Delphi Assembly Function Returning a Long String

Question

I am trying to learn inline assembly programming in Delphi, and to this end I have found this article highly helpful.

Now I wish to write an assembly function return

Answer 1

With the excellent aid of A.Bouchez, I managed to correct my own code, employing LStrSetLength:

function myfunc: AnsiString;
asm

  push eax

  // eax = @result
  mov edx, 3
  mov ecx, 1252
  call System.@LStrSetLength

  pop eax

  mov ecx, [eax]

  mov [ecx], 'A'
  mov [ecx] + 1, 'B'
  mov [ecx] + 2, 'C'

end;

Answer 2

You have to use some kind of:

function myfunc: AnsiString;
asm
  push eax // save @result
  call system.@LStrClr
  mov    eax,3                 {Length}
{$ifdef UNICODE}
  mov    edx,1252 // code page for Delphi 2009/2010
{$endif}
  call   system.@NewAnsiString
  pop edx
  mov [edx],eax
  mov [eax],$303132
end;

It will return a '210' string...

And it's always a good idea of putting a {$ifdef UNICODE} block to have your code compatible with version of Delphi prior to 2009.