Near constant time rotate that does not violate the standards

Question

I\'m having a heck of a time trying to come up with a constant time rotate that does not violate the C/C++ standards.

The problem is the edge/corner cases, where ope

Answer 1

An alternative to the extra modulo is to multiply by 0 or 1 (thanks to !!):

template  T rotlMod(T x, unsigned int y)
{
    y %= sizeof(T) * 8;
    return T((x << y) | (x >> ((!!y) * (sizeof(T) * 8 - y)));
}