Method's type signature is not PInvoke compatible while calling DLL method

Question

I have a DLL with interface

struct modeegPackage
{
    uint8_t     version;    // = 2
    uint8_t     count;      // packet counter. Increases by 1 each pack         


        

Answer 1

It is the array that is causing the problem. The pinvoke marshaller doesn't like dealing with it in the specific case of returning a structure by value as a function return value. It is in general troublesome, the way this is done is highly compiler dependent. With good odds that you'll have trouble since it sounds like you are using GCC. It is typically done by the caller allocating space for the return value on the stack and passing a pointer to it.

A crude but effective trick is to expand the array yourself, practical enough since it has only 6 elements. Substitute the array like this:

        /// unsigned int[6]
        public short data0;
        public short data1;
        //...
        public short data5;

Which will solve the exception. Whether you'll get the data correctly remains to be seen, if not then you may have to switch to MSVC.