nlg_digi.cpp

// Digi algorithm should never be used until at least 2 blocks are mined.
// Contains code by RealSolid & WDC
// Cleaned up for use in Guldencoin by GeertJohan (dead code removal since Guldencoin retargets every block)
unsigned int static GetNextWorkRequired_DIGI(const CBlockIndex* pindexLast, const CBlockHeader *pblock){
    // retarget timespan is set to a single block spacing because there is a retarget every block
    int64 retargetTimespan = nTargetSpacing;

    // get previous block
    const CBlockIndex* pindexPrev = pindexLast->pprev;
    assert(pindexPrev);

    // calculate actual timestpan between last block and previous block
    int64 nActualTimespan = pindexLast->GetBlockTime() - pindexPrev->GetBlockTime();
    printf("Digishield retarget\n");
    printf("nActualTimespan = %"PRI64d" before bounds\n", nActualTimespan);

    // limit difficulty changes between 50% and 125% (human view)
    if (nActualTimespan < (retargetTimespan - (retargetTimespan/4)) ) nActualTimespan = (retargetTimespan - (retargetTimespan/4));
    if (nActualTimespan > (retargetTimespan + (retargetTimespan/2)) ) nActualTimespan = (retargetTimespan + (retargetTimespan/2));

    // calculate new difficulty
    CBigNum bnNew;
    bnNew.SetCompact(pindexLast->nBits);
    bnNew *= nActualTimespan;
    bnNew /= retargetTimespan;

    // difficulty should never go below (human view) the starting difficulty
    if (bnNew > bnProofOfWorkLimit)
        bnNew = bnProofOfWorkLimit;

    /// debug print
    printf("nTargetTimespan = %"PRI64d" nActualTimespan = %"PRI64d"\n" , retargetTimespan, 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());

    // return compact (uint) difficulty
    return bnNew.GetCompact();
}

Looks clean! Kudos, mate!