InterestRateModel.sol

pragma solidity ^0.4.24;

/**
  * @title The Compound InterestRateModel Interface
  * @author Compound
  * @notice Any interest rate model should derive from this contract.
  * @dev These functions are specifically not marked `pure` as implementations of this
  *      contract may read from storage variables.
  */
contract InterestRateModel {

    /**
      * @notice Gets the current supply interest rate based on the given asset, total cash and total borrows
      * @dev The return value should be scaled by 1e18, thus a return value of
      *      `(true, 1000000000000)` implies an interest rate of 0.000001 or 0.0001% *per block*.
      * @param asset The asset to get the interest rate of
      * @param cash The total cash of the asset in the market
      * @param borrows The total borrows of the asset in the market
      * @return Success or failure and the supply interest rate per block scaled by 10e18
      */
    function getSupplyRate(address asset, uint cash, uint borrows) public view returns (uint, uint);

    /**
      * @notice Gets the current borrow interest rate based on the given asset, total cash and total borrows
      * @dev The return value should be scaled by 1e18, thus a return value of
      *      `(true, 1000000000000)` implies an interest rate of 0.000001 or 0.0001% *per block*.
      * @param asset The asset to get the interest rate of
      * @param cash The total cash of the asset in the market
      * @param borrows The total borrows of the asset in the market
      * @return Success or failure and the borrow interest rate per block scaled by 10e18
      */
    function getBorrowRate(address asset, uint cash, uint borrows) public view returns (uint, uint);
}