0 is not a power of 2

[Steven Schveighoffer via Digitalmars-d]

On 5/19/15 4:01 PM, deadalnix wrote:
> Have you tried things like :
>
> (x >> bsr(x)) == 1 ?
>
> I have no idea if this is faster or not, but worth trying.

Hm.. I think this would always succeed. Perhaps you mean:

1 << bsr(x) == x;

And ironically, still doesn't work for 0 :D

IIRC, bsr is a binary search (even when it's an instruction), I doubt 
it's as fast as subtraction and logic-and.

-Steve