From 9395e857db95481f6e2494d3a841632be0ff97c8 Mon Sep 17 00:00:00 2001
From: Aargh Rai <aargh.rai+git@gmail.com>
Date: Sat, 18 Jul 2026 14:02:18 +0530
Subject: fixed moved gen & adding messages on asserts

---
 src/engine/moves.c | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

(limited to 'src/engine')

diff --git a/src/engine/moves.c b/src/engine/moves.c
index 0c923a1..6f96109 100644
--- a/src/engine/moves.c
+++ b/src/engine/moves.c
@@ -76,7 +76,7 @@ int find_piece_on_square(position_t* p, int square) {
   if ((p->bitboards[BLACK_BISHOP] >> square) & 1) return BLACK_BISHOP;
   if ((p->bitboards[BLACK_KNIGHT] >> square) & 1) return BLACK_KNIGHT;
   if ((p->bitboards[BLACK_PAWN]   >> square) & 1) return BLACK_PAWN;
-  assert(0);
+  assert(0 && "Failed to find the piece on the square");
 }
 
 void position_make_move(position_t* position, move_t move) {
@@ -140,24 +140,40 @@ void position_make_move(position_t* position, move_t move) {
   }
 
   if (move.flags & MOVE_PROMOTE_Q) {
+    if (move.flags & MOVE_CAPTURE) {
+      int to_remove_piece_type = find_piece_on_square(position, move.to);
+      position->bitboards[to_remove_piece_type] &= ~((bitboard_t)1 << move.to);
+    }
     int q_type = position->turn == WHITE_TURN ? WHITE_QUEEN : BLACK_QUEEN;
     position->bitboards[q_type] |= (bitboard_t)1 << move.to;
     position->turn = !position->turn;
     return;
   }
   if (move.flags & MOVE_PROMOTE_R) {
+    if (move.flags & MOVE_CAPTURE) {
+      int to_remove_piece_type = find_piece_on_square(position, move.to);
+      position->bitboards[to_remove_piece_type] &= ~((bitboard_t)1 << move.to);
+    }
     int q_type = position->turn == WHITE_TURN ? WHITE_ROOK : BLACK_ROOK;
     position->bitboards[q_type] |= (bitboard_t)1 << move.to;
     position->turn = !position->turn;
     return;
   }
   if (move.flags & MOVE_PROMOTE_B) {
+    if (move.flags & MOVE_CAPTURE) {
+      int to_remove_piece_type = find_piece_on_square(position, move.to);
+      position->bitboards[to_remove_piece_type] &= ~((bitboard_t)1 << move.to);
+    }
     int q_type = position->turn == WHITE_TURN ? WHITE_BISHOP : BLACK_BISHOP;
     position->bitboards[q_type] |= (bitboard_t)1 << move.to;
     position->turn = !position->turn;
     return;
   }
   if (move.flags & MOVE_PROMOTE_N) {
+    if (move.flags & MOVE_CAPTURE) {
+      int to_remove_piece_type = find_piece_on_square(position, move.to);
+      position->bitboards[to_remove_piece_type] &= ~((bitboard_t)1 << move.to);
+    }
     int q_type = position->turn == WHITE_TURN ? WHITE_KNIGHT : BLACK_KNIGHT;
     position->bitboards[q_type] |= (bitboard_t)1 << move.to;
     position->turn = !position->turn;
@@ -206,6 +222,7 @@ int count_positions(position_t position, int depth) {
   moves_t moves;
   moves_init(&moves);
   get_legal_moves(&moves, position);
+
   int count = 0;
   for (int i = 0; i < moves.length; i++) {
     position_t copy = position;
@@ -221,6 +238,7 @@ void perft_divide(position_t position, int depth) {
   moves_t moves;
   moves_init(&moves);
   get_legal_moves(&moves, position);
+
   int nodes = 0;
   for (int i = 0; i < moves.length; i++) {
     position_t copy = position;
@@ -281,12 +299,11 @@ bool test_perft_position3() {
   d = count_positions(position, 3); if (d != 2812) return false;
   d = count_positions(position, 4); if (d != 43238) return false;
   d = count_positions(position, 5); if (d != 674624) return false;
-  perft_divide(position, 6);
-  d = count_positions(position, 6);
-  printf("%d\n", d);
-  if (d != 11030083) return false;
-  d = count_positions(position, 7); if (d != 178633661) return false;
-  d = count_positions(position, 8); if (d != 3009794393) return false;
+  d = count_positions(position, 6); if (d != 11030083) return false;
+
+  // my move gen too slow to verify this
+  // d = count_positions(position, 7); if (d != 178633661) return false;
+  // d = count_positions(position, 8); if (d != 3009794393) return false;
 
   return true;
 }
-- 
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