unsigned int static DarkGravityWave3(const CBlockIndex* pindexLast, const CBlockHeader *pblock) {
    /* current difficulty formula, darkcoin - DarkGravity v3, written by Evan Duffield - evan@darkcoin.io */
    const CBlockIndex *BlockLastSolved = pindexLast;
    const CBlockIndex *BlockReading = pindexLast;
    const CBlockHeader *BlockCreating = pblock;
    BlockCreating = BlockCreating;
    int64 nActualTimespan = 0;
    int64 LastBlockTime = 0;
    int64 PastBlocksMin = 24;
    int64 PastBlocksMax = 24;
    int64 CountBlocks = 0;
    CBigNum PastDifficultyAverage;
    CBigNum PastDifficultyAveragePrev;

    if (BlockLastSolved == NULL || BlockLastSolved->nHeight == 0 || BlockLastSolved->nHeight < PastBlocksMin) { 
        return bnProofOfWorkLimit.GetCompact(); 
    }
        
    for (unsigned int i = 1; BlockReading && BlockReading->nHeight > 0; i++) {
        if (PastBlocksMax > 0 && i > PastBlocksMax) { break; }
        CountBlocks++;

        if(CountBlocks <= PastBlocksMin) {
            if (CountBlocks == 1) { PastDifficultyAverage.SetCompact(BlockReading->nBits); }
            else { PastDifficultyAverage = ((PastDifficultyAveragePrev * CountBlocks)+(CBigNum().SetCompact(BlockReading->nBits))) / (CountBlocks+1); }
            PastDifficultyAveragePrev = PastDifficultyAverage;
        }

        if(LastBlockTime > 0){
            int64 Diff = (LastBlockTime - BlockReading->GetBlockTime());
            nActualTimespan += Diff;
        }
        LastBlockTime = BlockReading->GetBlockTime();      

        if (BlockReading->pprev == NULL) { assert(BlockReading); break; }
        BlockReading = BlockReading->pprev;
    }
    
    CBigNum bnNew(PastDifficultyAverage);

    int64 nTargetTimespan = CountBlocks*nTargetSpacing;

    if (nActualTimespan < nTargetTimespan/3)
        nActualTimespan = nTargetTimespan/3;
    if (nActualTimespan > nTargetTimespan*3)
        nActualTimespan = nTargetTimespan*3;

    // Retarget
    bnNew *= nActualTimespan;
    bnNew /= nTargetTimespan;
	/// debug print
	printf("DarkGravityWave3 RETARGET\n");
	printf("nTargetTimespan = %"PRI64d"    nActualTimespan = %"PRI64d"\n", nTargetTimespan, nActualTimespan);
	printf("Before: %08x  %s\n", pindexLast->nBits, CBigNum().SetCompact(pindexLast->nBits).getuint256().ToString().c_str());
	printf("After:  %08x  %s\n", bnNew.GetCompact(), bnNew.getuint256().ToString().c_str());
	
    if (bnNew > bnProofOfWorkLimit){
        bnNew = bnProofOfWorkLimit;
    }
     
    return bnNew.GetCompact();
}