X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fbitboard.cpp;h=9d9a16e8ba3614f51ff55eec3f14f813bd0d6e24;hb=3835f49aa10af094642d94b1765183c8bffd561b;hp=01c9954add14ac064a7955bf074ec86906e6d7f1;hpb=cb7f20913e04b051fea6ac9a4055a4e86be452d1;p=stockfish

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index 01c9954a..9d9a16e8 100644
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -248,6 +248,7 @@ namespace {
   void init_attacks();
   void init_between_bitboards();
   void init_pseudo_attacks();
+  SquareDelta squares_delta(Square orig, Square dest);
   Bitboard index_to_bitboard(int index, Bitboard mask);
   Bitboard sliding_attacks(int sq, Bitboard block, int dirs, int deltas[][2],
                            int fmin, int fmax, int rmin, int rmax);
@@ -453,6 +454,26 @@ namespace {
     return result;
   }
 
+  SquareDelta squares_delta(Square orig, Square dest) {
+
+    const SquareDelta deltas[] = { DELTA_N, DELTA_NE, DELTA_E, DELTA_SE,
+                                   DELTA_S, DELTA_SW, DELTA_W, DELTA_NW };
+
+    for (int idx = 0; idx < 8; idx++)
+    {
+        Square s = orig + deltas[idx];
+
+        while (square_is_ok(s) && square_distance(s, s - deltas[idx]) == 1)
+        {
+            if (s == dest)
+                return deltas[idx];
+
+            s += deltas[idx];
+        }
+    }
+    return DELTA_NONE;
+  }
+
   void init_between_bitboards() {
 
     Square s1, s2, s3;
@@ -462,13 +483,11 @@ namespace {
         for (s2 = SQ_A1; s2 <= SQ_H8; s2++)
         {
             BetweenBB[s1][s2] = EmptyBoardBB;
-            d = SquareDelta(DirectionTable[s1][s2]);
-
-            if (d == DELTA_NONE)
-                continue;
+            d = squares_delta(s1, s2);
 
-            for (s3 = s1 + d; s3 != s2; s3 += d)
-                set_bit(&(BetweenBB[s1][s2]), s3);
+            if (d != DELTA_NONE)
+                for (s3 = s1 + d; s3 != s2; s3 += d)
+                    set_bit(&(BetweenBB[s1][s2]), s3);
       }
   }