Question

Dear Delphi Folks who know Assembler —

I have this great routine that worked fine in the pre-Unicode world.

function StringRefCount(const Src: String): Integer;
asm
  test eax, eax
  je   @Exit
  mov  edx, eax
  mov  eax, [edx - 8]

@Exit:
end;

Given that my ASM skills are rudimentary at best, how might this be done in D2009+ ?

ADDED: This test fails:

procedure TestStringStuff.TestStringRefCount;
var
  TempString: string;
  TempResult: Integer;
  SecondString: string;
begin
  TempString := 'this is a temp string';
  TempResult := StringRefCount(TempString);
  CheckEquals(1, TempResult);
  SecondString := TempString;
  TempResult := StringRefCount(TempString);
  CheckEquals(2, TempResult);
end;

Thanks — I’m perfectly happy to admit to a major brain fart. 🙂

Nick

Answer 1

No changes are necessary to that code for 32-bit compilers. It’s the test case that’s faulty because string literals have built-in reference counts of −1.

For 64-bit code (and 32-bit code on newer compilers), you’re best off using the function by the same name already provided by the RTL.