Price Feed On-chain

Bracle Price feeds continuously stream price updates to blockchains, with each feed stored within a smart contract. Application developers can easily pass these contracts on their own, then deserialize the data to read the current feed value. Bracle Price Feeds also offer a "pull" model for price updates, where users are responsible for posting updates to the chain as needed. For more information on this model and its implications for integrators, refer to Bracles documentation. In the pull model, developers should integrate Bracle into both their on-chain and off-chain code:

• On-chain programs should read prices from the Bracle program deployed on the same chain.

Bracle provides BounceBit-specific SDK to assist with the integration process, both on-chain and off-chain. The simplest way to utilize Bracle price feeds is to integrate the relevant SDKs into your application."

Reading data feeds on-chain

To consume price data, your smart contract should reference IAggregator.sol, which defines the external functions implemented by Data Feeds.

IAggregator.sol

// SPDX-License-Identifier: LGPL-3.0
pragma solidity 0.8.20;

interface IAggregator {
  /**
   * @notice median from the most recent report
   */
  function latestAnswer() external view returns (int256);

  /**
   * @notice timestamp of block in which last report was transmitted
   */
  function latestTimestamp() external view returns (uint256);

  /**
   * @notice Aggregator round (NOT OCR round) in which last report was transmitted
   */
  function latestRound() external view returns (uint256);

  /**
   * @notice median of report from given aggregator round (NOT OCR round)
   * @param _roundId the aggregator round of the target report
   */
  function getAnswer(uint256 _roundId) external view returns (int256);

  /**
   * @notice timestamp of block in which report from given aggregator round was transmitted
   * @param _roundId aggregator round (NOT OCR round) of target report
   */
  function getTimestamp(uint256 _roundId) external view returns (uint256);

  /**
   * @return answers are stored in fixed-point format, with this many digits of precision
   */
  function decimals() external view returns (uint8);

  /**
   * @notice human-readable description of observable this contract is reporting on
   */
  function description() external view returns (string memory);

  /**
   * @notice aggregator contract version
   */
  function version() external view returns (uint256);

  /**
   * @notice details for the given aggregator round
   * @param _roundId target aggregator round (NOT OCR round). Must fit in uint32
   * @return roundId _roundId
   * @return answer median of report from given _roundId
   * @return startedAt timestamp of block in which report from given _roundId was transmitted
   * @return updatedAt timestamp of block in which report from given _roundId was transmitted
   * @return answeredInRound _roundId
   */
  function getRoundData(
    uint80 _roundId
  ) external view returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound);

  /**
   * @notice aggregator details for the most recently transmitted report
   * @return roundId aggregator round of latest report (NOT OCR round)
   * @return answer median of latest report
   * @return startedAt timestamp of block containing latest report
   * @return updatedAt timestamp of block containing latest report
   * @return answeredInRound aggregator round of latest report
   */
  function latestRoundData()
    external
    view
    returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound);
}

Example

// SPDX-License-Identifier: LGPL-3.0
pragma solidity 0.8.20;

import {IAggregator} from "../interfaces/IAggregator.sol";

/**
 * THIS IS AN EXAMPLE CONTRACT THAT USES HARDCODED
 * VALUES FOR CLARITY.
 * THIS IS AN EXAMPLE CONTRACT THAT USES UN-AUDITED CODE.
 * DO NOT USE THIS CODE IN PRODUCTION.
 */
contract DataConsumer {
    IAggregator internal dataFeed;

    /**
     * Network: BounceBit
     * Aggregator: BBTC/USD
     * Address: 0xf136f4Af2F431034C8803C4c892609292D915A46
     */
    constructor() {
        dataFeed = IAggregator(
            0xf136f4Af2F431034C8803C4c892609292D915A46
        );
    }

    /**
     * Returns the latest answer.
     */
    function getBracleDataFeedLatestAnswer() public view returns (int) {
        // prettier-ignore
        (
            /* uint80 roundID */,
            int answer,
            /*uint startedAt*/,
            /*uint timeStamp*/,
            /*uint80 answeredInRound*/
        ) = dataFeed.latestRoundData();
        return answer;
    }
}