Introduce least_significant_square_bb()

[stockfish] / src / bitboard.h

diff --git a/src/bitboard.h b/src/bitboard.h
index 29d8f66d41525533a8602c469b0f749920bd4c7f..1b6af3ead1afedbaba67526b32cd3f6762ffed4f 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -1,6 +1,6 @@
 /*
   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
@@ -23,19 +23,21 @@
 
 #include "types.h"
 
+namespace Stockfish {
+
 namespace Bitbases {
 
 void init();
 bool probe(Square wksq, Square wpsq, Square bksq, Color us);
 
-}
+} // namespace Stockfish::Bitbases
 
 namespace Bitboards {
 
 void init();
-const std::string pretty(Bitboard b);
+std::string pretty(Bitboard b);
 
-}
+} // namespace Stockfish::Bitboards
 
 constexpr Bitboard AllSquares = ~Bitboard(0);
 constexpr Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
@@ -412,6 +414,13 @@ inline Square msb(Bitboard b) {
 
 #endif
 
+/// least_significant_square_bb() returns the bitboard of the least significant
+/// square of a non-zero bitboard. It is equivalent to square_bb(lsb(bb)).
+
+inline Bitboard least_significant_square_bb(Bitboard b) {
+  assert(b);
+  return b & -b;
+}
 
 /// pop_lsb() finds and clears the least significant bit in a non-zero bitboard
 
@@ -430,4 +439,6 @@ inline Square frontmost_sq(Color c, Bitboard b) {
   return c == WHITE ? msb(b) : lsb(b);
 }
 
+} // namespace Stockfish
+
 #endif // #ifndef BITBOARD_H_INCLUDED