1 files changed, 31 insertions, 20 deletions

diff --git a/src/engine/fen.c b/src/engine/fen.c
index 187271e..a375b30 100644
--- a/src/engine/fen.c
+++ b/src/engine/fen.c
@@ -1,20 +1,21 @@
-#include "fen.h"
-#include "bitboard.h"
 #include <assert.h>
+#include <stdbool.h>
 #include <stdio.h>
+#include "fen.h"
+#include "bitboard.h"
 
 int get_castling(char c) {
   if (c == 'K') return WHITE_SHORT_CASTLE;
   if (c == 'Q') return WHITE_LONG_CASTLE;
   if (c == 'k') return BLACK_SHORT_CASTLE;
   if (c == 'q') return BLACK_LONG_CASTLE;
-  assert(0);
+  return -1;
 }
 
 int get_turn(char c) {
   if (c == 'w') return WHITE_TURN;
   if (c == 'b') return BLACK_TURN;
-  assert(0);
+  return -1;
 }
 
 int get_piece_enum_item(char c) {
@@ -32,7 +33,7 @@ int get_piece_enum_item(char c) {
   if (c == 'q') return BLACK_QUEEN;
   if (c == 'k') return BLACK_KING;
 
-  assert(0);
+  return -1;
 }
 
 /*
@@ -78,7 +79,7 @@ int get_piece_enum_item(char c) {
  *
  *  e.g. 1B6/2n5/p1N1P2R/P1K3N1/4Pk2/1Q2p2p/6nP/1B4R1 w - - 0 1
  */
-position_t load_fen(const char* fen) {
+struct fen_load load_fen(const char* fen) {
   position_t position = {0};
 
   int square = 56;
@@ -86,7 +87,7 @@ position_t load_fen(const char* fen) {
   char c;
   while ((c = fen[++i]) != ' ') {
     if (c >= '0' && c <= '9') {
-      assert(c != '9');
+      if (c == '9') return (struct fen_load) { true, position };
       square += c - '0';
       continue;
     }
@@ -96,57 +97,67 @@ position_t load_fen(const char* fen) {
     }
 
     int piece_type = get_piece_enum_item(c);
+    if (piece_type == -1) return (struct fen_load) { true, position };
     position.bitboards[piece_type] |= (bitboard_t)1 << square;
   }
 
   c = fen[++i];
-  position.turn = get_turn(c);
-  assert(fen[++i] == ' ');
+  int turn = get_turn(c);
+  if (turn == -1) return (struct fen_load) { true, position };
+  position.turn = turn;
+  if (fen[++i] != ' ') return (struct fen_load) { true, position };
 
   while ((c = fen[++i]) != ' ') {
     if (c == '-') continue;
-    position.castling |= get_castling(c);
+    int castling = get_castling(c);
+    if (castling == -1) return (struct fen_load) { true, position };
+    position.castling |= castling;
   }
 
   c = fen[++i];
   if (c >= 'a' && c <= 'z') {
-    assert(c <= 'h');
+    if (c > 'h') return (struct fen_load) { true, position };
     position.passantable_file = c - 'a' + 1;
     c = fen[++i];
-    assert(c >= '1' && c <= '8');
+    if (c < '1' && c > '8') return (struct fen_load) { true, position };
   } else {
     position.passantable_file = 0;
   }
-  assert(fen[++i] == ' ');
+  if (fen[++i] != ' ') return (struct fen_load) { true, position };
 
   while ((c = fen[++i]) != ' ') {
-    assert(c >= '0' && c <= '9');
+    if (c < '0' || c > '9') return (struct fen_load) { true, position };
     position.halfmove_clock *= 10;
     position.halfmove_clock += c - '0';
   }
 
   while ((c = fen[++i]) != 0) {
-    assert(c >= '0' && c <= '9');
+    if (c < '0' || c > '9') return (struct fen_load) { true, position };
     position.fullmove_clock *= 10;
     position.fullmove_clock += c - '0';
   }
 
-  assert_valid_position(position);
-  return position;
+  bool error = !check_valid_position(position);
+  return (struct fen_load) { error, position };
 }
 
 #ifdef TEST_MOD
 #include "bitboard.c"
-#include <stdbool.h>
 
 bool test_fen_no_passant() {
-  position_t p = load_fen("1B6/2n5/p1N1P2R/P1K3N1/4Pk2/1Q2p2p/6nP/1B4R1 w - - 0 1");
+  struct fen_load r = load_fen("1B6/2n5/p1N1P2R/P1K3N1/4Pk2/1Q2p2p/6nP/1B4R1 w - - 0 1");
+  if (r.failed) return false;
+
+  position_t p = r.position;
   if (p.castling != 0) return false;
   if (p.passantable_file != 0) return false;
   return true;
 }
 bool test_fen_passant() {
-  position_t p = load_fen("rnbqkbnr/ppp1p1pp/8/3pPp2/8/8/PPPP1PPP/RNBQKBNR w KQkq f6 0 3");
+  struct fen_load r = load_fen("rnbqkbnr/ppp1p1pp/8/3pPp2/8/8/PPPP1PPP/RNBQKBNR w KQkq f6 0 3");
+  if (r.failed) return false;
+
+  position_t p = r.position;
   if (
     p.castling != (
       WHITE_LONG_CASTLE | WHITE_SHORT_CASTLE |