I''m betting that I need to reference the m_Data differently than just listing it''s name. Should I do something like this->m_Data?

You can''t do that due to the way data from pointers is read. You CAN read data from classes and structures as long as you''re not reading it from a pointer. Examples:

RECT Rect;
Rect.right = 640;
_asm
{
mov eax, Rect.right
}

But to read data from a RECT*, you''d need to say something like this:

RECT* Rect = new RECT;
Rect->right = 640;
_asm
{
mov ebx, Rect
mov eax, DWORD PTR [ebx+8]; // Skip left and top
}

The compiler might not allow you to put Rect in ebx, you might have to say dwRect = (DWORD)Rect and put that in ebx instead. It amounts to the same thing.

As for how Rect->right is read in the second example, a RECT structure contains four DWORDs (4 bytes each), in this order: left, top, right, bottom. ebx pointed to the beginning of the structure, which is Rect->left. We incremented it by 8 so it pointed to Rect->right.

~CGameProgrammer( );

In either case, you can do this (pointer/reference):

__asm{  mov ebx, qword ptr [rect];  mov ecx, [ebx].right;  ...} 

No you can''t. Both of those commands are wrong. You cannot move a QWORD into a DWORD register, so there goes the first command. As for the second, registers don''t have a parameter called ".right", only the RECT structure does. So there goes the second. Assembly is not like C++ so don''t make assumptions about it until you know what you''re doing =)

~CGameProgrammer( );

You can do...

_asm{ mov ebx,rect mov eax,[ebx].right}

.right is an offset into the structure RECT. So it converts to [ebx+8]. So the second instruction was not wrong. I compiled it, I tested it and it moved the correct data in eax.

CGameProgrammer:

This is inline assembly, not processor assembly. It''s different from, let''s say, macro assembly, although minimally so in MSVC++. Both inline assembly and macro assembly are translated, because they are resolved by the compiler...

Oh, my mistake. Does the compiler look up the last value placed in ebx to find out what .right is referencing? Because more than one structure can have a "right" member.

~CGameProgrammer( );

Excuse me... I hit the "q" when I should have hit the "d". I''m so sorry. But I know that it works, I use it in my vector class.

Anyway, to answer your latest question: I think so... The .right member must still be visible to the function (public - unless the function is a friend of the class). That doesn''t prevent you from doing:

mov ebx, rect; // Assume rect has private member here.
mov eax, [ebx+12]; // This will work but shouldn''t be done.

if the member variable at +12 is private or protected. But then there are some major assumptions being made... Not good to do.

Yeah, and technically you don''t even need to write assembly to do that. You can do that in C++ with int datum = *(int *)(DWORD(Rect) + 12). But that is clearly very evil code. Let us never speak of it again.

~CGameProgrammer( );

If the name isn''t unique then you would need to use...

RECT *rect = new RECT; WINDOWPLACEMENT *winplace = new WINDOWPLACEMENT; asm { mov ebx,rect mov eax,[(rect ptr ebx).right] mov ebx,winplace mov eax,[(winplace ptr ebx).rcNormalPosition.right] } if (rect) delete rect; if (winplace) delete winplace;