ETH Price: $2,135.48 (+4.76%)

Transaction Decoder

Block:
14972594 at Jun-16-2022 09:36:32 AM +UTC
Transaction Fee:
0.009091698755771485 ETH $19.42
Gas Used:
173,957 Gas / 52.264058105 Gwei

Emitted Events:

488 izumiToken.Transfer( from=[Receiver] Bridge, to=0x65A8F07Bd9A8598E1b5B6C0a88F4779DBC077675, value=25656967761752370768423 )
489 Bridge.Relay( transferId=8E4228D54EA2ADF7B4040377BEF18927034E64D9BA9DE98DC9B4CA84BE0ACC1F, sender=0x65A8F07Bd9A8598E1b5B6C0a88F4779DBC077675, receiver=0x65A8F07Bd9A8598E1b5B6C0a88F4779DBC077675, token=izumiToken, amount=25656967761752370768423, srcChainId=137, srcTransferId=4CBADA9DFEB67F9E3697D0FE8CC594733EB5538DC6D1DAC7BEBD9362F71F8D17 )

Account State Difference:

  Address   Before After State Difference Code
0x5427FEFA...5E3DA1820
(Celer Network: cBridge V2)
(F2Pool Old)
3,085.153180021924269442 Eth3,085.153353978924269442 Eth0.000173957
0x9ad37205...4CEc5c200
0xbfa2F68b...7FA251424
(Celer Network: Relay Executor 4)
31.627395264695127809 Eth
Nonce: 19626
31.618303565939356324 Eth
Nonce: 19627
0.009091698755771485

Execution Trace

Bridge.relay( _relayRequest=0x0A1465A8F07BD9A8598E1B5B6C0A88F4779DBC077675121465A8F07BD9A8598E1B5B6C0A88F4779DBC0776751A149AD37205D608B8B219E6A2573F922094CEC5C200220A056EDDF452DF6324EA2728890130013A204CBADA9DFEB67F9E3697D0FE8CC594733EB5538DC6D1DAC7BEBD9362F71F8D17, _sigs=[7bHzpE7n/UrGqpIcvX9tqWXFy7/ieIcCQjpROTm5E+4Bqma9wnIe9sD9A9oqXnmz6hwH0GztFERGCYJpytncqhs=, QTS0Y22JdqFfR9EY+xm2wfQ40IyOVuqEz79os3J/L+B97HOxAxm0PItBlviJcU3ewKmF4NNqIUWAeji52FSRWBs=, gLYMs8uHRtvlUW4vqnO3QGX2jD958zrvJyREN3dS+b0cMlnqjrivzaPmGIPsW1dzD2LbAI9OqfczumLqRD9YIhs=, WW+fuIgMsfX3ychSYeP/zhmz7DWxphboUjsCqSUdO1lRXWrHpoL7Z+kRA2McjxqxlhHTomOTUCPtIVg4TJYnmxw=], _signers=[0x241A100333EEfA2efC389Ec836A6fF619fC1c644, 0x55f4A1BFc655cf55eD325F2338a1deE84f754Df2, 0x870cF8Dd5d9C8eB1403dfd6e6A4753f4d617A538, 0x87Af7619D4D1C70C19083664D0C6E748cC45c3bD, 0x95016E36Adb4e0151735Ced3992A7Fa54E16BD08, 0x954ADc74481634b4d278C459853b4e6cc17aE8D2, 0x98E9D288743839e96A8005a6B51C770Bbf7788C0, 0x9a66644084108a1bC23A9cCd50d6d63E53098dB6, 0x9AC5279013EdfEC74c5c2976FC831Ad0527402E0, 0x9Cd5006e1BfF785dad5869efd81a2c42545C9d9b, 0xa73B339c3fae27bedf7Cb72D9D000b08fc899609, 0xbfa2F68bf9Ad60Dc3cFB1cEF04730Eb7FA251424, 0xc74ACAb8C0a340f585d008cB521d64d2554171A8, 0xcF12DD34d7597D06ff98F85d2B9483D9D5f7D952, 0xd10c833f4305E1053a64Bc738c550381f48104Ca, 0xf3d912E7FB180ACDEa31A52797D55Ee2988AB907, 0xF4151eEbFa1B9C87dD92c8243A18B1bAEf8C1813, 0xF5AD7f3782E8A67BffA297684e27CF9fCC781Be1, 0xF6e93Eb288658de5E2E982f99D2b378B22959d15], _powers=[18303065010000000000000000, 3192384070000000000000000, 10000000000000000000000, 6009241975089000000000000, 13568115130000000000000000, 8007228920000000000000000, 200835160190000000000000000, 325603154529850000000000000, 8019069260000000000000000, 338304980410000000000000000, 101386280960000000000000000, 241983296500000000000000000, 75017010000000000000000000, 13331672240000000000000000, 150288640900000000000000000, 3611001000000000000000000, 428536060000000000000000, 399886170000000000000000, 56009499000000000000000000] )
  • Null: 0x000...001.aa85da68( )
  • Null: 0x000...001.aa85da68( )
  • Null: 0x000...001.aa85da68( )
  • Null: 0x000...001.aa85da68( )
  • izumiToken.transfer( recipient=0x65A8F07Bd9A8598E1b5B6C0a88F4779DBC077675, amount=25656967761752370768423 ) => ( True )
    File 1 of 2: Bridge
    // SPDX-License-Identifier: MIT
    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() {
            _setOwner(_msgSender());
        }
        /**
         * @dev Returns the address of the current owner.
         */
        function owner() public view virtual returns (address) {
            return _owner;
        }
        /**
         * @dev Throws if called by any account other than the owner.
         */
        modifier onlyOwner() {
            require(owner() == _msgSender(), "Ownable: caller is not the owner");
            _;
        }
        /**
         * @dev Leaves the contract without owner. It will not be possible to call
         * `onlyOwner` functions anymore. Can only be called by the current owner.
         *
         * NOTE: Renouncing ownership will leave the contract without an owner,
         * thereby removing any functionality that is only available to the owner.
         */
        function renounceOwnership() public virtual onlyOwner {
            _setOwner(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");
            _setOwner(newOwner);
        }
        function _setOwner(address newOwner) private {
            address oldOwner = _owner;
            _owner = newOwner;
            emit OwnershipTransferred(oldOwner, newOwner);
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "../utils/Context.sol";
    /**
     * @dev Contract module which allows children to implement an emergency stop
     * mechanism that can be triggered by an authorized account.
     *
     * This module is used through inheritance. It will make available the
     * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
     * the functions of your contract. Note that they will not be pausable by
     * simply including this module, only once the modifiers are put in place.
     */
    abstract contract Pausable is Context {
        /**
         * @dev Emitted when the pause is triggered by `account`.
         */
        event Paused(address account);
        /**
         * @dev Emitted when the pause is lifted by `account`.
         */
        event Unpaused(address account);
        bool private _paused;
        /**
         * @dev Initializes the contract in unpaused state.
         */
        constructor() {
            _paused = false;
        }
        /**
         * @dev Returns true if the contract is paused, and false otherwise.
         */
        function paused() public view virtual returns (bool) {
            return _paused;
        }
        /**
         * @dev Modifier to make a function callable only when the contract is not paused.
         *
         * Requirements:
         *
         * - The contract must not be paused.
         */
        modifier whenNotPaused() {
            require(!paused(), "Pausable: paused");
            _;
        }
        /**
         * @dev Modifier to make a function callable only when the contract is paused.
         *
         * Requirements:
         *
         * - The contract must be paused.
         */
        modifier whenPaused() {
            require(paused(), "Pausable: not paused");
            _;
        }
        /**
         * @dev Triggers stopped state.
         *
         * Requirements:
         *
         * - The contract must not be paused.
         */
        function _pause() internal virtual whenNotPaused {
            _paused = true;
            emit Paused(_msgSender());
        }
        /**
         * @dev Returns to normal state.
         *
         * Requirements:
         *
         * - The contract must be paused.
         */
        function _unpause() internal virtual whenPaused {
            _paused = false;
            emit Unpaused(_msgSender());
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @dev Contract module that helps prevent reentrant calls to a function.
     *
     * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
     * available, which can be applied to functions to make sure there are no nested
     * (reentrant) calls to them.
     *
     * Note that because there is a single `nonReentrant` guard, functions marked as
     * `nonReentrant` may not call one another. This can be worked around by making
     * those functions `private`, and then adding `external` `nonReentrant` entry
     * points to them.
     *
     * TIP: If you would like to learn more about reentrancy and alternative ways
     * to protect against it, check out our blog post
     * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
     */
    abstract contract ReentrancyGuard {
        // Booleans are more expensive than uint256 or any type that takes up a full
        // word because each write operation emits an extra SLOAD to first read the
        // slot's contents, replace the bits taken up by the boolean, and then write
        // back. This is the compiler's defense against contract upgrades and
        // pointer aliasing, and it cannot be disabled.
        // The values being non-zero value makes deployment a bit more expensive,
        // but in exchange the refund on every call to nonReentrant will be lower in
        // amount. Since refunds are capped to a percentage of the total
        // transaction's gas, it is best to keep them low in cases like this one, to
        // increase the likelihood of the full refund coming into effect.
        uint256 private constant _NOT_ENTERED = 1;
        uint256 private constant _ENTERED = 2;
        uint256 private _status;
        constructor() {
            _status = _NOT_ENTERED;
        }
        /**
         * @dev Prevents a contract from calling itself, directly or indirectly.
         * Calling a `nonReentrant` function from another `nonReentrant`
         * function is not supported. It is possible to prevent this from happening
         * by making the `nonReentrant` function external, and make it call a
         * `private` function that does the actual work.
         */
        modifier nonReentrant() {
            // On the first call to nonReentrant, _notEntered will be true
            require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
            // Any calls to nonReentrant after this point will fail
            _status = _ENTERED;
            _;
            // By storing the original value once again, a refund is triggered (see
            // https://eips.ethereum.org/EIPS/eip-2200)
            _status = _NOT_ENTERED;
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @dev Interface of the ERC20 standard as defined in the EIP.
     */
    interface IERC20 {
        /**
         * @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 `recipient`.
         *
         * Returns a boolean value indicating whether the operation succeeded.
         *
         * Emits a {Transfer} event.
         */
        function transfer(address recipient, 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 `sender` to `recipient` 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 sender,
            address recipient,
            uint256 amount
        ) external returns (bool);
        /**
         * @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);
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    import "../IERC20.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;
        function safeTransfer(
            IERC20 token,
            address to,
            uint256 value
        ) internal {
            _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
        }
        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));
        }
        function safeIncreaseAllowance(
            IERC20 token,
            address spender,
            uint256 value
        ) internal {
            uint256 newAllowance = token.allowance(address(this), spender) + value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
        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");
                uint256 newAllowance = oldAllowance - value;
                _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
            }
        }
        /**
         * @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");
            if (returndata.length > 0) {
                // Return data is optional
                require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
            }
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @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
         * ====
         */
        function isContract(address account) internal view returns (bool) {
            // This method relies on extcodesize, which returns 0 for contracts in
            // construction, since the code is only stored at the end of the
            // constructor execution.
            uint256 size;
            assembly {
                size := extcodesize(account)
            }
            return size > 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://diligence.consensys.net/posts/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/v0.5.11/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 functionCall(target, data, "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");
            require(isContract(target), "Address: call to non-contract");
            (bool success, bytes memory returndata) = target.call{value: value}(data);
            return _verifyCallResult(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) {
            require(isContract(target), "Address: static call to non-contract");
            (bool success, bytes memory returndata) = target.staticcall(data);
            return _verifyCallResult(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) {
            require(isContract(target), "Address: delegate call to non-contract");
            (bool success, bytes memory returndata) = target.delegatecall(data);
            return _verifyCallResult(success, returndata, errorMessage);
        }
        function _verifyCallResult(
            bool success,
            bytes memory returndata,
            string memory errorMessage
        ) private pure returns (bytes memory) {
            if (success) {
                return returndata;
            } else {
                // 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
                    assembly {
                        let returndata_size := mload(returndata)
                        revert(add(32, returndata), returndata_size)
                    }
                } else {
                    revert(errorMessage);
                }
            }
        }
    }
    // SPDX-License-Identifier: MIT
    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;
        }
    }
    // SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    /**
     * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
     *
     * These functions can be used to verify that a message was signed by the holder
     * of the private keys of a given address.
     */
    library ECDSA {
        /**
         * @dev Returns the address that signed a hashed message (`hash`) with
         * `signature`. This address can then be used for verification purposes.
         *
         * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
         * this function rejects them by requiring the `s` value to be in the lower
         * half order, and the `v` value to be either 27 or 28.
         *
         * IMPORTANT: `hash` _must_ be the result of a hash operation for the
         * verification to be secure: it is possible to craft signatures that
         * recover to arbitrary addresses for non-hashed data. A safe way to ensure
         * this is by receiving a hash of the original message (which may otherwise
         * be too long), and then calling {toEthSignedMessageHash} on it.
         *
         * Documentation for signature generation:
         * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
         * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
         */
        function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
            // Check the signature length
            // - case 65: r,s,v signature (standard)
            // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
            if (signature.length == 65) {
                bytes32 r;
                bytes32 s;
                uint8 v;
                // ecrecover takes the signature parameters, and the only way to get them
                // currently is to use assembly.
                assembly {
                    r := mload(add(signature, 0x20))
                    s := mload(add(signature, 0x40))
                    v := byte(0, mload(add(signature, 0x60)))
                }
                return recover(hash, v, r, s);
            } else if (signature.length == 64) {
                bytes32 r;
                bytes32 vs;
                // ecrecover takes the signature parameters, and the only way to get them
                // currently is to use assembly.
                assembly {
                    r := mload(add(signature, 0x20))
                    vs := mload(add(signature, 0x40))
                }
                return recover(hash, r, vs);
            } else {
                revert("ECDSA: invalid signature length");
            }
        }
        /**
         * @dev Overload of {ECDSA-recover} that receives the `r` and `vs` short-signature fields separately.
         *
         * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
         *
         * _Available since v4.2._
         */
        function recover(
            bytes32 hash,
            bytes32 r,
            bytes32 vs
        ) internal pure returns (address) {
            bytes32 s;
            uint8 v;
            assembly {
                s := and(vs, 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
                v := add(shr(255, vs), 27)
            }
            return recover(hash, v, r, s);
        }
        /**
         * @dev Overload of {ECDSA-recover} that receives the `v`, `r` and `s` signature fields separately.
         */
        function recover(
            bytes32 hash,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal pure returns (address) {
            // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
            // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
            // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
            // signatures from current libraries generate a unique signature with an s-value in the lower half order.
            //
            // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
            // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
            // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
            // these malleable signatures as well.
            require(
                uint256(s) <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
                "ECDSA: invalid signature 's' value"
            );
            require(v == 27 || v == 28, "ECDSA: invalid signature 'v' value");
            // If the signature is valid (and not malleable), return the signer address
            address signer = ecrecover(hash, v, r, s);
            require(signer != address(0), "ECDSA: invalid signature");
            return signer;
        }
        /**
         * @dev Returns an Ethereum Signed Message, created from a `hash`. This
         * produces hash corresponding to the one signed with the
         * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
         * JSON-RPC method as part of EIP-191.
         *
         * See {recover}.
         */
        function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
            // 32 is the length in bytes of hash,
            // enforced by the type signature above
            return keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
    32", hash));
        }
        /**
         * @dev Returns an Ethereum Signed Typed Data, created from a
         * `domainSeparator` and a `structHash`. This produces hash corresponding
         * to the one signed with the
         * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
         * JSON-RPC method as part of EIP-712.
         *
         * See {recover}.
         */
        function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
            return keccak256(abi.encodePacked("\\x19\\x01", domainSeparator, structHash));
        }
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
    import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
    import "./libraries/PbBridge.sol";
    import "./Pool.sol";
    contract Bridge is Pool {
        using SafeERC20 for IERC20;
        // liquidity events
        event Send(
            bytes32 transferId,
            address sender,
            address receiver,
            address token,
            uint256 amount,
            uint64 dstChainId,
            uint64 nonce,
            uint32 maxSlippage
        );
        event Relay(
            bytes32 transferId,
            address sender,
            address receiver,
            address token,
            uint256 amount,
            uint64 srcChainId,
            bytes32 srcTransferId
        );
        // gov events
        event MinSendUpdated(address token, uint256 amount);
        event MaxSendUpdated(address token, uint256 amount);
        mapping(bytes32 => bool) public transfers;
        mapping(address => uint256) public minSend; // send _amount must > minSend
        mapping(address => uint256) public maxSend;
        // min allowed max slippage uint32 value is slippage * 1M, eg. 0.5% -> 5000
        uint32 public minimalMaxSlippage;
        function send(
            address _receiver,
            address _token,
            uint256 _amount,
            uint64 _dstChainId,
            uint64 _nonce,
            uint32 _maxSlippage // slippage * 1M, eg. 0.5% -> 5000
        ) external nonReentrant whenNotPaused {
            bytes32 transferId = _send(_receiver, _token, _amount, _dstChainId, _nonce, _maxSlippage);
            IERC20(_token).safeTransferFrom(msg.sender, address(this), _amount);
            emit Send(transferId, msg.sender, _receiver, _token, _amount, _dstChainId, _nonce, _maxSlippage);
        }
        function sendNative(
            address _receiver,
            uint256 _amount,
            uint64 _dstChainId,
            uint64 _nonce,
            uint32 _maxSlippage
        ) external payable nonReentrant whenNotPaused {
            require(msg.value == _amount, "Amount mismatch");
            require(nativeWrap != address(0), "Native wrap not set");
            bytes32 transferId = _send(_receiver, nativeWrap, _amount, _dstChainId, _nonce, _maxSlippage);
            IWETH(nativeWrap).deposit{value: _amount}();
            emit Send(transferId, msg.sender, _receiver, nativeWrap, _amount, _dstChainId, _nonce, _maxSlippage);
        }
        function _send(
            address _receiver,
            address _token,
            uint256 _amount,
            uint64 _dstChainId,
            uint64 _nonce,
            uint32 _maxSlippage
        ) private returns (bytes32) {
            require(_amount > minSend[_token], "amount too small");
            require(maxSend[_token] == 0 || _amount <= maxSend[_token], "amount too large");
            require(_maxSlippage > minimalMaxSlippage, "max slippage too small");
            bytes32 transferId = keccak256(
                // uint64(block.chainid) for consistency as entire system uses uint64 for chain id
                abi.encodePacked(msg.sender, _receiver, _token, _amount, _dstChainId, _nonce, uint64(block.chainid))
            );
            require(transfers[transferId] == false, "transfer exists");
            transfers[transferId] = true;
            return transferId;
        }
        function relay(
            bytes calldata _relayRequest,
            bytes[] calldata _sigs,
            address[] calldata _signers,
            uint256[] calldata _powers
        ) external whenNotPaused {
            bytes32 domain = keccak256(abi.encodePacked(block.chainid, address(this), "Relay"));
            verifySigs(abi.encodePacked(domain, _relayRequest), _sigs, _signers, _powers);
            PbBridge.Relay memory request = PbBridge.decRelay(_relayRequest);
            bytes32 transferId = keccak256(
                abi.encodePacked(
                    request.sender,
                    request.receiver,
                    request.token,
                    request.amount,
                    request.srcChainId,
                    request.dstChainId,
                    request.srcTransferId
                )
            );
            require(transfers[transferId] == false, "transfer exists");
            transfers[transferId] = true;
            _updateVolume(request.token, request.amount);
            uint256 delayThreshold = delayThresholds[request.token];
            if (delayThreshold > 0 && request.amount > delayThreshold) {
                _addDelayedTransfer(transferId, request.receiver, request.token, request.amount);
            } else {
                _sendToken(request.receiver, request.token, request.amount);
            }
            emit Relay(
                transferId,
                request.sender,
                request.receiver,
                request.token,
                request.amount,
                request.srcChainId,
                request.srcTransferId
            );
        }
        function setMinSend(address[] calldata _tokens, uint256[] calldata _amounts) external onlyGovernor {
            require(_tokens.length == _amounts.length, "length mismatch");
            for (uint256 i = 0; i < _tokens.length; i++) {
                minSend[_tokens[i]] = _amounts[i];
                emit MinSendUpdated(_tokens[i], _amounts[i]);
            }
        }
        function setMaxSend(address[] calldata _tokens, uint256[] calldata _amounts) external onlyGovernor {
            require(_tokens.length == _amounts.length, "length mismatch");
            for (uint256 i = 0; i < _tokens.length; i++) {
                maxSend[_tokens[i]] = _amounts[i];
                emit MaxSendUpdated(_tokens[i], _amounts[i]);
            }
        }
        function setMinimalMaxSlippage(uint32 _minimalMaxSlippage) external onlyGovernor {
            minimalMaxSlippage = _minimalMaxSlippage;
        }
        // This is needed to receive ETH when calling `IWETH.withdraw`
        receive() external payable {}
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
    import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
    import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
    import "./interfaces/IWETH.sol";
    import "./libraries/PbPool.sol";
    import "./safeguard/Pauser.sol";
    import "./safeguard/VolumeControl.sol";
    import "./safeguard/DelayedTransfer.sol";
    import "./Signers.sol";
    // add liquidity and withdraw
    // withdraw can be used by user or liquidity provider
    contract Pool is Signers, ReentrancyGuard, Pauser, VolumeControl, DelayedTransfer {
        using SafeERC20 for IERC20;
        uint64 public addseq; // ensure unique LiquidityAdded event, start from 1
        mapping(address => uint256) public minAdd; // add _amount must > minAdd
        // map of successful withdraws, if true means already withdrew money or added to delayedTransfers
        mapping(bytes32 => bool) public withdraws;
        // erc20 wrap of gas token of this chain, eg. WETH, when relay ie. pay out,
        // if request.token equals this, will withdraw and send native token to receiver
        // note we don't check whether it's zero address. when this isn't set, and request.token
        // is all 0 address, guarantee fail
        address public nativeWrap;
        // liquidity events
        event LiquidityAdded(
            uint64 seqnum,
            address provider,
            address token,
            uint256 amount // how many tokens were added
        );
        event WithdrawDone(
            bytes32 withdrawId,
            uint64 seqnum,
            address receiver,
            address token,
            uint256 amount,
            bytes32 refid
        );
        event MinAddUpdated(address token, uint256 amount);
        function addLiquidity(address _token, uint256 _amount) external nonReentrant whenNotPaused {
            require(_amount > minAdd[_token], "amount too small");
            addseq += 1;
            IERC20(_token).safeTransferFrom(msg.sender, address(this), _amount);
            emit LiquidityAdded(addseq, msg.sender, _token, _amount);
        }
        function addNativeLiquidity(uint256 _amount) external payable nonReentrant whenNotPaused {
            require(msg.value == _amount, "Amount mismatch");
            require(nativeWrap != address(0), "Native wrap not set");
            require(_amount > minAdd[nativeWrap], "amount too small");
            addseq += 1;
            IWETH(nativeWrap).deposit{value: _amount}();
            emit LiquidityAdded(addseq, msg.sender, nativeWrap, _amount);
        }
        function withdraw(
            bytes calldata _wdmsg,
            bytes[] calldata _sigs,
            address[] calldata _signers,
            uint256[] calldata _powers
        ) external whenNotPaused {
            bytes32 domain = keccak256(abi.encodePacked(block.chainid, address(this), "WithdrawMsg"));
            verifySigs(abi.encodePacked(domain, _wdmsg), _sigs, _signers, _powers);
            // decode and check wdmsg
            PbPool.WithdrawMsg memory wdmsg = PbPool.decWithdrawMsg(_wdmsg);
            bytes32 wdId = keccak256(
                abi.encodePacked(wdmsg.chainid, wdmsg.seqnum, wdmsg.receiver, wdmsg.token, wdmsg.amount)
            );
            require(withdraws[wdId] == false, "withdraw already succeeded");
            withdraws[wdId] = true;
            _updateVolume(wdmsg.token, wdmsg.amount);
            uint256 delayThreshold = delayThresholds[wdmsg.token];
            if (delayThreshold > 0 && wdmsg.amount > delayThreshold) {
                _addDelayedTransfer(wdId, wdmsg.receiver, wdmsg.token, wdmsg.amount);
            } else {
                _sendToken(wdmsg.receiver, wdmsg.token, wdmsg.amount);
            }
            emit WithdrawDone(wdId, wdmsg.seqnum, wdmsg.receiver, wdmsg.token, wdmsg.amount, wdmsg.refid);
        }
        function executeDelayedTransfer(bytes32 id) external whenNotPaused {
            delayedTransfer memory transfer = _executeDelayedTransfer(id);
            _sendToken(transfer.receiver, transfer.token, transfer.amount);
        }
        function setMinAdd(address[] calldata _tokens, uint256[] calldata _amounts) external onlyGovernor {
            require(_tokens.length == _amounts.length, "length mismatch");
            for (uint256 i = 0; i < _tokens.length; i++) {
                minAdd[_tokens[i]] = _amounts[i];
                emit MinAddUpdated(_tokens[i], _amounts[i]);
            }
        }
        function _sendToken(
            address _receiver,
            address _token,
            uint256 _amount
        ) internal {
            if (_token == nativeWrap) {
                // withdraw then transfer native to receiver
                IWETH(nativeWrap).withdraw(_amount);
                (bool sent, ) = _receiver.call{value: _amount, gas: 50000}("");
                require(sent, "failed to send native token");
            } else {
                IERC20(_token).safeTransfer(_receiver, _amount);
            }
        }
        // set nativeWrap, for relay requests, if token == nativeWrap, will withdraw first then transfer native to receiver
        function setWrap(address _weth) external onlyOwner {
            nativeWrap = _weth;
        }
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
    import "@openzeppelin/contracts/access/Ownable.sol";
    import "./interfaces/ISigsVerifier.sol";
    contract Signers is Ownable, ISigsVerifier {
        using ECDSA for bytes32;
        bytes32 public ssHash;
        uint256 public triggerTime; // timestamp when last update was triggered
        // reset can be called by the owner address for emergency recovery
        uint256 public resetTime;
        uint256 public noticePeriod; // advance notice period as seconds for reset
        uint256 constant MAX_INT = 2**256 - 1;
        event SignersUpdated(address[] _signers, uint256[] _powers);
        event ResetNotification(uint256 resetTime);
        /**
         * @notice Verifies that a message is signed by a quorum among the signers
         * The sigs must be sorted by signer addresses in ascending order.
         * @param _msg signed message
         * @param _sigs list of signatures sorted by signer addresses
         * @param _signers sorted list of current signers
         * @param _powers powers of current signers
         */
        function verifySigs(
            bytes memory _msg,
            bytes[] calldata _sigs,
            address[] calldata _signers,
            uint256[] calldata _powers
        ) public view override {
            bytes32 h = keccak256(abi.encodePacked(_signers, _powers));
            require(ssHash == h, "Mismatch current signers");
            _verifySignedPowers(keccak256(_msg).toEthSignedMessageHash(), _sigs, _signers, _powers);
        }
        /**
         * @notice Update new signers.
         * @param _newSigners sorted list of new signers
         * @param _curPowers powers of new signers
         * @param _sigs list of signatures sorted by signer addresses
         * @param _curSigners sorted list of current signers
         * @param _curPowers powers of current signers
         */
        function updateSigners(
            uint256 _triggerTime,
            address[] calldata _newSigners,
            uint256[] calldata _newPowers,
            bytes[] calldata _sigs,
            address[] calldata _curSigners,
            uint256[] calldata _curPowers
        ) external {
            // use trigger time for nonce protection, must be ascending
            require(_triggerTime > triggerTime, "Trigger time is not increasing");
            // make sure triggerTime is not too large, as it cannot be decreased once set
            require(_triggerTime < block.timestamp + 3600, "Trigger time is too large");
            bytes32 domain = keccak256(abi.encodePacked(block.chainid, address(this), "UpdateSigners"));
            verifySigs(abi.encodePacked(domain, _triggerTime, _newSigners, _newPowers), _sigs, _curSigners, _curPowers);
            _updateSigners(_newSigners, _newPowers);
            triggerTime = _triggerTime;
        }
        /**
         * @notice reset signers, only used for init setup and emergency recovery
         */
        function resetSigners(address[] calldata _signers, uint256[] calldata _powers) external onlyOwner {
            require(block.timestamp > resetTime, "not reach reset time");
            resetTime = MAX_INT;
            _updateSigners(_signers, _powers);
        }
        function notifyResetSigners() external onlyOwner {
            resetTime = block.timestamp + noticePeriod;
            emit ResetNotification(resetTime);
        }
        function increaseNoticePeriod(uint256 period) external onlyOwner {
            require(period > noticePeriod, "notice period can only be increased");
            noticePeriod = period;
        }
        // separate from verifySigs func to avoid "stack too deep" issue
        function _verifySignedPowers(
            bytes32 _hash,
            bytes[] calldata _sigs,
            address[] calldata _signers,
            uint256[] calldata _powers
        ) private pure {
            require(_signers.length == _powers.length, "signers and powers length not match");
            uint256 totalPower; // sum of all signer.power
            for (uint256 i = 0; i < _signers.length; i++) {
                totalPower += _powers[i];
            }
            uint256 quorum = (totalPower * 2) / 3 + 1;
            uint256 signedPower; // sum of signer powers who are in sigs
            address prev = address(0);
            uint256 index = 0;
            for (uint256 i = 0; i < _sigs.length; i++) {
                address signer = _hash.recover(_sigs[i]);
                require(signer > prev, "signers not in ascending order");
                prev = signer;
                // now find match signer add its power
                while (signer > _signers[index]) {
                    index += 1;
                    require(index < _signers.length, "signer not found");
                }
                if (signer == _signers[index]) {
                    signedPower += _powers[index];
                }
                if (signedPower >= quorum) {
                    // return early to save gas
                    return;
                }
            }
            revert("quorum not reached");
        }
        function _updateSigners(address[] calldata _signers, uint256[] calldata _powers) private {
            require(_signers.length == _powers.length, "signers and powers length not match");
            address prev = address(0);
            for (uint256 i = 0; i < _signers.length; i++) {
                require(_signers[i] > prev, "New signers not in ascending order");
                prev = _signers[i];
            }
            ssHash = keccak256(abi.encodePacked(_signers, _powers));
            emit SignersUpdated(_signers, _powers);
        }
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    interface ISigsVerifier {
        /**
         * @notice Verifies that a message is signed by a quorum among the signers.
         * @param _msg signed message
         * @param _sigs list of signatures sorted by signer addresses
         * @param _signers sorted list of current signers
         * @param _powers powers of current signers
         */
        function verifySigs(
            bytes memory _msg,
            bytes[] calldata _sigs,
            address[] calldata _signers,
            uint256[] calldata _powers
        ) external view;
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    interface IWETH {
        function deposit() external payable;
        function withdraw(uint256) external;
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    // runtime proto sol library
    library Pb {
        enum WireType {
            Varint,
            Fixed64,
            LengthDelim,
            StartGroup,
            EndGroup,
            Fixed32
        }
        struct Buffer {
            uint256 idx; // the start index of next read. when idx=b.length, we're done
            bytes b; // hold serialized proto msg, readonly
        }
        // create a new in-memory Buffer object from raw msg bytes
        function fromBytes(bytes memory raw) internal pure returns (Buffer memory buf) {
            buf.b = raw;
            buf.idx = 0;
        }
        // whether there are unread bytes
        function hasMore(Buffer memory buf) internal pure returns (bool) {
            return buf.idx < buf.b.length;
        }
        // decode current field number and wiretype
        function decKey(Buffer memory buf) internal pure returns (uint256 tag, WireType wiretype) {
            uint256 v = decVarint(buf);
            tag = v / 8;
            wiretype = WireType(v & 7);
        }
        // count tag occurrences, return an array due to no memory map support
        // have to create array for (maxtag+1) size. cnts[tag] = occurrences
        // should keep buf.idx unchanged because this is only a count function
        function cntTags(Buffer memory buf, uint256 maxtag) internal pure returns (uint256[] memory cnts) {
            uint256 originalIdx = buf.idx;
            cnts = new uint256[](maxtag + 1); // protobuf's tags are from 1 rather than 0
            uint256 tag;
            WireType wire;
            while (hasMore(buf)) {
                (tag, wire) = decKey(buf);
                cnts[tag] += 1;
                skipValue(buf, wire);
            }
            buf.idx = originalIdx;
        }
        // read varint from current buf idx, move buf.idx to next read, return the int value
        function decVarint(Buffer memory buf) internal pure returns (uint256 v) {
            bytes10 tmp; // proto int is at most 10 bytes (7 bits can be used per byte)
            bytes memory bb = buf.b; // get buf.b mem addr to use in assembly
            v = buf.idx; // use v to save one additional uint variable
            assembly {
                tmp := mload(add(add(bb, 32), v)) // load 10 bytes from buf.b[buf.idx] to tmp
            }
            uint256 b; // store current byte content
            v = 0; // reset to 0 for return value
            for (uint256 i = 0; i < 10; i++) {
                assembly {
                    b := byte(i, tmp) // don't use tmp[i] because it does bound check and costs extra
                }
                v |= (b & 0x7F) << (i * 7);
                if (b & 0x80 == 0) {
                    buf.idx += i + 1;
                    return v;
                }
            }
            revert(); // i=10, invalid varint stream
        }
        // read length delimited field and return bytes
        function decBytes(Buffer memory buf) internal pure returns (bytes memory b) {
            uint256 len = decVarint(buf);
            uint256 end = buf.idx + len;
            require(end <= buf.b.length); // avoid overflow
            b = new bytes(len);
            bytes memory bufB = buf.b; // get buf.b mem addr to use in assembly
            uint256 bStart;
            uint256 bufBStart = buf.idx;
            assembly {
                bStart := add(b, 32)
                bufBStart := add(add(bufB, 32), bufBStart)
            }
            for (uint256 i = 0; i < len; i += 32) {
                assembly {
                    mstore(add(bStart, i), mload(add(bufBStart, i)))
                }
            }
            buf.idx = end;
        }
        // return packed ints
        function decPacked(Buffer memory buf) internal pure returns (uint256[] memory t) {
            uint256 len = decVarint(buf);
            uint256 end = buf.idx + len;
            require(end <= buf.b.length); // avoid overflow
            // array in memory must be init w/ known length
            // so we have to create a tmp array w/ max possible len first
            uint256[] memory tmp = new uint256[](len);
            uint256 i = 0; // count how many ints are there
            while (buf.idx < end) {
                tmp[i] = decVarint(buf);
                i++;
            }
            t = new uint256[](i); // init t with correct length
            for (uint256 j = 0; j < i; j++) {
                t[j] = tmp[j];
            }
            return t;
        }
        // move idx pass current value field, to beginning of next tag or msg end
        function skipValue(Buffer memory buf, WireType wire) internal pure {
            if (wire == WireType.Varint) {
                decVarint(buf);
            } else if (wire == WireType.LengthDelim) {
                uint256 len = decVarint(buf);
                buf.idx += len; // skip len bytes value data
                require(buf.idx <= buf.b.length); // avoid overflow
            } else {
                revert();
            } // unsupported wiretype
        }
        // type conversion help utils
        function _bool(uint256 x) internal pure returns (bool v) {
            return x != 0;
        }
        function _uint256(bytes memory b) internal pure returns (uint256 v) {
            require(b.length <= 32); // b's length must be smaller than or equal to 32
            assembly {
                v := mload(add(b, 32))
            } // load all 32bytes to v
            v = v >> (8 * (32 - b.length)); // only first b.length is valid
        }
        function _address(bytes memory b) internal pure returns (address v) {
            v = _addressPayable(b);
        }
        function _addressPayable(bytes memory b) internal pure returns (address payable v) {
            require(b.length == 20);
            //load 32bytes then shift right 12 bytes
            assembly {
                v := div(mload(add(b, 32)), 0x1000000000000000000000000)
            }
        }
        function _bytes32(bytes memory b) internal pure returns (bytes32 v) {
            require(b.length == 32);
            assembly {
                v := mload(add(b, 32))
            }
        }
        // uint[] to uint8[]
        function uint8s(uint256[] memory arr) internal pure returns (uint8[] memory t) {
            t = new uint8[](arr.length);
            for (uint256 i = 0; i < t.length; i++) {
                t[i] = uint8(arr[i]);
            }
        }
        function uint32s(uint256[] memory arr) internal pure returns (uint32[] memory t) {
            t = new uint32[](arr.length);
            for (uint256 i = 0; i < t.length; i++) {
                t[i] = uint32(arr[i]);
            }
        }
        function uint64s(uint256[] memory arr) internal pure returns (uint64[] memory t) {
            t = new uint64[](arr.length);
            for (uint256 i = 0; i < t.length; i++) {
                t[i] = uint64(arr[i]);
            }
        }
        function bools(uint256[] memory arr) internal pure returns (bool[] memory t) {
            t = new bool[](arr.length);
            for (uint256 i = 0; i < t.length; i++) {
                t[i] = arr[i] != 0;
            }
        }
    }
    // SPDX-License-Identifier: GPL-3.0-only
    // Code generated by protoc-gen-sol. DO NOT EDIT.
    // source: bridge.proto
    pragma solidity 0.8.9;
    import "./Pb.sol";
    library PbBridge {
        using Pb for Pb.Buffer; // so we can call Pb funcs on Buffer obj
        struct Relay {
            address sender; // tag: 1
            address receiver; // tag: 2
            address token; // tag: 3
            uint256 amount; // tag: 4
            uint64 srcChainId; // tag: 5
            uint64 dstChainId; // tag: 6
            bytes32 srcTransferId; // tag: 7
        } // end struct Relay
        function decRelay(bytes memory raw) internal pure returns (Relay memory m) {
            Pb.Buffer memory buf = Pb.fromBytes(raw);
            uint256 tag;
            Pb.WireType wire;
            while (buf.hasMore()) {
                (tag, wire) = buf.decKey();
                if (false) {}
                // solidity has no switch/case
                else if (tag == 1) {
                    m.sender = Pb._address(buf.decBytes());
                } else if (tag == 2) {
                    m.receiver = Pb._address(buf.decBytes());
                } else if (tag == 3) {
                    m.token = Pb._address(buf.decBytes());
                } else if (tag == 4) {
                    m.amount = Pb._uint256(buf.decBytes());
                } else if (tag == 5) {
                    m.srcChainId = uint64(buf.decVarint());
                } else if (tag == 6) {
                    m.dstChainId = uint64(buf.decVarint());
                } else if (tag == 7) {
                    m.srcTransferId = Pb._bytes32(buf.decBytes());
                } else {
                    buf.skipValue(wire);
                } // skip value of unknown tag
            }
        } // end decoder Relay
    }
    // SPDX-License-Identifier: GPL-3.0-only
    // Code generated by protoc-gen-sol. DO NOT EDIT.
    // source: contracts/libraries/proto/pool.proto
    pragma solidity 0.8.9;
    import "./Pb.sol";
    library PbPool {
        using Pb for Pb.Buffer; // so we can call Pb funcs on Buffer obj
        struct WithdrawMsg {
            uint64 chainid; // tag: 1
            uint64 seqnum; // tag: 2
            address receiver; // tag: 3
            address token; // tag: 4
            uint256 amount; // tag: 5
            bytes32 refid; // tag: 6
        } // end struct WithdrawMsg
        function decWithdrawMsg(bytes memory raw) internal pure returns (WithdrawMsg memory m) {
            Pb.Buffer memory buf = Pb.fromBytes(raw);
            uint256 tag;
            Pb.WireType wire;
            while (buf.hasMore()) {
                (tag, wire) = buf.decKey();
                if (false) {}
                // solidity has no switch/case
                else if (tag == 1) {
                    m.chainid = uint64(buf.decVarint());
                } else if (tag == 2) {
                    m.seqnum = uint64(buf.decVarint());
                } else if (tag == 3) {
                    m.receiver = Pb._address(buf.decBytes());
                } else if (tag == 4) {
                    m.token = Pb._address(buf.decBytes());
                } else if (tag == 5) {
                    m.amount = Pb._uint256(buf.decBytes());
                } else if (tag == 6) {
                    m.refid = Pb._bytes32(buf.decBytes());
                } else {
                    buf.skipValue(wire);
                } // skip value of unknown tag
            }
        } // end decoder WithdrawMsg
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    import "./Governor.sol";
    abstract contract DelayedTransfer is Governor {
        struct delayedTransfer {
            address receiver;
            address token;
            uint256 amount;
            uint256 timestamp;
        }
        mapping(bytes32 => delayedTransfer) public delayedTransfers;
        mapping(address => uint256) public delayThresholds;
        uint256 public delayPeriod; // in seconds
        event DelayedTransferAdded(bytes32 id);
        event DelayedTransferExecuted(bytes32 id, address receiver, address token, uint256 amount);
        event DelayPeriodUpdated(uint256 period);
        event DelayThresholdUpdated(address token, uint256 threshold);
        function setDelayThresholds(address[] calldata _tokens, uint256[] calldata _thresholds) external onlyGovernor {
            require(_tokens.length == _thresholds.length, "length mismatch");
            for (uint256 i = 0; i < _tokens.length; i++) {
                delayThresholds[_tokens[i]] = _thresholds[i];
                emit DelayThresholdUpdated(_tokens[i], _thresholds[i]);
            }
        }
        function setDelayPeriod(uint256 _period) external onlyGovernor {
            delayPeriod = _period;
            emit DelayPeriodUpdated(_period);
        }
        function _addDelayedTransfer(
            bytes32 id,
            address receiver,
            address token,
            uint256 amount
        ) internal {
            require(delayedTransfers[id].timestamp == 0, "delayed transfer already exists");
            delayedTransfers[id] = delayedTransfer({
                receiver: receiver,
                token: token,
                amount: amount,
                timestamp: block.timestamp
            });
            emit DelayedTransferAdded(id);
        }
        // caller needs to do the actual token transfer
        function _executeDelayedTransfer(bytes32 id) internal returns (delayedTransfer memory) {
            delayedTransfer memory transfer = delayedTransfers[id];
            require(transfer.timestamp > 0, "delayed transfer not exist");
            require(block.timestamp > transfer.timestamp + delayPeriod, "delayed transfer still locked");
            delete delayedTransfers[id];
            emit DelayedTransferExecuted(id, transfer.receiver, transfer.token, transfer.amount);
            return transfer;
        }
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/access/Ownable.sol";
    abstract contract Governor is Ownable {
        mapping(address => bool) public governors;
        event GovernorAdded(address account);
        event GovernorRemoved(address account);
        modifier onlyGovernor() {
            require(isGovernor(msg.sender), "Caller is not governor");
            _;
        }
        constructor() {
            _addGovernor(msg.sender);
        }
        function isGovernor(address _account) public view returns (bool) {
            return governors[_account];
        }
        function addGovernor(address _account) public onlyOwner {
            _addGovernor(_account);
        }
        function removeGovernor(address _account) public onlyOwner {
            _removeGovernor(_account);
        }
        function renounceGovernor() public {
            _removeGovernor(msg.sender);
        }
        function _addGovernor(address _account) private {
            require(!isGovernor(_account), "Account is already governor");
            governors[_account] = true;
            emit GovernorAdded(_account);
        }
        function _removeGovernor(address _account) private {
            require(isGovernor(_account), "Account is not governor");
            governors[_account] = false;
            emit GovernorRemoved(_account);
        }
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    import "@openzeppelin/contracts/access/Ownable.sol";
    import "@openzeppelin/contracts/security/Pausable.sol";
    abstract contract Pauser is Ownable, Pausable {
        mapping(address => bool) public pausers;
        event PauserAdded(address account);
        event PauserRemoved(address account);
        constructor() {
            _addPauser(msg.sender);
        }
        modifier onlyPauser() {
            require(isPauser(msg.sender), "Caller is not pauser");
            _;
        }
        function pause() public onlyPauser {
            _pause();
        }
        function unpause() public onlyPauser {
            _unpause();
        }
        function isPauser(address account) public view returns (bool) {
            return pausers[account];
        }
        function addPauser(address account) public onlyOwner {
            _addPauser(account);
        }
        function removePauser(address account) public onlyOwner {
            _removePauser(account);
        }
        function renouncePauser() public {
            _removePauser(msg.sender);
        }
        function _addPauser(address account) private {
            require(!isPauser(account), "Account is already pauser");
            pausers[account] = true;
            emit PauserAdded(account);
        }
        function _removePauser(address account) private {
            require(isPauser(account), "Account is not pauser");
            pausers[account] = false;
            emit PauserRemoved(account);
        }
    }
    // SPDX-License-Identifier: GPL-3.0-only
    pragma solidity 0.8.9;
    import "./Governor.sol";
    abstract contract VolumeControl is Governor {
        uint256 public epochLength; // seconds
        mapping(address => uint256) public epochVolumes; // key is token
        mapping(address => uint256) public epochVolumeCaps; // key is token
        mapping(address => uint256) public lastOpTimestamps; // key is token
        event EpochLengthUpdated(uint256 length);
        event EpochVolumeUpdated(address token, uint256 cap);
        function setEpochLength(uint256 _length) external onlyGovernor {
            epochLength = _length;
            emit EpochLengthUpdated(_length);
        }
        function setEpochVolumeCaps(address[] calldata _tokens, uint256[] calldata _caps) external onlyGovernor {
            require(_tokens.length == _caps.length, "length mismatch");
            for (uint256 i = 0; i < _tokens.length; i++) {
                epochVolumeCaps[_tokens[i]] = _caps[i];
                emit EpochVolumeUpdated(_tokens[i], _caps[i]);
            }
        }
        function _updateVolume(address _token, uint256 _amount) internal {
            if (epochLength == 0) {
                return;
            }
            uint256 cap = epochVolumeCaps[_token];
            if (cap == 0) {
                return;
            }
            uint256 volume = epochVolumes[_token];
            uint256 timestamp = block.timestamp;
            uint256 epochStartTime = (timestamp / epochLength) * epochLength;
            if (lastOpTimestamps[_token] < epochStartTime) {
                volume = _amount;
            } else {
                volume += _amount;
            }
            require(volume <= cap, "volume exceeds cap");
            epochVolumes[_token] = volume;
            lastOpTimestamps[_token] = timestamp;
        }
    }
    

    File 2 of 2: izumiToken
    // SPDX-License-Identifier: MIT
    
    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) {
            this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
            return msg.data;
        }
    }
    
    
    /**
     * @dev Interface of the ERC20 standard as defined in the EIP.
     */
    interface IERC20 {
        /**
         * @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 `recipient`.
         *
         * Returns a boolean value indicating whether the operation succeeded.
         *
         * Emits a {Transfer} event.
         */
        function transfer(address recipient, 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 `sender` to `recipient` 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 sender, address recipient, uint256 amount) external returns (bool);
    
        /**
         * @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 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 () {
            address msgSender = _msgSender();
            _owner = msgSender;
            emit OwnershipTransferred(address(0), msgSender);
        }
    
        /**
         * @dev Returns the address of the current owner.
         */
        function owner() public view virtual returns (address) {
            return _owner;
        }
    
        /**
         * @dev Throws if called by any account other than the owner.
         */
        modifier onlyOwner() {
            require(owner() == _msgSender(), "Ownable: caller is not the owner");
            _;
        }
    
        /**
         * @dev Leaves the contract without owner. It will not be possible to call
         * `onlyOwner` functions anymore. Can only be called by the current owner.
         *
         * NOTE: Renouncing ownership will leave the contract without an owner,
         * thereby removing any functionality that is only available to the owner.
         */
        function renounceOwnership() public virtual onlyOwner {
            emit OwnershipTransferred(_owner, address(0));
            _owner = 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");
            emit OwnershipTransferred(_owner, newOwner);
            _owner = newOwner;
        }
    }
    
    /**
     * @dev Implementation of the {IERC20} interface.
     *
     * This implementation is agnostic to the way tokens are created. This means
     * that a supply mechanism has to be added in a derived contract using {_mint}.
     * For a generic mechanism see {ERC20PresetMinterPauser}.
     *
     * TIP: For a detailed writeup see our guide
     * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
     * to implement supply mechanisms].
     *
     * We have followed general OpenZeppelin guidelines: functions revert instead
     * of returning `false` on failure. This behavior is nonetheless conventional
     * and does not conflict with the expectations of ERC20 applications.
     *
     * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
     * This allows applications to reconstruct the allowance for all accounts just
     * by listening to said events. Other implementations of the EIP may not emit
     * these events, as it isn't required by the specification.
     *
     * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
     * functions have been added to mitigate the well-known issues around setting
     * allowances. See {IERC20-approve}.
     */
    contract ERC20 is Context, IERC20 {
        mapping (address => uint256) private _balances;
    
        mapping (address => mapping (address => uint256)) private _allowances;
    
        uint256 private _totalSupply;
    
        string private _name;
        string private _symbol;
    
        /**
         * @dev Sets the values for {name} and {symbol}.
         *
         * The defaut value of {decimals} is 18. To select a different value for
         * {decimals} you should overload it.
         *
         * All three of these values are immutable: they can only be set once during
         * construction.
         */
        constructor (string memory name_, string memory symbol_) {
            _name = name_;
            _symbol = symbol_;
        }
    
        /**
         * @dev Returns the name of the token.
         */
        function name() public view virtual returns (string memory) {
            return _name;
        }
    
        /**
         * @dev Returns the symbol of the token, usually a shorter version of the
         * name.
         */
        function symbol() public view virtual returns (string memory) {
            return _symbol;
        }
    
        /**
         * @dev Returns the number of decimals used to get its user representation.
         * For example, if `decimals` equals `2`, a balance of `505` tokens should
         * be displayed to a user as `5,05` (`505 / 10 ** 2`).
         *
         * Tokens usually opt for a value of 18, imitating the relationship between
         * Ether and Wei. This is the value {ERC20} uses, unless this function is
         * overloaded;
         *
         * NOTE: This information is only used for _display_ purposes: it in
         * no way affects any of the arithmetic of the contract, including
         * {IERC20-balanceOf} and {IERC20-transfer}.
         */
        function decimals() public view virtual returns (uint8) {
            return 18;
        }
    
        /**
         * @dev See {IERC20-totalSupply}.
         */
        function totalSupply() public view virtual override returns (uint256) {
            return _totalSupply;
        }
    
        /**
         * @dev See {IERC20-balanceOf}.
         */
        function balanceOf(address account) public view virtual override returns (uint256) {
            return _balances[account];
        }
    
        /**
         * @dev See {IERC20-transfer}.
         *
         * Requirements:
         *
         * - `recipient` cannot be the zero address.
         * - the caller must have a balance of at least `amount`.
         */
        function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
            _transfer(_msgSender(), recipient, amount);
            return true;
        }
    
        /**
         * @dev See {IERC20-allowance}.
         */
        function allowance(address owner, address spender) public view virtual override returns (uint256) {
            return _allowances[owner][spender];
        }
    
        /**
         * @dev See {IERC20-approve}.
         *
         * Requirements:
         *
         * - `spender` cannot be the zero address.
         */
        function approve(address spender, uint256 amount) public virtual override returns (bool) {
            _approve(_msgSender(), spender, amount);
            return true;
        }
    
        /**
         * @dev See {IERC20-transferFrom}.
         *
         * Emits an {Approval} event indicating the updated allowance. This is not
         * required by the EIP. See the note at the beginning of {ERC20}.
         *
         * Requirements:
         *
         * - `sender` and `recipient` cannot be the zero address.
         * - `sender` must have a balance of at least `amount`.
         * - the caller must have allowance for ``sender``'s tokens of at least
         * `amount`.
         */
        function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
            _transfer(sender, recipient, amount);
    
            uint256 currentAllowance = _allowances[sender][_msgSender()];
            require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
            _approve(sender, _msgSender(), currentAllowance - amount);
    
            return true;
        }
    
        /**
         * @dev Atomically increases the allowance granted to `spender` by the caller.
         *
         * This is an alternative to {approve} that can be used as a mitigation for
         * problems described in {IERC20-approve}.
         *
         * Emits an {Approval} event indicating the updated allowance.
         *
         * Requirements:
         *
         * - `spender` cannot be the zero address.
         */
        function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
            _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
            return true;
        }
    
        /**
         * @dev Atomically decreases the allowance granted to `spender` by the caller.
         *
         * This is an alternative to {approve} that can be used as a mitigation for
         * problems described in {IERC20-approve}.
         *
         * Emits an {Approval} event indicating the updated allowance.
         *
         * Requirements:
         *
         * - `spender` cannot be the zero address.
         * - `spender` must have allowance for the caller of at least
         * `subtractedValue`.
         */
        function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
            uint256 currentAllowance = _allowances[_msgSender()][spender];
            require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
            _approve(_msgSender(), spender, currentAllowance - subtractedValue);
    
            return true;
        }
    
        /**
         * @dev Moves tokens `amount` from `sender` to `recipient`.
         *
         * This is internal function is equivalent to {transfer}, and can be used to
         * e.g. implement automatic token fees, slashing mechanisms, etc.
         *
         * Emits a {Transfer} event.
         *
         * Requirements:
         *
         * - `sender` cannot be the zero address.
         * - `recipient` cannot be the zero address.
         * - `sender` must have a balance of at least `amount`.
         */
        function _transfer(address sender, address recipient, uint256 amount) internal virtual {
            require(sender != address(0), "ERC20: transfer from the zero address");
            require(recipient != address(0), "ERC20: transfer to the zero address");
    
            _beforeTokenTransfer(sender, recipient, amount);
    
            uint256 senderBalance = _balances[sender];
            require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
            _balances[sender] = senderBalance - amount;
            _balances[recipient] += amount;
    
            emit Transfer(sender, recipient, amount);
        }
    
        /** @dev Creates `amount` tokens and assigns them to `account`, increasing
         * the total supply.
         *
         * Emits a {Transfer} event with `from` set to the zero address.
         *
         * Requirements:
         *
         * - `to` cannot be the zero address.
         */
        function _mint(address account, uint256 amount) internal virtual {
            require(account != address(0), "ERC20: mint to the zero address");
    
            _beforeTokenTransfer(address(0), account, amount);
    
            _totalSupply += amount;
            _balances[account] += amount;
            emit Transfer(address(0), account, amount);
        }
    
        /**
         * @dev Destroys `amount` tokens from `account`, reducing the
         * total supply.
         *
         * Emits a {Transfer} event with `to` set to the zero address.
         *
         * Requirements:
         *
         * - `account` cannot be the zero address.
         * - `account` must have at least `amount` tokens.
         */
        function _burn(address account, uint256 amount) internal virtual {
            require(account != address(0), "ERC20: burn from the zero address");
    
            _beforeTokenTransfer(account, address(0), amount);
    
            uint256 accountBalance = _balances[account];
            require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
            _balances[account] = accountBalance - amount;
            _totalSupply -= amount;
    
            emit Transfer(account, address(0), amount);
        }
    
        /**
         * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
         *
         * This internal function is equivalent to `approve`, and can be used to
         * e.g. set automatic allowances for certain subsystems, etc.
         *
         * Emits an {Approval} event.
         *
         * Requirements:
         *
         * - `owner` cannot be the zero address.
         * - `spender` cannot be the zero address.
         */
        function _approve(address owner, address spender, uint256 amount) internal virtual {
            require(owner != address(0), "ERC20: approve from the zero address");
            require(spender != address(0), "ERC20: approve to the zero address");
    
            _allowances[owner][spender] = amount;
            emit Approval(owner, spender, amount);
        }
    
        /**
         * @dev Hook that is called before any transfer of tokens. This includes
         * minting and burning.
         *
         * Calling conditions:
         *
         * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
         * will be to transferred to `to`.
         * - when `from` is zero, `amount` tokens will be minted for `to`.
         * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
         * - `from` and `to` are never both zero.
         *
         * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
         */
        function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
    }
    
    contract OperableToken is ERC20, Ownable  {
      address public operator;
      mapping(address=>bool) public trusted;
    
      modifier onlyTrusted {
          require(trusted[msg.sender] || msg.sender == owner(), "not trusted");
          _;
      }
      modifier onlyOperator {
          require(msg.sender == operator, "operator only");
          _;
      }
    
      constructor(string memory name, string memory symbol) ERC20(name, symbol) {
        operator = msg.sender;
      }
    
      function transferOperator(address newOperator) public onlyOperator {
        require(newOperator != address(0), "zero operator");
        operator = newOperator;
      }
    
      function addTrusted(address user) public onlyOperator {
          trusted[user] = true;
      }
    
      function removeTrusted(address user) public onlyOperator {
          trusted[user] = false;
      }
    
      function mint(address account, uint amount) public onlyTrusted {
        _mint(account, amount);
      }
    
      function burn(address account, uint amount) public onlyTrusted {
        _burn(account, amount);
      }
    
    }
    
    contract izumiToken is OperableToken {
      constructor() OperableToken("izumi Token", "iZi") {}
    }