implementing memory optimazied move using uint16_t instead of a four integers and one byte

2 files changed, 73 insertions, 65 deletions

diff --git a/src/board/board.cpp b/src/board/board.cpp
index 3b1383a..a533b63 100644
--- a/src/board/board.cpp
+++ b/src/board/board.cpp
@@ -88,14 +88,18 @@ uint8_t getToValueFromMove(uint16_t move) { return (move >> 8) & 63; };
 Position FindKing(Game *g, bool color) {
   return IndexToPosition(__builtin_ctzll(g->PieceBitboards[color][KING]));
 }
-UndoMove MakeMove(Move move, Game *g) {
+UndoMove MakeMove(uint16_t move, Game *g) {
+  uint8_t fromSquare = getFromValueFromMove(move);
+  uint8_t toSquare = getToValueFromMove(move);
+  PieceType promotion = getPromotionTypeFromMove(move);
+
   UndoMove undo = {};
 
-  undo.from = move.From;
-  undo.to = move.To;
+  undo.from = fromSquare;
+  undo.to = toSquare;
 
-  undo.movedPiece = g->pieces[PositionToIndex(move.From)];
-  undo.capturedPiece = g->pieces[PositionToIndex(move.To)];
+  undo.movedPiece = g->pieces[fromSquare];
+  undo.capturedPiece = g->pieces[toSquare];
 
   undo.oldTurn = g->turn;
   undo.oldCanEnpassant = g->canEnpassant;
@@ -112,8 +116,8 @@ UndoMove MakeMove(Move move, Game *g) {
   undo.OldBlackCastleQueen = g->blackCastleQueen;
 
   // play move
-  Piece piece = g->pieces[PositionToIndex(move.From)];
-  Piece piece2 = g->pieces[PositionToIndex(move.To)];
+  Piece piece = g->pieces[fromSquare];
+  Piece piece2 = g->pieces[toSquare];
 
   if (piece2.type != NONEPIECE) {
     if (piece2.color == g->turn) {
@@ -130,8 +134,9 @@ UndoMove MakeMove(Move move, Game *g) {
   }
 
   // Playing enpasstant
-  if (piece.type == PAWN && g->canEnpassant && move.To == g->enPassant) {
-    Position capturedPawn = move.To;
+  if (piece.type == PAWN && g->canEnpassant &&
+      IndexToPosition(toSquare) == g->enPassant) {
+    Position capturedPawn = IndexToPosition(toSquare);
     capturedPawn.rank += piece.color ? -1 : 1;
 
     undo.wasEnPassantCapture = true;
@@ -157,33 +162,37 @@ UndoMove MakeMove(Move move, Game *g) {
 
   // Adding enpassant
   if (piece.type == PAWN) {
-    Position to = move.To;
-    to.rank -= piece.color ? 2 : -2;
-    if (to == move.From) {
+    int to = toSquare;
+    // check if a pawn has moved two squares
+    to -= piece.color ? 2 * 8 : -2 * 8;
+    if (to == fromSquare) {
       g->canEnpassant = true;
-      Position target = move.From;
-      target.rank += piece.color ? 1 : -1;
-      g->enPassant = target;
+      int target = fromSquare;
+      target += piece.color ? 8 : -8;
+      g->enPassant = IndexToPosition(target);
     };
   }
 
-  // Promotions
-  if (piece.type == PAWN && move.To.rank == (piece.color ? 7 : 0)) {
-    piece.type = move.promotion == NONEPIECE ? QUEEN : move.promotion;
+  // promotion is always set and should only be aplied when reached final rank
+  // (default: knight)
+  if (piece.type == PAWN &&
+      IndexToPosition(toSquare).rank == (piece.color ? 7 : 0)) {
+    piece.type = promotion;
   }
 
   // caslte
-  if (piece.type == KING && move.From.rank == (piece.color ? 0 : 7) &&
-      std::abs(move.To.file - move.From.file) == 2) {
+  if (piece.type == KING &&
+      IndexToPosition(fromSquare).rank == (piece.color ? 0 : 7) &&
+      std::abs(toSquare - fromSquare) == 2) {
 
     undo.wasCastle = true;
-    undo.CastledSide = move.To.file > move.From.file;
+    undo.CastledSide = toSquare > fromSquare;
 
     if (undo.CastledSide) {
-      Position rookFrom = move.From;
+      Position rookFrom = IndexToPosition(fromSquare);
       rookFrom.file = 7;
 
-      Position rookTo = move.From;
+      Position rookTo = IndexToPosition(toSquare);
       rookTo.file = 5;
 
       uint64_t from = 1ULL << PositionToIndex(rookFrom);
@@ -203,10 +212,10 @@ UndoMove MakeMove(Move move, Game *g) {
       g->pieces[PositionToIndex(rookFrom)] = {false, NONEPIECE};
     } else {
       // Queenside: a -> d
-      Position rookFrom = move.From;
+      Position rookFrom = IndexToPosition(fromSquare);
       rookFrom.file = 0;
 
-      Position rookTo = move.From;
+      Position rookTo = IndexToPosition(toSquare);
       rookTo.file = 3;
 
       uint64_t from = 1ULL << PositionToIndex(rookFrom);
@@ -241,20 +250,21 @@ UndoMove MakeMove(Move move, Game *g) {
     }
   }
 
+  // if rook has moved
   if (piece.type == ROOK) {
-    if (piece.color) {                                  // White
-      if (move.From.rank == 0 && move.From.file == 0) { // a1
+    if (piece.color) {       // White
+      if (fromSquare == 0) { // a1
         g->whiteCastleQueen = false;
       }
-      if (move.From.rank == 0 && move.From.file == 7) { // h1
+      if (fromSquare == 7) { // h1
         g->whiteCastleKing = false;
       }
-    } else {                                            // Black
-      if (move.From.rank == 7 && move.From.file == 0) { // a8
+    } else {                     // Black
+      if (fromSquare == 7 * 8) { // a8
         g->blackCastleQueen = false;
       }
 
-      if (move.From.rank == 7 && move.From.file == 7) { // h8
+      if (fromSquare == 7 * 9) { // h8
         g->blackCastleKing = false;
       }
     }
@@ -262,24 +272,28 @@ UndoMove MakeMove(Move move, Game *g) {
 
   // this part is written with ai
   if (piece2.type == ROOK) {
-    if (piece2.color) {                           // White rook captured
-      if (move.To.rank == 0 && move.To.file == 0) // a1
+    if (piece2.color) {    // White rook captured
+      if (toSquare == 0) { // a1
         g->whiteCastleQueen = false;
-
-      if (move.To.rank == 0 && move.To.file == 7) // h1
+      }
+      if (toSquare == 7) { // h1
         g->whiteCastleKing = false;
-    } else {                                      // Black rook captured
-      if (move.To.rank == 7 && move.To.file == 0) // a8
+      }
+    } else {                   // Black rook captured
+      if (toSquare == 7 * 8) { // a8
         g->blackCastleQueen = false;
+      }
 
-      if (move.To.rank == 7 && move.To.file == 7) // h8
+      if (toSquare == 7 * 9) {
+        // h8
         g->blackCastleKing = false;
+      }
     }
   }
 
   // playing the moves
-  uint64_t from = 1ULL << PositionToIndex(move.From);
-  uint64_t to = 1ULL << PositionToIndex(move.To);
+  uint64_t from = 1ULL << fromSquare;
+  uint64_t to = 1ULL << toSquare;
 
   // remove moving piece from source
   g->PieceBitboards[piece.color][undo.movedPiece.type] ^= from;
@@ -297,14 +311,15 @@ UndoMove MakeMove(Move move, Game *g) {
   // add moving piece to destination
   g->PieceBitboards[piece.color][piece.type] ^= to;
 
-  if (piece.color)
+  if (piece.color) {
     g->WhitePieceBitboard ^= from | to;
-  else
+  } else {
     g->BlackPieceBitboard ^= from | to;
+  }
 
   g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
-  g->pieces[PositionToIndex(move.To)] = piece;
-  g->pieces[PositionToIndex(move.From)] = {false, NONEPIECE};
+  g->pieces[toSquare] = piece;
+  g->pieces[fromSquare] = {.color = false, .type = NONEPIECE};
 
   // changing who turn it is
   g->turn = !g->turn;
@@ -326,9 +341,9 @@ UndoMove MakeMove(Move move, Game *g) {
   return undo;
 };
 void UnMakeMove(UndoMove undo, Game *g) {
-  g->pieces[PositionToIndex(undo.from)] = undo.movedPiece;
+  g->pieces[undo.from] = undo.movedPiece;
 
-  g->pieces[PositionToIndex(undo.to)] = undo.capturedPiece;
+  g->pieces[undo.to] = undo.capturedPiece;
 
   if (undo.wasEnPassantCapture) {
     g->pieces[PositionToIndex(undo.enPassantCapturedSquare)] =
@@ -353,10 +368,10 @@ void UnMakeMove(UndoMove undo, Game *g) {
   if (undo.wasCastle) {
     if (undo.CastledSide) {
       // f -> h
-      Position rookFrom = undo.from;
+      Position rookFrom = IndexToPosition(undo.from);
       rookFrom.file = 5;
 
-      Position rookTo = undo.from;
+      Position rookTo = IndexToPosition(undo.from);
       rookTo.file = 7;
 
       g->pieces[PositionToIndex(rookTo)] = g->pieces[PositionToIndex(rookFrom)];
@@ -366,14 +381,17 @@ void UnMakeMove(UndoMove undo, Game *g) {
       };
     } else {
       // d -> a
-      Position rookFrom = undo.from;
+      Position rookFrom = IndexToPosition(undo.from);
       rookFrom.file = 3;
 
-      Position rookTo = undo.from;
+      Position rookTo = IndexToPosition(undo.from);
       rookTo.file = 0;
 
       g->pieces[PositionToIndex(rookTo)] = g->pieces[PositionToIndex(rookFrom)];
-      g->pieces[PositionToIndex(rookFrom)] = {false, NONEPIECE};
+      g->pieces[PositionToIndex(rookFrom)] = {
+          .color = false,
+          .type = NONEPIECE,
+      };
     }
   }
 
diff --git a/src/board/board.hpp b/src/board/board.hpp
index b27a9d1..b24811c 100644
--- a/src/board/board.hpp
+++ b/src/board/board.hpp
@@ -43,23 +43,13 @@ PieceType getPromotionTypeFromMove(uint16_t move);
 uint8_t getFromValueFromMove(uint16_t move);
 uint8_t getToValueFromMove(uint16_t move);
 
-struct Move {
-  Position From;
-  Position To;
-
-  PieceType promotion = NONEPIECE;
-  bool operator==(const Move &other) const {
-    return From == other.From && To == other.To && promotion == other.promotion;
-  }
-};
-
 enum Flag : std::uint8_t { EXACT, LOWERBOUND, UPPERBOUND };
 
 struct TranspositionsEntry {
   int depth = -1;
   int Eval = 0;
   Flag flag = EXACT;
-  Move bestMove = {};
+  uint16_t bestMove = {};
 };
 struct Game {
   Piece pieces[64];
@@ -85,8 +75,8 @@ struct UndoMove {
   Piece movedPiece;
   Piece capturedPiece;
 
-  Position from;
-  Position to;
+  uint8_t from;
+  uint8_t to;
 
   bool wasEnPassantCapture = false;
   Position enPassantCapturedSquare;
@@ -112,7 +102,7 @@ struct UndoMove {
 };
 
 int PositionToIndex(Position i);
-UndoMove MakeMove(Move move, Game *g);
+UndoMove MakeMove(uint16_t move, Game *g);
 void UnMakeMove(UndoMove undo, Game *g);
 
 Position FindKing(Game *g, bool color);