strcmp() and drivers

[piranha]

Solar: I have to say, that is disturbingly elegant. And it is tested OK, I was bored.

-JL

[NickJohnson]

I think I have a better way, that only requires one possible branch - it may be a bit faster (but it's untested):

Code: Select all

int strcmp(const char *s1, const char *s2)
{
    while (~((*s1)^(*s2))&((*s1)&(*s2)))
    {
        ++s1;
        ++s2;
    }
    
    return (*s1 - *s2);
}

It should be equivalent to ( !((s1*) != (*s2)) && (*s1) ), but more bit-twiddling-y. It only works to use ~ instead of ! because you only check common bits between *s1 and *s2, which is what makes it only one branch. I have no idea if four logical instructions and one branch is faster than two branches though.

[AUsername]

Edit:

It works!

Turns out we didn't have /ALIGN:512. D:

But it works!