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| // SPDX-License-Identifier: BUSL-1.1 | ||
| pragma solidity 0.8.15; | ||
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| import "../vendor/@chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol"; | ||
| import "../IPriceFeed.sol"; | ||
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| /** | ||
| * @title Multiplicative price feed | ||
| * @notice A custom price feed that multiplies the prices from two price feeds and returns the result | ||
| * @author Compound | ||
| */ | ||
| contract ReverseMultiplicativePriceFeed is IPriceFeed { | ||
| /** Custom errors **/ | ||
| error BadDecimals(); | ||
| error InvalidInt256(); | ||
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| /// @notice Version of the price feed | ||
| uint public constant VERSION = 1; | ||
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| /// @notice Description of the price feed | ||
| string public override description; | ||
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| /// @notice Number of decimals for returned prices | ||
| uint8 public immutable override decimals; | ||
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| /// @notice Chainlink price feed A | ||
| address public immutable priceFeedA; | ||
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| /// @notice Chainlink price feed B | ||
| address public immutable priceFeedB; | ||
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| /// @notice Combined scale of the two underlying Chainlink price feeds | ||
| int public immutable priceFeedAScalling; | ||
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| /// @notice Scale of this price feed | ||
| int public immutable priceFeedScale; | ||
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| /** | ||
| * @notice Construct a new multiplicative price feed | ||
| * @param priceFeedA_ The address of the first price feed to fetch prices from | ||
| * @param priceFeedB_ The address of the second price feed to fetch prices from that should be reversed | ||
| * @param decimals_ The number of decimals for the returned prices | ||
| * @param description_ The description of the price feed | ||
| **/ | ||
| constructor(address priceFeedA_, address priceFeedB_, uint8 decimals_, string memory description_) { | ||
| priceFeedA = priceFeedA_; | ||
| priceFeedB = priceFeedB_; | ||
| uint8 priceFeedADecimals = AggregatorV3Interface(priceFeedA_).decimals(); | ||
| priceFeedAScalling = signed256(10 ** (priceFeedADecimals)); | ||
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| if (decimals_ > 18) revert BadDecimals(); | ||
| decimals = decimals_; | ||
| description = description_; | ||
| priceFeedScale = int256(10 ** decimals); | ||
| } | ||
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Check warning Code scanning / Semgrep OSS There're no sanity checks for the constructor argument description_. Warning
There're no sanity checks for the constructor argument description_.
Check warning Code scanning / Semgrep OSS There're no sanity checks for the constructor argument priceFeedA_. Warning
There're no sanity checks for the constructor argument priceFeedA_.
Check warning Code scanning / Semgrep OSS There're no sanity checks for the constructor argument priceFeedB_. Warning
There're no sanity checks for the constructor argument priceFeedB_.
Check warning Code scanning / Semgrep OSS Consider making costructor payable to save gas. Warning
Consider making costructor payable to save gas.
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| /** | ||
| * @notice Calculates the latest round data using data from the two price feeds | ||
| * @return roundId Round id from price feed B | ||
| * @return answer Latest price | ||
| * @return startedAt Timestamp when the round was started; passed on from price feed B | ||
| * @return updatedAt Timestamp when the round was last updated; passed on from price feed B | ||
| * @return answeredInRound Round id in which the answer was computed; passed on from price feed B | ||
| * @dev Note: Only the `answer` really matters for downstream contracts that use this price feed (e.g. Comet) | ||
| **/ | ||
| function latestRoundData() override external view returns (uint80, int256, uint256, uint256, uint80) { | ||
| (, int256 priceA, , , ) = AggregatorV3Interface(priceFeedA).latestRoundData(); | ||
| (uint80 roundId_, int256 priceB, uint256 startedAt_, uint256 updatedAt_, uint80 answeredInRound_) = AggregatorV3Interface(priceFeedB).latestRoundData(); | ||
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| if (priceA <= 0 || priceB <= 0) return (roundId_, 0, startedAt_, updatedAt_, answeredInRound_); | ||
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| // int256 price = priceA * priceB * priceFeedScale / combinedScale; | ||
| int256 price = priceA * int256(10**(AggregatorV3Interface(priceFeedB).decimals())) * priceFeedScale / priceB / priceFeedAScalling; | ||
| return (roundId_, price, startedAt_, updatedAt_, answeredInRound_); | ||
| } | ||
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| function signed256(uint256 n) internal pure returns (int256) { | ||
| if (n > uint256(type(int256).max)) revert InvalidInt256(); | ||
| return int256(n); | ||
| } | ||
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| /** | ||
| * @notice Price for the latest round | ||
| * @return The version of the price feed contract | ||
| **/ | ||
| function version() external pure returns (uint256) { | ||
| return VERSION; | ||
| } | ||
| } | ||
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