magic bitboards via AI

1 files changed, 8 insertions, 84 deletions

diff --git a/src/engine/moves/attack.c b/src/engine/moves/attack.c
index e4923ea..2786ad3 100644
--- a/src/engine/moves/attack.c
+++ b/src/engine/moves/attack.c
@@ -51,95 +51,19 @@ static bool sliding_attacks_square(
   bool check_bishop
 ) {
   bitboard_t all_occupied = whites(position) | blacks(position);
-  int rank = square / 8;
-  int file = square % 8;
-
-  bitboard_t enemy_rooks  = (by_color == WHITE_TURN) ? position.bitboards[WHITE_ROOK]  : position.bitboards[BLACK_ROOK];
-  bitboard_t enemy_bishops = (by_color == WHITE_TURN) ? position.bitboards[WHITE_BISHOP] : position.bitboards[BLACK_BISHOP];
-  bitboard_t enemy_queens  = (by_color == WHITE_TURN) ? position.bitboards[WHITE_QUEEN]  : position.bitboards[BLACK_QUEEN];
 
   if (check_rook) {
-    bitboard_t rook_like = enemy_rooks | enemy_queens;
-
-    int r, idx;
-    r = rank + 1;
-    while (r < 8) {
-      idx = r * 8 + file;
-      if ((all_occupied >> idx) & 1) {
-        if ((rook_like >> idx) & 1) return true;
-        break;
-      }
-      r++;
-    }
-    r = rank - 1;
-    while (r >= 0) {
-      idx = r * 8 + file;
-      if ((all_occupied >> idx) & 1) {
-        if ((rook_like >> idx) & 1) return true;
-        break;
-      }
-      r--;
-    }
-    int f = file + 1;
-    while (f < 8) {
-      idx = rank * 8 + f;
-      if ((all_occupied >> idx) & 1) {
-        if ((rook_like >> idx) & 1) return true;
-        break;
-      }
-      f++;
-    }
-    f = file - 1;
-    while (f >= 0) {
-      idx = rank * 8 + f;
-      if ((all_occupied >> idx) & 1) {
-        if ((rook_like >> idx) & 1) return true;
-        break;
-      }
-      f--;
-    }
+    bitboard_t rook_like = (by_color == WHITE_TURN)
+      ? (position.bitboards[WHITE_ROOK] | position.bitboards[WHITE_QUEEN])
+      : (position.bitboards[BLACK_ROOK] | position.bitboards[BLACK_QUEEN]);
+    if (get_rook_attacks(square, all_occupied) & rook_like) return true;
   }
 
   if (check_bishop) {
-    bitboard_t bishop_like = enemy_bishops | enemy_queens;
-
-    int r, f, idx;
-    r = rank + 1; f = file + 1;
-    while (r < 8 && f < 8) {
-      idx = r * 8 + f;
-      if ((all_occupied >> idx) & 1) {
-        if ((bishop_like >> idx) & 1) return true;
-        break;
-      }
-      r++; f++;
-    }
-    r = rank - 1; f = file - 1;
-    while (r >= 0 && f >= 0) {
-      idx = r * 8 + f;
-      if ((all_occupied >> idx) & 1) {
-        if ((bishop_like >> idx) & 1) return true;
-        break;
-      }
-      r--; f--;
-    }
-    r = rank - 1; f = file + 1;
-    while (r >= 0 && f < 8) {
-      idx = r * 8 + f;
-      if ((all_occupied >> idx) & 1) {
-        if ((bishop_like >> idx) & 1) return true;
-        break;
-      }
-      r--; f++;
-    }
-    r = rank + 1; f = file - 1;
-    while (r < 8 && f >= 0) {
-      idx = r * 8 + f;
-      if ((all_occupied >> idx) & 1) {
-        if ((bishop_like >> idx) & 1) return true;
-        break;
-      }
-      r++; f--;
-    }
+    bitboard_t bishop_like = (by_color == WHITE_TURN)
+      ? (position.bitboards[WHITE_BISHOP] | position.bitboards[WHITE_QUEEN])
+      : (position.bitboards[BLACK_BISHOP] | position.bitboards[BLACK_QUEEN]);
+    if (get_bishop_attacks(square, all_occupied) & bishop_like) return true;
   }
 
   return false;