Using the Oracle Precompile (0x...1008)

Sei provides an Oracle Precompile at address 0x0000000000000000000000000000000000001008 that allows EVM contracts to read price data directly from Sei's native oracle module. This is crucial for DeFi applications needing reliable price feeds.

Key Functions (Solidity Interface):

interface ISeiOraclePrecompile {
    // --- Return Struct Definitions --- 
    struct OracleExchangeRate {
        string ExchangeRate;        // The exchange rate, represented as a string decimal.
        string LastUpdate;          // Timestamp of the last successful update (as string).
        int64  LastUpdateTimestamp; // Timestamp of the last successful update (as int64 epoch seconds).
    }

    struct DenomOracleExchangeRatePair {
        string Denom;                 // The denomination string (e.g., "usei", "uatom").
        OracleExchangeRate OracleExchangeRateVal; // The rate details.
    }

    struct OracleTwap {
        string Denom;           // The denomination string.
        string Twap;            // The time-weighted average price (as string decimal).
        int64  LookbackSeconds; // The lookback period used for calculation.
    }

    // --- View Functions --- 

    /**
     * @notice Gets the latest exchange rates for all tracked denominations.
     * @return rates An array of structs containing denom and rate information.
     */
    function getExchangeRates() external view returns (DenomOracleExchangeRatePair[] memory rates);

    /**
     * @notice Calculates and returns Time-Weighted Average Prices (TWAPs) for all tracked denominations.
     * @param lookbackSeconds The duration (in seconds) over which to calculate the TWAP.
     * @return twaps An array of structs containing denom and TWAP information.
     */
    function getOracleTwaps(uint64 lookbackSeconds) external view returns (OracleTwap[] memory twaps);
}

How to Use:

1. Interface: Define or import the ISeiOraclePrecompile interface in your contract.
2. Instantiate: Get a reference: ISeiOraclePrecompile constant seiOracle = ISeiOraclePrecompile(0x0000000000000000000000000000000000001008);
3. Call Functions: Invoke getExchangeRates() or getOracleTwaps(lookback_seconds).

Important Considerations:

• String Decimal Prices: The most critical point is that ExchangeRate and Twap values are returned as strings, not uint256. These strings represent potentially high-precision decimal numbers.
  • Handling in Solidity: You cannot directly cast these strings to uint256 or use them in standard arithmetic operations if they contain decimals. You must either:
    • Use a Solidity library designed for handling decimal strings or fixed-point arithmetic (e.g., ABDKMath64x64, PRBMath) to parse the string and convert it into a usable fixed-point representation.
    • Pass the string price off-chain for processing.
• Read-Only: Both functions are view functions (read-only) and are non-payable (msg.value must be 0).
• Gas: Gas costs are relatively low, primarily for reading oracle state.
• Available Denoms: The functions return data for all denominations currently tracked by the Sei oracle module.

Example Usage (Conceptual - requires parsing library):

// Assume FixedPoint library exists for string decimal parsing
import { FixedPoint } from "./FixedPoint.sol"; 

contract OracleUser {
    ISeiOraclePrecompile constant seiOracle = ISeiOraclePrecompile(0x...);

    function checkSeiPriceAgainstThreshold(string memory priceThreshold) public view {
        ISeiOraclePrecompile.DenomOracleExchangeRatePair[] memory rates = seiOracle.getExchangeRates();
        string memory currentPriceStr;
        for (uint i = 0; i < rates.length; i++) {
            if (keccak256(abi.encodePacked(rates[i].Denom)) == keccak256(abi.encodePacked("usei"))) { // Assuming "usei" price vs reference
                currentPriceStr = rates[i].OracleExchangeRateVal.ExchangeRate;
                break;
            }
        }
        require(bytes(currentPriceStr).length > 0, "Price not found");

        int256 currentPrice = FixedPoint.parseDecimal(currentPriceStr);
        int256 thresholdPrice = FixedPoint.parseDecimal(priceThreshold);

        require(currentPrice >= thresholdPrice, "Price is below threshold");
    }
}