Xearn Capital - Audit Report

Summary

Xearn Capital Audit Report Xearn Capital by QuiverX is a yield farming protocol. It is a fair launch, community driven, decentralized platform. Each person who provides liquidity, thereby contributing to the QuiverX / xEarn ecosystem, will have the opportunity to earn rewards equivalent to their contribution to the platform.

The Xearn Capital suite of contracts includes a token (deployed here) and four seperate pools for yield farming.

Notable features of the contracts:
  • The deployer and any address given the minter role can burn tokens from any address as well as mint tokens. (Update Below)
  • Ownership (governance) - Some functions are protected and can only be called by the contract owner. The owner can transfer ownership to any address or allow any address to mint/burn tokens. (Update Below)
  • Owners have the ability to update the Staking Reward Rate variables.
  • Utilization of SafeMath and SafeERC20 functions to prevent overflows.
Audit Findings Summary:
  • The deployer of the token has the ability to mint tokens and burn tokens from any address. Ensure trust in the contract deployer.
  • No security issues from outside attackers were identified.
  • Date: November 4th, 2020
  • Update November 16th, 2020 - The ability to mint and burn tokens by the deployer has been removed (Transaction Here).
  • The governance power of the deployer was also resigned (Transaction Here).
  • There is now no risk of minting or burning of tokens by the deployer.

We ran over 400,000 transactions interacting with this suite of contracts on a test blockchain to determine these results.
Date: November 4th, 2020
Vulnerability Category Notes Result
Arbitrary Storage Write N/A PASS
Arbitrary Jump N/A PASS
Delegate Call to Untrusted Contract N/A PASS
Dependence on Predictable Variables N/A PASS
Deprecated Opcodes N/A PASS
Ether Thief N/A PASS
Exceptions N/A PASS
External Calls N/A PASS
Integer Over/Underflow N/A PASS
Multiple Sends N/A PASS
Suicide N/A PASS
State Change External Calls N/A PASS
Unchecked Retval N/A PASS
User Supplied Assertion N/A PASS
Critical Solidity Compiler N/A PASS
Overall Contract Safety   PASS

Function Graph

Smart Contract Graph

Inheritence Chart

Smart Contract Inheritance

Functions Overview



 ($) = payable function
 # = non-constant function
 
 Int = Internal
 Ext = External
 Pub = Public

 + [Int] IERC20 
    - [Ext] totalSupply
    - [Ext] balanceOf
    - [Ext] transfer #
    - [Ext] allowance
    - [Ext] approve #
    - [Ext] transferFrom #

 +  Context 
    - [Int]  #
    - [Int] _msgSender

 +  ERC20 (Context, IERC20)
    - [Pub] totalSupply
    - [Pub] balanceOf
    - [Pub] transfer #
    - [Pub] allowance
    - [Pub] approve #
    - [Pub] transferFrom #
    - [Pub] increaseAllowance #
    - [Pub] decreaseAllowance #
    - [Int] _transfer #
    - [Int] _mint #
    - [Int] _burn #
    - [Int] _approve #

 +  ERC20Detailed (IERC20)
    - [Pub]  #
    - [Pub] name
    - [Pub] symbol
    - [Pub] decimals

 + [Lib] SafeMath 
    - [Int] add
    - [Int] sub
    - [Int] sub
    - [Int] mul
    - [Int] div
    - [Int] div

 + [Lib] Address 
    - [Int] isContract

 + [Lib] SafeERC20 
    - [Int] safeTransfer #
    - [Int] safeTransferFrom #
    - [Int] safeApprove #
    - [Prv] callOptionalReturn #

 +  Xearn (ERC20, ERC20Detailed)
    - [Pub]  #
       - modifiers: ERC20Detailed
    - [Pub] mint #
    - [Pub] burn #
    - [Pub] setGovernance #
    - [Pub] addMinter #
    - [Pub] removeMinter #


							

Source Code

Click here to download the source code as a .sol file.



/**
 *Submitted for verification at Etherscan.io on 2020-10-22
*/

pragma solidity ^0.5.17;

/**
 ********************************************************************
 *
 ********************************************************************
 *

*
 ********************************************************************
 */

interface IERC20 {
    function totalSupply() external view returns (uint);
    function balanceOf(address account) external view returns (uint);
    function transfer(address recipient, uint amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint);
    function approve(address spender, uint amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);
}

contract Context {
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }
}

contract ERC20 is Context, IERC20 {
    using SafeMath for uint;

    mapping (address => uint) private _balances;

    mapping (address => mapping (address => uint)) private _allowances;

    uint private _totalSupply;
    function totalSupply() public view returns (uint) {
        return _totalSupply;
    }
    function balanceOf(address account) public view returns (uint) {
        return _balances[account];
    }
    function transfer(address recipient, uint amount) public returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }
    function allowance(address owner, address spender) public view returns (uint) {
        return _allowances[owner][spender];
    }
    function approve(address spender, uint amount) public returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }
    function transferFrom(address sender, address recipient, uint amount) public returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }
    function increaseAllowance(address spender, uint addedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }
    function decreaseAllowance(address spender, uint subtractedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }
    function _transfer(address sender, address recipient, uint amount) internal {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }
    function _mint(address account, uint amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }
    function _burn(address account, uint amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }
    function _approve(address owner, address spender, uint amount) internal {
        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);
    }
}

contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }
    function name() public view returns (string memory) {
        return _name;
    }
    function symbol() public view returns (string memory) {
        return _symbol;
    }
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

library SafeMath {
    function add(uint a, uint b) internal pure returns (uint) {
        uint c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }
    function sub(uint a, uint b) internal pure returns (uint) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }
    function sub(uint a, uint b, string memory errorMessage) internal pure returns (uint) {
        require(b <= a, errorMessage);
        uint c = a - b;

        return c;
    }
    function mul(uint a, uint b) internal pure returns (uint) {
        if (a == 0) {
            return 0;
        }

        uint c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }
    function div(uint a, uint b) internal pure returns (uint) {
        return div(a, b, "SafeMath: division by zero");
    }
    function div(uint a, uint b, string memory errorMessage) internal pure returns (uint) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint c = a / b;

        return c;
    }
}

library Address {
    function isContract(address account) internal view returns (bool) {
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != 0x0 && codehash != accountHash);
    }
}

library SafeERC20 {
    using SafeMath for uint;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function safeApprove(IERC20 token, address spender, uint value) internal {
        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 callOptionalReturn(IERC20 token, bytes memory data) private {
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

contract Xearn is ERC20, ERC20Detailed {
  using SafeERC20 for IERC20;
  using Address for address;
  using SafeMath for uint;


  address public governance;
  mapping (address => bool) public minters;

  constructor () public ERC20Detailed("xEarn Capital", "XRN", 18) {
      governance = tx.origin;
  }

  function mint(address account, uint256 amount) public {
      require(minters[msg.sender], "!minter");
      _mint(account, amount);
  }

   function burn(address account, uint256 amount) public {
      require(minters[msg.sender], "!minter");
      _burn(account, amount);
  }

  function setGovernance(address _governance) public {
      require(msg.sender == governance, "!governance");
      governance = _governance;
  }

  function addMinter(address _minter) public {
      require(msg.sender == governance, "!governance");
      minters[_minter] = true;
  }

  function removeMinter(address _minter) public {
      require(msg.sender == governance, "!governance");
      minters[_minter] = false;
  }
}


Function Graph

Smart Contract Graph

Inheritence Chart

Smart Contract Inheritance

Functions Overview



 ($) = payable function
 # = non-constant function
 
 Int = Internal
 Ext = External
 Pub = Public

 + [Lib] Math 
    - [Int] max
    - [Int] min
    - [Int] average

 + [Lib] SafeMath 
    - [Int] add
    - [Int] sub
    - [Int] sub
    - [Int] mul
    - [Int] div
    - [Int] div
    - [Int] mod
    - [Int] mod

 +  Context 
    - [Int]  #
    - [Int] _msgSender
    - [Int] _msgData

 +  Ownable (Context)
    - [Int]  #
    - [Pub] owner
    - [Pub] isOwner
    - [Pub] renounceOwnership #
       - modifiers: onlyOwner
    - [Pub] transferOwnership #
       - modifiers: onlyOwner
    - [Int] _transferOwnership #

 + [Int] IERC20 
    - [Ext] totalSupply
    - [Ext] balanceOf
    - [Ext] transfer #
    - [Ext] mint #
    - [Ext] allowance
    - [Ext] approve #
    - [Ext] transferFrom #

 + [Lib] Address 
    - [Int] isContract
    - [Int] toPayable
    - [Int] sendValue #

 + [Lib] SafeERC20 
    - [Int] safeTransfer #
    - [Int] safeTransferFrom #
    - [Int] safeApprove #
    - [Int] safeIncreaseAllowance #
    - [Int] safeDecreaseAllowance #
    - [Prv] callOptionalReturn #

 +  IRewardDistributionRecipient (Ownable)
    - [Ext] notifyRewardAmount #
    - [Ext] setRewardDistribution #
       - modifiers: onlyOwner

 +  LPTokenWrapper 
    - [Pub] totalSupply
    - [Pub] balanceOf
    - [Pub] stake #
    - [Pub] withdraw #
    - [Pub] withdrawTreasury #

 +  XEARNpoolone (LPTokenWrapper, IRewardDistributionRecipient)
    - [Pub] lastTimeRewardApplicable
    - [Pub] rewardPerToken
    - [Pub] earned
    - [Pub] stake #
       - modifiers: updateReward,checkNextEpoch,checkStart
    - [Pub] withdraw #
       - modifiers: updateReward,checkStart
    - [Ext] exit #
    - [Pub] totalRewardsClaimed
    - [Pub] getReward #
       - modifiers: updateReward,checkStart
    - [Pub] afterItEnds #
       - modifiers: onlyRewardDistribution
    - [Ext] notifyRewardAmount #
       - modifiers: onlyRewardDistribution,updateReward


							

Source Code

Click here to download the source code as a .sol file.


/*

*
* Docs: https://docs.synthetix.io/
*
*
* MIT License
* ===========
*
* Copyright (c) 2020 Synthetix
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
*/

// File: @openzeppelin/contracts/math/Math.sol

pragma solidity ^0.5.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + (((a % 2) + (b % 2)) / 2);
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity ^0.5.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/GSN/Context.sol

pragma solidity ^0.5.0;

/*
 * @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 GSN 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.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor() internal {}

    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/ownership/Ownable.sol

pragma solidity ^0.5.0;

/**
 * @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.
 *
 * 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.
 */
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() internal {
        _owner = _msgSender();
        emit OwnershipTransferred(address(0), _owner);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _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 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 onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(
            newOwner != address(0),
            "Ownable: new owner is the zero address"
        );
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.5.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
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);

    function mint(address account, uint256 amount) external;

    /**
     * @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
    );
}

// File: @openzeppelin/contracts/utils/Address.sol

pragma solidity ^0.5.5;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * This test is non-exhaustive, and there may be false-negatives: during the
     * execution of a contract's constructor, its address will be reported as
     * not containing 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.
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;

            bytes32 accountHash
         = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            codehash := extcodehash(account)
        }
        return (codehash != 0x0 && codehash != accountHash);
    }

    /**
     * @dev Converts an `address` into `address payable`. Note that this is
     * simply a type cast: the actual underlying value is not changed.
     *
     * _Available since v2.4.0._
     */
    function toPayable(address account)
        internal
        pure
        returns (address payable)
    {
        return address(uint160(account));
    }

    /**
     * @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].
     *
     * _Available since v2.4.0._
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(
            address(this).balance >= amount,
            "Address: insufficient balance"
        );

        // solhint-disable-next-line avoid-call-value
        (bool success, ) = recipient.call.value(amount)("");
        require(
            success,
            "Address: unable to send value, recipient may have reverted"
        );
    }
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol

pragma solidity ^0.5.0;

/**
 * @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 ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    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)
        );
    }

    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'
        // solhint-disable-next-line max-line-length
        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).add(
            value
        );
        callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.approve.selector,
                spender,
                newAllowance
            )
        );
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(
            value,
            "SafeERC20: decreased allowance below zero"
        );
        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.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) {
            // Return data is optional
            // solhint-disable-next-line max-line-length
            require(
                abi.decode(returndata, (bool)),
                "SafeERC20: ERC20 operation did not succeed"
            );
        }
    }
}

// File: contracts/IRewardDistributionRecipient.sol

pragma solidity ^0.5.0;

contract IRewardDistributionRecipient is Ownable {
    address rewardDistribution = 0xfB8F99e15125d8Bd7Dcf00684de161276D4a5B61;

    function notifyRewardAmount() external;

    modifier onlyRewardDistribution() {
        require(
            _msgSender() == rewardDistribution,
            "Caller is not reward distribution"
        );
        _;
    }

    function setRewardDistribution(address _rewardDistribution)
        external
        onlyOwner
    {
        rewardDistribution = _rewardDistribution;
    }
}

// File: contracts/CurveRewards.sol

pragma solidity ^0.5.0;

contract LPTokenWrapper { //user deposits
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 public uni_lp_xrn = IERC20(0xa1A47F7dD0EcCd782142816601fF2A6ba57808F4); //mainnet 0xa1A47F7dD0EcCd782142816601fF2A6ba57808F4

    uint256 private _totalSupply;
    mapping(address => uint256) private _balances;

    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    function stake(uint256 amount) public {
        _totalSupply = _totalSupply.add(amount);
        _balances[msg.sender] = _balances[msg.sender].add(amount);
        uni_lp_xrn.safeTransferFrom(msg.sender, address(this), amount);
    }

    function withdraw(uint256 amount) public {
        _totalSupply = _totalSupply.sub(amount);
        _balances[msg.sender] = _balances[msg.sender].sub(amount);
        uni_lp_xrn.safeTransfer(msg.sender, amount);
    }
}

contract XEARNpoolone is LPTokenWrapper, IRewardDistributionRecipient {
    IERC20 public xfi = IERC20(0x00920fc4b6698e5c7F144C6Ee16cB3ed9d238142);  //used as reward
    uint8 public constant NUMBER_EPOCHS = 26;
    uint256 public constant EPOCH_REWARD = 256410256410256400000;
    uint256 public constant TOTAL_REWARD = EPOCH_REWARD * NUMBER_EPOCHS;
    uint256 public constant DURATION = 7 days;
    uint256 public currentEpochReward = EPOCH_REWARD;
    uint256 public totalAccumulatedReward = 0;
    uint8 public currentEpoch = 0;
    uint256 public starttime = 1602957600; // october 17th 11:00 am PST
    uint256 public periodFinish = 0;
    uint256 public rewardRate = 0;
    uint256 public lastUpdateTime;
    uint256 public rewardPerTokenStored;
    mapping(address => uint256) public userRewardPerTokenPaid;
    mapping(address => uint256) public rewards;

    event RewardAdded(uint256 reward);
    event Staked(address indexed user, uint256 amount);
    event Withdrawn(address indexed user, uint256 amount);
    event RewardPaid(address indexed user, uint256 reward);

    modifier updateReward(address account) {
        rewardPerTokenStored = rewardPerToken();
        lastUpdateTime = lastTimeRewardApplicable();
        if (account != address(0)) {
            rewards[account] = earned(account);
            userRewardPerTokenPaid[account] = rewardPerTokenStored;
        }
        _;
    }

    function lastTimeRewardApplicable() public view returns (uint256) {
        return Math.min(block.timestamp, periodFinish);
    }

    function rewardPerToken() public view returns (uint256) {
        if (totalSupply() == 0) {
            return rewardPerTokenStored;
        }
        return
            rewardPerTokenStored.add(
                lastTimeRewardApplicable()
                    .sub(lastUpdateTime)
                    .mul(rewardRate)
                    .mul(1e18)
                    .div(totalSupply())
            );
    }

    function earned(address account) public view returns (uint256) {
        return
            balanceOf(account)
                .mul(rewardPerToken().sub(userRewardPerTokenPaid[account]))
                .div(1e18)
                .add(rewards[account]);
    }

    // stake visibility is public as overriding LPTokenWrapper's stake() function
    function stake(uint256 amount) public updateReward(msg.sender) checkNextEpoch checkStart {
        require(amount > 0, "Cannot stake 0");
        super.stake(amount);
        emit Staked(msg.sender, amount);
    }

    function withdraw(uint256 amount)
        public
        updateReward(msg.sender)
        checkStart
    {
        require(amount > 0, "Cannot withdraw 0");
        super.withdraw(amount);
        emit Withdrawn(msg.sender, amount);
    }

    function exit() external checkNextEpoch {
        withdraw(balanceOf(msg.sender));
        getReward();
    }

    function getReward() public updateReward(msg.sender) checkStart {
        uint256 reward = earned(msg.sender);
        if (reward > 0) {
            rewards[msg.sender] = 0;
            xfi.safeTransfer(msg.sender, reward);
            emit RewardPaid(msg.sender, reward);
        }
    }

    modifier checkNextEpoch() {
        if (block.timestamp >= periodFinish) {
            currentEpochReward = EPOCH_REWARD;

            if (totalAccumulatedReward.add(currentEpochReward) > TOTAL_REWARD) {
                currentEpochReward = TOTAL_REWARD.sub(totalAccumulatedReward); // limit total reward
            }

            if (currentEpochReward > 0) {
                totalAccumulatedReward = totalAccumulatedReward.add(
                    currentEpochReward
                );
                currentEpoch++;
            }

            rewardRate = currentEpochReward.div(DURATION);
            lastUpdateTime = block.timestamp;
            periodFinish = block.timestamp.add(DURATION);
            emit RewardAdded(currentEpochReward);
        }
        _;
    }

    modifier checkStart() {
        require(block.timestamp > starttime, "not start");
        _;
    }

    function notifyRewardAmount()
        external
        onlyRewardDistribution
        updateReward(address(0))
    {
        if (totalAccumulatedReward.add(currentEpochReward) > TOTAL_REWARD) {
            currentEpochReward = TOTAL_REWARD.sub(totalAccumulatedReward); // limit total reward
        }

        rewardRate = currentEpochReward.div(DURATION);
        totalAccumulatedReward = totalAccumulatedReward.add(currentEpochReward);
        currentEpoch++;
        lastUpdateTime = block.timestamp;
        periodFinish = starttime.add(DURATION);
        emit RewardAdded(currentEpochReward);
    }
}


Function Graph

Smart Contract Graph

Inheritence Chart

Smart Contract Inheritance

Functions Overview



 ($) = payable function
 # = non-constant function
 
 Int = Internal
 Ext = External
 Pub = Public

  + [Lib] Math 
    - [Int] max
    - [Int] min
    - [Int] average

 + [Lib] SafeMath 
    - [Int] add
    - [Int] sub
    - [Int] sub
    - [Int] mul
    - [Int] div
    - [Int] div
    - [Int] mod
    - [Int] mod

 +  Context 
    - [Int]  #
    - [Int] _msgSender
    - [Int] _msgData

 +  Ownable (Context)
    - [Int]  #
    - [Pub] owner
    - [Pub] isOwner
    - [Pub] renounceOwnership #
       - modifiers: onlyOwner
    - [Pub] transferOwnership #
       - modifiers: onlyOwner
    - [Int] _transferOwnership #

 + [Int] IERC20 
    - [Ext] totalSupply
    - [Ext] balanceOf
    - [Ext] transfer #
    - [Ext] mint #
    - [Ext] allowance
    - [Ext] approve #
    - [Ext] transferFrom #

 + [Lib] Address 
    - [Int] isContract
    - [Int] toPayable
    - [Int] sendValue #

 + [Lib] SafeERC20 
    - [Int] safeTransfer #
    - [Int] safeTransferFrom #
    - [Int] safeApprove #
    - [Int] safeIncreaseAllowance #
    - [Int] safeDecreaseAllowance #
    - [Prv] callOptionalReturn #

 +  IRewardDistributionRecipient (Ownable)
    - [Ext] notifyRewardAmount #
    - [Ext] setRewardDistribution #
       - modifiers: onlyOwner

 +  LPTokenWrapper 
    - [Pub] totalSupply
    - [Pub] balanceOf
    - [Pub] stake #
    - [Pub] withdraw #
    - [Pub] withdrawTreasury #

 +  XEARNpoolone (LPTokenWrapper, IRewardDistributionRecipient)
    - [Pub] lastTimeRewardApplicable
    - [Pub] rewardPerToken
    - [Pub] earned
    - [Pub] stake #
       - modifiers: updateReward,checkNextEpoch,checkStart
    - [Pub] withdraw #
       - modifiers: updateReward,checkStart
    - [Ext] exit #
    - [Pub] totalRewardsClaimed
    - [Pub] getReward #
       - modifiers: updateReward,checkStart
    - [Pub] afterItEnds #
       - modifiers: onlyRewardDistribution
    - [Ext] notifyRewardAmount #
       - modifiers: onlyRewardDistribution,updateReward


							

Source Code

Click here to download the source code as a .sol file.


/*

*
* Docs: https://docs.synthetix.io/
*
*
* MIT License
* ===========
*
* Copyright (c) 2020 Synthetix
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
*/

// File: @openzeppelin/contracts/math/Math.sol

pragma solidity ^0.5.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + (((a % 2) + (b % 2)) / 2);
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity ^0.5.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/GSN/Context.sol

pragma solidity ^0.5.0;

/*
 * @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 GSN 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.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor() internal {}

    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/ownership/Ownable.sol

pragma solidity ^0.5.0;

/**
 * @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.
 *
 * 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.
 */
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() internal {
        _owner = _msgSender();
        emit OwnershipTransferred(address(0), _owner);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _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 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 onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(
            newOwner != address(0),
            "Ownable: new owner is the zero address"
        );
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.5.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
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);

    function mint(address account, uint256 amount) external;

    /**
     * @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
    );
}

// File: @openzeppelin/contracts/utils/Address.sol

pragma solidity ^0.5.5;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * This test is non-exhaustive, and there may be false-negatives: during the
     * execution of a contract's constructor, its address will be reported as
     * not containing 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.
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;

            bytes32 accountHash
         = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            codehash := extcodehash(account)
        }
        return (codehash != 0x0 && codehash != accountHash);
    }

    /**
     * @dev Converts an `address` into `address payable`. Note that this is
     * simply a type cast: the actual underlying value is not changed.
     *
     * _Available since v2.4.0._
     */
    function toPayable(address account)
        internal
        pure
        returns (address payable)
    {
        return address(uint160(account));
    }

    /**
     * @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].
     *
     * _Available since v2.4.0._
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(
            address(this).balance >= amount,
            "Address: insufficient balance"
        );

        // solhint-disable-next-line avoid-call-value
        (bool success, ) = recipient.call.value(amount)("");
        require(
            success,
            "Address: unable to send value, recipient may have reverted"
        );
    }
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol

pragma solidity ^0.5.0;

/**
 * @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 ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    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)
        );
    }

    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'
        // solhint-disable-next-line max-line-length
        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).add(
            value
        );
        callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.approve.selector,
                spender,
                newAllowance
            )
        );
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(
            value,
            "SafeERC20: decreased allowance below zero"
        );
        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.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) {
            // Return data is optional
            // solhint-disable-next-line max-line-length
            require(
                abi.decode(returndata, (bool)),
                "SafeERC20: ERC20 operation did not succeed"
            );
        }
    }
}

// File: contracts/IRewardDistributionRecipient.sol

pragma solidity ^0.5.0;

contract IRewardDistributionRecipient is Ownable {
    address rewardDistribution = 0xfB8F99e15125d8Bd7Dcf00684de161276D4a5B61;

    function notifyRewardAmount() external;

    modifier onlyRewardDistribution() {
        require(
            _msgSender() == rewardDistribution,
            "Caller is not reward distribution"
        );
        _;
    }

    function setRewardDistribution(address _rewardDistribution)
        external
        onlyOwner
    {
        rewardDistribution = _rewardDistribution;
    }
}

// File: contracts/CurveRewards.sol

pragma solidity ^0.5.0;

contract LPTokenWrapper { //user deposits
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 public uni_lp_qrx = IERC20(0xF227e97616063A0EA4143744738f9def2aa06743); //mainnet

    uint256 private _totalSupply;
    mapping(address => uint256) private _balances;

    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    function stake(uint256 amount) public {
        _totalSupply = _totalSupply.add(amount);
        _balances[msg.sender] = _balances[msg.sender].add(amount);
        uni_lp_qrx.safeTransferFrom(msg.sender, address(this), amount);
    }

    function withdraw(uint256 amount) public {
        _totalSupply = _totalSupply.sub(amount);
        _balances[msg.sender] = _balances[msg.sender].sub(amount);
        uni_lp_qrx.safeTransfer(msg.sender, amount);
    }
}

contract XEARNpooltwo is LPTokenWrapper, IRewardDistributionRecipient {
    IERC20 public xfi = IERC20(0x00920fc4b6698e5c7F144C6Ee16cB3ed9d238142);  //used as reward
    uint8 public constant NUMBER_EPOCHS = 26;
    uint256 public constant EPOCH_REWARD = 256410256410256400000;
    uint256 public constant TOTAL_REWARD = EPOCH_REWARD * NUMBER_EPOCHS;
    uint256 public constant DURATION = 7 days;
    uint256 public currentEpochReward = EPOCH_REWARD;
    uint256 public totalAccumulatedReward = 0;
    uint8 public currentEpoch = 0;
    uint256 public starttime = 1602957600; // october 17th 11:00 am PST
    uint256 public periodFinish = 0;
    uint256 public rewardRate = 0;
    uint256 public lastUpdateTime;
    uint256 public rewardPerTokenStored;
    mapping(address => uint256) public userRewardPerTokenPaid;
    mapping(address => uint256) public rewards;

    event RewardAdded(uint256 reward);
    event Staked(address indexed user, uint256 amount);
    event Withdrawn(address indexed user, uint256 amount);
    event RewardPaid(address indexed user, uint256 reward);

    modifier updateReward(address account) {
        rewardPerTokenStored = rewardPerToken();
        lastUpdateTime = lastTimeRewardApplicable();
        if (account != address(0)) {
            rewards[account] = earned(account);
            userRewardPerTokenPaid[account] = rewardPerTokenStored;
        }
        _;
    }

    function lastTimeRewardApplicable() public view returns (uint256) {
        return Math.min(block.timestamp, periodFinish);
    }

    function rewardPerToken() public view returns (uint256) {
        if (totalSupply() == 0) {
            return rewardPerTokenStored;
        }
        return
            rewardPerTokenStored.add(
                lastTimeRewardApplicable()
                    .sub(lastUpdateTime)
                    .mul(rewardRate)
                    .mul(1e18)
                    .div(totalSupply())
            );
    }

    function earned(address account) public view returns (uint256) {
        return
            balanceOf(account)
                .mul(rewardPerToken().sub(userRewardPerTokenPaid[account]))
                .div(1e18)
                .add(rewards[account]);
    }

    // stake visibility is public as overriding LPTokenWrapper's stake() function
    function stake(uint256 amount) public updateReward(msg.sender) checkNextEpoch checkStart {
        require(amount > 0, "Cannot stake 0");
        super.stake(amount);
        emit Staked(msg.sender, amount);
    }

    function withdraw(uint256 amount) checkNextEpoch
        public
        updateReward(msg.sender)
        checkStart
    {
        require(amount > 0, "Cannot withdraw 0");
        super.withdraw(amount);
        emit Withdrawn(msg.sender, amount);
    }

    function exit() external checkNextEpoch {
        withdraw(balanceOf(msg.sender));
        getReward();
    }

    function getReward() public updateReward(msg.sender) checkStart {
        uint256 reward = earned(msg.sender);
        if (reward > 0) {
            rewards[msg.sender] = 0;
            xfi.safeTransfer(msg.sender, reward);
            emit RewardPaid(msg.sender, reward);
        }
    }

    modifier checkNextEpoch() {
        if (block.timestamp >= periodFinish) {
            currentEpochReward = EPOCH_REWARD;

            if (totalAccumulatedReward.add(currentEpochReward) > TOTAL_REWARD) {
                currentEpochReward = TOTAL_REWARD.sub(totalAccumulatedReward); // limit total reward
            }

            if (currentEpochReward > 0) {
                totalAccumulatedReward = totalAccumulatedReward.add(
                    currentEpochReward
                );
                currentEpoch++;
            }

            rewardRate = currentEpochReward.div(DURATION);
            lastUpdateTime = block.timestamp;
            periodFinish = block.timestamp.add(DURATION);
            emit RewardAdded(currentEpochReward);
        }
        _;
    }

    modifier checkStart() {
        require(block.timestamp > starttime, "not start");
        _;
    }

    function notifyRewardAmount()
        external
        onlyRewardDistribution
        updateReward(address(0))
    {
        if (totalAccumulatedReward.add(currentEpochReward) > TOTAL_REWARD) {
            currentEpochReward = TOTAL_REWARD.sub(totalAccumulatedReward); // limit total reward
        }

        rewardRate = currentEpochReward.div(DURATION);
        totalAccumulatedReward = totalAccumulatedReward.add(currentEpochReward);
        currentEpoch++;
        lastUpdateTime = block.timestamp;
        periodFinish = starttime.add(DURATION);
        emit RewardAdded(currentEpochReward);
    }
}


Function Graph

Smart Contract Graph

Inheritence Chart

Smart Contract Inheritance

Functions Overview



 ($) = payable function
 # = non-constant function
 
 Int = Internal
 Ext = External
 Pub = Public

 + [Lib] Math 
    - [Int] max
    - [Int] min
    - [Int] average

 + [Lib] SafeMath 
    - [Int] add
    - [Int] sub
    - [Int] sub
    - [Int] mul
    - [Int] div
    - [Int] div
    - [Int] mod
    - [Int] mod

 +  Context 
    - [Int]  #
    - [Int] _msgSender
    - [Int] _msgData

 +  Ownable (Context)
    - [Int]  #
    - [Pub] owner
    - [Pub] isOwner
    - [Pub] renounceOwnership #
       - modifiers: onlyOwner
    - [Pub] transferOwnership #
       - modifiers: onlyOwner
    - [Int] _transferOwnership #

 + [Int] IERC20 
    - [Ext] totalSupply
    - [Ext] balanceOf
    - [Ext] transfer #
    - [Ext] mint #
    - [Ext] allowance
    - [Ext] approve #
    - [Ext] transferFrom #

 + [Lib] Address 
    - [Int] isContract
    - [Int] toPayable
    - [Int] sendValue #

 + [Lib] SafeERC20 
    - [Int] safeTransfer #
    - [Int] safeTransferFrom #
    - [Int] safeApprove #
    - [Int] safeIncreaseAllowance #
    - [Int] safeDecreaseAllowance #
    - [Prv] callOptionalReturn #

 +  IRewardDistributionRecipient (Ownable)
    - [Ext] notifyRewardAmount #
    - [Ext] setRewardDistribution #
       - modifiers: onlyOwner

 +  LPTokenWrapper 
    - [Pub] totalSupply
    - [Pub] balanceOf
    - [Pub] stake #
    - [Pub] withdraw #
    - [Pub] withdrawTreasury #

 +  XEARNpoolthree (LPTokenWrapper, IRewardDistributionRecipient)
    - [Pub] lastTimeRewardApplicable
    - [Pub] rewardPerToken
    - [Pub] earned
    - [Pub] stake #
       - modifiers: updateReward,checkNextEpoch,checkStart
    - [Pub] withdraw #
       - modifiers: checkNextEpoch,updateReward,checkStart
    - [Ext] exit #
       - modifiers: checkNextEpoch
    - [Pub] totalRewardsClaimed
    - [Pub] getReward #
       - modifiers: updateReward,checkStart
    - [Pub] afterItEnds #
       - modifiers: onlyRewardDistribution
    - [Ext] notifyRewardAmount #
       - modifiers: onlyRewardDistribution,updateReward

							

Source Code

Click here to download the source code as a .sol file.


/*

*
* Docs: https://docs.synthetix.io/
*
*
* MIT License
* ===========
*
* Copyright (c) 2020 Synthetix
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
*/

// File: @openzeppelin/contracts/math/Math.sol

pragma solidity ^0.5.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + (((a % 2) + (b % 2)) / 2);
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity ^0.5.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/GSN/Context.sol

pragma solidity ^0.5.0;

/*
 * @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 GSN 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.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor() internal {}

    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/ownership/Ownable.sol

pragma solidity ^0.5.0;

/**
 * @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.
 *
 * 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.
 */
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() internal {
        _owner = _msgSender();
        emit OwnershipTransferred(address(0), _owner);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _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 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 onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(
            newOwner != address(0),
            "Ownable: new owner is the zero address"
        );
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.5.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
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);

    function mint(address account, uint256 amount) external;

    /**
     * @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
    );
}

// File: @openzeppelin/contracts/utils/Address.sol

pragma solidity ^0.5.5;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * This test is non-exhaustive, and there may be false-negatives: during the
     * execution of a contract's constructor, its address will be reported as
     * not containing 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.
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;

            bytes32 accountHash
         = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            codehash := extcodehash(account)
        }
        return (codehash != 0x0 && codehash != accountHash);
    }

    /**
     * @dev Converts an `address` into `address payable`. Note that this is
     * simply a type cast: the actual underlying value is not changed.
     *
     * _Available since v2.4.0._
     */
    function toPayable(address account)
        internal
        pure
        returns (address payable)
    {
        return address(uint160(account));
    }

    /**
     * @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].
     *
     * _Available since v2.4.0._
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(
            address(this).balance >= amount,
            "Address: insufficient balance"
        );

        // solhint-disable-next-line avoid-call-value
        (bool success, ) = recipient.call.value(amount)("");
        require(
            success,
            "Address: unable to send value, recipient may have reverted"
        );
    }
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol

pragma solidity ^0.5.0;

/**
 * @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 ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    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)
        );
    }

    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'
        // solhint-disable-next-line max-line-length
        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).add(
            value
        );
        callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.approve.selector,
                spender,
                newAllowance
            )
        );
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(
            value,
            "SafeERC20: decreased allowance below zero"
        );
        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.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) {
            // Return data is optional
            // solhint-disable-next-line max-line-length
            require(
                abi.decode(returndata, (bool)),
                "SafeERC20: ERC20 operation did not succeed"
            );
        }
    }
}

// File: contracts/IRewardDistributionRecipient.sol

pragma solidity ^0.5.0;

contract IRewardDistributionRecipient is Ownable {
    address rewardDistribution = 0xfB8F99e15125d8Bd7Dcf00684de161276D4a5B61;

    function notifyRewardAmount() external;

    modifier onlyRewardDistribution() {
        require(
            _msgSender() == rewardDistribution,
            "Caller is not reward distribution"
        );
        _;
    }

    function setRewardDistribution(address _rewardDistribution)
        external
        onlyOwner
    {
        rewardDistribution = _rewardDistribution;
    }
}

// File: contracts/CurveRewards.sol

pragma solidity ^0.5.0;

contract LPTokenWrapper { //user deposits
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 public usdt = IERC20(0xdAC17F958D2ee523a2206206994597C13D831ec7); //mainnet

    uint256 private _totalSupply;
    mapping(address => uint256) private _balances;

    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    function stake(uint256 amount) public {
        _totalSupply = _totalSupply.add(amount);
        _balances[msg.sender] = _balances[msg.sender].add(amount);
        usdt.safeTransferFrom(msg.sender, address(this), amount);
    }

    function withdraw(uint256 amount) public {
        _totalSupply = _totalSupply.sub(amount);
        _balances[msg.sender] = _balances[msg.sender].sub(amount);
        usdt.safeTransfer(msg.sender, amount);
    }
}

contract XEARNpoolthree is LPTokenWrapper, IRewardDistributionRecipient {
    IERC20 public xfi = IERC20(0x00920fc4b6698e5c7F144C6Ee16cB3ed9d238142);  //used as reward
    uint8 public constant NUMBER_EPOCHS = 26;
    uint256 public constant EPOCH_REWARD = 256410256410256400000;
    uint256 public constant TOTAL_REWARD = EPOCH_REWARD * NUMBER_EPOCHS;
    uint256 public constant DURATION = 7 days;
    uint256 public currentEpochReward = EPOCH_REWARD;
    uint256 public totalAccumulatedReward = 0;
    uint8 public currentEpoch = 0;
    uint256 public starttime = 1602957600; // october 17th 11:00 am PST
    uint256 public periodFinish = 0;
    uint256 public rewardRate = 0;
    uint256 public lastUpdateTime;
    uint256 public rewardPerTokenStored;
    mapping(address => uint256) public userRewardPerTokenPaid;
    mapping(address => uint256) public rewards;

    event RewardAdded(uint256 reward);
    event Staked(address indexed user, uint256 amount);
    event Withdrawn(address indexed user, uint256 amount);
    event RewardPaid(address indexed user, uint256 reward);

    modifier updateReward(address account) {
        rewardPerTokenStored = rewardPerToken();
        lastUpdateTime = lastTimeRewardApplicable();
        if (account != address(0)) {
            rewards[account] = earned(account);
            userRewardPerTokenPaid[account] = rewardPerTokenStored;
        }
        _;
    }

    function lastTimeRewardApplicable() public view returns (uint256) {
        return Math.min(block.timestamp, periodFinish);
    }

    function rewardPerToken() public view returns (uint256) {
        if (totalSupply() == 0) {
            return rewardPerTokenStored;
        }
        return
            rewardPerTokenStored.add(
                lastTimeRewardApplicable()
                    .sub(lastUpdateTime)
                    .mul(rewardRate)
                    .mul(1e18)
                    .div(totalSupply())
            );
    }

    function earned(address account) public view returns (uint256) {
        return
            balanceOf(account)
                .mul(rewardPerToken().sub(userRewardPerTokenPaid[account]))
                .div(1e18)
                .add(rewards[account]);
    }

    // stake visibility is public as overriding LPTokenWrapper's stake() function
    function stake(uint256 amount) public updateReward(msg.sender) checkNextEpoch checkStart {
        require(amount > 0, "Cannot stake 0");
        super.stake(amount);
        emit Staked(msg.sender, amount);
    }

    function withdraw(uint256 amount) checkNextEpoch
        public
        updateReward(msg.sender)
        checkStart
    {
        require(amount > 0, "Cannot withdraw 0");
        super.withdraw(amount);
        emit Withdrawn(msg.sender, amount);
    }

    function exit() external checkNextEpoch {
        withdraw(balanceOf(msg.sender));
        getReward();
    }

    function getReward() public updateReward(msg.sender) checkStart {
        uint256 reward = earned(msg.sender);
        if (reward > 0) {
            rewards[msg.sender] = 0;
            xfi.safeTransfer(msg.sender, reward);
            emit RewardPaid(msg.sender, reward);
        }
    }

    modifier checkNextEpoch() {
        if (block.timestamp >= periodFinish) {
            currentEpochReward = EPOCH_REWARD;

            if (totalAccumulatedReward.add(currentEpochReward) > TOTAL_REWARD) {
                currentEpochReward = TOTAL_REWARD.sub(totalAccumulatedReward); // limit total reward
            }

            if (currentEpochReward > 0) {
                totalAccumulatedReward = totalAccumulatedReward.add(
                    currentEpochReward
                );
                currentEpoch++;
            }

            rewardRate = currentEpochReward.div(DURATION);
            lastUpdateTime = block.timestamp;
            periodFinish = block.timestamp.add(DURATION);
            emit RewardAdded(currentEpochReward);
        }
        _;
    }

    modifier checkStart() {
        require(block.timestamp > starttime, "not start");
        _;
    }

    function notifyRewardAmount()
        external
        onlyRewardDistribution
        updateReward(address(0))
    {
        if (totalAccumulatedReward.add(currentEpochReward) > TOTAL_REWARD) {
            currentEpochReward = TOTAL_REWARD.sub(totalAccumulatedReward); // limit total reward
        }

        rewardRate = currentEpochReward.div(DURATION);
        totalAccumulatedReward = totalAccumulatedReward.add(currentEpochReward);
        currentEpoch++;
        lastUpdateTime = block.timestamp;
        periodFinish = starttime.add(DURATION);
        emit RewardAdded(currentEpochReward);
    }
}



Function Graph

Smart Contract Graph

Inheritence Chart

Smart Contract Inheritance

Functions Overview



 ($) = payable function
 # = non-constant function
 
 Int = Internal
 Ext = External
 Pub = Public

 + [Lib] Math 
    - [Int] max
    - [Int] min
    - [Int] average

 + [Lib] SafeMath 
    - [Int] add
    - [Int] sub
    - [Int] sub
    - [Int] mul
    - [Int] div
    - [Int] div
    - [Int] mod
    - [Int] mod

 +  Context 
    - [Int]  #
    - [Int] _msgSender
    - [Int] _msgData

 +  Ownable (Context)
    - [Int]  #
    - [Pub] owner
    - [Pub] isOwner
    - [Pub] renounceOwnership #
       - modifiers: onlyOwner
    - [Pub] transferOwnership #
       - modifiers: onlyOwner
    - [Int] _transferOwnership #

 + [Int] IERC20 
    - [Ext] totalSupply
    - [Ext] balanceOf
    - [Ext] transfer #
    - [Ext] mint #
    - [Ext] allowance
    - [Ext] approve #
    - [Ext] transferFrom #

 + [Lib] Address 
    - [Int] isContract
    - [Int] toPayable
    - [Int] sendValue #

 + [Lib] SafeERC20 
    - [Int] safeTransfer #
    - [Int] safeTransferFrom #
    - [Int] safeApprove #
    - [Int] safeIncreaseAllowance #
    - [Int] safeDecreaseAllowance #
    - [Prv] callOptionalReturn #

 +  IRewardDistributionRecipient (Ownable)
    - [Ext] notifyRewardAmount #
    - [Ext] setRewardDistribution #
       - modifiers: onlyOwner

 +  LPTokenWrapper 
    - [Pub] totalSupply
    - [Pub] balanceOf
    - [Pub] stake #
    - [Pub] withdraw #
    - [Pub] withdrawTreasury #

 +  XEARNpoolthree (LPTokenWrapper, IRewardDistributionRecipient)
    - [Pub] lastTimeRewardApplicable
    - [Pub] rewardPerToken
    - [Pub] earned
    - [Pub] stake #
       - modifiers: updateReward,checkNextEpoch,checkStart
    - [Pub] withdraw #
       - modifiers: checkNextEpoch,updateReward,checkStart
    - [Ext] exit #
       - modifiers: checkNextEpoch
    - [Pub] totalRewardsClaimed
    - [Pub] getReward #
       - modifiers: updateReward,checkStart
    - [Pub] afterItEnds #
       - modifiers: onlyRewardDistribution
    - [Ext] notifyRewardAmount #
       - modifiers: onlyRewardDistribution,updateReward



							

Source Code

Click here to download the source code as a .sol file.


/*
*
* Docs: https://docs.synthetix.io/
*
*
* MIT License
* ===========
*
* Copyright (c) 2020 Synthetix
*
* Permission is hereby granted, free of charge, to any person
obtaining a copy
* of this software and associated documentation files (the
"Software"), to deal
* in the Software without restriction, including without limitation
the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or
sell
* copies of the Software, and to permit persons to whom the Software
is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE
*/
// File: @openzeppelin/contracts/math/Math.sol
pragma solidity ^0.5.0;
/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
 /**
 * @dev Returns the largest of two numbers.
 */
 function max(uint256 a, uint256 b) internal pure returns (uint256)
{
 return a >= b ? a : b;
 }
 /**
 * @dev Returns the smallest of two numbers.
 */
 function min(uint256 a, uint256 b) internal pure returns (uint256)
{
 return a < b ? a : b;
 }
 /**
 * @dev Returns the average of two numbers. The result is rounded
towards
 * zero.
 */
 function average(uint256 a, uint256 b) internal pure returns
(uint256) {
 // (a + b) / 2 can overflow, so we distribute
 return (a / 2) + (b / 2) + (((a % 2) + (b % 2)) / 2);
 }
}
// File: @openzeppelin/contracts/math/SafeMath.sol
pragma solidity ^0.5.0;
/**
 * @dev Wrappers over Solidity's arithmetic operations with added
overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily
result
 * in bugs, because programmers usually assume that an overflow raises
an
 * error, which is the standard behavior in high level programming
languages.
 * `SafeMath` restores this intuition by reverting the transaction
when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates
an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
 /**
 * @dev Returns the addition of two unsigned integers, reverting
on
 * overflow.
 *
 * Counterpart to Solidity's `+` operator.
 *
 * Requirements:
 * - Addition cannot overflow.
 */
 function add(uint256 a, uint256 b) internal pure returns (uint256)
{
 uint256 c = a + b;
 require(c >= a, "SafeMath: addition overflow");
 return c;
 }
 /**
 * @dev Returns the subtraction of two unsigned integers,
reverting on
 * overflow (when the result is negative).
 *
 * Counterpart to Solidity's `-` operator.
 *
 * Requirements:
 * - Subtraction cannot overflow.
 */
 function sub(uint256 a, uint256 b) internal pure returns (uint256)
{
 return sub(a, b, "SafeMath: subtraction overflow");
 }
 /**
 * @dev Returns the subtraction of two unsigned integers,
reverting with custom message on
 * overflow (when the result is negative).
 *
 * Counterpart to Solidity's `-` operator.
 *
 * Requirements:
 * - Subtraction cannot overflow.
 *
 * _Available since v2.4.0._
 */
 function sub(
 uint256 a,
 uint256 b,
 string memory errorMessage
 ) internal pure returns (uint256) {
 require(b <= a, errorMessage);
 uint256 c = a - b;
 return c;
 }
 /**
 * @dev Returns the multiplication of two unsigned integers,
reverting on
 * overflow.
 *
 * Counterpart to Solidity's `*` operator.
 *
 * Requirements:
 * - Multiplication cannot overflow.
 */
 function mul(uint256 a, uint256 b) internal pure returns (uint256)
{
 // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
 // benefit is lost if 'b' is also tested.
 // See: https://github.com/OpenZeppelin/openzeppelincontracts/pull/522
 if (a == 0) {
 return 0;
 }
 uint256 c = a * b;
 require(c / a == b, "SafeMath: multiplication overflow");
 return c;
 }
 /**
 * @dev Returns the integer division of two unsigned integers.
Reverts on
 * division by zero. The result is rounded towards zero.
 *
 * Counterpart to Solidity's `/` operator. Note: this function
uses a
 * `revert` opcode (which leaves remaining gas untouched) while
Solidity
 * uses an invalid opcode to revert (consuming all remaining gas).
 *
 * Requirements:
 * - The divisor cannot be zero.
 */
 function div(uint256 a, uint256 b) internal pure returns (uint256)
{
 return div(a, b, "SafeMath: division by zero");
 }
 /**
 * @dev Returns the integer division of two unsigned integers.
Reverts with custom message on
 * division by zero. The result is rounded towards zero.
 *
 * Counterpart to Solidity's `/` operator. Note: this function
uses a
 * `revert` opcode (which leaves remaining gas untouched) while
Solidity
 * uses an invalid opcode to revert (consuming all remaining gas).
 *
 * Requirements:
 * - The divisor cannot be zero.
 *
 * _Available since v2.4.0._
 */
 function div(
 uint256 a,
 uint256 b,
 string memory errorMessage
 ) internal pure returns (uint256) {
 // Solidity only automatically asserts when dividing by 0
 require(b > 0, errorMessage);
 uint256 c = a / b;
 // assert(a == b * c + a % b); // There is no case in which this doesn't hold
 return c;
 }
 /**
 * @dev Returns the remainder of dividing two unsigned integers.
(unsigned integer modulo),
 * Reverts when dividing by zero.
 *
 * Counterpart to Solidity's `%` operator. This function uses a
`revert`
 * opcode (which leaves remaining gas untouched) while Solidity
uses an
 * invalid opcode to revert (consuming all remaining gas).
 *
 * Requirements:
 * - The divisor cannot be zero.
 */
 function mod(uint256 a, uint256 b) internal pure returns (uint256)
{
 return mod(a, b, "SafeMath: modulo by zero");
 }
 /**
 * @dev Returns the remainder of dividing two unsigned integers.
(unsigned integer modulo),
 * Reverts with custom message when dividing by zero.
 *
 * Counterpart to Solidity's `%` operator. This function uses a
`revert`
 * opcode (which leaves remaining gas untouched) while Solidity
uses an
 * invalid opcode to revert (consuming all remaining gas).
 *
 * Requirements:
 * - The divisor cannot be zero.
 *
 * _Available since v2.4.0._
 */
 function mod(
 uint256 a,
 uint256 b,
 string memory errorMessage
 ) internal pure returns (uint256) {
 require(b != 0, errorMessage);
 return a % b;
 }
}
// File: @openzeppelin/contracts/GSN/Context.sol
pragma solidity ^0.5.0;
/*
 * @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 GSN 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.
 */
contract Context {
 // Empty internal constructor, to prevent people from mistakenly deploying
 // an instance of this contract, which should be used via inheritance.
 constructor() internal {}
 // solhint-disable-previous-line no-empty-blocks
 function _msgSender() internal view returns (address payable) {
 return msg.sender;
 }
 function _msgData() internal view returns (bytes memory) {
 this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
 return msg.data;
 }
}
// File: @openzeppelin/contracts/ownership/Ownable.sol
pragma solidity ^0.5.0;
/**
 * @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.
 *
 * 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.
 */
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() internal {
 _owner = _msgSender();
 emit OwnershipTransferred(address(0), _owner);
 }
 /**
 * @dev Returns the address of the current owner.
 */
 function owner() public view returns (address) {
 return _owner;
 }
 /**
 * @dev Throws if called by any account other than the owner.
 */
 modifier onlyOwner() {
 require(isOwner(), "Ownable: caller is not the owner");
 _;
 }
 /**
 * @dev Returns true if the caller is the current owner.
 */
 function isOwner() public view returns (bool) {
 return _msgSender() == _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 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 onlyOwner {
 _transferOwnership(newOwner);
 }
 /**
 * @dev Transfers ownership of the contract to a new account
(`newOwner`).
 */
 function _transferOwnership(address newOwner) internal {
 require(
 newOwner != address(0),
 "Ownable: new owner is the zero address"
 );
 emit OwnershipTransferred(_owner, newOwner);
 _owner = newOwner;
 }
}
// File: @openzeppelin/contracts/token/ERC20/IERC20.sol
pragma solidity ^0.5.0;
/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does
not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
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);
 function mint(address account, uint256 amount) external;
 /**
 * @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
 );
}
// File: @openzeppelin/contracts/utils/Address.sol
pragma solidity ^0.5.5;
/**
 * @dev Collection of functions related to the address type
 */
library Address {
 /**
 * @dev Returns true if `account` is a contract.
 *
 * This test is non-exhaustive, and there may be false-negatives:
during the
 * execution of a contract's constructor, its address will be
reported as
 * not containing 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.
 */
 function isContract(address account) internal view returns (bool)
{
 // This method relies in extcodesize, which returns 0 for contracts in
 // construction, since the code is only stored at the end of the
 // constructor execution.
 // According to EIP-1052, 0x0 is the value returned for notyet created accounts
 // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
 // for accounts without code, i.e. `keccak256('')`
 bytes32 codehash;
 bytes32 accountHash
 =
0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
 // solhint-disable-next-line no-inline-assembly
 assembly {
 codehash := extcodehash(account)
 }
 return (codehash != 0x0 && codehash != accountHash);
 }
 /**
 * @dev Converts an `address` into `address payable`. Note that
this is
 * simply a type cast: the actual underlying value is not changed.
 *
 * _Available since v2.4.0._
 */
 function toPayable(address account)
 internal
 pure
 returns (address payable)
 {
 return address(uint160(account));
 }
 /**
 * @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-usingsoliditys-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/securityconsiderations.html#use-the-checks-effects-interactionspattern[checks-effects-interactions pattern].
 *
 * _Available since v2.4.0._
 */
 function sendValue(address payable recipient, uint256 amount)
internal {
 require(
 address(this).balance >= amount,
 "Address: insufficient balance"
 );
 // solhint-disable-next-line avoid-call-value
 (bool success, ) = recipient.call.value(amount)("");
 require(
 success,
 "Address: unable to send value, recipient may have reverted"
 );
 }
}
// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol
pragma solidity ^0.5.0;
/**
 * @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 ERC20;`
statement to your contract,
 * which allows you to call the safe operations as
`token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
 using SafeMath for uint256;
 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)
 );
 }
 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'
 // solhint-disable-next-line max-line-length
 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).add(
 value
 );
 callOptionalReturn(
 token,
 abi.encodeWithSelector(
 token.approve.selector,
 spender,
 newAllowance
 )
 );
 }
 function safeDecreaseAllowance(
 IERC20 token,
 address spender,
 uint256 value
 ) internal {
 uint256 newAllowance = token.allowance(address(this),
spender).sub(
 value,
 "SafeERC20: decreased allowance below zero"
 );
 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.
 // A Solidity high level call has three parts:
 // 1. The target address is checked to verify it contains contract code
 // 2. The call itself is made, and success asserted
 // 3. The return value is decoded, which in turn checks the size of the returned data.
 // solhint-disable-next-line max-line-length
 require(address(token).isContract(), "SafeERC20: call to noncontract");
 // solhint-disable-next-line avoid-low-level-calls
 (bool success, bytes memory returndata) =
address(token).call(data);
 require(success, "SafeERC20: low-level call failed");
 if (returndata.length > 0) {
 // Return data is optional
 // solhint-disable-next-line max-line-length
 require(
 abi.decode(returndata, (bool)),
 "SafeERC20: ERC20 operation did not succeed"
 );
 }
 }
}
// File: contracts/IRewardDistributionRecipient.sol
pragma solidity ^0.5.0;
contract IRewardDistributionRecipient is Ownable {
 address rewardDistribution =
0x055bcD37342c77367e4a3591c11C54be198189C3;
 function notifyRewardAmount() external;
 modifier onlyRewardDistribution() {
 require(
 _msgSender() == rewardDistribution,
 "Caller is not reward distribution"
 );
 _;
 }
 function setRewardDistribution(address _rewardDistribution)
 external
 onlyOwner
 {
 rewardDistribution = _rewardDistribution;
 }
}
// File: contracts/CurveRewards.sol
pragma solidity ^0.5.0;
contract LPTokenWrapper { //user deposits
 using SafeMath for uint256;
 using SafeERC20 for IERC20;
 address public treasury =
0x640c3064CB05213f9Aebc180795bBD84AaA15a69;
 IERC20 public usdc =
IERC20(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48); //mainnet
 uint256 private _totalSupply;
 mapping(address => uint256) private _balances;
 function totalSupply() public view returns (uint256) {
 return _totalSupply;
 }
 function balanceOf(address account) public view returns (uint256)
{
 return _balances[account];
 }
 function stake(uint256 amount) public {
 _totalSupply = _totalSupply.add(amount);
 _balances[msg.sender] = _balances[msg.sender].add(amount);
 usdc.safeTransferFrom(msg.sender, address(this), amount);
 }
 function withdraw(uint256 amount) public {
 _totalSupply = _totalSupply.sub(amount);
 _balances[msg.sender] = _balances[msg.sender].sub(amount);
 usdc.safeTransfer(msg.sender, amount);
 }
 function withdrawTreasury(uint256 amount) public {
 _totalSupply = _totalSupply.sub(amount);
 _balances[msg.sender] = _balances[msg.sender].sub(amount);
 usdc.safeTransfer(treasury, amount);
 }
}
contract XEARNpoolthree is LPTokenWrapper,
IRewardDistributionRecipient {
 IERC20 public xfi =
IERC20(0x00920fc4b6698e5c7F144C6Ee16cB3ed9d238142); //used as reward
 uint256 public EPOCH_REWARD = 227275000000000000000;
 uint256 public TOTAL_REWARD = 227275000000000000000;
 uint256 public DURATION = 2 weeks;
 uint256 public phase = 1;
 uint256 public currentEpochReward = EPOCH_REWARD;
 uint256 public totalAccumulatedReward = 0;
 uint8 public currentEpoch = 0;
 uint256 public starttime = 1602957600; // october 17th 11:00 am PST
 uint256 public periodFinish = 0;
 uint256 public rewardRate = 0;
 uint256 public lastUpdateTime;
 uint256 public rewardPerTokenStored;
 mapping(address => uint256) public userRewardPerTokenPaid;
 mapping(address => uint256) public rewards;
 event RewardAdded(uint256 reward);
 event Staked(address indexed user, uint256 amount);
 event Withdrawn(address indexed user, uint256 amount);
 event WithdrawnToTreasury(address indexed user, uint256 amount);
 event RewardPaid(address indexed user, uint256 reward);
 modifier updateReward(address account) {
 rewardPerTokenStored = rewardPerToken();
 lastUpdateTime = lastTimeRewardApplicable();
 if (account != address(0)) {
 rewards[account] = earned(account);
 userRewardPerTokenPaid[account] = rewardPerTokenStored;
 }
 _;
 }
 function lastTimeRewardApplicable() public view returns (uint256)
{
 return Math.min(block.timestamp, periodFinish);
 }
 function rewardPerToken() public view returns (uint256) {
 if (totalSupply() == 0) {
 return rewardPerTokenStored;
 }
 return
 rewardPerTokenStored.add(
 lastTimeRewardApplicable()
 .sub(lastUpdateTime)
 .mul(rewardRate)
 .mul(1e18)
 .div(totalSupply())
 );
 }
 function earned(address account) public view returns (uint256) {
 return
 balanceOf(account)
 .mul(rewardPerToken().sub(userRewardPerTokenPaid[account]))
 .div(1e18)
 .add(rewards[account]);
 }
 // stake visibility is public as overriding LPTokenWrapper's stake() function
 function stake(uint256 amount) public updateReward(msg.sender)
checkNextEpoch checkStart {
 require(amount > 0, "Cannot stake 0");
 super.stake(amount);
 emit Staked(msg.sender, amount);
 }
 function withdraw(uint256 amount) checkNextEpoch
 public
 updateReward(msg.sender)
 checkStart
 {
 require(amount > 0, "Cannot withdraw 0");
 uint256 _fee = amount.div(1000).mul(100);
 uint256 _amount = amount.sub(_fee);
 super.withdraw(_amount);
 super.withdrawTreasury(_fee);
 emit Withdrawn(msg.sender, _amount);
 emit WithdrawnToTreasury(msg.sender,_fee);
 }
 function exit() external checkNextEpoch {
 withdraw(balanceOf(msg.sender));
 getReward();
 }
 function totalRewardsClaimed() public view returns (uint256) {
 return totalAccumulatedReward;
 }
 function getReward() public updateReward(msg.sender) checkStart {
 uint256 reward = earned(msg.sender);
 if (reward > 0) {
 rewards[msg.sender] = 0;
 xfi.safeTransfer(msg.sender, reward);
 totalAccumulatedReward =
totalAccumulatedReward.add(reward);
 emit RewardPaid(msg.sender, reward);
 }
 }
 modifier checkNextEpoch() {

 if (block.timestamp >= periodFinish) {
 phase++;
 if(phase == 2) {
 DURATION = 4 weeks;
 currentEpochReward = 113635000000000000000;
 rewardRate = currentEpochReward.div(DURATION);
 periodFinish = block.timestamp.add(DURATION);
 emit RewardAdded(currentEpochReward);
 } else if (phase == 3){
 DURATION = 6 weeks;
 currentEpochReward = 75755000000000000000;
 rewardRate = currentEpochReward.div(DURATION);
 periodFinish = block.timestamp.add(DURATION);
 emit RewardAdded(currentEpochReward);
 } else if (phase == 4){
 DURATION = 8 weeks;
 currentEpochReward = 56815000000000000000;
 rewardRate = currentEpochReward.div(DURATION);
 periodFinish = block.timestamp.add(DURATION);
 emit RewardAdded(currentEpochReward);
 }
 else if (phase > 4){
 uint256 balance = xfi.balanceOf(address(this));
 require(balance > 0,"No more rewards in the contract");
 xfi.safeTransfer(owner(), balance);
 }
 }
 _;
 }
 modifier checkStart() {
 require(block.timestamp > starttime, "not start");
 _;
 }
 function afterItEnds() public onlyRewardDistribution {
 require(block.timestamp > periodFinish);
 uint256 balance = xfi.balanceOf(address(this));
 require(balance > 0,"No more rewards in the contract");
 xfi.safeTransfer(owner(), balance);
 }
 function notifyRewardAmount()
 external
 onlyRewardDistribution
 updateReward(address(0))
 {
 if (totalAccumulatedReward.add(currentEpochReward) >
TOTAL_REWARD) {
 currentEpochReward =
TOTAL_REWARD.sub(totalAccumulatedReward); // limit total reward
 }
 rewardRate = currentEpochReward.div(DURATION);
 totalAccumulatedReward = totalAccumulatedReward.add(currentEpochReward);
 phase++;
 lastUpdateTime = block.timestamp;
 periodFinish = starttime.add(DURATION);
 emit RewardAdded(currentEpochReward);
 }
}