3_ArbSys预编译合约

ArbSys是每一条Arbitrum链中都存在的预编译的合约。顾名思义，ArbSys提供了一些系统级的合约功能支持。任何运行在Arbitrum链上的合约都可以调用ArbSys。

ArbSys在地址0x0000000000000000000000000000000000000064中。使用类似下面的方式调用它：

  1. uint256 txCount = ArbSys(address(100)).getTransactionCount();

下面是ArbSys提供的接口：

  1. /**
  2. * @title Precompiled contract that exists in every Arbitrum chain at address(100), 0x0000000000000000000000000000000000000064. Exposes a variety of system-level functionality.
  3.  */
  4. interface ArbSys {
  5.     /**
  6.     * @notice Get internal version number identifying an ArbOS build
  7.     * @return version number as int
  8.      */
  9.     function arbOSVersion() external pure returns (uint);
  11.     /**
  12.     * @notice Get Arbitrum block number (distinct from L1 block number; Arbitrum genesis block has block number 0)
  13.     * @return block number as int
  14.      */
  15.     function arbBlockNumber() external view returns (uint);
  17.     /**
  18.     * @notice Send given amount of Eth to dest from sender.
  19.     * This is a convenience function, which is equivalent to calling sendTxToL1 with empty calldataForL1.
  20.     * @param destination recipient address on L1
  21.     * @return unique identifier for this L2-to-L1 transaction.
  22.     */
  23.     function withdrawEth(address destination) external payable returns(uint);
  25.     /**
  26.     * @notice Send a transaction to L1
  27.     * @param destination recipient address on L1
  28.     * @param calldataForL1 (optional) calldata for L1 contract call
  29.     * @return a unique identifier for this L2-to-L1 transaction.
  30.     */
  31.     function sendTxToL1(address destination, bytes calldata calldataForL1) external payable returns(uint);
  35.     /**
  36.     * @notice get the number of transactions issued by the given external account or the account sequence number of the given contract
  37.     * @param account target account
  38.     * @return the number of transactions issued by the given external account or the account sequence number of the given contract
  39.     */
  40.     function getTransactionCount(address account) external view returns(uint256);
  42.     /**
  43.     * @notice get the value of target L2 storage slot
  44.     * This function is only callable from address 0 to prevent contracts from being able to call it
  45.     * @param account target account
  46.     * @param index target index of storage slot
  47.     * @return stotage value for the given account at the given index
  48.     */
  49.     function getStorageAt(address account, uint256 index) external view returns (uint256);
  51.     /**
  52.     * @notice check if current call is coming from l1
  53.     * @return true if the caller of this was called directly from L1
  54.     */
  55.     function isTopLevelCall() external view returns (bool);
  57.     event EthWithdrawal(address indexed destAddr, uint amount);
  59.     event L2ToL1Transaction(address caller, address indexed destination, uint indexed uniqueId,
  60.                             uint indexed batchNumber, uint indexInBatch,
  61.                             uint arbBlockNum, uint ethBlockNum, uint timestamp,
  62.                             uint callvalue, bytes data);
  63. }

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