diff --git a/src/bitboard.h b/src/bitboard.h
new file mode 100644
index 0000000..4112073
--- /dev/null
+++ b/src/bitboard.h
@@ -0,0 +1,70 @@
+/* bitboard.h - bitboard definitions.
+ *
+ * Copyright (C) 2021 Bruno Raoult ("br")
+ * Licensed under the GNU General Public License v3.0 or later.
+ * Some rights reserved. See COPYING.
+ *
+ * You should have received a copy of the GNU General Public License along with this
+ * program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
+ *
+ */
+
+#ifndef BITBOARD_H
+#define BITBOARD_H
+
+#include <bits.h>
+
+#include "chessdefs.h"
+#include "piece.h"
+
+enum bb_square {
+    A1 = 1UL <<  0, B1 = 1UL <<  1, C1 = 1UL <<  2, D1 = 1UL <<  3,
+    E1 = 1UL <<  4, F1 = 1UL <<  5, G1 = 1UL <<  6, H1 = 1UL <<  7,
+
+    A2 = 1UL <<  8, B2 = 1UL <<  9, C2 = 1UL << 10, D2 = 1UL << 11,
+    E2 = 1UL << 12, F2 = 1UL << 13, G2 = 1UL << 14, H2 = 1UL << 15,
+
+    A3 = 1UL << 16, B3 = 1UL << 17, C3 = 1UL << 18, D3 = 1UL << 19,
+    E3 = 1UL << 20, F3 = 1UL << 21, G3 = 1UL << 22, H3 = 1UL << 23,
+
+    A4 = 1UL << 24, B4 = 1UL << 25, C4 = 1UL << 26, D4 = 1UL << 27,
+    E4 = 1UL << 28, F4 = 1UL << 29, G4 = 1UL << 30, H4 = 1UL << 31,
+
+    A5 = 1UL << 32, B5 = 1UL << 33, C5 = 1UL << 34, D5 = 1UL << 35,
+    E5 = 1UL << 36, F5 = 1UL << 37, G5 = 1UL << 38, H5 = 1UL << 39,
+
+    A6 = 1UL << 40, B6 = 1UL << 41, C6 = 1UL << 42, D6 = 1UL << 43,
+    E6 = 1UL << 44, F6 = 1UL << 45, G6 = 1UL << 46, H6 = 1UL << 47,
+
+    A7 = 1UL << 48, B7 = 1UL << 49, C7 = 1UL << 50, D7 = 1UL << 51,
+    E7 = 1UL << 52, F7 = 1UL << 53, G7 = 1UL << 54, H7 = 1UL << 55,
+
+    A8 = 1UL << 56, B8 = 1UL << 57, C8 = 1UL << 58, D8 = 1UL << 59,
+    E8 = 1UL << 60, F8 = 1UL << 61, G8 = 1UL << 62, H8 = 1UL << 63,
+};
+
+enum bb_files {
+    F_1 = A1 | A2 | A3 | A4 | A5 | A6 | A7 | A8,
+    F_2 = B1 | B2 | B3 | B4 | B5 | B6 | B7 | B8,
+    F_3 = C1 | C2 | C3 | C4 | C5 | C6 | C7 | C8,
+    F_4 = D1 | D2 | D3 | D4 | D5 | D6 | D7 | D8,
+    F_5 = E1 | E2 | E3 | E4 | E5 | E6 | E7 | E8,
+    F_6 = F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8,
+    F_7 = G1 | G2 | G3 | G4 | G5 | G6 | G7 | G8,
+    F_8 = H1 | H2 | H3 | H4 | H5 | H6 | H7 | H8,
+};
+
+enum bb_ranges {
+    R_1 = A1 | B1 | C1 | D1 | E1 | F1 | G1 | H1,
+    R_2 = A2 | B2 | C2 | D2 | E2 | F2 | G2 | H2,
+    R_3 = A3 | B3 | C3 | D3 | E3 | F3 | G3 | H3,
+    R_4 = A4 | B4 | C4 | D4 | E4 | F4 | G4 | H4,
+    R_5 = A5 | B5 | C5 | D5 | E5 | F5 | G5 | H5,
+    R_6 = A6 | B6 | C6 | D6 | E6 | F6 | G6 | H6,
+    R_7 = A7 | B7 | C7 | D7 | E7 | F7 | G7 | H7,
+    R_8 = A8 | B8 | C8 | D8 | E8 | F8 | G8 | H8,
+};
+
+#endif  /* BOARD_H */
diff --git a/src/board.h b/src/board.h
index 93f12ab..6543eb2 100644
--- a/src/board.h
+++ b/src/board.h
@@ -77,32 +77,4 @@ enum x88_square {
     x88_A8=0x70, x88_B8, x88_C8, x88_D8, x88_E8, x88_F8, x88_G8, x88_H8,
 };
 
-/* necessary not to become mad to set bitboards
- */
-enum bb_square {
-    A1=(u64)1,     B1=(u64)A1<<1, C1=(u64)B1<<1, D1=(u64)C1<<1,
-    E1=(u64)D1<<1, F1=(u64)E1<<1, G1=(u64)F1<<1, H1=(u64)G1<<1,
-
-    A2=(u64)A1<<8, B2=(u64)B1<<8, C2=(u64)C1<<8, D2=(u64)D1<<8,
-    E2=(u64)E1<<8, F2=(u64)F1<<8, G2=(u64)G1<<8, H2=(u64)H1<<8,
-
-    A3=(u64)A2<<8, B3=(u64)B2<<8, C3=(u64)C2<<8, D3=(u64)D2<<8,
-    E3=(u64)E2<<8, F3=(u64)F2<<8, G3=(u64)G2<<8, H3=(u64)H2<<8,
-
-    A4=(u64)A3<<8, B4=(u64)B3<<8, C4=(u64)C3<<8, D4=(u64)D3<<8,
-    E4=(u64)E3<<8, F4=(u64)F3<<8, G4=(u64)G3<<8, H4=(u64)H3<<8,
-
-    A5=(u64)A4<<8, B5=(u64)B4<<8, C5=(u64)C4<<8, D5=(u64)D4<<8,
-    E5=(u64)E4<<8, F5=(u64)F4<<8, G5=(u64)G4<<8, H5=(u64)H4<<8,
-
-    A6=(u64)A5<<8, B6=(u64)B5<<8, C6=(u64)C5<<8, D6=(u64)D5<<8,
-    E6=(u64)E5<<8, F6=(u64)F5<<8, G6=(u64)G5<<8, H6=(u64)H5<<8,
-
-    A7=(u64)A6<<8, B7=(u64)B6<<8, C7=(u64)C6<<8, D7=(u64)D6<<8,
-    E7=(u64)E6<<8, F7=(u64)F6<<8, G7=(u64)G6<<8, H7=(u64)H6<<8,
-
-    A8=(u64)A7<<8, B8=(u64)B7<<8, C8=(u64)C7<<8, D8=(u64)D7<<8,
-    E8=(u64)E7<<8, F8=(u64)F7<<8, G8=(u64)G7<<8, H8=(u64)H7<<8,
-};
-
 #endif  /* BOARD_H */
diff --git a/src/move.c b/src/move.c
index e240a82..2a24eb5 100644
--- a/src/move.c
+++ b/src/move.c
@@ -21,6 +21,7 @@
 
 #include "chessdefs.h"
 #include "board.h"
+#include "bitboard.h"
 #include "piece.h"
 #include "move.h"
 #include "eval.h"
diff --git a/src/piece.c b/src/piece.c
index 96f2722..6bca6f1 100644
--- a/src/piece.c
+++ b/src/piece.c
@@ -21,6 +21,7 @@
 #include "chessdefs.h"
 #include "piece.h"
 #include "board.h"
+#include "bitboard.h"
 #include "position.h"
 
 static pool_t *pieces_pool;