Question

I have a dll coded in Delphi XE2 with the following code:

procedure xMain(MSG:String);export;
begin
  MessageBox(0,PWideChar(MSG),'Title',0);
end;

exports xMain;

Now, I am importing this function in a FASM application like so:

library  dllfile, "testdll.dll"

import   dllfile,\
         xMain,   "xMain"

And utilizing is as so:

section ".data" data readable writeable

szMSG     db "Message from FASM application!",0

section ".code" code readable executable

invoke    xMain,szMSG

But the resulting messagebox appears with distorted characters as so:

That is the exact result of the function call.

How do I go about solving this issue?

Answer 1

Here are two working samples (using FASM 1.70.03 for Windows):

Ansi version,

dll:

library testdll;

uses
  windows;

procedure xMain(MSG: PAnsiChar); export; stdcall;
begin
  MessageBoxA(0, PAnsiChar(MSG), 'Title', 0);
end;

exports xMain;

begin
end.

exe:

format PE CONSOLE 4.0
entry start

include 'win32a.inc'

section '.code' code readable executable
  start:
    invoke xMain, szMSG
    invoke ExitProcess, 0

section '.data' data readable writeable
    szMSG db 'Message from FASM application!', 0

section '.idata' import data readable writeable
  library kernel32, 'kernel32.dll',\
          dllfile, 'testdll.dll'

  include 'api\kernel32.inc'

  import dllfile,\
         xMain, 'xMain'

Unicode version,

dll:

library testdll;

uses
  windows;

procedure xMain(MSG: PChar); export; stdcall;
begin
  MessageBox(0, PChar(MSG), 'Title', 0);
end;

exports xMain;

begin
end.

exe:

format PE CONSOLE 4.0
entry start

include 'win32w.inc'

section '.code' code readable executable
  start:
    invoke xMain, szMSG
    invoke ExitProcess, 0

section '.data' data readable writeable
    szMSG du 'Message from FASM application!', 0

section '.idata' import data readable writeable
  library kernel32, 'kernel32.dll',\
          dllfile, 'testdll.dll'

  include 'api\kernel32.inc'

  import dllfile,\
         xMain, 'xMain'