Как вызывать функцию 16-битной DLL из 32-битного приложения

Надо использовать Thunks.

Кусок работающего только под Windows 95 кода

const

  Gfsr_SystemResources = 0;
  Gfsr_GdiResources = 1;
  Gfsr_UserResources = 2;
var

  hInst16: THandle;
  GFSR: Pointer;
  { Undocumented Kernel32 calls. }

function
 LoadLibrary16(LibraryName: PChar): THandle; stdcall
; external
 kernel32
  index 35;

procedure
 FreeLibrary16(HInstance: THandle); stdcall
; external
 kernel32 index
  36;

function
 GetProcAddress16(Hinstance: THandle; ProcName: PChar): Pointer;
  stdcall
;
  external
 kernel32 index 37;

procedure
 QT_Thunk; cdecl
; external
 kernel32 name 'QT_Thunk';
{ QT_Thunk needs a stack frame. }
{$STACKFRAMES On}
{ Thunking call to 16-bit USER.EXE. The ThunkTrash argument
allocates space on the stack for QT_Thunk. }

function
 NewGetFreeSystemResources(SysResource: Word): Word;
var

  ThunkTrash: array
[0..$20] of
 Word;
begin

  { Prevent the optimizer from getting rid of ThunkTrash. }
  ThunkTrash[0] := hInst16;
  hInst16 := LoadLibrary16('user.exe');
  if
 hInst16 < 32 then

    raise
 Exception.Create('Can''t load USER.EXE!');
  { Decrement the usage count. This doesn't really free the
  library, since USER.EXE is always loaded. }
  FreeLibrary16(hInst16);
  { Get the function pointer for the 16-bit function in USER.EXE. }
  GFSR := GetProcAddress16(hInst16, 'GetFreeSystemResources');
  if
 GFSR = nil
 then

    raise
 Exception.Create('Can''t get address of GetFreeSystemResources!');
  { Thunk down to USER.EXE. }
  asm

    push SysResource { push arguments }
    mov edx, GFSR { load 16-bit procedure pointer }
    call QT_Thunk { call thunk }
    mov Result, ax { save the result }
  end
;
end
;

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