Re: Hashing on System.Address

[Kilgallen@SpamCop.net (Larry Kilgallen)]

In article <u8y1dllt8.fsf@earthlink.net>, Matthew Heaney <matthewjheaney@earthlink.net> writes:
> Robert A Duff <bobduff@shell01.TheWorld.com> writes:
> 
>> "Matthew Heaney" <mheaney@on2.com> writes:
>> > Use System.Storage_Elements.To_Integer to convert the address to an
>> > Integer_Address, and then convert that to type Hash_Type.
>> 
>> It might be a good idea to divide that by 8, since most addresses have
>> zeros in the low three bits.
> 
> Good idea.  The other thing I haven't really figured out is what to do
> if you have a 64-bit address, and Hash_Type is only 32.  Ideally you'd
> like to compute a 32-bit hash value that uses all 64 bits of the
> address.

I think ignoring the high bits is better than ignoring the low bits,
since most data sets are likely to be somewhat localized.