From 27e879c62ecc019591201b1b1068b0c41870cfab Mon Sep 17 00:00:00 2001
From: Adam <adammegarules1@gmail.com>
Date: Mon, 3 Aug 2026 21:56:36 +0200
Subject: a big hell of a commit

---
 src/board/board.cpp | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 src/board/fen.cpp   | 15 +++---------
 2 files changed, 69 insertions(+), 15 deletions(-)

(limited to 'src/board')

diff --git a/src/board/board.cpp b/src/board/board.cpp
index 16efbd3..28183a2 100644
--- a/src/board/board.cpp
+++ b/src/board/board.cpp
@@ -61,6 +61,19 @@ UndoMove MakeMove(Move move, Game *g) {
     undo.wasEnPassantCapture = true;
     undo.enPassantCapturedSquare = capturedPawn;
     undo.enPassantCapturedPiece = g->pieces[PositionToIndex(capturedPawn)];
+
+    bool captuaredColor = !piece.color;
+    uint64_t square = 1ULL << PositionToIndex(capturedPawn);
+
+    g->PieceBitboards[captuaredColor][PAWN] ^= square;
+
+    if (captuaredColor)
+      g->WhitePieceBitboard ^= square;
+    else
+      g->BlackPieceBitboard ^= square;
+
+    g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
+
     g->pieces[PositionToIndex(capturedPawn)] = {false, NONEPIECE};
   }
 
@@ -69,11 +82,11 @@ UndoMove MakeMove(Move move, Game *g) {
   // Adding enpassant
   if (piece.type == PAWN) {
     Position to = move.To;
-    to.rank -= static_cast<uint8_t>(piece.color ? -2 : 2);
+    to.rank -= static_cast<uint8_t>(piece.color ? 2 : -2);
     if (to == move.From) {
       g->canEnpassant = true;
       Position target = move.From;
-      target.rank += static_cast<uint8_t>(piece.color ? -1 : 1);
+      target.rank += static_cast<uint8_t>(piece.color ? 1 : -1);
       g->enPassant = target;
     };
   }
@@ -98,6 +111,19 @@ UndoMove MakeMove(Move move, Game *g) {
       Position rookTo = move.From;
       rookTo.file = 5;
 
+      uint64_t from = 1ULL << PositionToIndex(rookFrom);
+      uint64_t to = 1ULL << PositionToIndex(rookTo);
+
+      g->PieceBitboards[piece.color][ROOK] ^= from;
+      g->PieceBitboards[piece.color][ROOK] ^= to;
+
+      if (piece.color)
+        g->WhitePieceBitboard ^= from | to;
+      else
+        g->BlackPieceBitboard ^= from | to;
+
+      g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
+
       g->pieces[PositionToIndex(rookTo)] = g->pieces[PositionToIndex(rookFrom)];
       g->pieces[PositionToIndex(rookFrom)] = {false, NONEPIECE};
     } else {
@@ -108,6 +134,19 @@ UndoMove MakeMove(Move move, Game *g) {
       Position rookTo = move.From;
       rookTo.file = 3;
 
+      uint64_t from = 1ULL << PositionToIndex(rookFrom);
+      uint64_t to = 1ULL << PositionToIndex(rookTo);
+
+      g->PieceBitboards[piece.color][ROOK] ^= from;
+      g->PieceBitboards[piece.color][ROOK] ^= to;
+
+      if (piece.color)
+        g->WhitePieceBitboard ^= from | to;
+      else
+        g->BlackPieceBitboard ^= from | to;
+
+      g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
+
       g->pieces[PositionToIndex(rookTo)] = g->pieces[PositionToIndex(rookFrom)];
       g->pieces[PositionToIndex(rookFrom)] = {false, NONEPIECE};
     }
@@ -162,6 +201,31 @@ UndoMove MakeMove(Move move, Game *g) {
   }
 
   // playing the moves
+  uint64_t from = 1ULL << PositionToIndex(move.From);
+  uint64_t to = 1ULL << PositionToIndex(move.To);
+
+  // remove moving piece from source
+  g->PieceBitboards[piece.color][undo.movedPiece.type] ^= from;
+
+  // remove captured piece
+  if (piece2.type != NONEPIECE) {
+    g->PieceBitboards[piece2.color][piece2.type] ^= to;
+
+    if (piece2.color)
+      g->WhitePieceBitboard ^= to;
+    else
+      g->BlackPieceBitboard ^= to;
+  }
+
+  // add moving piece to destination
+  g->PieceBitboards[piece.color][piece.type] ^= to;
+
+  if (piece.color)
+    g->WhitePieceBitboard ^= from | to;
+  else
+    g->BlackPieceBitboard ^= from | to;
+
+  g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
   g->pieces[PositionToIndex(move.To)] = piece;
   g->pieces[PositionToIndex(move.From)] = {false, NONEPIECE};
 
@@ -182,7 +246,6 @@ UndoMove MakeMove(Move move, Game *g) {
   if (g->halfMoveClock >= 50) {
     g->state = DRAW;
   }
-  UpdateHelpers(g);
   return undo;
 };
 void UnMakeMove(UndoMove undo, Game *g) {
diff --git a/src/board/fen.cpp b/src/board/fen.cpp
index fc52bfe..c4c5e7a 100644
--- a/src/board/fen.cpp
+++ b/src/board/fen.cpp
@@ -2,7 +2,6 @@
 #include "board.hpp"
 #include <cassert>
 #include <cctype>
-#include <cstdint>
 #include <cstdlib>
 #include <print>
 #include <string>
@@ -14,7 +13,7 @@ bool BLACK = false;
 void setBoardFen(const std::string fen, Game *g) {
   // example fen rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
   int file = 0;
-  int rank = 0;
+  int rank = 7;
 
   Position enpassant = {};
   enum parserState {
@@ -52,14 +51,6 @@ void setBoardFen(const std::string fen, Game *g) {
       }
     }
     if (parser_state == ENPASSANT) {
-      if (toupper(c) >= 'A' && toupper(c) <= 'H') {
-        enpassant.file = static_cast<uint8_t>(toupper(c) - 'A');
-        g->canEnpassant = true;
-      }
-      if (c >= '1' && c <= '8') {
-        enpassant.rank = static_cast<uint8_t>(c - '0');
-        g->canEnpassant = true;
-      }
       continue;
     }
     if (parser_state == CASTLE) {
@@ -111,8 +102,8 @@ void setBoardFen(const std::string fen, Game *g) {
       }
       if (c == '/') {
         file = 0;
-        rank++;
-        if (rank >= 8) {
+        rank--;
+        if (rank < 0) {
           std::println("Fatal: rank was to big");
           assert(false && "Malformed rank");
           exit(1);
-- 
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