My present code seems to work and looks like:
extern "C" void __stdcall stdway(char * string, char *str)
and I use a DEF file (the C++ one, not the MB one), such as:
LIBRARY waysyn1
EXPORTS
stdway @1
This seems to work in C/C++ (V6), VBA and MB; with the DEF function, the exported name
ends up to be stdway and not _stdway@8.
In MB, the declaration is:
Declare Sub stdway Lib "waysyn1.dll" (ByVal str1 As String, str2 As String)
Thanks for your help
Pierre Henrotay
Siemens Information and Communications
mailto:[EMAIL PROTECTED]
http://www.siemens.be/ic
> -----Original Message-----
> From: [EMAIL PROTECTED] [SMTP:[EMAIL PROTECTED]]
> Sent: Wednesday, December 04, 2002 1:47 PM
> To: HENROTAY PIERRE
> Cc: [EMAIL PROTECTED]
> Subject: SV: MI-L DLLs and MapBasic: calling convention ? (2)
>
> Pierre -
>
> You can use the functions from MapBasic with the "mangled" names:
>
> When you compile the functions with __stdcall in vc 6.0 you'll get the
> following "name decoration" :
>
> 1) the function name gets prefixed with "_"
> 2) the function name get postfixed with "@nn" where nn is the size in bytes
> of the all the function arguments.
> Strings is always transferred from MapBasic as char pointers, and
> pointers are 4 bytes
>
> example (from MITAB opensource library to read and write binary tab-files) :
>
> Declare Function mitab_c_get_text_vb Lib "mitab.dll"
> Alias "_mitab_c_get_text_vb@12"
> (ByVal feature As Integer, ByVal text As String, ByVal l As Integer) As
> Integer
>
> mitab_c_get_text_vb becomes: _mitab_c_get_text_vb@12
> size of argumentlist: 1 Mapbasic Integer, (4 bytes) + 1 textstring, pointer
> (4 bytes) + 1 MapBasic Integer( 4 bytes) = 12 Bytes
>
> regards
> Bo Thomsen
> GeoConsult
>
> -----Oprindelig meddelelse-----
> Fra: HENROTAY PIERRE [mailto:[EMAIL PROTECTED]]
> Sendt: 4. december 2002 11:26
> Til: '[EMAIL PROTECTED]'
> Emne: MI-L DLLs and MapBasic: calling convention ? (2)
>
>
>
> I was asking recently the following question (thanks to Warren Vick and Bo
> Thomsen for their input !)
>
> "I am creating DLLs in VC++, to be called from MB.
> By default, the argument uses the __cdecl argument passing convention
> (caller pops the stack).
> Is this OK or should I use __stdcall (the Pascal convention, called function
> pops the stack)."
>
> I need to add a few more info:
>
> 1) The DLLs are supposed to be accessible from MB, VB(A), C/C++ etc...
>
> 2) VBA cannot use DLLs with the __cdecl calling convention (Knowledge Base
> Article 213554): this leads to error 49, "Bad DLL calling convention";
> __stdcall is required (which is the case for most 32 bits DLL included with
> Windows).
>
> 3) The MB user guide says (chapter 10) nothing about whether __stdcall or
> __cdecl should be used, only to not use __fastcall. It does not say that MB
> (caller) is able to pop the stack; if not properly done, this is likely lead
> to problems at some time.
>
> So my present conclusion is that __stdcall is required. Problem is that this
> convention leads to name decoration (name is postfixed with @ and number of
> bytes for arg list). A VC++ DEF file is thus required to get the proper
> final name. Still investigating on this.
>
>
> Pierre Henrotay
> Siemens Information and Communications
> Siemens Business Services s.a./n.v.
>
>
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