1 files changed, 58 insertions, 0 deletions
diff --git a/src/bitboard.c b/src/bitboard.c
new file mode 100644
index 0000000..565f425
--- /dev/null
+++ b/src/bitboard.c
@@ -0,0 +1,58 @@
+#include "bitboard.h"
+#include <stdio.h>
+#include <inttypes.h>
+#include <assert.h>
+
+position_t position_starting() {
+  return (position_t) {
+    .bitboards = {
+      16ULL,
+      8ULL,
+      129ULL,
+      36ULL,
+      66ULL,
+      65280ULL,
+      1152921504606846976ULL,
+      576460752303423488ULL,
+      9295429630892703744ULL,
+      2594073385365405696ULL,
+      4755801206503243776ULL,
+      71776119061217280ULL,
+    },
+    .castling =
+      WHITE_SHORT_CASTLE | WHITE_LONG_CASTLE |
+      BLACK_SHORT_CASTLE | BLACK_LONG_CASTLE,
+    .turn = WHITE_TURN,
+    .passantable_file = 0,
+    .halfmove_clock = 0,
+    .fullmove_clock = 1
+  };
+}
+
+void assert_valid_position(position_t position) {
+  assert(check_valid_position(position) == true);
+}
+
+bool check_valid_position(position_t position) {
+  if (position.castling >
+    (
+      WHITE_SHORT_CASTLE | WHITE_LONG_CASTLE |
+      BLACK_SHORT_CASTLE | BLACK_LONG_CASTLE
+    )
+  ) return false;
+  if (position.turn != WHITE_TURN && position.turn != BLACK_TURN) return false;
+  if (position.passantable_file > 8) return false; // 0 means no passant
+  if (position.bitboards[WHITE_KING] == 0) return false;
+  if (position.bitboards[BLACK_KING] == 0) return false;
+  return true;
+}
+
+void print_bitboard(bitboard_t bitboard) {
+  printf("Bitboard(%" PRIu64 ")\n", bitboard);
+  for (int i = 7; i >= 0; i--) {
+    for (int j = 0; j < 8; j++) {
+      printf("%" PRIu64 "", (bitboard >> (8 * i + j)) & 1);
+    }
+    printf("\n");
+  }
+}