| 47 | } |
| 48 | |
| 49 | unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params& params) |
| 50 | { |
| 51 | if (params.fPowNoRetargeting) |
| 52 | return pindexLast->nBits; |
| 53 | |
| 54 | // Limit adjustment step |
| 55 | int64_t nActualTimespan = pindexLast->GetBlockTime() - nFirstBlockTime; |
| 56 | if (nActualTimespan < params.nPowTargetTimespan/4) |
| 57 | nActualTimespan = params.nPowTargetTimespan/4; |
| 58 | if (nActualTimespan > params.nPowTargetTimespan*4) |
| 59 | nActualTimespan = params.nPowTargetTimespan*4; |
| 60 | |
| 61 | // Retarget |
| 62 | const arith_uint256 bnPowLimit = UintToArith256(params.powLimit); |
| 63 | arith_uint256 bnNew; |
| 64 | bnNew.SetCompact(pindexLast->nBits); |
| 65 | bnNew *= nActualTimespan; |
| 66 | bnNew /= params.nPowTargetTimespan; |
| 67 | |
| 68 | if (bnNew > bnPowLimit) |
| 69 | bnNew = bnPowLimit; |
| 70 | |
| 71 | return bnNew.GetCompact(); |
| 72 | } |
| 73 | |
| 74 | bool CheckProofOfWork(uint256 hash, unsigned int nBits, const Consensus::Params& params) |
| 75 | { |