DataFieldParsing.sol

pragma solidity ^0.4.19;


contract Interchain {
    
    bytes public selector;
    bytes public destHash;
    
    function withdrawal(bytes32 destHash) returns(bytes4){
        return this.withdrawal.selector;
    }
    
    function parse(bytes _selector, bytes _destHash) returns (bytes b){
        selector = _selector;
        destHash = _destHash;
        b = strConcat(_selector,_destHash);
    }
    
    function strConcat(bytes _a, bytes _b) public  returns (bytes){
        bytes memory _aa = _a;
        bytes memory _bb = _b;
        bytes memory ab = new bytes(_aa.length + _bb.length);
        uint l = _aa.length;
        
        assembly{
            mstore(add(ab,32),mload(add(_aa,32)))
            mstore(add(add(ab,32),l),mload(add(_bb,32)))
        }
        bytes memory b = new bytes(36);
        assembly { mstore(add(b, 32), mload(add(ab,32))) }
        return b;
    }
    
}