Number of Bits Needed to Represent a Zero-Offset Integer

[bearophile via Digitalmars-d-learn]

Dominikus Dittes Scherkl:

> I would recommend to use something like this:
>
> /// returns the number of the highest set bit +1 in the given 
> value or 0 if no bit is set
> size_t bitlen(T)(const(T) a) pure @safe @nogc nothrow 
> if(isUnsigned!T)
> {
>    static if(T.sizeof <= size_t.sizeof) // doesn't work for 
> ulong on 32bit sys
>    {
>       return x ? core.bitop.bsr(x)+1 : 0;
>    }
>    else static if(T.sizeof == 8) // ulong if size_t == uint
>    {
>       return x ? x>>32 ? core.bitop.bsr(x)+33 : 
> core.bitop.bsr(x)+1 : 0;
>    }
> }

Is this good to be added to Phobos? Perhaps with a more 
descriptive name?

Bye,
bearophile