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Old 2020-11-07, 06:39   #1
paulunderwood
 
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Default 2^n-3

How easy would it be to alter gpuOwl to crunch 2^n-3?

Is the current gpuowl.cl hackable to do this? If so what needs to be changed? Is it just a matter of hacking the carry code?
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Old 2020-11-07, 06:47   #2
axn
 
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Quote:
Originally Posted by paulunderwood View Post
Is it just a matter of hacking the carry code?
Doubtful. With +/-1 you get the mod for free as a result of the IBDWT itself. Not sure what additional thing needs to be done to do the same for -3.
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Old 2020-11-07, 07:04   #3
preda
 
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Quote:
Originally Posted by paulunderwood View Post
How easy would it be to alter gpuOwl to crunch 2^n-3?

Is the current gpuowl.cl hackable to do this? If so what needs to be changed? Is it just a matter of hacking the carry code?
One problem is that gpuowl.cl is very heavily optimized for the "-1" case -- the weighting/unweighting. A lot of tricks have been applied in that area. To change, a logical approach would be to unoptimize (i.e. produce clean & slow code, that can be checked to be correct), then implement the new functionality, then optionally reoptimize the new code.

Another approach is to start from a clean-slate, and import blocks from gpuowl.cl if/when they prove useful.

Last fiddled with by preda on 2020-11-07 at 07:06
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