf
+// http://web.archive.org/web/20201107002606/https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf
 
 // First and second hash functions for indexing the cuckoo tables
 inline int H1(Key h) { return h & 0x1fff; }
@@ -129,7 +130,7 @@ void Position::init() {
   // Prepare the cuckoo tables
   std::memset(cuckoo, 0, sizeof(cuckoo));
   std::memset(cuckooMove, 0, sizeof(cuckooMove));
-  int count = 0;
+  [[maybe_unused]] int count = 0;
   for (Piece pc : Pieces)
       for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
           for (Square s2 = Square(s1 + 1); s2 <= SQ_H8; ++s2)
@@ -568,8 +569,7 @@ bool Position::pseudo_legal(const Move m) const {
                         : MoveList<NON_EVASIONS>(*this).contains(m);
 
   // Is not a promotion, so promotion piece must be empty
-  if (promotion_type(m) - KNIGHT != NO_PIECE_TYPE)
-      return false;
+  assert(promotion_type(m) - KNIGHT == NO_PIECE_TYPE);
 
   // If the 'from' square is not occupied by a piece belonging to the side to
   // move, the move is obviously not legal.
@@ -765,9 +765,6 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
       // Update board and piece lists
       remove_piece(capsq);
 
-      if (type_of(m) == EN_PASSANT)
-          board[capsq] = NO_PIECE;
-
       // Update material hash key and prefetch access to materialTable
       k ^= Zobrist::psq[captured][capsq];
       st->materialKey ^= Zobrist::psq[captured][pieceCount[captured]];
@@ -1013,9 +1010,9 @@ void Position::do_null_move(StateInfo& newSt) {
   }
 
   st->key ^= Zobrist::side;
+  ++st->rule50;
   prefetch(TT.first_entry(key()));
 
-  ++st->rule50;
   st->pliesFromNull = 0;
 
   sideToMove = ~sideToMove;
@@ -1054,7 +1051,10 @@ Key Position::key_after(Move m) const {
   if (captured)
       k ^= Zobrist::psq[captured][to];
 
-  return k ^ Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from];
+  k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from];
+
+  return (captured || type_of(pc) == PAWN)
+      ? k : adjust_key50<true>(k);
 }
 
 
@@ -1099,10 +1099,12 @@ bool Position::see_ge(Move m, Value threshold) const {
       // Don't allow pinned pieces to attack as long as there are
       // pinners on their original square.
       if (pinners(~stm) & occupied)
+      {
           stmAttackers &= ~blockers_for_king(stm);
 
-      if (!stmAttackers)
-          break;
+          if (!stmAttackers)
+              break;
+      }
 
       res ^= 1;