Luciano,
you should follow binary compatible DLL requirements :
- stdcall call convention
- ordinal types only (shortstring may work too because they are
char[256] and 0-th byte is the length)
- pointers (be attentive: if memory was allocated in DLL, you should
free it in DLL too)
You can also use any suggestions and examples for writing DLL in C/C++.
On 06/06/2015 12:00, fpc-pascal-requ...@lists.freepascal.org wrote:
Date: Sat, 6 Jun 2015 04:16:29 -0300
From: luciano de souza<luchya...@gmail.com>
To: fpc-pascal<fpc-pascal@lists.freepascal.org>
Subject: [fpc-pascal] Writing a DLL to be use in a VBA code
Message-ID:
<CAOUY=rWeygi89xf=67axqfqz8jcfthk4okl18woxp+bqp35...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Hello all,
At work, I need to create a Excel sheet containing certain more
complex functions. I tried to use only VBA, but I released I will more
productive if I could use a DLL writen in Pascal for the heavier code.
Let see this DLL:
library test;
{$mode objfpc}{$H+}
function concatenate(name: string): string; cdecl;
begin
result := 'Freepascal ' + name;
end;
function first(names: array of string):string; cdecl; // Warning:
cdecl'ared functions have no high parameter
begin
result := names[0];
end;
exports
concatenate;
first;
end.
The compiler also raised this error: "test.pas(10,1) Fatal: Internal
error 201003031".
I don't know what I am doing wrong. But actually, the reason of my
message started from another point.
Freepascal codes works with strings as usual. DLLs works with pchar. I
could have declared the functions as the following:
function concatenate(name: pchar): pchar; cdecl;
function first(names: array of pchar): pchar; cdecl;
In the body of the functions, I would treat the conversions from pchar
to string and from string to pchar again. But, when I used "cdecl", am
I making this conversion automatically? Is there a compilation switch
that allows me to write strings and the compiled code having correctly
treated the allocations and disallocation of strings?
Suppose this VBA code:
public declare function concatenate lib "test" (name as string) as string
Is this the correct way to write the called function in Freepascal?
function concatenate(name: string): string; cdecl;
begin
result := 'Freepascal ' + name;
end;
-- Luciano de Souza
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