Re: Wrapping around stdcall

[Marcus Meissner]

On Tue, Jul 05, 2005 at 07:42:23PM +0200, Maarten Lankhorst wrote:
> I have been trying to get some work done on a class returned by
> CreateTextServices, but the differences between windows' stdcall and
> linux' are giving me a few headaches. right now I've done it pretty much
> like this:
>
> /* These macros are taken from wine/dlls/msvcrt/cpp.c */
> #ifdef __i386__  /* thiscall functions are i386-specific */
>
> #define THISCALL(func) __thiscall_ ## func
> #define THISCALL_NAME(func) __ASM_NAME("__thiscall_" #func)
> #define DEFINE_THISCALL_WRAPPER(func) \
>     extern void THISCALL(func)(); \
>     __ASM_GLOBAL_FUNC(__thiscall_ ## func, \
>                       "popl %eax\n\t" \
>                       "pushl %ecx\n\t" \
>                       "pushl %eax\n\t" \
>                       "jmp " __ASM_NAME(#func) )
> #else /* __i386__ */
>
> #define THISCALL(func) func
> #define THISCALL_NAME(func) __ASM_NAME(#func)
> #define DEFINE_THISCALL_WRAPPER(func) /* nothing */
>
> #endif /* __i386__ */
> DEFINE_THISCALL_WRAPPER(fnTextSrv_TxSendMessage);
> static HRESULT __stdcall fnTextSrv_TxSendMessage(ITextServices *iface,
>                                               UINT msg,
>                                               WPARAM wparam,
>                                               LPARAM lparam,
>                                               LRESULT* plresult)
> { .... }
>
> static const ITextServicesVtbl textservices_Vtbl =
> {
>    fnTextSrv_QueryInterface,
>    fnTextSrv_AddRef,
>    fnTextSrv_Release,
>    THISCALL(fnTextSrv_TxSendMessage),
>    ... };
>
> This works, however it is not clean, it gives me 2 compiler warnings:
> 1: fnTextServ_TxSendMessage defined but not used

You can mark it as used with a __GNUC__ ifdef... like this:

#ifdef __GNUC__
__attribute__((used))
#endif
static HRESULT __stdcall fnTextSrv_TxSendMessage(ITextServices *iface,
> 2: initialisation from incompatible pointer type (in the vtable)

Hmm, unclear. You would need to change the extern void THISCALL(func)(); to
be the correct prototype.

__typeof__() games might not work.
> I wonder how I can do this cleaner (Meaning no compiler warnings without
>  ugly hacks). Also I would like to know how to call a function like
> __thiscall_fnTextSrv_TxSendMessage, because some methods I need are
> implemented in windows' stdcall. And I would like to know wether
> include/textserv.h needs to be adjusted now that I know they are not WINAPI.

Adding "thiscall" to gcc would perhaps help in the long run ... :/ Fun fun fun...

Ciao, Marcus