From: protonspring <mike@whiteley.org>
Date: Sun, 1 Mar 2020 09:03:36 +0000 (-0700)
Subject: Consolidate Square Flipping
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=960d59d54143d84aab26deae65279a611fc989f4

Consolidate Square Flipping

Add a flip_rank() and flip_file() so that all of the square flipping can be consolidated.

STC
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 57234 W: 11064 L: 10969 D: 35201
Ptnml(0-2): 822, 6562, 13801, 6563, 869
http://tests.stockfishchess.org/tests/view/5e5d2f2aafe6254521f2ffaa

closes https://github.com/official-stockfish/Stockfish/pull/2568

No functional change.
---

diff --git a/src/endgame.cpp b/src/endgame.cpp
index 5fdd307e..16c072be 100644
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -74,9 +74,9 @@ namespace {
     assert(pos.count<PAWN>(strongSide) == 1);
 
     if (file_of(pos.square<PAWN>(strongSide)) >= FILE_E)
-        sq = Square(int(sq) ^ 7); // Mirror SQ_H1 -> SQ_A1
+        sq = flip_file(sq);
 
-    return strongSide == WHITE ? sq : ~sq;
+    return strongSide == WHITE ? sq : flip_rank(sq);
   }
 
 } // namespace
diff --git a/src/psqt.cpp b/src/psqt.cpp
index 8bad7ed4..f6f5933c 100644
--- a/src/psqt.cpp
+++ b/src/psqt.cpp
@@ -114,7 +114,7 @@ void init() {
           File f = map_to_queenside(file_of(s));
           psq[ pc][ s] = score + (type_of(pc) == PAWN ? PBonus[rank_of(s)][file_of(s)]
                                                       : Bonus[pc][rank_of(s)][f]);
-          psq[~pc][~s] = -psq[pc][s];
+          psq[~pc][flip_rank(s)] = -psq[pc][s];
       }
   }
 }
diff --git a/src/syzygy/tbprobe.cpp b/src/syzygy/tbprobe.cpp
index 721a0ef5..6f369455 100644
--- a/src/syzygy/tbprobe.cpp
+++ b/src/syzygy/tbprobe.cpp
@@ -66,7 +66,6 @@ enum TBType { KEY, WDL, DTZ }; // Used as template parameter
 enum TBFlag { STM = 1, Mapped = 2, WinPlies = 4, LossPlies = 8, Wide = 16, SingleValue = 128 };
 
 inline WDLScore operator-(WDLScore d) { return WDLScore(-int(d)); }
-inline Square operator^=(Square& s, int i) { return s = Square(int(s) ^ i); }
 inline Square operator^(Square s, int i) { return Square(int(s) ^ i); }
 
 const std::string PieceToChar = " PNBRQK  pnbrqk";
@@ -743,7 +742,7 @@ Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* resu
     // the triangle A1-D1-D4.
     if (file_of(squares[0]) > FILE_D)
         for (int i = 0; i < size; ++i)
-            squares[i] ^= 7; // Horizontal flip: SQ_H1 -> SQ_A1
+            squares[i] = flip_file(squares[i]);
 
     // Encode leading pawns starting with the one with minimum MapPawns[] and
     // proceeding in ascending order.
@@ -762,7 +761,7 @@ Ret do_probe_table(const Position& pos, T* entry, WDLScore wdl, ProbeState* resu
     // piece is below RANK_5.
     if (rank_of(squares[0]) > RANK_4)
         for (int i = 0; i < size; ++i)
-            squares[i] ^= SQ_A8; // Vertical flip: SQ_A8 -> SQ_A1
+            squares[i] = flip_rank(squares[i]);
 
     // Look for the first piece of the leading group not on the A1-D4 diagonal
     // and ensure it is mapped below the diagonal.
@@ -1344,7 +1343,7 @@ void Tablebases::init(const std::string& paths) {
                 if (leadPawnsCnt == 1)
                 {
                     MapPawns[sq] = availableSquares--;
-                    MapPawns[sq ^ 7] = availableSquares--; // Horizontal flip
+                    MapPawns[flip_file(sq)] = availableSquares--;
                 }
                 LeadPawnIdx[leadPawnsCnt][sq] = idx;
                 idx += Binomial[leadPawnsCnt - 1][MapPawns[sq]];
diff --git a/src/types.h b/src/types.h
index 58d05d2c..d4937fd6 100644
--- a/src/types.h
+++ b/src/types.h
@@ -358,8 +358,12 @@ constexpr Color operator~(Color c) {
   return Color(c ^ BLACK); // Toggle color
 }
 
-constexpr Square operator~(Square s) {
-  return Square(s ^ SQ_A8); // Vertical flip SQ_A1 -> SQ_A8
+constexpr Square flip_rank(Square s) {
+  return Square(s ^ SQ_A8);
+}
+
+constexpr Square flip_file(Square s) {
+  return Square(s ^ SQ_H1);
 }
 
 constexpr Piece operator~(Piece pc) {