Quote from: mtrlt on July 25, 2013, 12:28:57 AM

I might have found a bug in hp7. I copied the hp7 code over to Reaper, and found some weird behavior. I noticed that many shares/blocks it found, had a difficulty with a fractional part of 0.

Function: FermatProbablePrimalityTestFast. It does a Fermat test, and if it fails, it calculates the fractional part. However, there's a fast division test before the Fermat test. If the fast division test is succesful, the function is returned from and the fractional part isn't calculated. If it just happened to be the last number in a chain, the fractional part isn't calculated and is left at 0. This means if the difficulty is for example 6.2, and the miner found a block of difficulty 6.3, it's possible that the fractional part was left uncalculated, and the miner thinks it's difficulty 6.0. The block doesn't get submitted and lots of profit has been lost.

The same applies to EulerLagrangeLifchitzPrimalityTestFast.

Right now I don't have git set up, I can't submit a patch.

Thanks mtrlt... the code you copied is all the commits up to the tag 'v0.1.1xpm-hp7' or including more recent commits in the last 16 hours?

Mikaelh has been changing this section of the code to avoid calculating the fractional part when the chain length was insufficient to pass the difficulty. e.g. commit 64528eb & 27c3cdf