There is target adjustment in sph-sgminer depending on the coin, this is what DM_SELECT(1, 256, 65536) does. Currently for darkcoin and myriadcoin-groestl truediffone is multiplied by 1, for quarkcoin and qubitcoin it's multiplied by 256 and for scrypt it's multiplied by 65536.
so here may be the problem - quarks should have diff1 similar as sha256 coins (so multiplier = 1)
Are you sure about this? Because for example hash of BTC block 10 (difficulty = 1) is:
000000002c05cc2e78923c34df87fd108b22221ac6076c18f3ade378a4d915e9
and hash of QRK block 600 (difficulty = 1.01576304) is:
00000096b99f154706b957c0e36cc4bf3789849e8a0684278dffac607b404641
so QRK definitely has higher target than BTC for this difficulty, otherwise this block would not be accepted. I'm not an expert in this, though.
Also take a look at:
https://github.com/bitcoin/bitcoin/blob/master/src/rpcblockchain.cpp#L36and
https://github.com/MaxGuevara/quark/blob/master/src/rpcblockchain.cpp#L31In BTC dDiff is multiplied/divided by 256 until nShift is 29 while in QRK it's multiplied/divided by 256 until nShift is 30 - so IMHO for two difficulties with the same value target value will be shifted by 8 bits.
Note that sph-sgminer displays network difficulty correctly for Quark and QubitCoin. It wouldn't be correct with wrong multiplier.
on our forum i'm about to ask about the possibility of forking this version and adapting it to Quark, so hopefully we can raise a bounty for this , i'd rather you yourself get this phm, as you seems to have done a great job adapting the original SGminer for the C code algos, and it seems like the work to refine this to a Quark GPU miner would not be that extensive?
BtW re the suprnova mix of valid and invalid i can confirm i was mining with both CPU and GPU on the same worker, so the GPU would have been generating invalid and CPU valid.
curious thing about it was it did generate valid shares, it was showing found blocks for a time.