Re: OT: Re: Sieve of Erastosthenes optimized to the max

Vir Campestris <vir.campestris@invalid.invalid> writes:

(replying to two messages at once)
>
On 10/08/2024 15:07, Tim Rentsch wrote:
>

I suspect the cost of extracting the divided value from the 7
bytes will be prohibitive.  You may find it's best to have one
table for the N/30 parts (big entries, word aligned) and another
for the N%30 part (small entries, byte aligned).  BICBW.

>
Two tables, absolutely.  What does BICBW stand for?

>
But I Could Be Wrong.  I thought that one was fairly well known.

Ah.  No wonder I didn't know it. ;)

On 11/08/2024 08:00, Tim Rentsch wrote:
>

Note that the %30 tables can be shared.  There are 8 of them, one
for each of the eight residues mod 30 of the original prime.

>
I started coding that up.  Then it occurred to me that there wasn't
going to be much saving by storing a pointer (8 bytes on my machine)
to the correct 8-byte long table.  I suppose I could store a byte array
index instead, but I've gone off in other directions.

Right, I was meaning keeping track of the index, not a pointer.

You've picked up my cache management tweak.

It's an interesting idea, although I'm not sure how well it
integrates with what I've done.

I'll read through your code.  But it might not be today.  We've got the
hottest day of the year here, and I don't have aircon in my garden
office.  In winter the computer and me are enough to keep it warm, but
right now it's getting warmer by the minute.

My sympathies.  I too find it hard to work when it's too hot.

I see you have started looking at my code... I'll take a look.