callWithData.sol

contract Test1 {
    function add(int a, int b) returns(bytes){  //Simply add the two arguments and return
        return abi.encode(a+b);
    }
}

contract Test2 {
    Test1 test1;

    function Test2(){
        test1 = new Test1(); 
    }
    
    function testAdd() constant returns(bytes) {
        //encoded add(int256,int256) call add(2,2) expected return 4
        bytes memory a = hex"a5f3c23b00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000002";
        return callWithData(address(test1), a);
    }
  
    function callWithData(address dest, bytes data) private returns (bytes c) {
        assembly {
            let freemem := mload(0x40)
            
            pop(
            call(      
                5000,
                dest,
                0,
                add(data, 0x20),
                mload(data),
                0,
                0
            )
            )
            
            let size := returndatasize
            returndatacopy(freemem, 0, size)
            
            return (freemem, size)
        }
    }
}