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Search: Posts Made By: Robert Holmes
Forum: Math 2021-01-29, 22:29
Replies: 6
Views: 1,563
Posted By Robert Holmes
The key term here is supersingular elliptic...

The key term here is supersingular elliptic curves. For p = 2 mod 3, any curve of the form y^2 = x^3 + B is supersingular, p > 3.

Another common case is p = 3 mod 4, in which case y^2 = x^3 + x...
Forum: Factoring 2016-10-11, 15:11
Replies: 32
Views: 6,229
Posted By Robert Holmes
It's siller than that---those extra `prefetchw`...

It's siller than that---those extra `prefetchw` instructions are put there by the compiler! Change the Makefile line from
CFLAGS=-O3 -march=k8 -mtune=k8 -funroll-loops

to

CFLAGS=-O3...
Forum: Factoring 2016-10-11, 04:43
Replies: 32
Views: 6,229
Posted By Robert Holmes
Instead of using the where command on gdb, can...

Instead of using the where command on gdb, can you try the following instead: x/32i $rip? It should tell us precisely what the illegal instruction is.

By the way, the assembler is entirely in its...
Forum: Lounge 2013-07-23, 02:23
Replies: 60
Views: 6,913
Posted By Robert Holmes
To answer the original question, the C99 standard...

To answer the original question, the C99 standard does dictate that 'long long' must have at least 64 bits.

It is also worth mentioning that the stdint.h [u]intXX_t types are not guaranteed to...
Forum: Soap Box 2013-06-18, 23:01
Replies: 760
Views: 76,597
Posted By Robert Holmes
This is quite off-topic, but an update: L(1/4)...

This is quite off-topic, but an update: L(1/4) has now been upgraded (http://hal.inria.fr/hal-00835446) to the quasi-polynomial O(q^{\log k / \log \log q}).
Forum: Programming 2013-05-16, 01:48
Replies: 13
Views: 3,268
Posted By Robert Holmes
This is reducible to a generic addition chain...

This is reducible to a generic addition chain problem. With those relatively small sizes, it might be worth to precompute the (near-)optimal programs using SAT solvers (like this...
Forum: Programming 2013-05-15, 21:58
Replies: 13
Views: 3,268
Posted By Robert Holmes
How large do you expect the N to grow,...

How large do you expect the N to grow, realistically?
Forum: Programming 2013-04-13, 01:37
Replies: 4
Views: 8,828
Posted By Robert Holmes
The reason your the original code fails is deep...

The reason your the original code fails is deep in the C++ standard's language. In short, when you want the compiler to deduce argument types, those types must not be dependent types. In the above...
Forum: Programming 2013-03-30, 02:36
Replies: 77
Views: 17,541
Posted By Robert Holmes
It's actually that way in GMP:...

It's actually that way in GMP: http://gmplib.org/devel/asm.html

Nehalem is slightly slower than Core 2, probably due to some loop control change in Nehalem, as the performance of ADD/ADC is...
Forum: Factoring 2013-03-16, 21:31
Replies: 36
Views: 8,977
Posted By Robert Holmes
To nitpick, there is such a thing as '10': it's a...

To nitpick, there is such a thing as '10': it's a multi-character literal. '10' translates to the integer 0x3130 (or 0x3031, depending on your endianness).

Of course this was clearly not the...
Forum: Factoring 2013-03-15, 22:45
Replies: 14
Views: 1,714
Posted By Robert Holmes
Thank you both for the info and pointers.

Thank you both for the info and pointers.
Forum: Factoring 2013-03-15, 22:00
Replies: 14
Views: 1,714
Posted By Robert Holmes
Can this not be somewhat fixed by lowering the...

Can this not be somewhat fixed by lowering the factor bases, and putting more pressure on the splitting of large primes (effectively trading space for time with rho, ECM, etc)? Or does doing this...
Forum: Computer Science & Computational Number Theory 2012-08-09, 00:44
Replies: 103
Views: 14,601
Posted By Robert Holmes
If there is interest in resubmission, there is an...

If there is interest in resubmission, there is an upcoming venue with perhaps more interest in such things: ARITH 2013 (http://www.arithsymposium.org/).
Forum: Computer Science & Computational Number Theory 2012-08-01, 00:44
Replies: 103
Views: 14,601
Posted By Robert Holmes
Just for the record, there is a document with...

Just for the record, there is a document with Granlund's timings for all recent architectures, including the Sandy Bridge:

http://gmplib.org/~tege/x86-timing.pdf

Good luck with the submission!
Forum: Computer Science & Computational Number Theory 2012-08-01, 00:09
Replies: 103
Views: 14,601
Posted By Robert Holmes
I'd like to point out that estimating the...

I'd like to point out that estimating the K-folded loops (end of page 13) as simply cycles/F is not extremely accurate, as it assumes infinite execution units. On the Core 2, a MUL can finish at most...
Forum: Programming 2012-07-26, 03:39
Replies: 36
Views: 5,695
Posted By Robert Holmes
I was wrong. The carry-saving instruction, be it...

I was wrong. The carry-saving instruction, be it SBB or SETC, can be run parallel to IMUL, so it should not factor in lower-bound estimates.

Ignoring the non-critical instructions in the loop, we...
Forum: Programming 2012-07-24, 23:48
Replies: 36
Views: 5,695
Posted By Robert Holmes
Ooh, I like it!

Ooh, I like it!
Forum: Programming 2012-07-23, 23:58
Replies: 36
Views: 5,695
Posted By Robert Holmes
Also note that the rotate-with-carry instructions...

Also note that the rotate-with-carry instructions are slow (microcoded as actual rotates + carry fiddling) compared to SETC or SBB. It's likely faster to do a SHL + SETC explicitly.

One option to...
Forum: Programming 2012-07-22, 03:26
Replies: 36
Views: 5,695
Posted By Robert Holmes
Not sure if I'm adding anything new here, but...

Not sure if I'm adding anything new here, but here's a new version of the loop I wrote, with a slight register change (thanks George for the SBB hint, how could I miss that?):


; r10 = x[]
...
Forum: Programming 2012-07-21, 00:54
Replies: 36
Views: 5,695
Posted By Robert Holmes
In the case of RSI, you call the lower 8 bits SIL...

In the case of RSI, you call the lower 8 bits SIL (silly, I know), therefore:


# Sometime before the loop
XOR %ESI, %ESI # Also zeroes upper RSI bits, 1 byte shorter
# .... loop
SETC %SIL #...
Forum: Programming 2012-07-20, 20:09
Replies: 36
Views: 5,695
Posted By Robert Holmes
Do you have a free register? You can avoid the...

Do you have a free register? You can avoid the comparison by performing a SETC REG right after the SUBQ, provided you have an available register to put that into.

Not sure if this helps the loop...
Forum: Science & Technology 2012-06-19, 12:10
Replies: 8
Views: 2,878
Posted By Robert Holmes
What do you mean "index-calculus-like"? It's...

What do you mean "index-calculus-like"? It's simple discrete log transfer by evaluating pairings.
Forum: GMP-ECM 2012-02-24, 11:39
Replies: 13
Views: 5,089
Posted By Robert Holmes
Some interesting developments as of yesterday: ...

Some interesting developments as of yesterday:

Improved addition chains for Edward's curve ECM: http://eprint.iacr.org/2012/089

and

More ECM-friendly curve families:...
Forum: Programming 2012-01-18, 05:18
Replies: 357
Views: 30,067
Posted By Robert Holmes
Can't do it. Not possible.

Can't do it. Not possible.
Forum: Programming 2011-11-28, 17:50
Replies: 60
Views: 16,691
Posted By Robert Holmes
Oops. For what it's worth, Sandy...

Oops.



For what it's worth, Sandy Bridge does have 2 LEA-capable ports.
Showing results 1 to 25 of 106

 
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