feaT: add pawn promotions

2 files changed, 21 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index 2b7275f..4471c37 100644
--- a/src/main.c
+++ b/src/main.c
@@ -233,6 +233,17 @@ int apply_move(Move move, int* board) {
     // printf("Captured %s\n", pieces[target_piece]);
   }
 
+  if ((piece & NO_COLOR) == PAWN) {
+    int rank = move.destination / 16;
+    if (rank == 0) {
+      board[move.destination] = QUEEN | BLACK;
+      return target_piece | PROMOTION_HAPPENED;
+    } else if (rank == 7) {
+      board[move.destination] = QUEEN | WHITE;
+      return target_piece | PROMOTION_HAPPENED;
+    }
+  }
+
   if ((piece & NO_COLOR) == KING && abs(move.destination - move.origin) == 2) {
     // CASTLE!
     if (move.destination == 2) {
@@ -260,6 +271,14 @@ int apply_move(Move move, int* board) {
 void reverse_move(Move move, int captured_piece, int* board) {
   int piece = board[move.destination];
 
+  if (captured_piece & PROMOTION_HAPPENED) {
+    board[move.destination] = captured_piece ^ PROMOTION_HAPPENED;
+    if (piece % 2 == WHITE) {
+      board[move.origin] = PAWN | WHITE;
+    } else board[move.origin] = PAWN | BLACK;
+    return;
+  }
+
   board[move.origin] = piece;
   board[move.destination] = captured_piece;
 
diff --git a/src/pieces.h b/src/pieces.h
index fd0abaf..fe4d307 100644
--- a/src/pieces.h
+++ b/src/pieces.h
@@ -15,6 +15,7 @@ char* COLORS[] = { "white", "black" };
 #define QUEEN  0b1010
 #define KING   0b1100
 
+#define PROMOTION_HAPPENED 0b100000
 
 char* pieces[] = {
   ".", "*",
@@ -41,3 +42,4 @@ int blackPawnAttackMoves[] = { -17, -15, 0 };
 #define FILE_MASK 0b1111
 
 #define DESTINATION_MASK 0b1111111
+