unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params& params)
{
unsigned int nProofOfWorkLimit = UintToArith256(params.powLimit).GetCompact();
// Genesis block
if (pindexLast == NULL)
return nProofOfWorkLimit;
// Only change once per difficulty adjustment interval
if ((pindexLast->nHeight+1) % params.DifficultyAdjustmentInterval() != 0)
{
if (params.AllowMinDifficultyBlocks(pblock->GetBlockTime()))
{
/* khal's port of this code from Bitcoin to the old namecoind
has a bug: Comparison of block times is done by an unsigned
difference. Consequently, the minimum difficulty is also
applied if the block's timestamp is earlier than the preceding
block's. Reproduce this. */
if (pblock->GetBlockTime() < pindexLast->GetBlockTime())
return nProofOfWorkLimit;
// Special difficulty rule for testnet:
// If the new block's timestamp is more than 2* 10 minutes
// then allow mining of a min-difficulty block.
if (pblock->GetBlockTime() > pindexLast->GetBlockTime() + params.nPowTargetSpacing*2)
return nProofOfWorkLimit;
else
{
// Return the last non-special-min-difficulty-rules-block
const CBlockIndex* pindex = pindexLast;
while (pindex->pprev && pindex->nHeight % params.DifficultyAdjustmentInterval() != 0 && pindex->nBits == nProofOfWorkLimit)
pindex = pindex->pprev;
return pindex->nBits;
}
}
return pindexLast->nBits;
}
/* Adapt the retargeting interval after merge-mining start
according to the changed Namecoin rules. */
int nBlocksBack = params.DifficultyAdjustmentInterval() - 1;
if (pindexLast->nHeight >= params.nAuxpowStartHeight
&& (pindexLast->nHeight + 1 > params.DifficultyAdjustmentInterval()))
nBlocksBack = params.DifficultyAdjustmentInterval();
// Go back by what we want to be 14 days worth of blocks
int nHeightFirst = pindexLast->nHeight - nBlocksBack;
assert(nHeightFirst >= 0);
const CBlockIndex* pindexFirst = pindexLast->GetAncestor(nHeightFirst);
assert(pindexFirst);
return CalculateNextWorkRequired(pindexLast, pindexFirst->GetBlockTime(), params);
}
int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev)
{
int64_t nOldTime = pblock->nTime;
int64_t nNewTime = std::max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());
if (nOldTime < nNewTime)
pblock->nTime = nNewTime;
// Updating time can change work required on testnet:
if (consensusParams.AllowMinDifficultyBlocks(pblock->GetBlockTime()))
pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, consensusParams);
return nNewTime - nOldTime;
}
