file - consensus.h

inline unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params& params) {

// Get the last block's header

const CBlockHeader *pLastBlock = &pindexLast->GetBlockHeader();

// Determine the time span of the last 2016 blocks

const CBlockIndex *pindexFirst = pindexLast;

for (int i = 0; i < params.DifficultyAdjustmentInterval() - 1 && pindexFirst; i++)

pindexFirst = pindexFirst->pprev;

int64_t nActualTimespan = pLastBlock->GetBlockTime() - pindexFirst->GetBlockTime();

// Limit the adjustment step

int64_t nActualTimespanMax = params.nPowTargetTimespan * 4;

int64_t nActualTimespanMin = params.nPowTargetTimespan / 4;

if (nActualTimespan < nActualTimespanMin)

nActualTimespan = nActualTimespanMin;

if (nActualTimespan > nActualTimespanMax)

nActualTimespan = nActualTimespanMax;

// Retarget

arith_uint256 bnNew;

const arith_uint256 bnPowLimit = UintToArith256(params.powLimit);

bnNew.SetCompact(pLastBlock->nBits);

bnNew *= nActualTimespan;

bnNew /= params.nPowTargetTimespan;

// Check the bounds

if (bnNew > bnPowLimit)

bnNew = bnPowLimit;

return bnNew.GetCompact();