Code:
	LONGLONG l1=0;
	PLONGLONG pl1=&l1;

__asm {
			push eax      ; Save registers we will overwrite (eax, ebx, edx).
			push ebx
			push edx
			_emit 0x0F    ; The RDTSC instruction consists of these two bytes.
			_emit 0x31
			mov ebx, pl1 ; Put the address where the timestamp goes in ebx.
			mov [ebx],eax   ; Save low 4 bytes of timestamp there.
			mov [ebx+4],edx ; Save high 4 bytes of timestamp next.
			pop edx         ; Restore overwritten registers.
			pop ebx
			pop eax
}
so hab ichs mal gemacht

EDIT: Wenn du das einmal am Anfang und einmal am Ende machst hast du deine Zeitdiff.

sast