Hi Mattias, Many thanks for your prompt response :-) The declarations for the C functions involved are:
// Callback function pointer def typedef unsigned (__cdecl *ioCallbackPtr)(unsigned char *buffer, unsigned long count, unsigned long filePtr); // Declaration for function I call from C# void *tpFunction(void *, ioCallbackPtr, unsigned long); // Declaration for fread() - called from the callback size_t fread(void *buffer, size_t size, size_t count, FILE *stream); I'll make the changes you suggest, i.e. setting CallingConvention.Cdecl in the fread() DllImport attribute and attempt to verify the version of the C runtime that's being used (although I don't believe the initial function actually uses the FILE pointer). If the initial function expects the callback to be called with the cdecl calling convention, can that be specified in the C# declaration for the callback? Best regards, Ron ----- Original Message ----- From: Mattias Sjögren <[EMAIL PROTECTED]> Date: Tuesday, January 27, 2004 2:01 pm Subject: Re: [ADVANCED-DOTNET] Callbacks from unmanaged code > Ron, > > Can you post the C function declarations? That would make it > easier to help > you find errors. Some things you should keep in mind > > - The CRT functions use the cdecl calling conventions. You should > set > CallingConvention.Cdecl in the fread() DllImport attribute. > > - If the callback function is supposed to use the cdecl convention > too, you > have to fix that (which is non trivial). Delegates are marshaled > to stdcall > function pointers by default. > > - If the third party library uses the FILE pointer internally, you > have to > verify that you're using the same C runtime version. > > > Mattias > > -- > Mattias Sjögren > [EMAIL PROTECTED] > > =================================== > This list is hosted by DevelopMentor® http://www.develop.com > Some .NET courses you may be interested in: > > NEW! Guerrilla ASP.NET, 26 Jan 2004, in Los Angeles > http://www.develop.com/courses/gaspdotnetls > > View archives and manage your subscription(s) at > http://discuss.develop.com =================================== This list is hosted by DevelopMentor® http://www.develop.com Some .NET courses you may be interested in: NEW! Guerrilla ASP.NET, 26 Jan 2004, in Los Angeles http://www.develop.com/courses/gaspdotnetls View archives and manage your subscription(s) at http://discuss.develop.com
