seg fault

[stoic herald]

for some reason when trying to use a member variable of a class i get a seg fault. i get the seg fault 100% of the time in debug and only sometimes normally

[obsidian plank]

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@stoic herald

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[stoic herald]

void Bitboard::setPiece(int square)
{
    board |= (1ULL << square);
}

void Bitboard::removePiece(int square)
{
    board &= ~(1ULL << square);
}

[lilac gorge]

In the debugger, look at what this is 😛

You probably have a void pointer or otherwise garbage pointer to your class instance

[stoic herald]

both functions cause seg fault

class Bitboard
{
public:
    Bitboard() : board(0ULL) {};

    void setPiece(int square);
    void removePiece(int square);
    bool isOccupied(int square);
    void print();

private:
    uint64_t board;
};

also heres the bitboard class

[stoic herald]

i have a std array of the class instance

[lilac gorge]

what OS are you on

and what compiler

[stoic herald]

windows

[stoic herald]

g++ i think
one sec ill check

yea g++

[lilac gorge]

ok

have you ever used WSL?

[stoic herald]

no?

[lilac gorge]

there's a tool called address sanitizer that will help you debug this but it doesn't work well for gcc on windows

it does, however, work in WSL

[stoic herald]

is there some other way to check why i get a seg fault?

[tranquil rain]

Why aren't you using something like std::bitset @stoic herald

[stoic herald]

what is it?

[tranquil rain]

It does what youre currently doing manually

its a bitfield

pieces.set(N) pieces.reset(N) pieces.flip(N) where N is the bit index

!cppref bitset

[obsidian plank]

cppreference.com

std::bitset

template<std::size_t N>
class bitset;

Defined in

<bitset>

[stoic herald]

thx

uh
now i got a seg fault in bitset

[tranquil rain]

the segfault is not an issue of this class

its caused by something else

show the usage of the class please

i told u about bitset so u dont do the bitwise stuff manually and do something wrong somewhere:

class Bitboard
{
public:
    Bitboard() : board{} {};

    void setPiece(int square) {
      board.set(square);
    }
    void removePiece(int square) {
      board.reset(square);
    }
    bool isOccupied(int square) {
      return board.test(square);
    }
    void print();

private:
    std::bitset<8*8> board{};
};

[stoic herald]

std::vector<Move> MoveGen::generatePawnMoves(Board& board, bool isWhite)
{
    legalMoves.clear();

    Bitboard bitboard = board.getBitboards()[isWhite ? PieceTypes::WhitePawn : PieceTypes::BlackPawn];
    // bitboard.toString();
    
    for (int square = 0; square < 64; square++)
    {
        int file = square % 8;
        int rank = (square / 8);

        if (isWhite)
        {
            if (!bitboard.isOccupied(square))
            {
                continue;
            }

            //std::cout << bitboard.isOccupied(square + 8) << '\n';
            if (rank == 1 && !bitboard.isOccupied(square + 8) && !bitboard.isOccupied(square + 16))
            {
                //std::cout << "this called" << '\n';
                legalMoves.push_back(Move{ square, square + 16 });
            }
            if (!bitboard.isOccupied(square + 8) && rank < 6)
            {
                legalMoves.push_back(Move{ square, square + 8 });
            }
            //if (bitboard.isOccupied(square)) std::cout << "Test: " << bitboard.isOccupied(50) << ' ' << square << '\n';

        }
    }

    return legalMoves;
}

heres a function that uses the bitboards

(ignore that what its supposed to do is false)

[tranquil rain]

show me where the board& gets passed in

Bitboard bitboard = board.getBitboards()[isWhite ? PieceTypes::WhitePawn : PieceTypes::BlackPawn];

[stoic herald]

std::vector<Move> legalMoves = draggedPiece->getLegalMoves(*this);

[tranquil rain]

ensure this is correct also

[stoic herald]

wdym? that it is in fact from 0 to 11 so its inside the array? yes it is

[tranquil rain]

theres an issue somewhere somehow

[stoic herald]

i can send a bunch of code related to the bitboards

[lilac gorge]

Of course

But I recommend address sanitizer because memory errors manifest far from their source, address sanitizer helps you find the problem at its source

You can step around in a debugger and try to see where things go wrong

If your project is small you can use address sanitizer on godbolt.org otherwise I would try to setup WSL and build/run with gcc there

[stoic herald]

if i cant fix the problem after some time then ill try to setup WSL

[stoic herald]

std::array<Bitboard, 12> bitboards;

std::array<Bitboard, 12> Board::getBitboards()
{
    return bitboards;
}

void Board::makeMove(int fromFile, int fromRank, int toFile, int toRank, PieceTypes pieceType)
{
    int square = (8 * fromRank) + fromFile;

    

    board[square]->move(toFile, toRank);
    board[(8 * toRank) + toFile] = std::move(board[square]);
    bitboards[pieceType].removePiece(square);
    bitboards[pieceType].setPiece((8 * toRank) + toFile);
}

[lilac gorge]

how much code is it total?

could you send us everything?

[stoic herald]

its in a few cpps though

i could also live share if you use vscode

[tranquil rain]

do u have a memcpy or a memset anywhere?

[stoic herald]

no

[tranquil rain]

weird

[stoic herald]

i can also send a zip archive of it

[lilac gorge]

it would be best if you could either send a few files directly or send a minimal reproducible portion

[stoic herald]

not really minimal but yea

[lilac gorge]

It would be good if we could reproduct with just the bitboard stuff, none of the graphics things

It might not be possible, memory errors manifest far from their source

[stoic herald]

i can try

[lilac gorge]

But it would be helpful yeah

[stoic herald]

with a quick test i did where it just kinda looped from 0 to 63 and set and reset each bit there were no seg faults

oh

i think i found the bug

im apparently trying to access bitboards[3131961357]

[tranquil rain]

🤣

[stoic herald]

Pawn::Pawn(bool isWhitePiece, int rank, int file, TextureLoader& textureLoader) : Piece(isWhitePiece ? PieceTypes::WhitePawn : PieceTypes::BlackPawn, isWhitePiece, rank, file)

for some reason the first parameter of Piece gets initialized with garbage

ok i fixed

thanks for the help

[obsidian plank]

@stoic herald Has your question been resolved? If so, type !solved :)

[stoic herald]

!solved

[obsidian plank]

Thank you and let us know if you have any more questions!

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[lilac gorge]

that would in fact do it

[tranquil rain]

dont forget the bitset!!!