This is one example, but it illustrates a general concept that I think
is really useful and I personally have used numerous times for lots of
other instructions than SCAS. If there is a way to achieve this
without using a naked function then please advise.
Keeping the __asm syntax, I'd be surprised if this did not work:
template<typename T>
int find_first_nonzero_scas(T* x, int cnt)
{
int result = 0;
__asm {
xor eax, eax
mov edi, x
mov ecx, cnt
}
if (sizeof (T) == 1)
__asm { rep scasb; mov result, edi }
if (sizeof (T) == 2)
__asm { rep scasw; mov result, edi }
if (sizeof (T) == 4)
__asm { rep scasl; mov result, edi }
result -= reinterpret_cast<int>(x);
result /= sizeof(T);
return --result;
}
Paolo
