Topic: Nexus - Pure SHA3 + CPU/GPU + nPoS + 15 Active Innovations + More to Come - page 305. (Read 785514 times)

	/** Determines the Decimal of nBits per Channel for a decent "Frame of Reference".
		Has no functionality in Network Operation. **/
	double GetDifficulty(unsigned int nBits, int nChannel)
	{
		if(nChannel == 1)
			return nBits / 10000000.0;
			
		double dDiff =
			(double)0x0000ffff / (double)(nBits & 0x00ffffff);

		int nShift = nBits >> 24;
		while(nShift > 124)
		{
			dDiff = dDiff / 256.0;
			nShift--;
		}
		
		while(nShift < 124)
		{
			dDiff = dDiff * 256.0;
			nShift++;
		}
		
		return dDiff * 64;
	}

	unsigned int ShieldTargetGPU(const CBlockIndex* pindex, bool output)
	{
		const CBlockIndex* pindexFirst = GetLastChannelIndex(pindex, 2);
		if (pindexFirst->pprev == NULL)
			return bnProofOfWorkStart[2].GetCompact();
			
		const CBlockIndex* pindexLast = GetLastChannelIndex(pindexFirst->pprev, 2);
		if (pindexLast->pprev == NULL)
			return bnProofOfWorkStart[2].GetCompact();

			
		int64 nBlockTime = max(pindexFirst->GetBlockTime() - pindexLast->GetBlockTime(), (int64) 1);
		int64 nBlockTarget = nTargetTimespan;
		
		
		double nChainMod = GetFractionalSubsidy(GetChainAge(pindexFirst->GetBlockTime()), 0, 20.0) / (pindexFirst->nReleasedReserve[0] + 1);
		nChainMod = min(nChainMod, 1.0);
		nChainMod = max(nChainMod, (pindex->nVersion == 1) ? 0.75 : 0.5);
		
		
		/** Enforce Block Version 2 Rule. Chain mod changes block time requirements, not actual mod after block times. **/
		if(pindex->nVersion >= 2)
			nBlockTarget *= nChainMod;
		
		
		double nBlockMod = (double) nBlockTarget / nBlockTime; 
		nBlockMod = min(nBlockMod, 1.125);
		nBlockMod = max(nBlockMod, 0.75);
		
		
		int64 nUpperBound = nBlockTarget;
		int64 nLowerBound = nBlockTarget * nBlockMod;
		
		if(pindex->nVersion == 1)
			nLowerBound *= nChainMod;
		
		///set maximum [difficulty] up to 8%, and minimum [difficulty] down to 75%
		nLowerBound = min(nLowerBound, (int64)(nUpperBound + (nUpperBound / 8)));
		nLowerBound = max(nLowerBound, (3 * nUpperBound ) / 4);
			
		CBigNum bnNew;
		bnNew.SetCompact(pindexFirst->nBits);
		
		bnNew *= nUpperBound;
		bnNew /= nLowerBound;
		
		if (bnNew > bnProofOfWorkLimit[2])
			bnNew = bnProofOfWorkLimit[2];
			
		if(output)
		{
			int64 nDays, nHours, nMinutes;
			GetChainTimes(GetChainAge(pindexFirst->GetBlockTime()), nDays, nHours, nMinutes);
			
			printf("RETARGET[GPU] time=%I64d [%f %%]\n\tchain time: [%I64d / %I64d]\n\treleased reward: %I64d [%f %%]\n\tdifficulty: [%f to %f]\n\tGPU height: %I64d [AGE %I64d days, %I64d hours, %I64d minutes]\n\n", 
			nBlockTime, (100.0 * ((double)nLowerBound / nUpperBound)), nBlockTarget, nBlockTime, pindexFirst->nReleasedReserve[0] / COIN, 100.0 * nChainMod, GetDifficulty(pindexFirst->nBits, 2), GetDifficulty(bnNew.GetCompact(), 2), pindexFirst->nChannelHeight, nDays, nHours, nMinutes);
		}
		
		return bnNew.GetCompact();
	}