Contract Source Code:
File 1 of 1 : Oracle
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/**
* @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, with an overflow flag.
*
* _Available since v3.4._
*/
function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
}
/**
* @dev Returns the substraction of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b > a) return (false, 0);
return (true, a - b);
}
/**
* @dev Returns the multiplication of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryMul(uint256 a, uint256 b) internal pure returns (bool, 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 (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
}
/**
* @dev Returns the division of two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b == 0) return (false, 0);
return (true, a / b);
}
/**
* @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b == 0) return (false, 0);
return (true, a % b);
}
/**
* @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) {
require(b <= a, "SafeMath: subtraction overflow");
return a - b;
}
/**
* @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) {
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, reverting 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) {
require(b > 0, "SafeMath: division by zero");
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting 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) {
require(b > 0, "SafeMath: modulo by zero");
return a % b;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {trySub}.
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
return a - b;
}
/**
* @dev Returns the integer division of two unsigned integers, reverting with custom message on
* division by zero. The result is rounded towards zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryDiv}.
*
* 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, string memory errorMessage) internal pure returns (uint256) {
require(b > 0, errorMessage);
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting with custom message when dividing by zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryMod}.
*
* 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, string memory errorMessage) internal pure returns (uint256) {
require(b > 0, errorMessage);
return a % b;
}
}
// File contracts/lib/Babylonian.sol
pragma solidity ^0.6.0;
library Babylonian {
function sqrt(uint256 y) internal pure returns (uint256 z) {
if (y > 3) {
z = y;
uint256 x = y / 2 + 1;
while (x < z) {
z = x;
x = (y / x + x) / 2;
}
} else if (y != 0) {
z = 1;
}
// else z = 0
}
}
// File contracts/lib/FixedPoint.sol
pragma solidity ^0.6.0;
// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
library FixedPoint {
// range: [0, 2**112 - 1]
// resolution: 1 / 2**112
struct uq112x112 {
uint224 _x;
}
// range: [0, 2**144 - 1]
// resolution: 1 / 2**112
struct uq144x112 {
uint256 _x;
}
uint8 private constant RESOLUTION = 112;
uint256 private constant Q112 = uint256(1) << RESOLUTION;
uint256 private constant Q224 = Q112 << RESOLUTION;
// encode a uint112 as a UQ112x112
function encode(uint112 x) internal pure returns (uq112x112 memory) {
return uq112x112(uint224(x) << RESOLUTION);
}
// encodes a uint144 as a UQ144x112
function encode144(uint144 x) internal pure returns (uq144x112 memory) {
return uq144x112(uint256(x) << RESOLUTION);
}
// divide a UQ112x112 by a uint112, returning a UQ112x112
function div(uq112x112 memory self, uint112 x) internal pure returns (uq112x112 memory) {
require(x != 0, "FixedPoint: DIV_BY_ZERO");
return uq112x112(self._x / uint224(x));
}
// multiply a UQ112x112 by a uint, returning a UQ144x112
// reverts on overflow
function mul(uq112x112 memory self, uint256 y) internal pure returns (uq144x112 memory) {
uint256 z;
require(y == 0 || (z = uint256(self._x) * y) / y == uint256(self._x), "FixedPoint: MULTIPLICATION_OVERFLOW");
return uq144x112(z);
}
// returns a UQ112x112 which represents the ratio of the numerator to the denominator
// equivalent to encode(numerator).div(denominator)
function fraction(uint112 numerator, uint112 denominator) internal pure returns (uq112x112 memory) {
require(denominator > 0, "FixedPoint: DIV_BY_ZERO");
return uq112x112((uint224(numerator) << RESOLUTION) / denominator);
}
// decode a UQ112x112 into a uint112 by truncating after the radix point
function decode(uq112x112 memory self) internal pure returns (uint112) {
return uint112(self._x >> RESOLUTION);
}
// decode a UQ144x112 into a uint144 by truncating after the radix point
function decode144(uq144x112 memory self) internal pure returns (uint144) {
return uint144(self._x >> RESOLUTION);
}
// take the reciprocal of a UQ112x112
function reciprocal(uq112x112 memory self) internal pure returns (uq112x112 memory) {
require(self._x != 0, "FixedPoint: ZERO_RECIPROCAL");
return uq112x112(uint224(Q224 / self._x));
}
// square root of a UQ112x112
function sqrt(uq112x112 memory self) internal pure returns (uq112x112 memory) {
return uq112x112(uint224(Babylonian.sqrt(uint256(self._x)) << 56));
}
}
// File contracts/interfaces/IUniswapV2Pair.sol
pragma solidity ^0.6.0;
interface IUniswapV2Pair {
event Approval(address indexed owner, address indexed spender, uint256 value);
event Transfer(address indexed from, address indexed to, uint256 value);
function name() external pure returns (string memory);
function symbol() external pure returns (string memory);
function decimals() external pure returns (uint8);
function totalSupply() external view returns (uint256);
function balanceOf(address owner) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
function approve(address spender, uint256 value) external returns (bool);
function transfer(address to, uint256 value) external returns (bool);
function transferFrom(
address from,
address to,
uint256 value
) external returns (bool);
function DOMAIN_SEPARATOR() external view returns (bytes32);
function PERMIT_TYPEHASH() external pure returns (bytes32);
function nonces(address owner) external view returns (uint256);
function permit(
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) external;
event Mint(address indexed sender, uint256 amount0, uint256 amount1);
event Burn(address indexed sender, uint256 amount0, uint256 amount1, address indexed to);
event Swap(address indexed sender, uint256 amount0In, uint256 amount1In, uint256 amount0Out, uint256 amount1Out, address indexed to);
event Sync(uint112 reserve0, uint112 reserve1);
function MINIMUM_LIQUIDITY() external pure returns (uint256);
function factory() external view returns (address);
function token0() external view returns (address);
function token1() external view returns (address);
function getReserves()
external
view
returns (
uint112 reserve0,
uint112 reserve1,
uint32 blockTimestampLast
);
function price0CumulativeLast() external view returns (uint256);
function price1CumulativeLast() external view returns (uint256);
function kLast() external view returns (uint256);
function mint(address to) external returns (uint256 liquidity);
function burn(address to) external returns (uint256 amount0, uint256 amount1);
function swap(
uint256 amount0Out,
uint256 amount1Out,
address to,
bytes calldata data
) external;
function skim(address to) external;
function sync() external;
function initialize(address, address) external;
}
// File contracts/lib/UniswapV2OracleLibrary.sol
pragma solidity ^0.6.0;
// library with helper methods for oracles that are concerned with computing average prices
library UniswapV2OracleLibrary {
using FixedPoint for *;
// helper function that returns the current block timestamp within the range of uint32, i.e. [0, 2**32 - 1]
function currentBlockTimestamp() internal view returns (uint32) {
return uint32(block.timestamp % 2**32);
}
// produces the cumulative price using counterfactuals to save gas and avoid a call to sync.
function currentCumulativePrices(address pair)
internal
view
returns (
uint256 price0Cumulative,
uint256 price1Cumulative,
uint32 blockTimestamp
)
{
blockTimestamp = currentBlockTimestamp();
price0Cumulative = IUniswapV2Pair(pair).price0CumulativeLast();
price1Cumulative = IUniswapV2Pair(pair).price1CumulativeLast();
// if time has elapsed since the last update on the pair, mock the accumulated price values
(uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast) = IUniswapV2Pair(pair).getReserves();
if (blockTimestampLast != blockTimestamp) {
// subtraction overflow is desired
uint32 timeElapsed = blockTimestamp - blockTimestampLast;
// addition overflow is desired
// counterfactual
price0Cumulative += uint256(FixedPoint.fraction(reserve1, reserve0)._x) * timeElapsed;
// counterfactual
price1Cumulative += uint256(FixedPoint.fraction(reserve0, reserve1)._x) * timeElapsed;
}
}
}
// File @openzeppelin/contracts/utils/[email protected]
pragma solidity >=0.6.0 <0.8.0;
/*
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with 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.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address payable) {
return msg.sender;
}
function _msgData() internal view virtual 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/access/[email protected]
pragma solidity >=0.6.0 <0.8.0;
/**
* @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.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev Initializes the contract setting the deployer as the initial owner.
*/
constructor () internal {
address msgSender = _msgSender();
_owner = msgSender;
emit OwnershipTransferred(address(0), msgSender);
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view virtual returns (address) {
return _owner;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
_;
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions anymore. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby removing any functionality that is only available to the owner.
*/
function renounceOwnership() public virtual onlyOwner {
emit OwnershipTransferred(_owner, address(0));
_owner = address(0);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
}
// File contracts/owner/Operator.sol
pragma solidity 0.6.12;
contract Operator is Context, Ownable {
address private _operator;
event OperatorTransferred(address indexed previousOperator, address indexed newOperator);
constructor() internal {
_operator = _msgSender();
emit OperatorTransferred(address(0), _operator);
}
function operator() public view returns (address) {
return _operator;
}
modifier onlyOperator() {
require(_operator == msg.sender, "operator: caller is not the operator");
_;
}
function isOperator() public view returns (bool) {
return _msgSender() == _operator;
}
function transferOperator(address newOperator_) public onlyOwner {
_transferOperator(newOperator_);
}
function _transferOperator(address newOperator_) internal {
require(newOperator_ != address(0), "operator: zero address given for new operator");
emit OperatorTransferred(address(0), newOperator_);
_operator = newOperator_;
}
}
// File contracts/utils/Epoch.sol
pragma solidity ^0.6.0;
contract Epoch is Operator {
using SafeMath for uint256;
uint256 private period;
uint256 private startTime;
uint256 private lastEpochTime;
uint256 private epoch;
/* ========== CONSTRUCTOR ========== */
constructor(
uint256 _period,
uint256 _startTime,
uint256 _startEpoch
) public {
period = _period;
startTime = _startTime;
epoch = _startEpoch;
lastEpochTime = startTime.sub(period);
}
/* ========== Modifier ========== */
modifier checkStartTime {
require(now >= startTime, 'Epoch: not started yet');
_;
}
modifier checkEpoch {
uint256 _nextEpochPoint = nextEpochPoint();
if (now < _nextEpochPoint) {
require(msg.sender == operator(), 'Epoch: only operator allowed for pre-epoch');
_;
} else {
_;
for (;;) {
lastEpochTime = _nextEpochPoint;
++epoch;
_nextEpochPoint = nextEpochPoint();
if (now < _nextEpochPoint) break;
}
}
}
/* ========== VIEW FUNCTIONS ========== */
function getCurrentEpoch() public view returns (uint256) {
return epoch;
}
function getPeriod() public view returns (uint256) {
return period;
}
function getStartTime() public view returns (uint256) {
return startTime;
}
function getLastEpochTime() public view returns (uint256) {
return lastEpochTime;
}
function nextEpochPoint() public view returns (uint256) {
return lastEpochTime.add(period);
}
/* ========== GOVERNANCE ========== */
function setPeriod(uint256 _period) external onlyOperator {
require(_period >= 1 hours && _period <= 48 hours, '_period: out of range');
period = _period;
}
function setEpoch(uint256 _epoch) external onlyOperator {
epoch = _epoch;
}
}
// File contracts/Oracle.sol
pragma solidity 0.6.12;
// fixed window oracle that recomputes the average price for the entire period once every period
// note that the price average is only guaranteed to be over at least 1 period, but may be over a longer period
contract Oracle is Epoch {
using FixedPoint for *;
using SafeMath for uint256;
/* ========== STATE VARIABLES ========== */
// uniswap
address public token0;
address public token1;
IUniswapV2Pair public pair;
// oracle
uint32 public blockTimestampLast;
uint256 public price0CumulativeLast;
uint256 public price1CumulativeLast;
FixedPoint.uq112x112 public price0Average;
FixedPoint.uq112x112 public price1Average;
/* ========== CONSTRUCTOR ========== */
constructor(
IUniswapV2Pair _pair,
uint256 _period,
uint256 _startTime
) public Epoch(_period, _startTime, 0) {
pair = _pair;
token0 = pair.token0();
token1 = pair.token1();
price0CumulativeLast = pair.price0CumulativeLast(); // fetch the current accumulated price value (1 / 0)
price1CumulativeLast = pair.price1CumulativeLast(); // fetch the current accumulated price value (0 / 1)
uint112 reserve0;
uint112 reserve1;
(reserve0, reserve1, blockTimestampLast) = pair.getReserves();
require(reserve0 != 0 && reserve1 != 0, "Oracle: NO_RESERVES"); // ensure that there's liquidity in the pair
}
/* ========== MUTABLE FUNCTIONS ========== */
/** @dev Updates 1-day EMA price from Uniswap. */
function update() external checkEpoch {
(uint256 price0Cumulative, uint256 price1Cumulative, uint32 blockTimestamp) = UniswapV2OracleLibrary.currentCumulativePrices(address(pair));
uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
if (timeElapsed == 0) {
// prevent divided by zero
return;
}
// overflow is desired, casting never truncates
// cumulative price is in (uq112x112 price * seconds) units so we simply wrap it after division by time elapsed
price0Average = FixedPoint.uq112x112(uint224((price0Cumulative - price0CumulativeLast) / timeElapsed));
price1Average = FixedPoint.uq112x112(uint224((price1Cumulative - price1CumulativeLast) / timeElapsed));
price0CumulativeLast = price0Cumulative;
price1CumulativeLast = price1Cumulative;
blockTimestampLast = blockTimestamp;
emit Updated(price0Cumulative, price1Cumulative);
}
// note this will always return 0 before update has been called successfully for the first time.
function consult(address _token, uint256 _amountIn) external view returns (uint144 amountOut) {
if (_token == token0) {
amountOut = price0Average.mul(_amountIn).decode144();
} else {
require(_token == token1, "Oracle: INVALID_TOKEN");
amountOut = price1Average.mul(_amountIn).decode144();
}
}
function twap(address _token, uint256 _amountIn) external view returns (uint144 _amountOut) {
(uint256 price0Cumulative, uint256 price1Cumulative, uint32 blockTimestamp) = UniswapV2OracleLibrary.currentCumulativePrices(address(pair));
uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
if (_token == token0) {
_amountOut = FixedPoint.uq112x112(uint224((price0Cumulative - price0CumulativeLast) / timeElapsed)).mul(_amountIn).decode144();
} else if (_token == token1) {
_amountOut = FixedPoint.uq112x112(uint224((price1Cumulative - price1CumulativeLast) / timeElapsed)).mul(_amountIn).decode144();
}
}
event Updated(uint256 price0CumulativeLast, uint256 price1CumulativeLast);
}