refactor: separate bitboard functionality

1 files changed, 30 insertions, 0 deletions

diff --git a/src/bitboard.c b/src/bitboard.c
new file mode 100644
index 0000000..e9a7d53
--- /dev/null
+++ b/src/bitboard.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include "bitboard.h"
+
+/* Print bitboard on screen in the same way squares appear in memory
+ * (i.e the board is actually flipped along X) */
+void print_bitboard(Bitboard bb) {
+  for (U64 index = 0; index < 64; index++) {
+    printf("%lu", (bb >> index) & 1);
+    if ((index + 1) % 8 == 0) printf("\n");
+  }
+  printf("\n\n");
+}
+
+/* Return bitboard cardinality, aka number of elements in the set */
+inline int pop_count(Bitboard bb){
+  if (bb == 0) return 0;
+  return pop_count(bb >> 1) + (bb & 1);
+}
+
+/* Return Bitboard with only Least Single Bit */
+inline Bitboard ls1b(Bitboard bb) {
+  return bb & -bb;
+}
+
+/* Log base 2 (aka Trailing Zero Count)
+ * Only works for SINGLE Bitboards
+ * Useful for calculating bit-index of LS1B */
+inline Bitboard bitscan(Bitboard bb) {
+  return pop_count(ls1b(bb) - 1);
+}