Fw: [fpc-pascal] AsciiZ confusion

[afpTeam]

Let me remove some comments....(sorry)

> Hi,
>
> Sorry this is a long message, but hard to explain.  I have a DLL I wrote 
> in FreePascal 2.0.2, which is communicating between a Delphi program and a 
> PowerBasic Dll, like follows...
>
> PBdll exports PBSub ByRef as AsciiZ   <> MyFreePascall_DLL <> 
> DelphiDLLstubByRef_Variants
>
> As noted, the Delphi Program integrates a DLL stub which forces me to make 
> calls using it's pre-defined "Variants Only" format.
>
> The problem comes when I pass data into FPC via "parameters" byRef through 
> a procedure, into the PowerBasic DLL. The first parameter returns 
> unmodified and the second parameter returns only one character wide, as if 
> FPC is trying to receive back a pointer only, to the string space where 
> the PB data resides.  Or possibly it's just garbage and looks this way.
>
> The FPC DLL is setup as follows:
> ============================
 {$LONGSTRINGS ON}

library DelphiXchg;

uses Variants, strings;

 //Declare PowerBasic external
procedure subXchngAsciiZ(Data1, DATA2:string)stdcall;external 'PB.DLL';

//Declare the Delphi calling stub (variants only);
function Delphstub(var vD1,vD2:variant):variant;stdcall;export;

begin
    if vD1 = 'test' then subXchngAsciiZ(vD1, vD2);

exports
Delphstub;        //unused

begin
end.
>
> ==========================
> When the Delphi calling program sends in the variant vD1:='test', (through 
> FPC to the PB DLL), FPC only gets back 'test' unmodified and variant vD2 
> is coming back as 'g', (only the first character, instead of 'good', (ahhh 
> but vD2 did get modified at least)).
>
> I thought that zero or null terminated AsciiZ data would handle the string 
> array length automatically in FPC, on < 255 wide, but now I'm supposing I 
> may have to break the variants out, use explicit calls internally by typed 
> pointer reference and then reload the outgoing variants with the result 
> data from the pointers to the explicit variables before returning, but 
> I've had no success in figuring out how to set that up correctly.
>
> Should it really be that much handling to pass AsciiZ on Variant types as 
> parameters, or am I overlooking something stupid simple?  The only example 
> I have to go by is a VB program that makes calls directly across to PB, 
> using ByRef ASCIIZ, so the problem seems mostly from being forced to use 
> the Variant types in parameters from the Delphi calling program.
>
> Thanks for any ideas.
>
> AFP
>
>
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>
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> 



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