Hi,
I need to adapt a snippet of code interfacing a low-level driver
written in C++ so as to make it work under C#. I can compile and make
it work without any problem in C++, but I can't guess how to make it
work in C#.
Broadly speaking, the difficulty finds itself in the passing of a
struct as variable to a DLL function in C#.
The struct (itself containing another struct) looks like this:
In C++
=====
struct {
short s11;
short s12;
short s13;
short s14;
struct2 sa[20]
} struct1
struct{
long l21;
long l22;
long l23;
long l24;
short s21;
short s22;
short s23;
short s24;
} struct2
In C# (Adapting the long to int type so as to occupy 4 bytes)
====
struct {
short s11;
short s12;
short s13;
short s14;
struct2 sa[20]
} struct1
struct{
int l21; // long in C++ --> int in C# (4 bytes)
int l22;
int l23;
int l24;
short s21;
short s22;
short s23;
short s24;
} struct2
and the function looks like this:
In C++
=====
Declaration...
-----------------
int function1 (struct1* pStruct1);
Call...
--------
int1 = function1 (&pStruct1); // Once pStruct1 filled with data
In C# (Here come the problems):
========================
Declaration...
-----------------
[DllImport(_dllLocation)]
public static extern int function1(
struct1 pStruct1,
);
Call...
-------
int1 = StaticClass.function1(pStruct1); // Once pStruct1 filled with
data
***********************
I've tried different alternatives, but with no result at all:
1) Declaring...
Before the struct... [StructLayout(LayoutKind.Sequential, Pack=1,
Size=488)] / Size=24)]
Between the fields in the struct... [FieldOffset(0)] / [FieldOffset
(2)] / ...
I receive an error HRESULT "(HRESULT Exception: 0x80070057
(E_INVALIDARG))"
2) Declaring...
Before the struct array... [MarshalAs
(UnmanagedType.SafeArray,SizeConst=20)
I receive the same error
3) Letting pStruct only declared, but no filled with data, the
function is allowed to be called, but no processing is observed.
Could any help / recommendation be given, I would be really grateful,
since I am at a standstill at this moment and I don't know how to go
on.
Thanks a lot.
