RE: [cinvoke-dev] Calling a function from a VCL DLL

[Will Weisser]

There were two issues here:

1) MyFunc uses the cdecl calling convention, not stdcall.
2) C/Invoke was underflowing the intel fp stack, and apparently VCL
dll's set the fp control register not to ignore stack fault exceptions.

As of now there is a patch in Subversion to fix #2, but I know you can't
compile C/Invoke from source right now because you don't have VC++, so
when I get home I'll work on getting you a new .dll.

        -W.W.


-----Original Message-----
From: address@hidden
[mailto:address@hidden On Behalf Of
Shmuel Zeigerman
Sent: Monday, August 14, 2006 5:55 AM
To: address@hidden
Subject: [cinvoke-dev] Calling a function from a VCL DLL

My installation of C/Invoke (cinvoke.dll + cinvoke_lua.dll)
fails on a DLL (mydll.dll) created by Borland C++ Builder.

* The C/Invoke failure takes place only if 'mydll'
   is built with the option "use VCL".

* This same DLL that fails, works fine if used without
   C/Invoke, i.e. via LoadLibrary() and GetProcAddress().

* Debugging shows that something incorrect takes place in
   the function cinv_function_invoke. It's being called,
   returns and shortly after that the programs crashes.

* Two debuggers gave the following messages:
   a) Project c:\exe\lua.exe faulted with message:
      'floating point stack check at 0x10002130'.
   b) Program received signal SIGFPE, Arithmetic Exception.

Here's the C and Lua codes:

// unit1.cpp
#include <vcl.h>
extern "C" __declspec(dllexport)
int __stdcall MyFunc(void)
{
   return 2006;
}

-- test1.lua
require ("cinvoke_lua")
lib = clibrary.new ("mydll", "stdcall")
MyFunc = lib:get_function (Cint, "MyFunc")
print (MyFunc ())

-- 
Shmuel


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