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

Автор: Nomadic

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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