// Contract: starfighter
// Target function: function _checkContractOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data) private returns (bool)
startTimestamp`
    // - [224]      `burned`
    // - [225]      `nextInitialized`
    mapping(uint256 => uint256) private _packedOwnerships;

    // Mapping owner address to address data.
    //
    // Bits Layout:
    // - [0..63]    `balance`
    // - [64..127]  `numberMinted`
    // - [128..191] `numberBurned`
    // - [192..255] `aux`
    mapping(address => uint256) private _packedAddressData;

    // Mapping from token ID to approved address.
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
        _currentIndex = _startTokenId();}

    //Returns the starting token ID
    function _startTokenId() internal view virtual returns (uint256) {
        return 0;}

    //Returns the next token ID to be minted
    function _nextTokenId() internal view returns (uint256) {
        return _currentIndex;}

    //Returns the total number of tokens in existence
    function totalSupply() public view override returns (uint256) {
        // Counter underflow is impossible as _burnCounter cannot be incremented
        // more than `_currentIndex - _startTokenId()` times.
        unchecked {return _currentIndex - _burnCounter - _startTokenId();}}

    //Returns the total amount of tokens minted in the contract
    function _totalMinted() internal view returns (uint256) {
        // Counter underflow is impossible as _currentIndex does not decrement,
        // and it is initialized to `_startTokenId()`
        unchecked {
            return _currentIndex - _startTokenId();}}

    //Returns the total number of tokens burned
    function _totalBurned() internal view returns (uint256) {
        return _burnCounter;}

    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        // The interface IDs are constants representing the first 4 bytes of the XOR of
        // all function selectors in the interface. See: https://eips.ethereum.org/EIPS/eip-165
        // e.g. `bytes4(i.functionA.selector ^ i.functionB.selector ^ ...)`
        return
            interfaceId == 0x01ffc9a7 || interfaceId == 0x80ac58cd || interfaceId == 0x5b5e139f;}

    function balanceOf(address owner) public view override returns (uint256) {
        if (owner == address(0)) revert BalanceQueryForZeroAddress();
        return _packedAddressData[owner] & BITMASK_ADDRESS_DATA_ENTRY;}

    function _numberMinted(address owner) internal view returns (uint256) {
        return (_packedAddressData[owner] >> BITPOS_NUMBER_MINTED) & BITMASK_ADDRESS_DATA_ENTRY;}

    function _numberBurned(address owner) internal view returns (uint256) {
        return (_packedAddressData[owner] >> BITPOS_NUMBER_BURNED) & BITMASK_ADDRESS_DATA_ENTRY;}

    function _getAux(address owner) internal view returns (uint64) {
        return uint64(_packedAddressData[owner] >> BITPOS_AUX);}

    function _setAux(address owner, uint64 aux) internal {
        uint256 packed = _packedAddressData[owner];
        uint256 auxCasted;
        assembly { // Cast aux without masking.
            auxCasted := aux}
        packed = (packed & BITMASK_AUX_COMPLEMENT) | (auxCasted << BITPOS_AUX);
        _packedAddressData[owner] = packed;}

    function _packedOwnershipOf(uint256 tokenId) private view returns (uint256) {
        uint256 curr = tokenId;
        unchecked {
            if (_startTokenId() <= curr)
                if (curr < _currentIndex) {
                    uint256 packed = _packedOwnerships[curr];
                    // If not burned.
                    if (packed & BITMASK_BURNED == 0) {
                        // Invariant:
                        // There will always be an ownership that has an address and is not burned
                        // before an ownership that does not have an address and is not burned.
                        // Hence, curr will not underflow.
                        //
                        // We can directly compare the packed value.
                        // If the address is zero, packed is zero.
                        while (packed == 0) {
                            packed = _packedOwnerships[--curr];}
                        return packed;}}}
        revert OwnerQueryForNonexistentToken();}

    function _unpackedOwnership(uint256 packed) private pure returns (TokenOwnership memory ownership) {
        ownership.addr = address(uint160(packed));
        ownership.startTimestamp = uint64(packed >> BITPOS_START_TIMESTAMP);
        ownership.burned = packed & BITMASK_BURNED != 0;}

    function _ownershipAt(uint256 index) internal view returns (TokenOwnership memory) {
        return _unpackedOwnership(_packedOwnerships[index]);}

    function _initializeOwnershipAt(uint256 index) internal {
        if (_packedOwnerships[index] == 0) {
            _packedOwnerships[index] = _packedOwnershipOf(index);}}

    function _ownershipOf(uint256 tokenId) internal view returns (TokenOwnership memory) {
        return _unpackedOwnership(_packedOwnershipOf(tokenId));}

    function ownerOf(uint256 tokenId) public view override returns (address) {
        return address(uint160(_packedOwnershipOf(tokenId)));}

    function name() public view virtual override returns (string memory) {
        return _name;}

    function symbol() public view virtual override returns (string memory) {
        return _symbol;}

    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        if (!_exists(tokenId)) revert URIQueryForNonexistentToken();
        string memory baseURI = _baseURI();
        return bytes(baseURI).length != 0 ? string(abi.encodePacked(baseURI, _toString(tokenId))) : '';}

    //Base URI for computing {tokenURI}. 
    function _baseURI() internal view virtual returns (string memory) {
        return '';}

    function _addressToUint256(address value) private pure returns (uint256 result) {
        assembly {
            result := value}}

    function _boolToUint256(bool value) private pure returns (uint256 result) {
        assembly {
            result := value}}

    function approve(address to, uint256 tokenId) public override {
        address owner = address(uint160(_packedOwnershipOf(tokenId)));
        if (to == owner) revert ApprovalToCurrentOwner();
        if (_msgSenderERC721A() != owner)
            if (!isApprovedForAll(owner, _msgSenderERC721A())) {
                revert ApprovalCallerNotOwnerNorApproved();}
        _tokenApprovals[tokenId] = to;
        emit Approval(owner, to, tokenId);}

    function getApproved(uint256 tokenId) public view override returns (address) {
        if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();
        return _tokenApprovals[tokenId];}

    function setApprovalForAll(address operator, bool approved) public virtual override {
        if (operator == _msgSenderERC721A()) revert ApproveToCaller();
        _operatorApprovals[_msgSenderERC721A()][operator] = approved;
        emit ApprovalForAll(_msgSenderERC721A(), operator, approved);}

    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];}

    function transferFrom(address from, address to, uint256 tokenId) public virtual override {
        _transfer(from, to, tokenId);}

    function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
        safeTransferFrom(from, to, tokenId, '');}

    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public virtual override {
        _transfer(from, to, tokenId);
        if (to.code.length != 0)
            if (!_checkContractOnERC721Received(from, to, tokenId, _data)) {
                revert TransferToNonERC721ReceiverImplementer();}}

    //Returns whether `tokenId` exists
    function _exists(uint256 tokenId) internal view returns (bool) {
        return _startTokenId() <= tokenId && tokenId < _currentIndex && _packedOwnerships[tokenId] & BITMASK_BURNED == 0;}

    //Equivalent to `_safeMint(to, quantity, '')`
    function _safeMint(address to, uint256 quantity) internal {
        _safeMint(to, quantity, '');}

    //Safely mints `quantity` tokens and transfers them to `to`
    function _safeMint(address to, uint256 quantity, bytes memory _data) internal {
        uint256 startTokenId = _currentIndex;
        if (to == address(0)) revert MintToZeroAddress();
        if (quantity == 0) revert MintZeroQuantity();
        _beforeTokenTransfers(address(0), to, startTokenId, quantity);
        // Overflows are incredibly unrealistic.
        // balance or numberMinted overflow if current value of either + quantity > 1.8e19 (2**64) - 1
        // updatedIndex overflows if _currentIndex + quantity > 1.2e77 (2**256) - 1
        unchecked {
            // Updates:
            // - `balance += quantity`.
            // - `numberMinted += quantity`.
            //
            // We can directly add to the balance and number minted.
            _packedAddressData[to] += quantity * ((1 << BITPOS_NUMBER_MINTED) | 1);
            // Updates:
            // - `address` to the owner.
            // - `startTimestamp` to the timestamp of minting.
            // - `burned` to `false`.
            // - `nextInitialized` to `quantity == 1`.
            _packedOwnerships[startTokenId] =
                _addressToUint256(to) |
                (block.timestamp << BITPOS_START_TIMESTAMP) |
                (_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED);
            uint256 updatedIndex = startTokenId;
            uint256 end = updatedIndex + quantity;
            if (to.code.length != 0) {
                do {
                    emit Transfer(address(0), to, updatedIndex);
                    if (!_checkContractOnERC721Received(address(0), to, updatedIndex++, _data)) {
                        revert TransferToNonERC721ReceiverImplementer();}} 
                while (updatedIndex < end);
                // Reentrancy protection
                if (_currentIndex != startTokenId) revert();} 
                else {
                do {emit Transfer(address(0), to, updatedIndex++);} while (updatedIndex < end);}
            _currentIndex = updatedIndex;}
        _afterTokenTransfers(address(0), to, startTokenId, quantity);}

    //Mints `quantity` tokens and transfers them to `to`
    function _mint(address to, uint256 quantity) internal {
        uint256 startTokenId = _currentIndex;
        if (to == address(0)) revert MintToZeroAddress();
        if (quantity == 0) revert MintZeroQuantity();
        _beforeTokenTransfers(address(0), to, startTokenId, quantity);
        // Overflows are incredibly unrealistic.
        // balance or numberMinted overflow if current value of either + quantity > 1.8e19 (2**64) - 1
        // updatedIndex overflows if _currentIndex + quantity > 1.2e77 (2**256) - 1
        unchecked {
            // Updates:
            // - `balance += quantity`.
            // - `numberMinted += quantity`.
            //
            // We can directly add to the balance and number minted.
            _packedAddressData[to] += quantity * ((1 << BITPOS_NUMBER_MINTED) | 1);
            // Updates:
            // - `address` to the owner.
            // - `startTimestamp` to the timestamp of minting.
            // - `burned` to `false`.
            // - `nextInitialized` to `quantity == 1`.
            _packedOwnerships[startTokenId] =
                _addressToUint256(to) |
                (block.timestamp << BITPOS_START_TIMESTAMP) |
                (_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED);
            uint256 updatedIndex = startTokenId;
            uint256 end = updatedIndex + quantity;
            do {emit Transfer(address(0), to, updatedIndex++);} while (updatedIndex < end);
            _currentIndex = updatedIndex;}
        _afterTokenTransfers(address(0), to, startTokenId, quantity);}

    //Transfers `tokenId` from `from` to `to`
    function _transfer(address from, address to, uint256 tokenId) private {
        uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);
        if (address(uint160(prevOwnershipPacked)) != from) revert TransferFromIncorrectOwner();
        bool isApprovedOrOwner = (_msgSenderERC721A() == from ||
            isApprovedForAll(from, _msgSenderERC721A()) ||
            getApproved(tokenId) == _msgSenderERC721A());
        if (!isApprovedOrOwner) revert TransferCallerNotOwnerNorApproved();
        if (to == address(0)) revert TransferToZeroAddress();
        _beforeTokenTransfers(from, to, tokenId, 1);
        // Clear approvals from the previous owner.
        delete _tokenApprovals[tokenId];
        // Underflow of the sender's balance is impossible because we check for
        // ownership above and the recipient's balance can't realistically overflow.
        // Counter overflow is incredibly unrealistic as tokenId would have to be 2**256.
        unchecked {
            // We can directly increment and decrement the balances.
            --_packedAddressData[from]; // Updates: `balance -= 1`.
            ++_packedAddressData[to]; // Updates: `balance += 1`.
            // Updates:
            // - `address` to the next owner.
            // - `startTimestamp` to the timestamp of transfering.
            // - `burned` to `false`.
            // - `nextInitialized` to `true`.
            _packedOwnerships[tokenId] =
                _addressToUint256(to) |
                (block.timestamp << BITPOS_START_TIMESTAMP) |
                BITMASK_NEXT_INITIALIZED;
            // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
            if (prevOwnershipPacked & BITMASK_NEXT_INITIALIZED == 0) {
                uint256 nextTokenId = tokenId + 1;
                // If the next slot's address is zero and not burned (i.e. packed value is zero).
                if (_packedOwnerships[nextTokenId] == 0) {
                    // If the next slot is within bounds.
                    if (nextTokenId != _currentIndex) {
                        // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
                        _packedOwnerships[nextTokenId] = prevOwnershipPacked;}}}}
        emit Transfer(from, to, tokenId);
        _afterTokenTransfers(from, to, tokenId, 1);}

    //Equivalent to `_burn(tokenId, false)`
    function _burn(uint256 tokenId) internal virtual {
        _burn(tokenId, false);}

    //Destroys `tokenId`
    function _burn(uint256 tokenId, bool approvalCheck) internal virtual {
        uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);
        address from = address(uint160(prevOwnershipPacked));
        if (approvalCheck) {
            bool isApprovedOrOwner = (_msgSenderERC721A() == from || isApprovedForAll(from, _msgSenderERC721A()) || getApproved(tokenId) == _msgSenderERC721A());
            if (!isApprovedOrOwner) revert TransferCallerNotOwnerNorApproved();}
        _beforeTokenTransfers(from, address(0), tokenId, 1);
        // Clear approvals from the previous owner.
        delete _tokenApprovals[tokenId];
        // Underflow of the sender's balance is impossible because we check for
        // ownership above and the recipient's balance can't realistically overflow.
        // Counter overflow is incredibly unrealistic as tokenId would have to be 2**256.
        unchecked {
            // Updates:
            // - `balance -= 1`.
            // - `numberBurned += 1`.
            //
            // We can directly decrement the balance, and increment the number burned.
            // This is equivalent to `packed -= 1; packed += 1 << BITPOS_NUMBER_BURNED;`.
            _packedAddressData[from] += (1 << BITPOS_NUMBER_BURNED) - 1;
            // Updates:
            // - `address` to the last owner.
            // - `startTimestamp` to the timestamp of burning.
            // - `burned` to `true`.
            // - `nextInitialized` to `true`.
            _packedOwnerships[tokenId] =
                _addressToUint256(from) |
                (block.timestamp << BITPOS_START_TIMESTAMP) |
                BITMASK_BURNED | 
                BITMASK_NEXT_INITIALIZED;
            // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
            if (prevOwnershipPacked & BITMASK_NEXT_INITIALIZED == 0) {
                uint256 nextTokenId = tokenId + 1;
                // If the next slot's address is zero and not burned (i.e. packed value is zero).
                if (_packedOwnerships[nextTokenId] == 0) {
                    // If the next slot is within bounds.
                    if (nextTokenId != _currentIndex) {
                        // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
                        _packedOwnerships[nextTokenId] = prevOwnershipPacked;}}}}
        emit Transfer(from, address(0), tokenId);
        _afterTokenTransfers(from, address(0), tokenId, 1);
        // Overflow not possible, as _burnCounter cannot be exceed _currentIndex times.
        unchecked {_burnCounter++;}}