Introduce single_bit() helper

[stockfish] / src / bitboard.h

diff --git a/src/bitboard.h b/src/bitboard.h
index 241970f834c398b765069d89f261185e700db6d4..6f3a0048226eb620e6e9c07d9c4185145ad27b68 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -207,6 +207,14 @@ inline Bitboard same_color_squares(Square s) {
 }
 
 
+/// single_bit() returns true if in the 'b' bitboard is set a single bit (or if
+/// b == 0).
+
+inline bool single_bit(Bitboard b) {
+  return !(b & (b - 1));
+}
+
+
 /// first_1() finds the least significant nonzero bit in a nonzero bitboard.
 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
 /// nonzero bitboard.