From 2c2a70b69869f149c0407a62f1bf4c39899027a7 Mon Sep 17 00:00:00 2001
From: Aargh Rai <aargh.rai+git@gmail.com>
Date: Wed, 27 May 2026 18:02:44 +0530
Subject: restructing

---
 src/engine/bitboard.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 src/engine/bitboard.c

(limited to 'src/engine/bitboard.c')

diff --git a/src/engine/bitboard.c b/src/engine/bitboard.c
new file mode 100644
index 0000000..4746020
--- /dev/null
+++ b/src/engine/bitboard.c
@@ -0,0 +1,75 @@
+#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 =
+      ((bitboard_t)1 << WHITE_SHORT_CASTLE) |
+      ((bitboard_t)1 << WHITE_LONG_CASTLE) |
+      ((bitboard_t)1 << BLACK_SHORT_CASTLE) |
+      ((bitboard_t)1 << BLACK_LONG_CASTLE),
+    .turn = WHITE_TURN,
+    .passantable_file = 0,
+  };
+}
+
+void assert_valid_position(position_t position) {
+  assert(position.castling <= 
+    (
+      ((bitboard_t)1 << WHITE_SHORT_CASTLE) |
+      ((bitboard_t)1 << WHITE_LONG_CASTLE) |
+      ((bitboard_t)1 << BLACK_SHORT_CASTLE) |
+      ((bitboard_t)1 << BLACK_LONG_CASTLE)
+    )
+  );
+  assert(position.turn == WHITE_TURN || position.turn == BLACK_TURN);
+  assert(position.passantable_file <= 8);
+  assert(position.bitboards[WHITE_KING] != 0);
+  assert(position.bitboards[BLACK_KING] != 0);
+}
+
+bitboard_t whites(position_t position) {
+  return
+    position.bitboards[WHITE_KING] |
+    position.bitboards[WHITE_QUEEN] |
+    position.bitboards[WHITE_ROOK] |
+    position.bitboards[WHITE_BISHOP] |
+    position.bitboards[WHITE_KNIGHT] |
+    position.bitboards[WHITE_PAWN];
+}
+
+bitboard_t blacks(position_t position) {
+  return
+    position.bitboards[BLACK_KING] |
+    position.bitboards[BLACK_QUEEN] |
+    position.bitboards[BLACK_ROOK] |
+    position.bitboards[BLACK_BISHOP] |
+    position.bitboards[BLACK_KNIGHT] |
+    position.bitboards[BLACK_PAWN];
+}
+
+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");
+  }
+}
-- 
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