Switch to hardware PEXT

[stockfish] / src / bitboard.cpp

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index 27ba65747d6faf05cf4cdb3e2442aa0f0b7cdbe6..d4b433fcdc7e0e9e5756ccc75ed8696a7ab24dfd 100644 (file)
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -79,23 +79,6 @@ 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.
 
@@ -296,7 +279,12 @@ namespace {
         b = size = 0;
         do {
             occupancy[size] = b;
-            reference[size++] = sliding_attack(deltas, s, b);
+            reference[size] = sliding_attack(deltas, s, b);
+
+            if (HasPext)
+                attacks[s][_pext_u64(b, masks[s])] = reference[size];
+
+            size++;
             b = (b - masks[s]) & masks[s];
         } while (b);
 
@@ -305,6 +293,9 @@ namespace {
         if (s < SQ_H8)
             attacks[s + 1] = attacks[s] + size;
 
+        if (HasPext)
+            continue;
+
         booster = MagicBoosters[Is64Bit][rank_of(s)];
 
         // Find a magic for square 's' picking up an (almost) random number