perf(board): making is square attacked helper use modern bitboard aproach

1 files changed, 17 insertions, 43 deletions

diff --git a/src/moves.cpp b/src/moves.cpp
index 44e78b2..531d8a9 100644
--- a/src/moves.cpp
+++ b/src/moves.cpp
@@ -553,64 +553,38 @@ static void GenerateKingMoves(const Game &g, const uint8_t &from,
 bool IsSquareAttacked(const Game &g, Position square, bool byColor) {
   int target = PositionToIndex(square);
 
-  // Pawn attacks: a pawn of byColor attacks diagonally "forward" from its
-  // own perspective. White pawns (rank increases toward rank 7) attack from
-  // one rank below the target; Black pawns attack from one rank above.
-  int pawnRank = square.rank + (byColor ? -1 : 1);
-
-  if (pawnRank >= 0 && pawnRank < 8) {
-    for (int fileOffset : {-1, 1}) {
-      int file = square.file + fileOffset;
-      if (file < 0 || file >= 8)
-        continue;
-
-      Piece p = g.pieces[pawnRank * 8 + file];
-      if (p.type == PAWN && p.color == byColor) {
-        return true;
-      }
-    }
+  uint64_t pawns_attacks =
+      PAWN_ATTACKS[static_cast<size_t>(!byColor)][static_cast<size_t>(target)];
+  pawns_attacks &= g.PieceBitboards[static_cast<size_t>(byColor)][PAWN];
+  if (pawns_attacks > 0) {
+    return true;
   }
 
   // Knight attacks
-  constexpr std::array<int, 8> knightOffsets{-17, -15, -10, -6, 6, 10, 15, 17};
-  for (int offset : knightOffsets) {
-    int from = target + offset;
-    if (from < 0 || from >= 64)
-      continue;
-
-    int fileDiff = std::abs((from % 8) - (target % 8));
-    if (fileDiff != 1 && fileDiff != 2)
-      continue;
-
-    Piece p = g.pieces[from];
-    if (p.type == KNIGHT && p.color == byColor)
-      return true;
+  uint64_t knightAttacks = KNIGHT_ATTACKS[static_cast<size_t>(target)];
+  knightAttacks &= g.PieceBitboards[static_cast<size_t>(byColor)][KNIGHT];
+  if (knightAttacks > 0) {
+    return true;
   }
 
   // King attacks
-  constexpr std::array<int, 8> kingOffsets{-9, -8, -7, -1, 1, 7, 8, 9};
-  for (int offset : kingOffsets) {
-    int from = target + offset;
-    if (from < 0 || from >= 64)
-      continue;
-    if (std::abs((from % 8) - (target % 8)) > 1)
-      continue;
-
-    Piece p = g.pieces[from];
-    if (p.type == KING && p.color == byColor)
-      return true;
+  uint64_t king_attacks = KING_ATTACKS[static_cast<size_t>(target)];
+  king_attacks &= g.PieceBitboards[static_cast<size_t>(byColor)][KING];
+  if (king_attacks > 0) {
+    return true;
   }
-
   // Rooks + queens (orthogonal rays)
   constexpr std::array<int, 4> rookDirs{-8, 8, -1, 1};
   for (int dir : rookDirs) {
     int pos = target;
     while (true) {
       int next = pos + dir;
-      if (next < 0 || next >= 64)
+      if (next < 0 || next >= 64) {
         break;
-      if ((dir == 1 || dir == -1) && next / 8 != pos / 8)
+      }
+      if ((dir == 1 || dir == -1) && next / 8 != pos / 8) {
         break; // horizontal wrap
+      }
 
       Piece p = g.pieces[next];
       if (p.type != NONEPIECE) {