Question

I need to implement a Win32 DLL and need call it by C# DllImport in WinCE.
So I create a Win32 Smart Device Project and choice Windows Mobile 5.0 Smartphone SDK,
and create a dll project with Export symbols option.
Then I add extern “C” key word before function declare:

.h

#ifdef WINCE2_EXPORTS
#define WINCE2_API __declspec(dllexport)
#else
#define WINCE2_API extern "C" __declspec(dllimport)
#endif
extern "C" WINCE2_API int __cdecl Add(int A,int B);

.cpp

extern "C" WINCE2_API int __cdecl Add(int A,int B)
{
    return A+B;
}

When I use DllImport in C#:

[DllImport("WinCE2.dll", EntryPoint = "Add")]
static extern int Add(int A, int B);

I always got a System.MissingMethodException in WinCE 5.0 emulator and WinCE6.0 Device.

I searched some information on google, found some solution.
First, Add .def in project:

LIBRARY     "WinCE2"
EXPORTS
Add         DATA 

But in a forum someone say __declspec(dllexport) can replace the .def file.
But this solution also got System.MissingMethodException.

Then I found a solution on Stack Overflow:
May I need add __cdecl key word.
And I created a Win32 DLL Project, I found the project setting will add __cdecl in default.
But Win32 Smartphone project is not.
So I try it, but also got System.MissingMethodException.
Then I try the same code in Win32 DLL and call by C#, it can work.
So I don’t why wince can’t work.
I had copied the dll to wince executable file folder
Can anyone share me some expeience?

Answer 1

You built this using the Smartphone SDK, which is ARM-based. The CE 5.0 emulator emulated x86, so it’s not going to be callable there. If your CE 6.0 device is likewise x86-based, it too is going to have the same problem. Try building it using an x86 SDK.