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-rw-r--r--src/board/board.cpp41
-rw-r--r--src/board/board.hpp1
-rw-r--r--src/bot.cpp8
-rw-r--r--src/uci.cpp2
-rw-r--r--src/zobrist.cpp33
-rw-r--r--src/zobrist.hpp4
6 files changed, 72 insertions, 17 deletions
diff --git a/src/board/board.cpp b/src/board/board.cpp
index 81a3c4e..faabfac 100644
--- a/src/board/board.cpp
+++ b/src/board/board.cpp
@@ -142,7 +142,10 @@ static void movePiece(const uint8_t &fromSquare, const Piece &fromPiece,
}
g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
+ xorSquare(fromSquare, g);
+ xorSquare(toSquare, g);
g->pieces[toSquare] = fromPiece;
+ xorSquare(toSquare, g);
g->pieces[fromSquare] = {.color = false, .type = NONEPIECE};
};
@@ -173,6 +176,8 @@ Undo MakeMove(uint16_t move, Game *g) {
undo.OldBlackCastleKing = g->blackCastleKing;
undo.OldBlackCastleQueen = g->blackCastleQueen;
+ undo.ZobristKey = g->hash;
+
// play move
Piece movingPiece = g->pieces[fromSquare];
Piece captuaredPiece = g->pieces[toSquare];
@@ -196,6 +201,9 @@ Undo MakeMove(uint16_t move, Game *g) {
}
// Playing enpasstant
+
+ xorEnpassantKey(g); // remove existing key
+
if (movingPiece.type == PAWN && g->canEnpassant &&
IndexToPosition(toSquare) == g->enPassant) {
Position capturedPawn = IndexToPosition(toSquare);
@@ -217,6 +225,7 @@ Undo MakeMove(uint16_t move, Game *g) {
}
g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
+ xorSquare(static_cast<uint8_t>(PositionToIndex(capturedPawn)), g);
g->pieces[PositionToIndex(capturedPawn)] = {.color = false,
.type = NONEPIECE};
}
@@ -236,10 +245,6 @@ Undo MakeMove(uint16_t move, Game *g) {
};
}
- // promotion is always set and should only be aplied when reached final rank
- // (default: knight)
- // because we use only two bits of memory for promotion we cant represent a
- // none type so we always have knight set and only it last rank and its pawn
if (movingPiece.type == PAWN &&
IndexToPosition(toSquare).rank == (movingPiece.color ? 7 : 0)) {
movingPiece.type = promotion;
@@ -269,7 +274,7 @@ Undo MakeMove(uint16_t move, Game *g) {
rookFrom.file = 0;
rookTo.file = 3;
- }
+ };
uint64_t from = 1ULL << PositionToIndex(rookFrom);
uint64_t to = 1ULL << PositionToIndex(rookTo);
@@ -283,16 +288,22 @@ Undo MakeMove(uint16_t move, Game *g) {
}
g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
+ xorSquare(static_cast<uint8_t>(PositionToIndex(rookFrom)), g);
g->pieces[PositionToIndex(rookTo)] = g->pieces[PositionToIndex(rookFrom)];
+ xorSquare(static_cast<uint8_t>(PositionToIndex(rookTo)), g);
g->pieces[PositionToIndex(rookFrom)] = {.type = NONEPIECE};
}
// remove castling right if king has moved
if (movingPiece.type == KING) {
if (movingPiece.color) {
+ xorCastleKey(true, true, g);
+ xorCastleKey(true, false, g);
g->whiteCastleKing = false;
g->whiteCastleQueen = false;
} else {
+ xorCastleKey(false, true, g);
+ xorCastleKey(false, false, g);
g->blackCastleKing = false;
g->blackCastleQueen = false;
}
@@ -302,38 +313,45 @@ Undo MakeMove(uint16_t move, Game *g) {
if (movingPiece.type == ROOK) {
if (movingPiece.color) { // White
if (fromSquare == 0) { // a1
+ xorCastleKey(true, false, g);
g->whiteCastleQueen = false;
}
if (fromSquare == 7) { // h1
+ xorCastleKey(true, true, g);
g->whiteCastleKing = false;
}
} else { // Black
if (fromSquare == 7 * 8) { // a8
+ xorCastleKey(false, false, g);
g->blackCastleQueen = false;
}
if (fromSquare == 7 * 9) { // h8
+ xorCastleKey(false, true, g);
g->blackCastleKing = false;
}
}
}
- // this part is written with ai
if (captuaredPiece.type == ROOK) {
if (captuaredPiece.color) { // White rook captured
if (toSquare == 0) { // a1
+ xorCastleKey(true, false, g);
g->whiteCastleQueen = false;
}
if (toSquare == 7) { // h1
+ xorCastleKey(true, true, g);
g->whiteCastleKing = false;
}
} else { // Black rook captured
if (toSquare == 7 * 8) { // a8
+ xorCastleKey(false, false, g);
g->blackCastleQueen = false;
}
if (toSquare == 7 * 9) {
// h8
+ xorCastleKey(false, true, g);
g->blackCastleKing = false;
}
}
@@ -344,13 +362,10 @@ Undo MakeMove(uint16_t move, Game *g) {
// changing who turn it is
g->turn = !g->turn;
+ xorSidekey(g); // toggle the side key
+ xorEnpassantKey(g); // add new en passant key
- // 3 fold check
- uint64_t key = GenerateZobristKey(g);
-
- undo.ZobristKey = key;
-
- g->history.push_back(key);
+ g->history.push_back(g->hash);
return undo;
};
@@ -432,4 +447,6 @@ void UndoMove(Undo undo, Game *g) {
g->history.pop_back();
g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
+
+ g->hash = undo.ZobristKey;
};
diff --git a/src/board/board.hpp b/src/board/board.hpp
index a64289e..2b3ac6a 100644
--- a/src/board/board.hpp
+++ b/src/board/board.hpp
@@ -68,6 +68,7 @@ struct Game {
Position enPassant;
bool canEnpassant = false;
GameState state = TURN;
+ uint64_t hash = 0;
std::vector<uint64_t> history;
std::unordered_map<uint64_t, TranspositionsEntry> *Transpositions = nullptr;
};
diff --git a/src/bot.cpp b/src/bot.cpp
index e9b0b4d..969606e 100644
--- a/src/bot.cpp
+++ b/src/bot.cpp
@@ -171,14 +171,12 @@ static int search(int depth, Game *b, int alpha, int beta, int ply) {
return 0;
}
}
- const uint64_t gameHash = GenerateZobristKey(b);
-
- if (isRepetionDraw(gameHash, b)) {
+ if (isRepetionDraw(b->hash, b)) {
return 0;
};
TranspositionsEntry *entry = nullptr;
- if (auto it = b->Transpositions->find(gameHash);
+ if (auto it = b->Transpositions->find(b->hash);
it != b->Transpositions->end()) {
entry = &it->second;
if (entry->depth >= depth) {
@@ -241,7 +239,7 @@ static int search(int depth, Game *b, int alpha, int beta, int ply) {
flag = UPPERBOUND;
}
- (*b->Transpositions)[gameHash] = {
+ (*b->Transpositions)[b->hash] = {
.depth = depth, .Eval = bestScore, .flag = flag, .bestMove = bestMove};
}
return bestScore;
diff --git a/src/uci.cpp b/src/uci.cpp
index 812a0cd..6e30014 100644
--- a/src/uci.cpp
+++ b/src/uci.cpp
@@ -96,6 +96,8 @@ Game initBoard(
uint64_t key = GenerateZobristKey(&g);
g.history.push_back(key);
+
+ g.hash = key;
return g;
};
static void PrintBitboard(uint64_t bb, const std::string &name) {
diff --git a/src/zobrist.cpp b/src/zobrist.cpp
index c06f1a2..afef3e6 100644
--- a/src/zobrist.cpp
+++ b/src/zobrist.cpp
@@ -348,6 +348,39 @@ void InitZobrist() {
SideKey = PolyglotRandom64[idx];
}
+void xorCastleKey(bool color, bool IS_KING_SIDE, Game *g) {
+ const bool WHITE = true;
+
+ if (color == WHITE && IS_KING_SIDE && g->whiteCastleKing) {
+ g->hash ^= CastleKeys[0];
+ };
+ if (color == WHITE && !IS_KING_SIDE && g->whiteCastleQueen) {
+ g->hash ^= CastleKeys[1];
+ };
+ if (color == !WHITE && IS_KING_SIDE && g->blackCastleKing) {
+ g->hash ^= CastleKeys[2];
+ };
+ if (color == !WHITE && !IS_KING_SIDE && g->blackCastleQueen) {
+ g->hash ^= CastleKeys[3];
+ };
+}
+void xorSidekey(Game *g) { g->hash ^= SideKey; }
+void xorEnpassantKey(Game *g) {
+ if (g->canEnpassant && IsEnpassantLegal(g)) {
+ g->hash ^= EnPassantKeys[g->enPassant.file];
+ }
+}
+void xorSquare(uint8_t square, Game *g) {
+ Piece p = g->pieces[square];
+ if (p.type == NONEPIECE) {
+ return;
+ }
+ g->hash ^= PieceKeys[p.color][p.type][square];
+}
+
+/*
+ * should be only called at start of game
+ */
uint64_t GenerateZobristKey(Game *b) {
uint64_t key = 0;
diff --git a/src/zobrist.hpp b/src/zobrist.hpp
index e23facf..b72b0f2 100644
--- a/src/zobrist.hpp
+++ b/src/zobrist.hpp
@@ -5,3 +5,7 @@ struct Game;
void InitZobrist();
uint64_t GenerateZobristKey(Game *b);
+void xorCastleKey(bool color, bool IS_KING_SIDE, Game *g);
+void xorSidekey(Game *g);
+void xorEnpassantKey(Game *g);
+void xorSquare(uint8_t square, Game *g); \ No newline at end of file
generated by cgit v1.2.3 (git 2.39.1) at 2026-08-24 23:38:02 +0000