updated README

.gitignore

@@ -1,6 +1,6 @@
 /*
 !/src
-/include/chess/generated/*
+/src/generated
 !/CMakeLists.txt
 !/README.md
 !/LICENSE
@@ -8,5 +8,6 @@
 !/lib
 !.gitkeep
 !/include
+/include/chess/generated/*
 !/.gitignore
 !/test

CMakeLists.txt

@@ -1,29 +1,36 @@
 cmake_minimum_required(VERSION 3.18)
 project(chess C)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+set(CMAKE_C_STANDARD 99)
 include_directories(include)
 file(GLOB SOURCES "src/chess/*.c")
-file(GLOB LIB_SOURCES "src/common/*.c")
+file(GLOB CODE_GEN_LIB_SOURCES "src/common/preCodeGen/*.c")
+file(GLOB LIB_SOURCES "src/common/*/*.c" "src/generated/*.c")
 
-add_executable(genMoveConsts src/generateCode/moveConsts.c src/common/bitboard.c
-	src/common/print.c)
+add_executable(genMoveConsts src/generateCode/moveConsts.c ${CODE_GEN_LIB_SOURCES})
 add_custom_command(
 	OUTPUT moveConsts.h  # Output file from code generation
 	COMMAND genMoveConsts > include/chess/generated/moveConsts.h
 	DEPENDS genMoveConsts # Depends on the code generation executable
 	)
-add_custom_target(generateCode DEPENDS moveConsts.h)
+
+add_executable(genZobrist src/generateCode/zobrist.c ${CODE_GEN_LIB_SOURCES})
+add_custom_command(
+	OUTPUT zobristConsts.c  # Output file from code generation
+	COMMAND genZobrist > src/generated/zobristConsts.c
+	DEPENDS genZobrist # Depends on the code generation executable
+	)
+
+add_custom_target(generateCode DEPENDS moveConsts.h zobristConsts.c)
 
 find_package(PkgConfig REQUIRED)
 pkg_check_modules(GTK4 REQUIRED IMPORTED_TARGET gtk4)
 pkg_check_modules(LIBRSVG REQUIRED IMPORTED_TARGET librsvg-2.0)
 
 add_executable(findMagicNumber src/findMagicNumber.c ${LIB_SOURCES})
-set_property(TARGET findMagicNumber PROPERTY C_STANDARD 99)
 add_dependencies(findMagicNumber generateCode)
 
 add_executable(${PROJECT_NAME} ${SOURCES} ${LIB_SOURCES})
-set_property(TARGET ${PROJECT_NAME} PROPERTY C_STANDARD 99)
 target_link_libraries(${PROJECT_NAME} PRIVATE PkgConfig::GTK4 PkgConfig::LIBRSVG)
 add_dependencies(${PROJECT_NAME} generateCode)
 
@@ -39,11 +46,9 @@ if(CMAKE_BUILD_TYPE MATCHES "Release")
 endif()
 
 add_executable(chessNoComputer ${SOURCES} ${LIB_SOURCES})
-set_property(TARGET chessNoComputer PROPERTY C_STANDARD 99)
 target_link_libraries(chessNoComputer PRIVATE PkgConfig::GTK4 PkgConfig::LIBRSVG)
 add_dependencies(chessNoComputer generateCode)
 target_compile_definitions(chessNoComputer PUBLIC NO_COMPUTER)
 
 add_executable(moveGenTest test/moveGen.c src/chess/move.c ${LIB_SOURCES})
-set_property(TARGET moveGenTest PROPERTY C_STANDARD 99)
 add_test(NAME moveGen COMMAND moveGenTest)

README.md

@@ -69,5 +69,12 @@ Alpha-Beta is based on [minimax](https://en.wikipedia.org/wiki/Minimax) with an
 added upper and lower bound for the position score with makes it much faster
 than minimax.
 
-The evaluation is currently simple because the only keeps track of the material
-and checkmate. Here is currently the most room for optimizations.
+The engine has a partly implemented UCI interface with its code in `src/uci.c`.
+
+To detect repetitions we need a way to easily lookup, if the position already accrued. This done by
+calculating a [Zobrist Hash](https://www.chessprogramming.org/Zobrist_Hashing) for the board
+position. Zobrist Hashing is really nice because it allows incremental updating. With this hash the
+engine has implemented its own hash tables, which allow for detecting repetitions. Later on this can
+also be used for a [transposition table](https://www.chessprogramming.org/Transposition_Table).
+
+The evaluation is currently simple. Here is currently the most room for optimizations.

include/chess/bitboard.h

@@ -2,9 +2,9 @@
 #include <stdint.h>
 #include <chess/types.h>
 
-bool bitsetGet(uint_least64_t bitset, uint_least8_t i);
-uint_least64_t bitsetClear(uint_least64_t bitset, uint_least8_t i);
-uint_least64_t bitsetSet(uint_least64_t bitset, uint_least8_t i);
+#define REPETETION_TABLE_LENGTH 1024
+#define START_FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
+
 bool bitboardGet(const uint_least64_t *board, struct piece_t piece, uint_least8_t i);
 uint_least64_t bitboardGetMask(const uint_least64_t *board, struct piece_t piece);
 void bitboardSetMask(uint_least64_t *board, struct piece_t piece, uint_least64_t value);
@@ -13,6 +13,6 @@ uint_least64_t bitboardMaskAllPieces(const uint_least64_t *board);
 void bitboardClear(uint_least64_t *board, struct piece_t piece, uint_least8_t i);
 void bitboardSet(uint_least64_t *board, struct piece_t piece, uint_least8_t i);
 struct piece_t pieceAtField(const uint_least64_t *board, uint_least8_t i);
-struct gameState_t newGameState(uint_least64_t *board, char *FEN);
-uint_least8_t getFile(const uint_least8_t field);
-uint_least8_t getRank(const uint_least8_t field);
+struct gameState_t newGameState(uint_least64_t *board,
+		struct zobristTableElement *repetitionTableStore, const char *FEN);
+struct gameState_t parseFen(uint_least64_t *board, const char *FEN);

include/chess/bitset.h

@@ -0,0 +1,6 @@
+#include <stdint.h>
+#include <stdbool.h>
+
+bool bitsetGet(uint_least64_t bitset, uint_least8_t i);
+uint_least64_t bitsetClear(uint_least64_t bitset, uint_least8_t i);
+uint_least64_t bitsetSet(uint_least64_t bitset, uint_least8_t i);

include/chess/move.h

@@ -17,6 +17,7 @@ enum spezialMoves {
 struct move_t {
 	uint_least8_t src, dst, spezialMove;
 	uint_least8_t srcPiece, dstPiece, capturedPiece;
+	uint_least64_t hash;
 };
 
 void genDirectionConsts();
@@ -24,8 +25,8 @@ uint_least8_t validMoves(struct gameState_t gameState, struct move_t *moves);
 uint_least8_t pieceValidMoves(struct gameState_t gameState, struct piece_t piece, uint_least8_t src,
 		struct move_t *moves, bool promotion);
 
-void undoMove(uint_least64_t *board, struct move_t move, bool color);
-struct gameState_t makeMove(struct gameState_t gameState, struct move_t move);
+void undoMove(struct gameState_t gameState, struct move_t move, bool color);
+struct gameState_t makeMove(struct gameState_t gameState, const struct move_t move);
 void initMagicTable();
 bool kingInCheck(const uint_least64_t *board, const bool color);
 uint_least8_t getBaseRankI(bool color);

include/chess/print.h

@@ -2,26 +2,29 @@
 #include <stdint.h>
 #include <chess/move.h>
 
-#define fprintArray(file, printer, arr) \
+#define fprintArrayCustomLength(file, printer, arr, length) \
 	do { \
 		fprintf(file, "{"); \
-		for(size_t i = 0; i < LENGTH(arr); ++i) { \
+		for(size_t i = 0; i < length; ++i) { \
 			printer(file, arr[i]); \
-			if (i < LENGTH(arr) - 1) { \
+			if (i < length - 1) { \
 				fprintf(file, ", "); \
 			} \
 		} \
     fprintf(file, " }"); \
 	} while(0)
+#define fprintArray(file, printer, arr) fprintArrayCustomLength(file, printer, arr, LENGTH(arr))
 
-#define fdefineArray(file, declaration, printer, arr) \
+#define fdefineArrayCustomLength(file, declaration, printer, arr, length) \
 	do { \
-    fprintf(file, "%s[%zu] = ", declaration, LENGTH(arr)); \
-		fprintArray(file, printer, arr); \
+    fprintf(file, "%s[%zu] = ", declaration, length); \
+		fprintArrayCustomLength(file, printer, arr, length); \
 		fprintf(file, ";\n"); \
 	} while(0)
+#define fdefineArray(file, declaration, printer, arr) fdefineArrayCustomLength(file, declaration, printer, arr, LENGTH(arr))
 
-#define defineArray(declaration, printer, arr) fdefineArray(stdout, declaration, printer, arr)
+#define defineArrayCustomLength(declaration, printer, arr, length) fdefineArrayCustomLength(stdout, declaration, printer, arr, length)
+#define defineArray(declaration, printer, arr) defineArrayCustomLength(declaration, printer, arr, LENGTH(arr))
 
 void printerll(FILE *file, long long num);
 void printerull(FILE *file, unsigned long long num);

include/chess/types.h

@@ -3,6 +3,7 @@
 
 #include <stdbool.h>
 #include <stdint.h>
+#include <stddef.h>
 
 #define BOARD_SIZE 8
 #define TOTAL_BOARD_SIZE (BOARD_SIZE * BOARD_SIZE)
@@ -35,6 +36,16 @@ enum directions {
 	NORTH, NORTHWEST, WEST, SOUTHWEST, SOUTH, SOUTHEAST,  EAST, NORTHEAST, DIRECTION_LENGTH
 };
 
+struct zobristTableElement {
+	uint_least64_t hash;
+	int_least16_t value;
+};
+
+struct zobristTable {
+	struct zobristTableElement *arr;
+	size_t length;
+};
+
 struct moveDst_t {
 	uint_least8_t length;
 	uint_least8_t dst[8];
@@ -53,6 +64,8 @@ struct castle_t {
 
 struct gameState_t {
 	uint_least64_t *board;
+	uint_least64_t zobrist;
+	struct zobristTable repetitionTable;
 	bool color; // color to move
 	struct castle_t canCastle[2];
 

include/chess/util.h

@@ -0,0 +1,18 @@
+#ifndef CHESS_UTIL_H
+#define CHESS_UTIL_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <chess/types.h>
+
+uint_least64_t rand_64();
+uint_least64_t zobristPieceI(struct piece_t piece, uint_least8_t field);
+uint_least8_t getFile(const uint_least8_t field);
+uint_least8_t getRank(const uint_least8_t field);
+
+struct zobristTable initZobirstTable(struct zobristTableElement *table, size_t length);
+void zobristTableIter(const struct zobristTable table, const uint_least64_t key, void *result,
+		void (*callback)(struct zobristTableElement *element, const uint_least64_t key, void *result));
+
+#endif

include/chess/zobristConsts.h

@@ -0,0 +1,16 @@
+#ifndef CHESS_ZOBRIST_CONSTS_H
+#define CHESS_ZOBRIST_CONSTS_H
+
+#include "chess/types.h"
+#include <stdint.h>
+
+#define ZOBRIST_CASTLE_LENGTH 2
+#define ZOBRIST_PIECE_LENGTH (TOTAL_BOARD_SIZE * 2 * PIECES_LENGTH)
+
+extern const uint_least64_t ZOBRIST_PIECE[];
+extern const uint_least64_t ZOBRIST_BLACK_MOVE;
+extern const uint_least64_t ZOBRIST_SHORT_CASTLE[ZOBRIST_CASTLE_LENGTH];
+extern const uint_least64_t ZOBRIST_LONG_CASTLE[ZOBRIST_CASTLE_LENGTH];
+extern const uint_least64_t ZOBRIST_EN_PASSENT_FILE[BOARD_SIZE];
+
+#endif

src/chess/evaluate.c

@@ -9,16 +9,16 @@
 #define INT_16_SAFE_MAX (INT_LEAST16_MAX - 1)
 
 #ifdef __GNUC__ // Check if using GCC or compatible compiler
-static int_least16_t countOnes(uint_least64_t num) {
+static int_least16_t countOnes(const uint_least64_t num) {
     return __builtin_popcountll(num); // Use GCC built-in function if available
 }
 #elif defined(_MSC_VER) // Check if using Microsoft Visual C++
 #include <intrin.h>
-static int_least16_t countOnes(uint_least64_t num) {
+static int_least16_t countOnes(const uint_least64_t num) {
     return __popcnt64(num); // Use MSVC intrinsic if available
 }
 #else
-static int_least16_t countOnes(uint_least64_t num) {
+static int_least16_t countOnes(const uint_least64_t num) {
     int_least16_t count = 0;
     while(num) {
         count += num & 1;
@@ -29,6 +29,7 @@ static int_least16_t countOnes(uint_least64_t num) {
 #endif
 
 static int_least16_t evaluate(const struct gameState_t gameState) {
+	if(gameState.halfMoveCounter == 50) return 0;
 	int_least16_t value = 0;
 	const uint_least64_t *board = gameState.board;
 	int_least16_t pieceValues[PIECES_LENGTH];
@@ -63,7 +64,7 @@ static int_least16_t alphaBeta(const struct gameState_t gameState, int_fast16_t
 		const struct move_t move = moves[i];
 		const struct gameState_t newGameState = makeMove(gameState, move);
 		const int_least16_t score = -alphaBeta(newGameState, -beta, -alpha, depth - 1);
-		undoMove(gameState.board, move, gameState.color);
+		undoMove(newGameState, move, gameState.color);
 		if(score >= beta) {
 			return beta; // beta-cutoff
 		}
@@ -84,7 +85,7 @@ static struct move_t searchRoot(const struct gameState_t gameState, uint_least8_
 		const struct move_t move = moves[i];
 		const struct gameState_t newGameState = makeMove(gameState, move);
 		const int_least16_t score = -alphaBeta(newGameState, -beta, -alpha, depth - 1);
-		undoMove(gameState.board, move, gameState.color);
+		undoMove(newGameState, move, gameState.color);
 		if(score > alpha) {
 			alpha = score; // alpha acts like max in MiniMax
 			selectedMove = move;

src/chess/main.c

@@ -10,8 +10,7 @@
 #include <chess/move.h>
 #include <chess/bitboard.h>
 #include "evaluate.h"
-
-#define START_FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
+#include <chess/util.h>
 
 struct drawData_t {
 	RsvgHandle **piecesSvg;
@@ -189,8 +188,9 @@ static void app_activate(GApplication *app, gpointer data) {
 	GtkWindow *window = GTK_WINDOW(gtk_window_new());
 	static RsvgHandle *piecesSvg[2 * PIECES_LENGTH];
 	static uint_least64_t board[BITBOARD_LENGTH];
+	static struct zobristTableElement repetitionTableStore[REPETETION_TABLE_LENGTH];
 	static struct gameState_t gameState;
-	gameState = newGameState(board, START_FEN);
+	gameState = newGameState(board, repetitionTableStore, START_FEN);
 	{
 		static struct move_t moves[TOTAL_BOARD_SIZE];
 		static struct drawData_t drawData = {piecesSvg, &gameState, NOT_SELECTED, moves, 0, NOT_SELECTED};

src/chess/move.c

@@ -9,6 +9,10 @@
 #include <stdio.h>
 #include "magicNumber.h"
 #include <chess/magic.h>
+#include <chess/util.h>
+#include <chess/bitset.h>
+#include <chess/zobristConsts.h>
+#include <string.h>
 
 #ifdef _MSC_VER
 #include <intrin.h>
@@ -29,7 +33,7 @@ static uint_least8_t trailingBits(uint_least64_t num) {
 	unsigned long i;
 	_BitScanForward(&i, num);
 	return i;
-#elif
+#else
 	uint_least8_t count = 0;
 	while ((num & 1) == 0) { // Keep shifting num right until the least significant bit is 1
 		num >>= 1;
@@ -154,7 +158,16 @@ static void castleMoveRook(uint_least64_t *board, uint_least8_t spezialMove, boo
 	}
 }
 
-void undoMove(uint_least64_t *board, struct move_t move, bool color) {
+static void zobristTableUndoMoveCallback(struct zobristTableElement *element, const uint_least64_t key,
+		void *resultVoid) {
+	if(element->hash == key) {
+		if(--element->value == 0) element->hash = 0;
+	}
+	fprintf(stderr, "Error: Position does not in repetitionTable in undoMove (move.c)");
+}
+
+void undoMove(const struct gameState_t gameState, struct move_t move, bool color) {
+	uint_least64_t *board = gameState.board;
 	const struct piece_t srcPiece = {move.srcPiece, color};
 	const struct piece_t dstPiece = {move.dstPiece, color};
 	bitboardSet(board, srcPiece, move.src);
@@ -164,38 +177,95 @@ void undoMove(uint_least64_t *board, struct move_t move, bool color) {
 		bitboardSet(board, piece, getCapturePos(move.src, move.dst, move.spezialMove));
 	}
 	castleMoveRook(board, move.spezialMove, color, true);
+	zobristTableIter(gameState.repetitionTable, gameState.zobrist, NULL, zobristTableUndoMoveCallback);
+}
+
+static void setCastleInfoRook(struct castle_t *canCastle, uint_least8_t posOnRank) {
+	switch(posOnRank) {
+		case 0:
+			canCastle->longCastle = false;
+			break;
+		case BOARD_SIZE - 1:
+			canCastle->shortCastle = false;
+			break;
+	}
+}
+
+static void setCastleInfo(struct castle_t *canCastle, const bool color, const struct move_t move) {
+	{
+		struct castle_t *canCastleCurrentPlayer = canCastle + color;
+		if(canCastleCurrentPlayer->longCastle || canCastleCurrentPlayer->shortCastle) {
+			if(move.dstPiece == KING) {
+				canCastleCurrentPlayer->longCastle = false;
+				canCastleCurrentPlayer->shortCastle = false;
+			}
+			else {
+				setCastleInfoRook(canCastleCurrentPlayer, move.src - getBaseRankI(color));
+			}
+		}
+	}
+	{
+		// if the rook is captured
+		struct castle_t *canCastleOther = canCastle + !color;
+		if(canCastleOther->longCastle || canCastleOther->shortCastle) {
+			setCastleInfoRook(canCastleOther, move.dst - getBaseRankI(!color));
+		}
+	}
 }
 
 static void addMove(struct addMoveCtx_t ctx, struct piece_t movedPiece, uint_least8_t src,
 		uint_least8_t dst, uint_least8_t spezialMove, uint_least8_t promotionPiece) {
-	uint_least64_t *board = ctx.gameState.board;
-	uint_least8_t *movesLength = ctx.movesLength;
-	uint_least8_t capturedPiece = NOT_SELECTED;
-	const uint_least8_t dstPiece = promotionPiece == NOT_SELECTED ? movedPiece.type : promotionPiece;
-	const struct piece_t pieceAll = {ALL_PIECES, movedPiece.color};
-	if(bitboardGet(board, pieceAll, dst)) return;
+	struct gameState_t gameState = ctx.gameState;
+	uint_least64_t *board = gameState.board;
 	{
-		const struct piece_t pieceAllOtherColor = {ALL_PIECES, !movedPiece.color};
+		const struct piece_t pieceAll = {ALL_PIECES, movedPiece.color};
+		if(bitboardGet(board, pieceAll, dst)) return;
+	}
+	uint_least8_t *movesLength = ctx.movesLength;
+	uint_least8_t capturedPieceType = NOT_SELECTED;
+	const uint_least8_t dstPieceType = promotionPiece == NOT_SELECTED ? movedPiece.type : promotionPiece;
+	uint_least64_t hash = ZOBRIST_PIECE[zobristPieceI(movedPiece, src)] ^ ZOBRIST_BLACK_MOVE;
+	{
+		const struct piece_t dstPiece = {dstPieceType, movedPiece.color};
+		hash ^= ZOBRIST_PIECE[zobristPieceI(dstPiece, dst)];
+	}
+	{
+		const bool otherColor = !movedPiece.color;
+		const struct piece_t pieceAllOtherColor = {ALL_PIECES, otherColor};
 		const uint_least8_t capturePos = getCapturePos(src, dst, spezialMove);
 		if(bitboardGet(board, pieceAllOtherColor, capturePos)) {
 			for(uint_least8_t pieceType = QUEEN; pieceType < PIECES_LENGTH; ++pieceType) {
 				const struct piece_t piece = {pieceType, !movedPiece.color};
 				if(bitboardGet(board, piece, capturePos)) {
-					capturedPiece = pieceType;
+					const struct piece_t capturedPiece = {pieceType, otherColor};
+					hash ^= ZOBRIST_PIECE[zobristPieceI(capturedPiece, dst)];
+					capturedPieceType = pieceType;
 					break;
 				}
 			}
 		}
 	}
-	const struct move_t move = {src, dst, spezialMove, movedPiece.type, dstPiece, capturedPiece};
-	makeMove(ctx.gameState, move); 
+	if(gameState.enPassantTo != NOT_SELECTED) hash ^= ZOBRIST_EN_PASSENT_FILE[getFile(gameState.enPassantTo)];
+	if(spezialMove == FUTURE_EN_PASSANT) hash ^= ZOBRIST_EN_PASSENT_FILE[getFile(src)];
+	struct move_t move = {src, dst, spezialMove, movedPiece.type, dstPieceType, capturedPieceType, hash};
 	{
-		const bool color = ctx.gameState.color;
+		struct castle_t canCastle[2];
+		memcpy(canCastle, gameState.canCastle, sizeof canCastle);
+		setCastleInfo(canCastle, gameState.color, move);
+		for(uint_least8_t color = BLACK; color <= WHITE; ++color) {
+			if(canCastle[color].shortCastle != gameState.canCastle[color].shortCastle) hash ^= ZOBRIST_SHORT_CASTLE[color];
+			if(canCastle[color].longCastle != gameState.canCastle[color].longCastle) hash ^= ZOBRIST_LONG_CASTLE[color];
+		}
+		move.hash = hash;
+	}
+	struct gameState_t newGameState = makeMove(gameState, move); 
+	{
+		const bool color = gameState.color;
 		if(!kingInCheck(board, color)) {
 			ctx.moves[*movesLength] = move;
 			++*movesLength;
 		}
-		undoMove(board, move, color);
+		undoMove(newGameState, move, color);
 	}
 }
 
@@ -303,7 +373,7 @@ uint_least8_t pieceValidMoves(struct gameState_t gameState, struct piece_t piece
 					uint_least8_t dst = src + DIRECTION_MODIFIER[pawnDirection];
 					if(!bitboardGetAllPieces(board, dst)) {
 						movePawn(addmoveCtx, piece.color, src, dst, promotion, 0);
-						if(getFile(src) == (piece.color == WHITE ? BOARD_SIZE - 2 : 1)) {
+						if(getRank(src) == (piece.color == WHITE ? BOARD_SIZE - 2 : 1)) {
 							dst += DIRECTION_MODIFIER[pawnDirection];
 							if(!bitboardGetAllPieces(board, dst)) {
 								movePawn(addmoveCtx, piece.color, src, dst, promotion, FUTURE_EN_PASSANT);
@@ -337,18 +407,17 @@ uint_least8_t validMoves(struct gameState_t gameState, struct move_t *moves) {
 	return movesLength;
 }
 
-static void setCastleInfo(struct castle_t *canCastle, uint_least8_t posOnRank) {
-	switch(posOnRank) {
-		case 0:
-			canCastle->longCastle = false;
-			break;
-		case BOARD_SIZE - 1:
-			canCastle->shortCastle = false;
-			break;
+static void zobristTableMakeMoveCallback(struct zobristTableElement *element, const uint_least64_t key,
+		void *resultVoid) {
+	if(element->hash == key) {
+		++element->value;
+		return;
 	}
+	element->hash = key;
+	element->value = 1;
 }
 
-struct gameState_t makeMove(struct gameState_t gameState, struct move_t move) {
+struct gameState_t makeMove(struct gameState_t gameState, const struct move_t move) {
 	uint_least64_t *board = gameState.board;
 	const struct piece_t srcPiece = {move.srcPiece, gameState.color};
 	const struct piece_t dstPiece = {move.dstPiece, gameState.color};
@@ -359,25 +428,7 @@ struct gameState_t makeMove(struct gameState_t gameState, struct move_t move) {
 		bitboardClear(board, capturedPiece, getCapturePos(move.src, move.dst, move.spezialMove));
 	}
 	castleMoveRook(board, move.spezialMove, gameState.color, false);
-	{
-		struct castle_t *canCastleCurrentPlayer = gameState.canCastle + gameState.color;
-		if(canCastleCurrentPlayer->longCastle || canCastleCurrentPlayer->shortCastle) {
-			if(move.dstPiece == KING) {
-				canCastleCurrentPlayer->longCastle = false;
-				canCastleCurrentPlayer->shortCastle = false;
-			}
-			else {
-				setCastleInfo(canCastleCurrentPlayer, move.src - getBaseRankI(gameState.color));
-			}
-		}
-	}
-	{
-		// if the rook is captured
-		struct castle_t *canCastleOther = gameState.canCastle + !gameState.color;
-		if(canCastleOther->longCastle || canCastleOther->shortCastle) {
-			setCastleInfo(canCastleOther, move.dst - getBaseRankI(!gameState.color));
-		}
-	}
+	setCastleInfo(gameState.canCastle, gameState.color, move);
 	{
 		const int_least8_t dist = (int_least8_t)move.dst - (int_least8_t)move.src;
 		gameState.enPassantTo = move.spezialMove == FUTURE_EN_PASSANT ? move.src + dist / 2 : NOT_SELECTED;
@@ -385,5 +436,7 @@ struct gameState_t makeMove(struct gameState_t gameState, struct move_t move) {
 	if(move.capturedPiece != NOT_SELECTED || srcPiece.type == PAWN) gameState.halfMoveCounter = 0;
 	else ++gameState.halfMoveCounter;
 	gameState.color = !gameState.color;
+	gameState.zobrist ^= move.hash;
+	zobristTableIter(gameState.repetitionTable, gameState.zobrist, NULL, zobristTableMakeMoveCallback);
 	return gameState;
 }

src/common/postCodeGen/bitboard.c

@@ -1,20 +1,12 @@
+#include "chess/zobristConsts.h"
 #include <ctype.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <chess/types.h>
 #include <stdlib.h>
-
-bool bitsetGet(uint_least64_t bitset, uint_least8_t i) {
-	return (bitset >> i) & 1u;
-}
-
-uint_least64_t bitsetClear(uint_least64_t bitset, uint_least8_t i) {
-	return bitset & ~((uint_least64_t)1 << i);
-}
-
-uint_least64_t bitsetSet(uint_least64_t bitset, uint_least8_t i) {
-	return bitset | ((uint_least64_t)1 << i);
-}
+#include <chess/util.h>
+#include <chess/bitset.h>
+#include <chess/bitboard.h>
 
 uint_least64_t bitboardGetMask(const uint_least64_t *board, struct piece_t piece) {
 	return board[piece.color * PIECES_LENGTH + piece.type];
@@ -75,70 +67,78 @@ struct piece_t pieceAtField(const uint_least64_t *board, uint_least8_t i) {
 	}
 }
 
-struct gameState_t newGameState(uint_least64_t *board, char *FEN) {
-		struct gameState_t gameState = {board};
-		for(uint_least8_t i = 0; i < BITBOARD_LENGTH; ++i) {
-			board[i] = 0;
-		}
-		for(uint_least8_t field = 0; *FEN != ' '; ++FEN) {
-			struct piece_t piece;
-			switch(tolower(*FEN)) {
-				case 'k':
-					piece.type = KING;
-					break;
-				case 'q':
-					piece.type = QUEEN;
-					break;
-				case 'r':
-					piece.type = ROOK;
-					break;
-				case 'n':
-					piece.type = KNIGHT;
-					break;
-				case 'b':
-					piece.type = BISHOP;
-					break;
-				case 'p':
-					piece.type = PAWN;
-					break;
-				case '/':
-					continue;
-				default:
-					if(isdigit(*FEN)) {
-						field += *FEN - '0';
-					}
-					continue;
-			}
-			if(isalpha(*FEN)) piece.color = isupper(*FEN);
-			bitboardSet(board, piece, field);
-			++field;
-		}
-		gameState.color = *++FEN == 'w' ? WHITE : BLACK;
-		FEN += 2;
-		if(*FEN == '-') ++FEN;
-		else {
-			for(; *FEN != ' '; ++FEN) {
-				struct castle_t *playerCastle = gameState.canCastle + (isupper(*FEN) ? WHITE : BLACK);
-				if(tolower(*FEN) == 'k') playerCastle->shortCastle = true;
-				else playerCastle->longCastle = true;
-			}
-		}
-		if(*++FEN == '-'){
-			++FEN;
-			gameState.enPassantTo = NOT_SELECTED;
-		}
-		else {
-			gameState.enPassantTo = *FEN++ - 'a';
-			gameState.enPassantTo += (BOARD_SIZE - *FEN++) * BOARD_SIZE;
-		}
-		gameState.halfMoveCounter = atoi(++FEN);
-		return gameState;
+struct gameState_t parseFen(uint_least64_t *board, const char *FEN) {
+}
+
+struct gameState_t newGameState(uint_least64_t *board,
+		struct zobristTableElement *repetitionTableStore, const char *FEN) {
+	struct gameState_t gameState = {board, 0};
+	for(uint_least8_t i = 0; i < BITBOARD_LENGTH; ++i) {
+		board[i] = 0;
 	}
-
-uint_least8_t getFile(const uint_least8_t field) {
-	return field % BOARD_SIZE;
-}
-
-uint_least8_t getRank(const uint_least8_t field) {
-	return field / BOARD_SIZE;
+	for(uint_least8_t field = 0; *FEN != ' '; ++FEN) {
+		struct piece_t piece;
+		switch(tolower(*FEN)) {
+			case 'k':
+				piece.type = KING;
+				break;
+			case 'q':
+				piece.type = QUEEN;
+				break;
+			case 'r':
+				piece.type = ROOK;
+				break;
+			case 'n':
+				piece.type = KNIGHT;
+				break;
+			case 'b':
+				piece.type = BISHOP;
+				break;
+			case 'p':
+				piece.type = PAWN;
+				break;
+			case '/':
+				continue;
+			default:
+				if(isdigit(*FEN)) {
+					field += *FEN - '0';
+				}
+				continue;
+		}
+		if(isalpha(*FEN)) piece.color = isupper(*FEN);
+		bitboardSet(board, piece, field);
+		gameState.zobrist ^= ZOBRIST_PIECE[zobristPieceI(piece, field)];
+		++field;
+	}
+	gameState.color = *++FEN == 'w' ? WHITE : BLACK;
+	if(gameState.color == BLACK) gameState.zobrist ^= ZOBRIST_BLACK_MOVE;
+	FEN += 2;
+	if(*FEN == '-') ++FEN;
+	else {
+		for(; *FEN != ' '; ++FEN) {
+			const bool color = isupper(*FEN) ? WHITE : BLACK;
+			struct castle_t *playerCastle = gameState.canCastle + color;
+			if(tolower(*FEN) == 'k') {
+				playerCastle->shortCastle = true;
+				gameState.zobrist ^= ZOBRIST_SHORT_CASTLE[color];
+			}
+			else {
+				playerCastle->longCastle = true;
+				gameState.zobrist ^= ZOBRIST_LONG_CASTLE[color];
+			}
+		}
+	}
+	if(*++FEN == '-'){
+		++FEN;
+		gameState.enPassantTo = NOT_SELECTED;
+	}
+	else {
+		const uint_least8_t enPassentFile = *FEN++ - 'a';
+		gameState.zobrist ^= ZOBRIST_EN_PASSENT_FILE[enPassentFile];
+		gameState.enPassantTo = enPassentFile;
+		gameState.enPassantTo += (BOARD_SIZE - *FEN++) * BOARD_SIZE;
+	}
+	gameState.halfMoveCounter = atoi(++FEN);
+	gameState.repetitionTable = initZobirstTable(repetitionTableStore, REPETETION_TABLE_LENGTH);
+	return gameState;
 }

src/common/postCodeGen/magic.c

@@ -1,7 +1,7 @@
 #include <stdint.h>
 #include <chess/types.h>
 #include <chess/generated/moveConsts.h>
-#include <chess/bitboard.h>
+#include <chess/bitset.h>
 
 uint_least64_t slidingMovementMask(const uint_least8_t *direction, uint_least8_t directionLength,
 		uint_least8_t field, uint_least64_t blockMask) {

src/common/preCodeGen/bitset.c

@@ -0,0 +1,14 @@
+#include <chess/bitset.h>
+
+bool bitsetGet(uint_least64_t bitset, uint_least8_t i) {
+	return (bitset >> i) & 1u;
+}
+
+uint_least64_t bitsetClear(uint_least64_t bitset, uint_least8_t i) {
+	return bitset & ~((uint_least64_t)1 << i);
+}
+
+uint_least64_t bitsetSet(uint_least64_t bitset, uint_least8_t i) {
+	return bitset | ((uint_least64_t)1 << i);
+}
+

src/common/preCodeGen/print.c

@@ -2,7 +2,8 @@
 #include "chess/types.h"
 #include <stdio.h>
 #include <stdint.h>
-#include <chess/bitboard.h>
+#include <chess/bitset.h>
+#include <chess/util.h>
 
 void printerll(FILE *file, long long num) {
 	fprintf(file, "%lld", num);

src/common/preCodeGen/util.c

@@ -0,0 +1,78 @@
+#include "chess/types.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <chess/util.h>
+
+uint_least64_t rand_64() {
+	uint_least64_t u1, u2, u3, u4;
+  u1 = (uint_least64_t)(rand()) & 0xFFFF; u2 = (uint_least64_t)(rand()) & 0xFFFF;
+  u3 = (uint_least64_t)(rand()) & 0xFFFF; u4 = (uint_least64_t)(rand()) & 0xFFFF;
+  return u1 | (u2 << 16) | (u3 << 32) | (u4 << 48);
+}
+
+uint_least64_t zobristPieceI(struct piece_t piece, uint_least8_t field) {
+	return field * 2 * PIECES_LENGTH + piece.color * PIECES_LENGTH + piece.type;
+}
+
+uint_least8_t getFile(const uint_least8_t field) {
+	return field % BOARD_SIZE;
+}
+
+uint_least8_t getRank(const uint_least8_t field) {
+	return field / BOARD_SIZE;
+}
+
+struct zobristTable initZobirstTable(struct zobristTableElement *table, size_t length) {
+	for(size_t i = 0; i < length; ++i) {
+		table[i].hash = 0;
+	}
+	return (struct zobristTable){table, length};
+}
+
+static size_t zobristTableInitialI(const struct zobristTable table, const uint_least64_t key) {
+	return key % table.length;
+}
+
+void zobristTableIter(const struct zobristTable table, const uint_least64_t key, void *result,
+		void (*callback)(struct zobristTableElement *element, const uint_least64_t key, void *result)) {
+	const size_t initI = zobristTableInitialI(table, key);
+	size_t i = initI;
+	do {
+		struct zobristTableElement *element = table.arr + i;
+		if(element->hash == 0 || element->hash == key) {
+			callback(element, key, result);
+		}
+		++i;
+		if(i >= table.length) i = 0;
+	} while(i != initI);
+	fprintf(stderr, "Error: zobrist table is full");
+	exit(1);
+}
+
+static void zobristTableItemPtrCallback(struct zobristTableElement *element, const uint_least64_t key,
+		void *resultVoid) {
+	struct zobristTableElement **result = resultVoid;
+	if(element->hash == key) {
+		*result = element;
+		return;
+	} // if(hash == 0)
+	*result = NULL;
+}
+
+static struct zobristTableElement* zobristTableItemPtr(const struct zobristTable table, const uint_least64_t key) {
+	struct zobristTableElement *result;
+	zobristTableIter(table, key, &result, zobristTableItemPtrCallback);
+	return result;
+}
+
+void zobristTableDelete(struct zobristTable table, const uint_least64_t key) {
+	struct zobristTableElement *element = zobristTableItemPtr(table, key);
+	if(element != NULL) element->hash = 0;
+}
+
+int_least16_t* zobristTableGetPtr(const struct zobristTable table, const uint_least64_t key) {
+	struct zobristTableElement *element = zobristTableItemPtr(table, key);
+	if(element == NULL) return NULL;
+	return &element->value;
+}

src/findMagicNumber.c

@@ -9,18 +9,13 @@
 #include <chess/magic.h>
 #include <chess/generated/moveConsts.h>
 #include <chess/bitboard.h>
+#include <chess/bitset.h>
+#include <chess/util.h>
 
 #define MAX_BITS 12
 #define MAX_SIZE (1 << MAX_BITS)
 #define ATTACK_TABLE_LENGTH (2 * MAX_SIZE * TOTAL_BOARD_SIZE)
 
-static uint_least64_t rand_64() {
-	uint_least64_t u1, u2, u3, u4;
-  u1 = (uint_least64_t)(rand()) & 0xFFFF; u2 = (uint_least64_t)(rand()) & 0xFFFF;
-  u3 = (uint_least64_t)(rand()) & 0xFFFF; u4 = (uint_least64_t)(rand()) & 0xFFFF;
-  return u1 | (u2 << 16) | (u3 << 32) | (u4 << 48);
-}
-
 static uint_least64_t randFewBits() {
 	return rand_64() & rand_64() & rand_64();
 }

src/generateCode/moveConsts.c

@@ -2,8 +2,9 @@
 #include <chess/types.h>
 #include <stdint.h>
 #include <inttypes.h>
-#include <chess/bitboard.h>
+#include <chess/bitset.h>
 #include <chess/print.h>
+#include <chess/util.h>
 
 static void printerMoveDst(FILE *file, struct moveDst_t moveDst) {
 	fprintf(file, "{ %" PRIuLEAST8 ", ", moveDst.length);

src/generateCode/zobrist.c

@@ -0,0 +1,39 @@
+#include "chess/types.h"
+#include "chess/zobristConsts.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <chess/util.h>
+#include <stdlib.h>
+#include <chess/print.h>
+#include <inttypes.h>
+
+int main() {
+	srand(0xc0229b8e);
+	printf("#include <stdint.h>\n");
+	{
+		uint_least64_t zobristPiece[ZOBRIST_PIECE_LENGTH];
+		for(uint_least8_t color = BLACK; color <= WHITE; ++color) {
+			for(uint_least8_t pieceType = KING; pieceType < PIECES_LENGTH; ++pieceType) {
+				const struct piece_t piece = {pieceType, color};
+				for(uint_least8_t field = 0; field < TOTAL_BOARD_SIZE; ++field) {
+					zobristPiece[zobristPieceI(piece, field)] = rand_64();
+				}
+			}
+		}
+		defineArray("const uint_least64_t ZOBRIST_PIECE", printerull, zobristPiece);
+	}
+	printf("const uint_least64_t ZOBRIST_BLACK_MOVE = %" PRIuLEAST64 "u;\n", rand_64());
+	{
+		uint_least64_t zobristRest[4 + BOARD_SIZE]; // 4 for castling
+		for(uint_least8_t i = 0; i < LENGTH(zobristRest); ++i) {
+			zobristRest[i] = rand_64();
+		}
+		uint_least64_t *zobristRestPtr = zobristRest;
+		const size_t castleLength = 2;
+		defineArrayCustomLength("const uint_least64_t ZOBRIST_SHORT_CASTLE", printerull, zobristRestPtr, castleLength);
+		zobristRestPtr += castleLength;
+		defineArrayCustomLength("const uint_least64_t ZOBRIST_LONG_CASTLE", printerull, zobristRestPtr, castleLength);
+		zobristRestPtr += castleLength;
+		defineArrayCustomLength("const uint_least64_t ZOBRIST_EN_PASSENT_FILE", printerull, zobristRestPtr, (size_t)BOARD_SIZE);
+	}
+}

src/uci.c

@@ -0,0 +1,72 @@
+#include "chess/move.h"
+#include "chess/types.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <stdatomic.h>
+#include <stdbool.h>
+#include <string.h>
+#include <stddef.h>
+#include <chess/bitboard.h>
+
+atomic_bool searchShouldStop;
+
+#define customStrCmp(input, cmd) customStrCmpFunc(&(input), cmd, sizeof(cmd))
+static bool customStrCmpFunc(char **input, const char *cmd, const size_t length) {
+	bool result = strncmp(*input, cmd, length) == 0;
+	if(result) *input += length + 1;
+	return result;
+}
+
+int main() {
+	char input[4096];
+	struct gameState_t gameState;
+	uint_least64_t board[TOTAL_BOARD_SIZE];
+	gameState.repetitionTable = (struct zobristTable){NULL};
+	initMagicTable();
+	while(true) {
+		char *inputPtr = input;
+		if(fgets(input, sizeof input, stdin) == NULL) {
+			perror("Error: reading stdin: ");
+			continue;
+		}
+		if(customStrCmp(inputPtr, "uci")) {
+			printf(
+					"id name NoNameChessEngine\n"
+					"id author MrGeorgen\n"
+					"uciok\n"
+					);
+			continue;
+		}
+		if(customStrCmp(inputPtr, "isready")) {
+			printf("readyok\n");
+			continue;
+		}
+		if(customStrCmp(inputPtr, "position")) {
+			if(gameState.repetitionTable.arr == NULL) {
+				fprintf(stderr, "Error: required uicnewgame before a position command\n");
+				continue;
+			}
+			if(customStrCmp(inputPtr, "startpos")) {
+				gameState = parseFen(board, START_FEN);
+				continue;
+			}
+			if(customStrCmp(inputPtr, "fen")) {
+				gameState = parseFen(board, inputPtr);
+				continue;
+			}
+		}
+		if(customStrCmp(inputPtr, "quit")) {
+			return 0;
+		}
+		if(customStrCmp(inputPtr, "go")) {
+			while(*inputPtr != '\0') {
+				//if(customStrCmp(inputPtr, "wtime"))
+			}
+			continue;
+		}
+		if(customStrCmp(inputPtr, "stop")) {
+			searchShouldStop = true;
+			continue;
+		}
+	}
+}

test/moveGen.c

@@ -21,14 +21,15 @@ static uint_least64_t perft(const struct gameState_t gameState, const uint_least
 	for(uint_least8_t i = 0; i < movesLength; ++i) {
 		const struct gameState_t newGameState = makeMove(gameState, moves[i]);
 		nodes += perft(newGameState, depth - 1);
-		undoMove(gameState.board, moves[i], gameState.color);
+		undoMove(newGameState, moves[i], gameState.color);
 	}
 	return nodes;
 }
 
 static void test(struct perf_t perf, const uint_least8_t i) {
 		uint_least64_t board[BITBOARD_LENGTH];
-		const struct gameState_t gameState = newGameState(board, perf.FEN);
+		struct zobristTableElement repetitionTableStore[REPETETION_TABLE_LENGTH];
+		const struct gameState_t gameState = newGameState(board, repetitionTableStore, perf.FEN);
 		const uint_least64_t nodes = perft(gameState, perf.depth);
 		if(perf.nodes != nodes) {
 			printf("Test %" PRIuLEAST16 " failed: FEN: %s, depth: %" PRIuLEAST8 " calculated nodes: %" PRIuLEAST64
@@ -38,7 +39,7 @@ static void test(struct perf_t perf, const uint_least8_t i) {
 			for(uint_least8_t j = 0; j < movesLength; ++j) {
 				const struct gameState_t newGameState = makeMove(gameState, moves[j]);
 				const uint_least64_t nodes = perft(newGameState, perf.depth - 1);
-				undoMove(gameState.board, moves[j], gameState.color);
+				undoMove(newGameState, moves[j], gameState.color);
 				{
 					printMove(moves[j]);
 					printf(" %" PRIuLEAST64 "\n", nodes);