Create Solidity Interface

Just like in the MD5 section, we will start off by first demonstrating the Solidity interface for the Calculator precompile before guiding you on how to build the CalculatorPlus precompile. To start, let's take a look at the Calculator Solidity interface:

solidity/interfaces/ICalculator.sol

// SPDX-License-Identifier: MIT
 
pragma solidity >=0.8.0;
 
interface ICalculator {
    function add(uint value1, uint value2) external view returns(uint result);
 
    function nextTwo(uint value1) external view returns(uint result1, uint result2);
 
    function repeat(uint times, string memory text) external view returns(string memory result);
}

With this in mind, let's define the CalculatorPlus Solidity interface. Your interface should have the following three functions:

powOfThree: takes in an unsigned integer base, and returns three unsigned integers named secondPow, thirdPow, fourthPow .
moduloPlus: takes in unsigned integers dividend and divisor as input, and returns two unsigned integers named multiple and remainder .
simplFrac: takes in unsigned integers named numerator and denominator, and returns two unsigned integers named simplNum and simplDenom

Generate the ABI

Now that we have an interface of our precompile, let's create an ABI of our Solidity interface. Open the terminal (control + `), change to the /contracts directory and run the following command to compile the solidity interface to the ABI:

# Go to the upper contracts directory of your project
cd contracts
 
# Compile ICalculatorPlus.sol to ABI
npx solc@latest --abi ./contracts/interfaces/ICalculatorPlus.sol -o ./abis --base-path . --include-path ./node_modules
 
# Rename using this script or manually
mv ./abis/contracts_interfaces_ICalculatorPlus_sol_ICalculatorPlus.abi ./abis/ICalculatorPlus.abi

Now you should have a file called ICalculatorPlus.abi in the folder /contracts/abis with the following content:

/contracts/abis/ICalculatorPlus.abi

[
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "dividend",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "divisor",
        "type": "uint256"
      }
    ],
    "name": "moduloPlus",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "multiple",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "remainder",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "base",
        "type": "uint256"
      }
    ],
    "name": "powOfThree",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "secondPow",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "thirdPow",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "fourthPow",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "numerator",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "denominator",
        "type": "uint256"
      }
    ],
    "name": "simplFrac",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "simplNum",
        "type": "uint256"
      },
      {
        "internalType": "uint256",
        "name": "simplDenom",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  }
]

Solution

Generate the ABI

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