Add PEXT software implementation

[stockfish] / src / bitboard.cpp

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index bfacc4121a0312b2d2461239008344c940c3857f..27ba65747d6faf05cf4cdb3e2442aa0f0b7cdbe6 100644 (file)
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -79,6 +79,23 @@ namespace {
   }
 }
 
+
+/// Intel PEXT (parallel extraction) software implementation
+Bitboard pext(Bitboard b, Bitboard mask) {
+
+  Bitboard res = 0;
+
+  for (Bitboard bb = 1; mask; bb += bb)
+  {
+      if (b & mask & -mask)
+          res |= bb;
+
+      mask &= mask - 1;
+  }
+  return res;
+}
+
+
 /// lsb()/msb() finds the least/most significant bit in a non-zero bitboard.
 /// pop_lsb() finds and clears the least significant bit in a non-zero bitboard.