GM Price Oracle

GM Lending/Looping asset prices are obtained via a combination of the USDC Chainlink Oracle and previously deployed GMI Price Oracle contracts. As such, this current Oracle version behaves more like a Price Router in practice, but for simplicity's and posterity's sakes, it is labeled as a Price Oracle here.

At deployment, the Oracle contract stores addresses (the GMX GM token addresses and the USDC token address) for use in getUnderlyingPrice(). The contract has no constructor.

getUnderlyingPrice

function getUnderlyingPrice(ERC20 asset) external view returns (uint256)

Retrieves the current price of the token provided. If the asset is USDC, then the function calls the internal function getPriceFromChainlink() and relays the USDC price returned by that function call (see the section below for details). If the asset is a valid GM token (gmBTC, gmETH, or gmSOL), then the respective GMI price oracle contract is stored in the oracle variable. getPrice() is then called on the oracle instance, and the final price is returned. If the asset is not a valid GM token, then the function returns zero.

To see how getPrice() interacts with GMX architecture to retrieve current asset prices, please head to the GMI Token Oracles section.

Parameters:

Name	Type	Description
asset	ERC20	Retrieves the price for this asset

Returns:

Name	Type	Description
x	uint256	The price of the GM token, determined by the GMX reader contract. The price will have 18 decimals. If USDC, the price is returned by the Chainlink Arbitrum Mainnet USDC Price Feed.

getPriceFromChainlink

function getPriceFromChainlink() internal view returns (uint256)

Retrieves the current price of USDC. Chainlink's USDC price feed address is typecast to the AggregatorV3Interface type. The function then calls latestRoundData() on the price feed instance to retrieve the latest round's price. After a type conversion, the answer is fed back into getUnderlyingPrice() where it is upscaled to 18 decimals to play nice with collateral asset decimals, and the final price is returned by the function.

Parameters:

Name	Type	Description
feedId	address	The Chainlink Price Feed contract address of the token

Returns:

Name	Type	Description
answer	uint256	The Oracle-returned price (with 8 decimals) of the token.