Rewrite some bitboard init code

[stockfish] / src / bitboard.cpp

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index a377703b5b170dbbed3b99ab07892516fe639cc1..a6502330ab7b23105c4ba917f5e502f91a712d68 100644 (file)
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -45,6 +45,7 @@ Bitboard AdjacentFilesBB[FILE_NB];
 Bitboard InFrontBB[COLOR_NB][RANK_NB];
 Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
 Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
+Bitboard LineBB[SQUARE_NB][SQUARE_NB];
 Bitboard DistanceRingsBB[SQUARE_NB][8];
 Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
 Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
@@ -150,11 +151,11 @@ void Bitboards::print(Bitboard b) {
 
 void Bitboards::init() {
 
-  for (int k = 0, i = 0; i < 8; i++)
+  for (int k = 0, i = 0; i < 8; ++i)
       while (k < (2 << i))
           MS1BTable[k++] = i;
 
-  for (int i = 0; i < 64; i++)
+  for (int i = 0; i < 64; ++i)
       BSFTable[bsf_index(1ULL << i)] = Square(i);
 
   for (Square s = SQ_A1; s <= SQ_H8; ++s)
@@ -163,7 +164,7 @@ void Bitboards::init() {
   FileBB[FILE_A] = FileABB;
   RankBB[RANK_1] = Rank1BB;
 
-  for (int i = 1; i < 8; i++)
+  for (int i = 1; i < 8; ++i)
   {
       FileBB[i] = FileBB[i - 1] << 1;
       RankBB[i] = RankBB[i - 1] << 8;
@@ -197,7 +198,7 @@ void Bitboards::init() {
   for (Color c = WHITE; c <= BLACK; ++c)
       for (PieceType pt = PAWN; pt <= KING; ++pt)
           for (Square s = SQ_A1; s <= SQ_H8; ++s)
-              for (int k = 0; steps[pt][k]; k++)
+              for (int k = 0; steps[pt][k]; ++k)
               {
                   Square to = s + Square(c == WHITE ? steps[pt][k] : -steps[pt][k]);
 
@@ -211,21 +212,23 @@ void Bitboards::init() {
   init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, magic_index<ROOK>);
   init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, magic_index<BISHOP>);
 
-  for (Square s = SQ_A1; s <= SQ_H8; ++s)
+  for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
   {
-      PseudoAttacks[QUEEN][s]  = PseudoAttacks[BISHOP][s] = attacks_bb<BISHOP>(s, 0);
-      PseudoAttacks[QUEEN][s] |= PseudoAttacks[  ROOK][s] = attacks_bb<  ROOK>(s, 0);
-  }
+      PseudoAttacks[QUEEN][s1]  = PseudoAttacks[BISHOP][s1] = attacks_bb<BISHOP>(s1, 0);
+      PseudoAttacks[QUEEN][s1] |= PseudoAttacks[  ROOK][s1] = attacks_bb<  ROOK>(s1, 0);
 
-  for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
       for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
-          if (PseudoAttacks[QUEEN][s1] & s2)
-          {
-              Square delta = (s2 - s1) / square_distance(s1, s2);
+      {
+          Piece pc = (PseudoAttacks[BISHOP][s1] & s2) ? W_BISHOP :
+                     (PseudoAttacks[ROOK][s1]   & s2) ? W_ROOK   : NO_PIECE;
+
+          if (pc == NO_PIECE)
+              continue;
 
-              for (Square s = s1 + delta; s != s2; s += delta)
-                  BetweenBB[s1][s2] |= s;
-          }
+          LineBB[s1][s2] = (attacks_bb(pc, s1, 0) & attacks_bb(pc, s2, 0)) | s1 | s2;
+          BetweenBB[s1][s2] = attacks_bb(pc, s1, SquareBB[s2]) & attacks_bb(pc, s2, SquareBB[s1]);
+      }
+  }
 }
 
 
@@ -235,7 +238,7 @@ namespace {
 
     Bitboard attack = 0;
 
-    for (int i = 0; i < 4; i++)
+    for (int i = 0; i < 4; ++i)
         for (Square s = sq + deltas[i];
              is_ok(s) && square_distance(s, s - deltas[i]) == 1;
              s += deltas[i])
@@ -322,7 +325,7 @@ namespace {
             // looks up the correct sliding attack in the attacks[s] database.
             // Note that we build up the database for square 's' as a side
             // effect of verifying the magic.
-            for (i = 0; i < size; i++)
+            for (i = 0; i < size; ++i)
             {
                 Bitboard& attack = attacks[s][index(s, occupancy[i])];