Whitenoise challenge submission

whitenoise.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.15;
interface ISolution {
    /// @dev Returns the EOA you will be calling the Challenge contract
    ///      from. Used to ensure your solution cannot be used by other
    ///      participants.
    function owner() external view returns (address);

    /// @dev Your solution to the problem.
    /// @return abi.encodePacked(uint128(evenSum), uint128(oddSum))
    function solve(uint256) external returns (uint256);
}
contract Solution is ISolution {
    address public constant owner = 0xOWNERADDRESS;
    
    constructor() { } 
    
    /// @dev Your solution to the problem.
    // @return abi.encodePacked(uint128(evenSum), uint128(oddSum))
    /// 8 bit packed
    function solve(uint256 input) external pure returns (uint256 ret) {
        assembly {
            let even
            let odd
            let aux

            for { let i := 0} lt(i, 32) { i:= add(i,1) }
            {
                aux := shr(mul(sub(31, i), 8) , and(input, shr(mul(i, 8), 0xff00000000000000000000000000000000000000000000000000000000000000)))
                switch mod(aux,2)
                case 0 { even := add(even, aux) }
                case 1 { odd := add(odd, aux) }
            }

            ret := or(odd, shl(128, even))
        }
    }
}