rook moves

1 files changed, 63 insertions, 0 deletions

diff --git a/src/search/rook_moves.c b/src/search/rook_moves.c
new file mode 100644
index 0000000..749210e
--- /dev/null
+++ b/src/search/rook_moves.c
@@ -0,0 +1,63 @@
+#include "search.h"
+
+void get_rook_moves(moves_t* moves, position_t position) {
+  assert_valid_position(position);
+
+  bitboard_t friendly_rooks;
+  bitboard_t friendly_pieces;
+  bitboard_t enemy_pieces;
+  if (position.turn == WHITE_TURN) {
+    friendly_pieces = whites(position);
+    enemy_pieces = blacks(position);
+    friendly_rooks = position.bitboards[WHITE_ROOK];
+  } else {
+    friendly_pieces = blacks(position);
+    enemy_pieces = whites(position);
+    friendly_rooks = position.bitboards[BLACK_ROOK];
+  }
+  
+  while (friendly_rooks) {
+    int from = __builtin_ctzll(friendly_rooks);
+    friendly_rooks &= friendly_rooks - 1;
+
+    int og_rank = from / 8; // range: [0, 7]
+    int og_file = from % 8; // range: [0, 7]
+    int rank = og_rank + 1, file = og_file, index = rank * 8 + file;
+
+
+    while (rank < 8 && !occupied_by(friendly_pieces, index)) {
+      add_move(moves, from, index);
+      if (occupied_by(enemy_pieces, index)) {
+        break;
+      }
+      index = ++rank * 8 + file;
+    }
+
+    rank = og_rank - 1, file = og_file, index = rank * 8 + file;
+    while (rank >= 0 && !occupied_by(friendly_pieces, index)) {
+      add_move(moves, from, index);
+      if (occupied_by(enemy_pieces, index)) {
+        break;
+      }
+      index = --rank * 8 + file;
+    }
+
+    rank = og_rank, file = og_file + 1, index = rank * 8 + file;
+    while (file < 8 && !occupied_by(friendly_pieces, index)) {
+      add_move(moves, from, index);
+      if (occupied_by(enemy_pieces, index)) {
+        break;
+      }
+      index = rank * 8 + ++file;
+    }
+    
+    rank = og_rank, file = og_file - 1, index = rank * 8 + file;
+    while (file >= 0 && !occupied_by(friendly_pieces, index)) {
+      add_move(moves, from, index);
+      if (occupied_by(enemy_pieces, index)) {
+        break;
+      }
+      index = rank * 8 + --file;
+    }
+  }
+}