Cryo Explorer Ethereum Mainnet

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

library CalldataBytesLib {
    function toU8(bytes calldata _bytes, uint256 _start) internal pure returns (uint8) {
        return uint8(_bytes[_start]);
    }

    function toU16(bytes calldata _bytes, uint256 _start) internal pure returns (uint16) {
        unchecked {
            uint256 end = _start + 2;
            return uint16(bytes2(_bytes[_start:end]));
        }
    }

    function toU32(bytes calldata _bytes, uint256 _start) internal pure returns (uint32) {
        unchecked {
            uint256 end = _start + 4;
            return uint32(bytes4(_bytes[_start:end]));
        }
    }

    function toU64(bytes calldata _bytes, uint256 _start) internal pure returns (uint64) {
        unchecked {
            uint256 end = _start + 8;
            return uint64(bytes8(_bytes[_start:end]));
        }
    }

    function toU128(bytes calldata _bytes, uint256 _start) internal pure returns (uint128) {
        unchecked {
            uint256 end = _start + 16;
            return uint128(bytes16(_bytes[_start:end]));
        }
    }

    function toU256(bytes calldata _bytes, uint256 _start) internal pure returns (uint256) {
        unchecked {
            uint256 end = _start + 32;
            return uint256(bytes32(_bytes[_start:end]));
        }
    }

    function toAddr(bytes calldata _bytes, uint256 _start) internal pure returns (address) {
        unchecked {
            uint256 end = _start + 20;
            return address(bytes20(_bytes[_start:end]));
        }
    }

    function toB32(bytes calldata _bytes, uint256 _start) internal pure returns (bytes32) {
        unchecked {
            uint256 end = _start + 32;
            return bytes32(_bytes[_start:end]);
        }
    }
}

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

library Transfer {
    using SafeERC20 for IERC20;

    address internal constant ADDRESS_ZERO = address(0);

    error Transfer_NativeFailed(address _to, uint256 _value);
    error Transfer_ToAddressIsZero();

    function native(address _to, uint256 _value) internal {
        if (_to == ADDRESS_ZERO) revert Transfer_ToAddressIsZero();
        (bool success, ) = _to.call{ value: _value }("");
        if (!success) revert Transfer_NativeFailed(_to, _value);
    }

    function token(address _token, address _to, uint256 _value) internal {
        if (_to == ADDRESS_ZERO) revert Transfer_ToAddressIsZero();
        IERC20(_token).safeTransfer(_to, _value);
    }

    function nativeOrToken(address _token, address _to, uint256 _value) internal {
        if (_token == ADDRESS_ZERO) {
            native(_to, _value);
        } else {
            token(_token, _to, _value);
        }
    }
}

// SPDX-License-Identifier: MIT

// modified from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/structs/BitMaps.sol
pragma solidity ^0.8.20;

type BitMap256 is uint256;

using BitMaps for BitMap256 global;

library BitMaps {
    /**
     * @dev Returns whether the bit at `index` is set.
     */
    function get(BitMap256 bitmap, uint8 index) internal pure returns (bool) {
        uint256 mask = 1 << index;
        return BitMap256.unwrap(bitmap) & mask != 0;
    }

    /**
     * @dev Sets the bit at `index`.
     */
    function set(BitMap256 bitmap, uint8 index) internal pure returns (BitMap256) {
        uint256 mask = 1 << index;
        return BitMap256.wrap(BitMap256.unwrap(bitmap) | mask);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.4) (token/ERC20/extensions/IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 * ==== Security Considerations
 *
 * There are two important considerations concerning the use of `permit`. The first is that a valid permit signature
 * expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be
 * considered as an intention to spend the allowance in any specific way. The second is that because permits have
 * built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should
 * take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be
 * generally recommended is:
 *
 * ```solidity
 * function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public {
 *     try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {}
 *     doThing(..., value);
 * }
 *
 * function doThing(..., uint256 value) public {
 *     token.safeTransferFrom(msg.sender, address(this), value);
 *     ...
 * }
 * ```
 *
 * Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of
 * `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also
 * {SafeERC20-safeTransferFrom}).
 *
 * Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so
 * contracts should have entry points that don't rely on permit.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     *
     * CAUTION: See Security Considerations above.
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.3) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/IERC20Permit.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance + value));
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance - value));
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeWithSelector(token.approve.selector, spender, value);

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, 0));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Use a ERC-2612 signature to set the `owner` approval toward `spender` on `token`.
     * Revert on invalid signature.
     */
    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        require(returndata.length == 0 || abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return
            success && (returndata.length == 0 || abi.decode(returndata, (bool))) && Address.isContract(address(token));
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     *
     * Furthermore, `isContract` will also return true if the target contract within
     * the same transaction is already scheduled for destruction by `SELFDESTRUCT`,
     * which only has an effect at the end of a transaction.
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.8.0/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.4) (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

interface ILayerZeroPriceFeed {
    /**
     * @dev
     * priceRatio: (USD price of 1 unit of remote native token in unit of local native token) * PRICE_RATIO_DENOMINATOR
     */

    struct Price {
        uint128 priceRatio; // float value * 10 ^ 20, decimal awared. for aptos to evm, the basis would be (10^18 / 10^8) * 10 ^20 = 10 ^ 30.
        uint64 gasPriceInUnit; // for evm, it is in wei, for aptos, it is in octas.
        uint32 gasPerByte;
    }

    struct UpdatePrice {
        uint32 eid;
        Price price;
    }

    /**
     * @dev
     *    ArbGasInfo.go:GetPricesInArbGas
     *
     */
    struct ArbitrumPriceExt {
        uint64 gasPerL2Tx; // L2 overhead
        uint32 gasPerL1CallDataByte;
    }

    struct UpdatePriceExt {
        uint32 eid;
        Price price;
        ArbitrumPriceExt extend;
    }

    error LZ_PriceFeed_OnlyPriceUpdater();
    error LZ_PriceFeed_InsufficientFee(uint256 provided, uint256 required);
    error LZ_PriceFeed_UnknownL2Eid(uint32 l2Eid);

    function nativeTokenPriceUSD() external view returns (uint128);

    function getFee(uint32 _dstEid, uint256 _callDataSize, uint256 _gas) external view returns (uint256);

    function getPrice(uint32 _dstEid) external view returns (Price memory);

    function getPriceRatioDenominator() external view returns (uint128);

    function estimateFeeByEid(
        uint32 _dstEid,
        uint256 _callDataSize,
        uint256 _gas
    ) external view returns (uint256 fee, uint128 priceRatio, uint128 priceRatioDenominator, uint128 nativePriceUSD);

    function estimateFeeOnSend(
        uint32 _dstEid,
        uint256 _callDataSize,
        uint256 _gas
    ) external payable returns (uint256 fee, uint128 priceRatio, uint128 priceRatioDenominator, uint128 nativePriceUSD);
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

interface IWorker {
    event SetWorkerLib(address workerLib);
    event SetPriceFeed(address priceFeed);
    event SetDefaultMultiplierBps(uint16 multiplierBps);
    event SetSupportedOptionTypes(uint32 dstEid, uint8[] optionTypes);
    event Withdraw(address lib, address to, uint256 amount);

    error Worker_NotAllowed();
    error Worker_OnlyMessageLib();
    error Worker_RoleRenouncingDisabled();

    function setPriceFeed(address _priceFeed) external;

    function priceFeed() external view returns (address);

    function setDefaultMultiplierBps(uint16 _multiplierBps) external;

    function defaultMultiplierBps() external view returns (uint16);

    function withdrawFee(address _lib, address _to, uint256 _amount) external;

    function setSupportedOptionTypes(uint32 _eid, uint8[] calldata _optionTypes) external;

    function getSupportedOptionTypes(uint32 _eid) external view returns (uint8[] memory);
}

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";
import { Transfer } from "@layerzerolabs/lz-evm-protocol-v2/contracts/libs/Transfer.sol";

import { ILayerZeroPriceFeed } from "../../interfaces/ILayerZeroPriceFeed.sol";
import { IDVN } from "../interfaces/IDVN.sol";
import { IDVNFeeLib } from "../interfaces/IDVNFeeLib.sol";
import { DVNOptions } from "../libs/DVNOptions.sol";

contract DVNFeeLib is Ownable, IDVNFeeLib {
    using DVNOptions for bytes;

    uint16 internal constant EXECUTE_FIXED_BYTES = 68; // encoded: funcSigHash + params -> 4  + (32 * 2)
    uint16 internal constant SIGNATURE_RAW_BYTES = 65; // not encoded
    // callData(updateHash) = 132 (4 + 32 * 4), padded to 32 = 160 and encoded as bytes with an 64 byte overhead = 224
    uint16 internal constant UPDATE_HASH_BYTES = 224;

    uint256 private immutable nativeDecimalsRate;

    constructor(uint256 _nativeDecimalsRate) {
        nativeDecimalsRate = _nativeDecimalsRate;
    }

    // ================================ OnlyOwner ================================
    function withdrawToken(address _token, address _to, uint256 _amount) external onlyOwner {
        // transfers native if _token is address(0x0)
        Transfer.nativeOrToken(_token, _to, _amount);
    }

    // ========================= External =========================
    /// @dev get fee function that can change state. e.g. paying priceFeed
    /// @param _params fee params
    /// @param _dstConfig dst config
    /// @param //_options options
    function getFeeOnSend(
        FeeParams calldata _params,
        IDVN.DstConfig calldata _dstConfig,
        bytes calldata _options
    ) external payable returns (uint256) {
        if (_dstConfig.gas == 0) revert DVN_EidNotSupported(_params.dstEid);

        _decodeDVNOptions(_options); // todo: validate options

        uint256 callDataSize = _getCallDataSize(_params.quorum);

        // for future versions where priceFeed charges a fee
        //        uint256 priceFeedFee = ILayerZeroPriceFeed(_params.priceFeed).getFee(_params.dstEid, callDataSize, _dstConfig.gas);
        //        (uint256 fee, , , uint128 nativePriceUSD) = ILayerZeroPriceFeed(_params.priceFeed).estimateFeeOnSend{
        //            value: priceFeedFee
        //        }(_params.dstEid, callDataSize, _dstConfig.gas);

        (uint256 fee, , , uint128 nativePriceUSD) = ILayerZeroPriceFeed(_params.priceFeed).estimateFeeOnSend(
            _params.dstEid,
            callDataSize,
            _dstConfig.gas
        );

        return
            _applyPremium(
                fee,
                _dstConfig.multiplierBps,
                _params.defaultMultiplierBps,
                _dstConfig.floorMarginUSD,
                nativePriceUSD
            );
    }

    // ========================= View =========================
    /// @dev get fee view function
    /// @param _params fee params
    /// @param _dstConfig dst config
    /// @param //_options options
    function getFee(
        FeeParams calldata _params,
        IDVN.DstConfig calldata _dstConfig,
        bytes calldata _options
    ) external view returns (uint256) {
        if (_dstConfig.gas == 0) revert DVN_EidNotSupported(_params.dstEid);

        _decodeDVNOptions(_options); // validate options

        uint256 callDataSize = _getCallDataSize(_params.quorum);
        (uint256 fee, , , uint128 nativePriceUSD) = ILayerZeroPriceFeed(_params.priceFeed).estimateFeeByEid(
            _params.dstEid,
            callDataSize,
            _dstConfig.gas
        );
        return
            _applyPremium(
                fee,
                _dstConfig.multiplierBps,
                _params.defaultMultiplierBps,
                _dstConfig.floorMarginUSD,
                nativePriceUSD
            );
    }

    // ========================= Internal =========================
    function _getCallDataSize(uint256 _quorum) internal pure returns (uint256) {
        uint256 totalSignatureBytes = _quorum * SIGNATURE_RAW_BYTES;
        if (totalSignatureBytes % 32 != 0) {
            totalSignatureBytes = totalSignatureBytes - (totalSignatureBytes % 32) + 32;
        }
        // getFee should charge on execute(updateHash)
        // totalSignatureBytesPadded also has 64 overhead for bytes
        return uint256(EXECUTE_FIXED_BYTES) + UPDATE_HASH_BYTES + totalSignatureBytes + 64;
    }

    function _applyPremium(
        uint256 _fee,
        uint16 _bps,
        uint16 _defaultBps,
        uint128 _marginUSD,
        uint128 _nativePriceUSD
    ) internal view returns (uint256) {
        uint16 multiplierBps = _bps == 0 ? _defaultBps : _bps;

        uint256 feeWithMultiplier = (_fee * multiplierBps) / 10000;
        if (_nativePriceUSD == 0 || _marginUSD == 0) {
            return feeWithMultiplier;
        }

        uint256 feeWithFloorMargin = _fee + (_marginUSD * nativeDecimalsRate) / _nativePriceUSD;

        return feeWithFloorMargin > feeWithMultiplier ? feeWithFloorMargin : feeWithMultiplier;
    }

    function _decodeDVNOptions(bytes calldata _options) internal pure returns (uint256) {
        uint256 cursor;
        while (cursor < _options.length) {
            (uint8 optionType, , uint256 newCursor) = _options.nextDVNOption(cursor);
            cursor = newCursor;
            revert DVN_UnsupportedOptionType(optionType);
        }
        if (cursor != _options.length) revert DVNOptions.DVN_InvalidDVNOptions(cursor);

        return 0; // todo: precrime fee model
    }

    // send funds here to pay for price feed directly
    receive() external payable {}
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

import { IWorker } from "../../interfaces/IWorker.sol";
import { ILayerZeroDVN } from "./ILayerZeroDVN.sol";

interface IDVN is IWorker, ILayerZeroDVN {
    struct DstConfigParam {
        uint32 dstEid;
        uint64 gas;
        uint16 multiplierBps;
        uint128 floorMarginUSD;
    }

    struct DstConfig {
        uint64 gas;
        uint16 multiplierBps;
        uint128 floorMarginUSD; // uses priceFeed PRICE_RATIO_DENOMINATOR
    }

    event SetDstConfig(DstConfigParam[] params);

    function dstConfig(uint32 _dstEid) external view returns (uint64, uint16, uint128);
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

import { IDVN } from "./IDVN.sol";

interface IDVNFeeLib {
    struct FeeParams {
        address priceFeed;
        uint32 dstEid;
        uint64 confirmations;
        address sender;
        uint64 quorum;
        uint16 defaultMultiplierBps;
    }

    error DVN_UnsupportedOptionType(uint8 optionType);
    error DVN_EidNotSupported(uint32 eid);

    function getFeeOnSend(
        FeeParams calldata _params,
        IDVN.DstConfig calldata _dstConfig,
        bytes calldata _options
    ) external payable returns (uint256 fee);

    function getFee(
        FeeParams calldata _params,
        IDVN.DstConfig calldata _dstConfig,
        bytes calldata _options
    ) external view returns (uint256 fee);
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

interface ILayerZeroDVN {
    struct AssignJobParam {
        uint32 dstEid;
        bytes packetHeader;
        bytes32 payloadHash;
        uint64 confirmations;
        address sender;
    }

    // @notice query price and assign jobs at the same time
    // @param _dstEid - the destination endpoint identifier
    // @param _packetHeader - version + nonce + path
    // @param _payloadHash - hash of guid + message
    // @param _confirmations - block confirmation delay before relaying blocks
    // @param _sender - the source sending contract address
    // @param _options - options
    function assignJob(AssignJobParam calldata _param, bytes calldata _options) external payable returns (uint256 fee);

    // @notice query the dvn fee for relaying block information to the destination chain
    // @param _dstEid the destination endpoint identifier
    // @param _confirmations - block confirmation delay before relaying blocks
    // @param _sender - the source sending contract address
    // @param _options - options
    function getFee(
        uint32 _dstEid,
        uint64 _confirmations,
        address _sender,
        bytes calldata _options
    ) external view returns (uint256 fee);
}

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

import { BytesLib } from "solidity-bytes-utils/contracts/BytesLib.sol";

import { BitMap256 } from "@layerzerolabs/lz-evm-protocol-v2/contracts/messagelib/libs/BitMaps.sol";
import { CalldataBytesLib } from "@layerzerolabs/lz-evm-protocol-v2/contracts/libs/CalldataBytesLib.sol";

library DVNOptions {
    using CalldataBytesLib for bytes;
    using BytesLib for bytes;

    uint8 internal constant WORKER_ID = 2;
    uint8 internal constant OPTION_TYPE_PRECRIME = 1;

    error DVN_InvalidDVNIdx();
    error DVN_InvalidDVNOptions(uint256 cursor);

    /// @dev group dvn options by its idx
    /// @param _options [dvn_id][dvn_option][dvn_id][dvn_option]...
    ///        dvn_option = [option_size][dvn_idx][option_type][option]
    ///        option_size = len(dvn_idx) + len(option_type) + len(option)
    ///        dvn_id: uint8, dvn_idx: uint8, option_size: uint16, option_type: uint8, option: bytes
    /// @return dvnOptions the grouped options, still share the same format of _options
    /// @return dvnIndices the dvn indices
    function groupDVNOptionsByIdx(
        bytes memory _options
    ) internal pure returns (bytes[] memory dvnOptions, uint8[] memory dvnIndices) {
        if (_options.length == 0) return (dvnOptions, dvnIndices);

        uint8 numDVNs = getNumDVNs(_options);

        // if there is only 1 dvn, we can just return the whole options
        if (numDVNs == 1) {
            dvnOptions = new bytes[](1);
            dvnOptions[0] = _options;

            dvnIndices = new uint8[](1);
            dvnIndices[0] = _options.toUint8(3); // dvn idx
            return (dvnOptions, dvnIndices);
        }

        // otherwise, we need to group the options by dvn_idx
        dvnIndices = new uint8[](numDVNs);
        dvnOptions = new bytes[](numDVNs);
        unchecked {
            uint256 cursor = 0;
            uint256 start = 0;
            uint8 lastDVNIdx = 255; // 255 is an invalid dvn_idx

            while (cursor < _options.length) {
                ++cursor; // skip worker_id

                // optionLength asserted in getNumDVNs (skip check)
                uint16 optionLength = _options.toUint16(cursor);
                cursor += 2;

                // dvnIdx asserted in getNumDVNs (skip check)
                uint8 dvnIdx = _options.toUint8(cursor);

                // dvnIdx must equal to the lastDVNIdx for the first option
                // so it is always skipped in the first option
                // this operation slices out options whenever the scan finds a different lastDVNIdx
                if (lastDVNIdx == 255) {
                    lastDVNIdx = dvnIdx;
                } else if (dvnIdx != lastDVNIdx) {
                    uint256 len = cursor - start - 3; // 3 is for worker_id and option_length
                    bytes memory opt = _options.slice(start, len);
                    _insertDVNOptions(dvnOptions, dvnIndices, lastDVNIdx, opt);

                    // reset the start and lastDVNIdx
                    start += len;
                    lastDVNIdx = dvnIdx;
                }

                cursor += optionLength;
            }

            // skip check the cursor here because the cursor is asserted in getNumDVNs
            // if we have reached the end of the options, we need to process the last dvn
            uint256 size = cursor - start;
            bytes memory op = _options.slice(start, size);
            _insertDVNOptions(dvnOptions, dvnIndices, lastDVNIdx, op);

            // revert dvnIndices to start from 0
            for (uint8 i = 0; i < numDVNs; ++i) {
                --dvnIndices[i];
            }
        }
    }

    function _insertDVNOptions(
        bytes[] memory _dvnOptions,
        uint8[] memory _dvnIndices,
        uint8 _dvnIdx,
        bytes memory _newOptions
    ) internal pure {
        // dvnIdx starts from 0 but default value of dvnIndices is 0,
        // so we tell if the slot is empty by adding 1 to dvnIdx
        if (_dvnIdx == 255) revert DVN_InvalidDVNIdx();
        uint8 dvnIdxAdj = _dvnIdx + 1;

        for (uint256 j = 0; j < _dvnIndices.length; ++j) {
            uint8 index = _dvnIndices[j];
            if (dvnIdxAdj == index) {
                _dvnOptions[j] = abi.encodePacked(_dvnOptions[j], _newOptions);
                break;
            } else if (index == 0) {
                // empty slot, that means it is the first time we see this dvn
                _dvnIndices[j] = dvnIdxAdj;
                _dvnOptions[j] = _newOptions;
                break;
            }
        }
    }

    /// @dev get the number of unique dvns
    /// @param _options the format is the same as groupDVNOptionsByIdx
    function getNumDVNs(bytes memory _options) internal pure returns (uint8 numDVNs) {
        uint256 cursor = 0;
        BitMap256 bitmap;

        // find number of unique dvn_idx
        unchecked {
            while (cursor < _options.length) {
                ++cursor; // skip worker_id

                uint16 optionLength = _options.toUint16(cursor);
                cursor += 2;
                if (optionLength < 2) revert DVN_InvalidDVNOptions(cursor); // at least 1 byte for dvn_idx and 1 byte for option_type

                uint8 dvnIdx = _options.toUint8(cursor);

                // if dvnIdx is not set, increment numDVNs
                // max num of dvns is 255, 255 is an invalid dvn_idx
                // The order of the dvnIdx is not required to be sequential, as enforcing the order may weaken
                // the composability of the options. e.g. if we refrain from enforcing the order, an OApp that has
                // already enforced certain options can append additional options to the end of the enforced
                // ones without restrictions.
                if (dvnIdx == 255) revert DVN_InvalidDVNIdx();
                if (!bitmap.get(dvnIdx)) {
                    ++numDVNs;
                    bitmap = bitmap.set(dvnIdx);
                }

                cursor += optionLength;
            }
        }
        if (cursor != _options.length) revert DVN_InvalidDVNOptions(cursor);
    }

    /// @dev decode the next dvn option from _options starting from the specified cursor
    /// @param _options the format is the same as groupDVNOptionsByIdx
    /// @param _cursor the cursor to start decoding
    /// @return optionType the type of the option
    /// @return option the option
    /// @return cursor the cursor to start decoding the next option
    function nextDVNOption(
        bytes calldata _options,
        uint256 _cursor
    ) internal pure returns (uint8 optionType, bytes calldata option, uint256 cursor) {
        unchecked {
            // skip worker id
            cursor = _cursor + 1;

            // read option size
            uint16 size = _options.toU16(cursor);
            cursor += 2;

            // read option type
            optionType = _options.toU8(cursor + 1); // skip dvn_idx

            // startCursor and endCursor are used to slice the option from _options
            uint256 startCursor = cursor + 2; // skip option type and dvn_idx
            uint256 endCursor = cursor + size;
            option = _options[startCursor:endCursor];
            cursor += size;
        }
    }
}

// SPDX-License-Identifier: Unlicense
/*
 * @title Solidity Bytes Arrays Utils
 * @author Gonçalo Sá <[email protected]>
 *
 * @dev Bytes tightly packed arrays utility library for ethereum contracts written in Solidity.
 *      The library lets you concatenate, slice and type cast bytes arrays both in memory and storage.
 */
pragma solidity >=0.8.0 <0.9.0;


library BytesLib {
    function concat(
        bytes memory _preBytes,
        bytes memory _postBytes
    )
        internal
        pure
        returns (bytes memory)
    {
        bytes memory tempBytes;

        assembly {
            // Get a location of some free memory and store it in tempBytes as
            // Solidity does for memory variables.
            tempBytes := mload(0x40)

            // Store the length of the first bytes array at the beginning of
            // the memory for tempBytes.
            let length := mload(_preBytes)
            mstore(tempBytes, length)

            // Maintain a memory counter for the current write location in the
            // temp bytes array by adding the 32 bytes for the array length to
            // the starting location.
            let mc := add(tempBytes, 0x20)
            // Stop copying when the memory counter reaches the length of the
            // first bytes array.
            let end := add(mc, length)

            for {
                // Initialize a copy counter to the start of the _preBytes data,
                // 32 bytes into its memory.
                let cc := add(_preBytes, 0x20)
            } lt(mc, end) {
                // Increase both counters by 32 bytes each iteration.
                mc := add(mc, 0x20)
                cc := add(cc, 0x20)
            } {
                // Write the _preBytes data into the tempBytes memory 32 bytes
                // at a time.
                mstore(mc, mload(cc))
            }

            // Add the length of _postBytes to the current length of tempBytes
            // and store it as the new length in the first 32 bytes of the
            // tempBytes memory.
            length := mload(_postBytes)
            mstore(tempBytes, add(length, mload(tempBytes)))

            // Move the memory counter back from a multiple of 0x20 to the
            // actual end of the _preBytes data.
            mc := end
            // Stop copying when the memory counter reaches the new combined
            // length of the arrays.
            end := add(mc, length)

            for {
                let cc := add(_postBytes, 0x20)
            } lt(mc, end) {
                mc := add(mc, 0x20)
                cc := add(cc, 0x20)
            } {
                mstore(mc, mload(cc))
            }

            // Update the free-memory pointer by padding our last write location
            // to 32 bytes: add 31 bytes to the end of tempBytes to move to the
            // next 32 byte block, then round down to the nearest multiple of
            // 32. If the sum of the length of the two arrays is zero then add
            // one before rounding down to leave a blank 32 bytes (the length block with 0).
            mstore(0x40, and(
              add(add(end, iszero(add(length, mload(_preBytes)))), 31),
              not(31) // Round down to the nearest 32 bytes.
            ))
        }

        return tempBytes;
    }

    function concatStorage(bytes storage _preBytes, bytes memory _postBytes) internal {
        assembly {
            // Read the first 32 bytes of _preBytes storage, which is the length
            // of the array. (We don't need to use the offset into the slot
            // because arrays use the entire slot.)
            let fslot := sload(_preBytes.slot)
            // Arrays of 31 bytes or less have an even value in their slot,
            // while longer arrays have an odd value. The actual length is
            // the slot divided by two for odd values, and the lowest order
            // byte divided by two for even values.
            // If the slot is even, bitwise and the slot with 255 and divide by
            // two to get the length. If the slot is odd, bitwise and the slot
            // with -1 and divide by two.
            let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
            let mlength := mload(_postBytes)
            let newlength := add(slength, mlength)
            // slength can contain both the length and contents of the array
            // if length < 32 bytes so let's prepare for that
            // v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
            switch add(lt(slength, 32), lt(newlength, 32))
            case 2 {
                // Since the new array still fits in the slot, we just need to
                // update the contents of the slot.
                // uint256(bytes_storage) = uint256(bytes_storage) + uint256(bytes_memory) + new_length
                sstore(
                    _preBytes.slot,
                    // all the modifications to the slot are inside this
                    // next block
                    add(
                        // we can just add to the slot contents because the
                        // bytes we want to change are the LSBs
                        fslot,
                        add(
                            mul(
                                div(
                                    // load the bytes from memory
                                    mload(add(_postBytes, 0x20)),
                                    // zero all bytes to the right
                                    exp(0x100, sub(32, mlength))
                                ),
                                // and now shift left the number of bytes to
                                // leave space for the length in the slot
                                exp(0x100, sub(32, newlength))
                            ),
                            // increase length by the double of the memory
                            // bytes length
                            mul(mlength, 2)
                        )
                    )
                )
            }
            case 1 {
                // The stored value fits in the slot, but the combined value
                // will exceed it.
                // get the keccak hash to get the contents of the array
                mstore(0x0, _preBytes.slot)
                let sc := add(keccak256(0x0, 0x20), div(slength, 32))

                // save new length
                sstore(_preBytes.slot, add(mul(newlength, 2), 1))

                // The contents of the _postBytes array start 32 bytes into
                // the structure. Our first read should obtain the `submod`
                // bytes that can fit into the unused space in the last word
                // of the stored array. To get this, we read 32 bytes starting
                // from `submod`, so the data we read overlaps with the array
                // contents by `submod` bytes. Masking the lowest-order
                // `submod` bytes allows us to add that value directly to the
                // stored value.

                let submod := sub(32, slength)
                let mc := add(_postBytes, submod)
                let end := add(_postBytes, mlength)
                let mask := sub(exp(0x100, submod), 1)

                sstore(
                    sc,
                    add(
                        and(
                            fslot,
                            0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00
                        ),
                        and(mload(mc), mask)
                    )
                )

                for {
                    mc := add(mc, 0x20)
                    sc := add(sc, 1)
                } lt(mc, end) {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } {
                    sstore(sc, mload(mc))
                }

                mask := exp(0x100, sub(mc, end))

                sstore(sc, mul(div(mload(mc), mask), mask))
            }
            default {
                // get the keccak hash to get the contents of the array
                mstore(0x0, _preBytes.slot)
                // Start copying to the last used word of the stored array.
                let sc := add(keccak256(0x0, 0x20), div(slength, 32))

                // save new length
                sstore(_preBytes.slot, add(mul(newlength, 2), 1))

                // Copy over the first `submod` bytes of the new data as in
                // case 1 above.
                let slengthmod := mod(slength, 32)
                let mlengthmod := mod(mlength, 32)
                let submod := sub(32, slengthmod)
                let mc := add(_postBytes, submod)
                let end := add(_postBytes, mlength)
                let mask := sub(exp(0x100, submod), 1)

                sstore(sc, add(sload(sc), and(mload(mc), mask)))

                for {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } lt(mc, end) {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } {
                    sstore(sc, mload(mc))
                }

                mask := exp(0x100, sub(mc, end))

                sstore(sc, mul(div(mload(mc), mask), mask))
            }
        }
    }

    function slice(
        bytes memory _bytes,
        uint256 _start,
        uint256 _length
    )
        internal
        pure
        returns (bytes memory)
    {
        require(_length + 31 >= _length, "slice_overflow");
        require(_bytes.length >= _start + _length, "slice_outOfBounds");

        bytes memory tempBytes;

        assembly {
            switch iszero(_length)
            case 0 {
                // Get a location of some free memory and store it in tempBytes as
                // Solidity does for memory variables.
                tempBytes := mload(0x40)

                // The first word of the slice result is potentially a partial
                // word read from the original array. To read it, we calculate
                // the length of that partial word and start copying that many
                // bytes into the array. The first word we copy will start with
                // data we don't care about, but the last `lengthmod` bytes will
                // land at the beginning of the contents of the new array. When
                // we're done copying, we overwrite the full first word with
                // the actual length of the slice.
                let lengthmod := and(_length, 31)

                // The multiplication in the next line is necessary
                // because when slicing multiples of 32 bytes (lengthmod == 0)
                // the following copy loop was copying the origin's length
                // and then ending prematurely not copying everything it should.
                let mc := add(add(tempBytes, lengthmod), mul(0x20, iszero(lengthmod)))
                let end := add(mc, _length)

                for {
                    // The multiplication in the next line has the same exact purpose
                    // as the one above.
                    let cc := add(add(add(_bytes, lengthmod), mul(0x20, iszero(lengthmod))), _start)
                } lt(mc, end) {
                    mc := add(mc, 0x20)
                    cc := add(cc, 0x20)
                } {
                    mstore(mc, mload(cc))
                }

                mstore(tempBytes, _length)

                //update free-memory pointer
                //allocating the array padded to 32 bytes like the compiler does now
                mstore(0x40, and(add(mc, 31), not(31)))
            }
            //if we want a zero-length slice let's just return a zero-length array
            default {
                tempBytes := mload(0x40)
                //zero out the 32 bytes slice we are about to return
                //we need to do it because Solidity does not garbage collect
                mstore(tempBytes, 0)

                mstore(0x40, add(tempBytes, 0x20))
            }
        }

        return tempBytes;
    }

    function toAddress(bytes memory _bytes, uint256 _start) internal pure returns (address) {
        require(_bytes.length >= _start + 20, "toAddress_outOfBounds");
        address tempAddress;

        assembly {
            tempAddress := div(mload(add(add(_bytes, 0x20), _start)), 0x1000000000000000000000000)
        }

        return tempAddress;
    }

    function toUint8(bytes memory _bytes, uint256 _start) internal pure returns (uint8) {
        require(_bytes.length >= _start + 1 , "toUint8_outOfBounds");
        uint8 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x1), _start))
        }

        return tempUint;
    }

    function toUint16(bytes memory _bytes, uint256 _start) internal pure returns (uint16) {
        require(_bytes.length >= _start + 2, "toUint16_outOfBounds");
        uint16 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x2), _start))
        }

        return tempUint;
    }

    function toUint32(bytes memory _bytes, uint256 _start) internal pure returns (uint32) {
        require(_bytes.length >= _start + 4, "toUint32_outOfBounds");
        uint32 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x4), _start))
        }

        return tempUint;
    }

    function toUint64(bytes memory _bytes, uint256 _start) internal pure returns (uint64) {
        require(_bytes.length >= _start + 8, "toUint64_outOfBounds");
        uint64 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x8), _start))
        }

        return tempUint;
    }

    function toUint96(bytes memory _bytes, uint256 _start) internal pure returns (uint96) {
        require(_bytes.length >= _start + 12, "toUint96_outOfBounds");
        uint96 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0xc), _start))
        }

        return tempUint;
    }

    function toUint128(bytes memory _bytes, uint256 _start) internal pure returns (uint128) {
        require(_bytes.length >= _start + 16, "toUint128_outOfBounds");
        uint128 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x10), _start))
        }

        return tempUint;
    }

    function toUint256(bytes memory _bytes, uint256 _start) internal pure returns (uint256) {
        require(_bytes.length >= _start + 32, "toUint256_outOfBounds");
        uint256 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x20), _start))
        }

        return tempUint;
    }

    function toBytes32(bytes memory _bytes, uint256 _start) internal pure returns (bytes32) {
        require(_bytes.length >= _start + 32, "toBytes32_outOfBounds");
        bytes32 tempBytes32;

        assembly {
            tempBytes32 := mload(add(add(_bytes, 0x20), _start))
        }

        return tempBytes32;
    }

    function equal(bytes memory _preBytes, bytes memory _postBytes) internal pure returns (bool) {
        bool success = true;

        assembly {
            let length := mload(_preBytes)

            // if lengths don't match the arrays are not equal
            switch eq(length, mload(_postBytes))
            case 1 {
                // cb is a circuit breaker in the for loop since there's
                //  no said feature for inline assembly loops
                // cb = 1 - don't breaker
                // cb = 0 - break
                let cb := 1

                let mc := add(_preBytes, 0x20)
                let end := add(mc, length)

                for {
                    let cc := add(_postBytes, 0x20)
                // the next line is the loop condition:
                // while(uint256(mc < end) + cb == 2)
                } eq(add(lt(mc, end), cb), 2) {
                    mc := add(mc, 0x20)
                    cc := add(cc, 0x20)
                } {
                    // if any of these checks fails then arrays are not equal
                    if iszero(eq(mload(mc), mload(cc))) {
                        // unsuccess:
                        success := 0
                        cb := 0
                    }
                }
            }
            default {
                // unsuccess:
                success := 0
            }
        }

        return success;
    }

    function equalStorage(
        bytes storage _preBytes,
        bytes memory _postBytes
    )
        internal
        view
        returns (bool)
    {
        bool success = true;

        assembly {
            // we know _preBytes_offset is 0
            let fslot := sload(_preBytes.slot)
            // Decode the length of the stored array like in concatStorage().
            let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
            let mlength := mload(_postBytes)

            // if lengths don't match the arrays are not equal
            switch eq(slength, mlength)
            case 1 {
                // slength can contain both the length and contents of the array
                // if length < 32 bytes so let's prepare for that
                // v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
                if iszero(iszero(slength)) {
                    switch lt(slength, 32)
                    case 1 {
                        // blank the last byte which is the length
                        fslot := mul(div(fslot, 0x100), 0x100)

                        if iszero(eq(fslot, mload(add(_postBytes, 0x20)))) {
                            // unsuccess:
                            success := 0
                        }
                    }
                    default {
                        // cb is a circuit breaker in the for loop since there's
                        //  no said feature for inline assembly loops
                        // cb = 1 - don't breaker
                        // cb = 0 - break
                        let cb := 1

                        // get the keccak hash to get the contents of the array
                        mstore(0x0, _preBytes.slot)
                        let sc := keccak256(0x0, 0x20)

                        let mc := add(_postBytes, 0x20)
                        let end := add(mc, mlength)

                        // the next line is the loop condition:
                        // while(uint256(mc < end) + cb == 2)
                        for {} eq(add(lt(mc, end), cb), 2) {
                            sc := add(sc, 1)
                            mc := add(mc, 0x20)
                        } {
                            if iszero(eq(sload(sc), mload(mc))) {
                                // unsuccess:
                                success := 0
                                cb := 0
                            }
                        }
                    }
                }
            }
            default {
                // unsuccess:
                success := 0
            }
        }

        return success;
    }
}