Hi people is there a way i can access a pointer to a structure member directly from in line assembler i tried this
procedure test(eu:PImageDosHeader);assembler;
asm
push eu._lfanew
end;
It won't compile but if i use this
procedure test(eu:Pointer);
var
xx:TImageDosHeader;
begin
xx:=TImageDosHeader(eu^);
asm
push xx._lfanew
end;
end;
It works great.Any idea how can i access a structure trough a pointer in inline asm? is a matter of optimizing the code
Yet another workaround:
procedure test(eu:PImageDosHeader);
asm
push eu.TImageDosHeader._lfanew
end;
mov eax, TMyStruct(ebx).A by mov eax, ebx.TMyStruct.A and mov eax, TMyStruct(ebx).B by mov eax, ebx.TMyStruct.B.The following works:
type
PMyStruct = ^TMyStruct;
TMyStruct = record
A, B: cardinal;
end;
procedure ShowCard(Card: cardinal);
begin
ShowMessage(IntToHex(Card, 8));
end;
procedure test(Struct: PMyStruct);
asm
push ebx // We must not alter ebx
mov ebx, eax // eax is Struct; save in ebx
mov eax, TMyStruct(ebx).A
call ShowCard
mov eax, TMyStruct(ebx).B
call ShowCard
pop ebx // Restore ebx
end;
procedure TForm6.FormCreate(Sender: TObject);
var
MyStruct: TMyStruct;
begin
MyStruct.A := $22222222;
MyStruct.B := $44444444;
test(@MyStruct);
end;
test to: `asm mov ecx, eax mov eax,TMyStruct(ecx).A call ShowCard mov eax,TMyStruct(ecx).B call ShowCardI would write it like this:
procedure test(const eu: TImageDosHeader);
asm
push TImageDosHeader([EAX])._lfanew
end;
The pertinent documentation is here.
symbols section contains four syntactic options for STRUCs