SEE Pruning Tweak (#2183)

[stockfish] / src / bitbase.cpp

diff --git a/src/bitbase.cpp b/src/bitbase.cpp
index 3c9bf6e89e03c9aab7cd83a8948c0c914c4e2e49..2b1a5517fb8152df1809f0f508e082177660fb39 100644 (file)
--- a/src/bitbase.cpp
+++ b/src/bitbase.cpp
@@ -2,7 +2,7 @@
   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
@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cassert>
 #include <numeric>
 #include <vector>
@@ -28,8 +27,9 @@
 
 namespace {
 
-  // There are 24 possible pawn squares: the first 4 files and ranks from 2 to 7
-  const unsigned MAX_INDEX = 2*24*64*64; // stm * psq * wksq * bksq = 196608
+  // There are 24 possible pawn squares: files A to D and ranks from 2 to 7.
+  // Positions with the pawn on files E to H will be mirrored before probing.
+  constexpr unsigned MAX_INDEX = 2*24*64*64; // stm * psq * wksq * bksq = 196608
 
   // Each uint32_t stores results of 32 positions, one per bit
   uint32_t KPKBitbase[MAX_INDEX / 32];
@@ -152,9 +152,9 @@ namespace {
     // as WIN, the position is classified as WIN, otherwise the current position is
     // classified as UNKNOWN.
 
-    const Color  Them = (Us == WHITE ? BLACK : WHITE);
-    const Result Good = (Us == WHITE ? WIN   : DRAW);
-    const Result Bad  = (Us == WHITE ? DRAW  : WIN);
+    constexpr Color  Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Result Good = (Us == WHITE ? WIN   : DRAW);
+    constexpr Result Bad  = (Us == WHITE ? DRAW  : WIN);
 
     Result r = INVALID;
     Bitboard b = PseudoAttacks[KING][ksq[Us]];