I have the following asm code:
; int __stdcall wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nShowCmd)
_wWinMain@16 proc near
var_8= dword ptr -8
var_4= dword ptr -4
hInstance= dword ptr 8
hPrevInstance= dword ptr 0Ch
lpCmdLine= dword ptr 10h
nShowCmd= dword ptr 14h
push ebp
mov ebp, esp
sub esp, 8
mov [ebp+var_4], 5
mov eax, [ebp+var_4]
add eax, 1
mov [ebp+var_8], eax
xor eax, eax
mov esp, ebp
pop ebp
retn 10h
From what I read, you have 3 types of return instruction: ret, retn and retf, meaning return, return near and return far. They allow an optional argument nBytes, that I guess it's the number of bytes to pop, from the defined variables. When should I use retn or retf instead of ret? How can I calculate the optional parameter, nBytes?