Delphi Loadlibrary returns 0 (LastErrorcde=3221225616) What does this mean?

Question

I need to use a 3rd party dll in our main app. When I staticly link to the provided DLL it works ok and I can the DLLs exported functions. But we don't want our main app dependend on this dll on startup so I tried to dynamicly load the DLL when I need it :

DLLHandle := LoadLibrary('3rdparty.dll');
ret := GetLastError();
if DLLHandle = 0 then
begin
  err := SysErrorMessage(ret);
  Writeln(err);
end //...

but did doesnt work : The LoadLibrary function returns 0 and the LastErrorcode is 3221225616. Because I don't know what I'm doing wrong I tried the same (on the same pc) coded in c and it works : but what doesn't it work with delphi ? : I call the same LoadLibrary function on the same dll!

When I monitor with ProcMon I see that the 3rdparty dll gets loaded and that also the dependand dlls of the 3rdparty dll gets loaded. : So windows certainly finds the DLL. But somewhere it the loading process it fails : When I try to load the DLL with LoadLibraryEX with DONT_RESOLVE_DLL_REFERENCES or LOAD_LIBRARY_AS_DATAFILE it also works (but I can't offcourse call the needed functions...)

I'm out of ideas : hope you guys can help me further...

thx in adv. Kristof

Answer 1

Does this work?

var
  SavedCW: word;

...

SavedCW := Get8087CW;
Set8087CW(SavedCW or $7);
DLLHandle := LoadLibrary('3rdparty.dll');
Set8087CW(SavedCW);
if DLLHandle = 0 then
begin
  ret := GetLastError();  
  err := SysErrorMessage(ret);
  Writeln(err);
end //...

Some discussion:

The error code, 3221225616, seems, when asking Google, to be the result of an invalid floating point operation. Now, this seems very technical; indeed, what does loading a library have to do with floating point computations? The floating point control word (CW) is a bitfield where the bits specify how the processor should handle floating-point errors; it is actually rather common that unexpected floating point errors can be dealt with by changing one of these bits to 1 (which by the way is the default state). For an other example, see this question of mine, in which I get a totally unexpected division by zero error, which is dealt with by setting the "div by zero" bit of the control word to 1.

Answer 2

3221225616 = STATUS_FLOAT_INVALID_OPERATION. My wild guess is that the FPU CW is different in your Delphi and C apps, and that your DLL's initialization is sensitive to this.