Add attacker and check logic with tests

test/chess_ffi.py

@@ -87,6 +87,16 @@ gen_queen_moves   = _bind_opt("gen_queen_moves",   *PIECE_SIG)
 gen_king_moves    = _bind_opt("gen_king_moves",    *PIECE_SIG)
 
 
+# Attack checks.
+ATTACKED_SIG = (C.POINTER(Board), C.c_int, C.c_int)
+INCHECK_ARGS = (C.POINTER(Board), C.c_int)
+ATTACKERS_TO = (C.POINTER(Board), C.c_int, C.c_int)
+
+square_attacked = _bind_opt("square_attacked", ATTACKED_SIG, C.c_bool)
+in_check = _bind_opt("in_check", INCHECK_ARGS, C.c_bool)
+attackers_to = _bind_opt("attackers_to", ATTACKERS_TO, C.c_uint64)
+
+
 # Attack cache tables.
 KnightArr = (C.c_uint64 * 64)
 KingArr   = (C.c_uint64 * 64)
@@ -102,8 +112,8 @@ except ValueError:
 
 def init_attack_caches():
     if create_knight_attack_cache: create_knight_attack_cache()
-    if create_king_attack_cache:   create_king_attack_cache()
-    if create_pawn_attack_cache:   create_pawn_attack_cache()
+    if create_king_attack_cache: create_king_attack_cache()
+    if create_pawn_attack_cache: create_pawn_attack_cache()
 
 
 def load_fen(board, fen):
@@ -116,6 +126,18 @@ def gen_moves(board, captures_only=False, cap=256):
     return buf, n
 
 
+def is_square_attacked(board, sq, by):
+    return bool(square_attacked(C.byref(board), int(sq), int(by)))
+
+
+def is_in_check(board, side):
+    return bool(in_check(C.byref(board), int(side)))
+
+
+def get_attackers_to(board, sq, by):
+    return int(attackers_to(C.byref(board), int(sq), int(by)))
+
+
 def sq_to_coord(sq):
     return chr(ord('a') + (sq % 8)) + chr(ord('1') + (sq // 8))
 
@@ -137,7 +159,7 @@ def popcount(x: int) -> int:
     return x.bit_count()
 
 
-def draw_bb(mask: int, origin: int | None = None) -> str:
+def draw_bb(mask, origin=None):
     print("\n")
     lines = []
     for r in range(7, -1, -1):