Parsing the TxnInput

Parsing.sol

contract Parsing {
    
    function callNumber(uint256 number) public view returns(bytes32){
        bytes32 hash = keccak256("callNumber(uint256)");
        return hash;
    }
    
    function callAddress(address _addr) public view returns(bytes32){
        bytes32 hash = keccak256("callAddress(address _addr)");
        return hash;
    }
    
    function parsing(bytes _txnInput) public view returns(uint) {
        uint length = _txnInput.length;
        
        //pseudocode
        //1. copy the first 8 bytes in byte array  
        //2. copy the 32 byte which hold the parameter in a byte array (which is hex)
        //3. convert hex into decimal and get the method parameter
        // Is this pseudocode right ?
        
        //       bytes32 result;
        //       uint j=10;
        //       for(uint i=0;i<length-10;i++) {
        //           result[i] = _txnData[j];
        //           j++;
        //       }
        //   }
        return length;
    }
}