// Deprecated for Bitcoin Gold
unsigned int BitcoinGetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params& params)
{
assert(pindexLast != nullptr);
unsigned int nProofOfWorkLimit = UintToArith256(params.PowLimit(false)).GetCompact();
// Only change once per difficulty adjustment interval
if ((pindexLast->nHeight+1) % params.DifficultyAdjustmentInterval() != 0)
{
if (params.fPowAllowMinDifficultyBlocks)
{
// 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;
}
// Go back by what we want to be 14 days worth of blocks
int nHeightFirst = pindexLast->nHeight - (params.DifficultyAdjustmentInterval()-1);
assert(nHeightFirst >= 0);
const CBlockIndex* pindexFirst = pindexLast->GetAncestor(nHeightFirst);
assert(pindexFirst);
return BitcoinCalculateNextWorkRequired(pindexLast, pindexFirst->GetBlockTime(), params);
}
unsigned int CalculateNextWorkRequired(arith_uint256 bnAvg,
int64_t nLastBlockTime, int64_t nFirstBlockTime,
const Consensus::Params& params)
{
// Limit adjustment step
// Use medians to prevent time-warp attacks
int64_t nActualTimespan = nLastBlockTime - nFirstBlockTime;
LogPrint("pow", " nActualTimespan = %d before dampening\n", nActualTimespan);
nActualTimespan = params.AveragingWindowTimespan() + (nActualTimespan - params.AveragingWindowTimespan())/4;
LogPrint("pow", " nActualTimespan = %d before bounds\n", nActualTimespan);
if (nActualTimespan < params.MinActualTimespan())
nActualTimespan = params.MinActualTimespan();
if (nActualTimespan > params.MaxActualTimespan())
nActualTimespan = params.MaxActualTimespan();
// Retarget
const arith_uint256 bnPowLimit = UintToArith256(params.powLimit);
arith_uint256 bnNew {bnAvg};
bnNew /= params.AveragingWindowTimespan();
bnNew *= nActualTimespan;
if (bnNew > bnPowLimit)
bnNew = bnPowLimit;
/// debug print
LogPrint("pow", "GetNextWorkRequired RETARGET\n");
LogPrint("pow", "params.AveragingWindowTimespan() = %d nActualTimespan = %d\n", params.AveragingWindowTimespan(), nActualTimespan);
LogPrint("pow", "Current average: %08x %s\n", bnAvg.GetCompact(), bnAvg.ToString());
LogPrint("pow", "After: %08x %s\n", bnNew.GetCompact(), bnNew.ToString());
return bnNew.GetCompact();
}
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;
// Jupitercoin: Special rules for minimum difficulty blocks with Digishield
if (AllowDigishieldMinDifficultyForBlock(pindexLast, pblock, params))
{
// Special difficulty rule for testnet:
// If the new block's timestamp is more than 2* nTargetSpacing minutes
// then allow mining of a min-difficulty block.
return nProofOfWorkLimit;
}
// Only change once per difficulty adjustment interval
if ((pindexLast->nHeight+1) % params.DifficultyAdjustmentInterval() != 0)
{
if (params.fPowAllowMinDifficultyBlocks)
{
// 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;
}
// Litecoin: This fixes an issue where a 51% attack can change difficulty at will.
// Go back the full period unless it's the first retarget after genesis. Code courtesy of Art Forz
int blockstogoback = params.DifficultyAdjustmentInterval()-1;
if ((pindexLast->nHeight+1) != params.DifficultyAdjustmentInterval())
blockstogoback = params.DifficultyAdjustmentInterval();
// Go back by what we want to be 14 days worth of blocks
int nHeightFirst = pindexLast->nHeight - blockstogoback;
assert(nHeightFirst >= 0);
const CBlockIndex* pindexFirst = pindexLast->GetAncestor(nHeightFirst);
assert(pindexFirst);
return CalculateJupitercoinNextWorkRequired(pindexLast, pindexFirst->GetBlockTime(), params);
}
int64_t GetActualMiningTimespan(const CBlockIndex* pindexLast, const Consensus::Params& params) {
int64_t TotalTime = 0;
if (pindexLast->nHeight >= params.DifficultyAdjustmentInterval() - 1) {
const CBlockIndex* pindex = pindexLast;
for (int i = 0; i < params.DifficultyAdjustmentInterval() && pindex != NULL; i++) {
CBlock block;
if (!ReadBlockFromDisk(block, pindex)) {
LogPrintf("ERROR : %s() Read block fail at block hash %s\n", __func__, pindex->GetBlockHash().ToString());
return params.nPowTargetTimespan;
}
TotalTime += (pindex->nTime - block.vtx[0].nLockTime);
pindex = pindex->pprev;
}
}
return TotalTime;
}
unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params& params)
{
assert(pindexLast != nullptr);
int nHeight = pindexLast->nHeight + 1;
bool postfork = nHeight >= params.BTGHeight;
unsigned int nProofOfWorkLimit = UintToArith256(params.PowLimit(postfork)).GetCompact();
if (postfork == false) {
return BitcoinGetNextWorkRequired(pindexLast, pblock, params);
}
else if (nHeight < params.BTGHeight + params.BTGPremineWindow) {
return nProofOfWorkLimit;
}
else if (nHeight < params.BTGHeight + params.BTGPremineWindow + params.nPowAveragingWindow){
return UintToArith256(params.powLimitStart).GetCompact();
}
const CBlockIndex* pindexFirst = pindexLast;
arith_uint256 bnTot {0};
for (int i = 0; pindexFirst && i < params.nPowAveragingWindow; i++) {
arith_uint256 bnTmp;
bnTmp.SetCompact(pindexFirst->nBits);
bnTot += bnTmp;
pindexFirst = pindexFirst->pprev;
}
if (pindexFirst == NULL)
return nProofOfWorkLimit;
arith_uint256 bnAvg {bnTot / params.nPowAveragingWindow};
return CalculateNextWorkRequired(bnAvg, pindexLast->GetMedianTimePast(), pindexFirst->GetMedianTimePast(), params);
}
unsigned int CalculateNextWorkRequired(arith_uint256 bnAvg, int64_t nLastBlockTime, int64_t nFirstBlockTime, const Consensus::Params& params)
{
// Limit adjustment
int64_t nActualTimespan = nLastBlockTime - nFirstBlockTime;
if (nActualTimespan < params.MinActualTimespan())
nActualTimespan = params.MinActualTimespan();
if (nActualTimespan > params.MaxActualTimespan())
nActualTimespan = params.MaxActualTimespan();
// Retarget
const arith_uint256 bnPowLimit = UintToArith256(params.PowLimit(true));
arith_uint256 bnNew {bnAvg};
bnNew /= params.AveragingWindowTimespan();
bnNew *= nActualTimespan;
if (bnNew > bnPowLimit)
bnNew = bnPowLimit;
return bnNew.GetCompact();
}
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;
}
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);
}
bool CheckProofOfWork(uint256 hash, unsigned int nBits, bool postfork, const Consensus::Params& params)
{
bool fNegative;
bool fOverflow;
arith_uint256 bnTarget;
bnTarget.SetCompact(nBits, &fNegative, &fOverflow);
// Check range
if (fNegative || bnTarget == 0 || fOverflow || bnTarget > UintToArith256(params.PowLimit(postfork)))
return false;
// Check proof of work matches claimed amount
if (UintToArith256(hash) > bnTarget)
return false;
return true;
}
// Depricated for Bitcoin Gold
unsigned int BitcoinCalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params& params)
{
if (params.fPowNoRetargeting)
return pindexLast->nBits;
// Limit adjustment step
int64_t nActualTimespan = pindexLast->GetBlockTime() - nFirstBlockTime;
if (nActualTimespan < params.nPowTargetTimespanLegacy/4)
nActualTimespan = params.nPowTargetTimespanLegacy/4;
if (nActualTimespan > params.nPowTargetTimespanLegacy*4)
nActualTimespan = params.nPowTargetTimespanLegacy*4;
// Retarget
const arith_uint256 bnPowLimit = UintToArith256(params.PowLimit(false));
arith_uint256 bnNew;
bnNew.SetCompact(pindexLast->nBits);
bnNew *= nActualTimespan;
bnNew /= params.nPowTargetTimespanLegacy;
if (bnNew > bnPowLimit)
bnNew = bnPowLimit;
return bnNew.GetCompact();
}
unsigned int GetNextWorkRequiredV1(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.fPowAllowMinDifficultyBlocks)
{
// 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;
}
// Go back by what we want to be 1 hourworth of blocks
int nBlocksLookupRange = params.DifficultyAdjustmentInterval()-1;
if (pindexLast->nHeight > 99988) {
nBlocksLookupRange = params.DifficultyAdjustmentInterval() * 24;
}
const CBlockIndex* pindexFirst = pindexLast->GetAncestor( pindexLast->nHeight - nBlocksLookupRange);
assert(pindexFirst);
// Limit adjustment step
int64_t nActualTimespan = pindexLast->GetBlockTime() - pindexFirst->GetBlockTime();
if (pindexLast->nHeight > 101908) {
nActualTimespan = nActualTimespan / 3;
} else if (pindexLast->nHeight > 99988) {
nActualTimespan = nActualTimespan / 24;
}
LogPrintf(" nActualTimespan = %d before bounds\n", nActualTimespan);
if (nActualTimespan < params.nPowTargetTimespan/4)
nActualTimespan = params.nPowTargetTimespan/4;
if (nActualTimespan > params.nPowTargetTimespan*4)
nActualTimespan = params.nPowTargetTimespan*4;
// Retarget
const arith_uint256 bnPowLimit = UintToArith256(params.powLimit);
arith_uint256 bnNew;
arith_uint256 bnOld;
bnNew.SetCompact(pindexLast->nBits);
bnOld = bnNew;
bnNew *= nActualTimespan;
bnNew /= params.nPowTargetTimespan;
if (bnNew > bnPowLimit)
bnNew = bnPowLimit;
/// debug print
LogPrintf("GetNextWorkRequired RETARGET\n");
LogPrintf("params.nPowTargetTimespan = %d nActualTimespan = %d\n", params.nPowTargetTimespan, nActualTimespan);
LogPrintf("Before: %08x %s\n", pindexLast->nBits, bnOld.ToString());
LogPrintf("After: %08x %s\n", bnNew.GetCompact(), bnNew.ToString());
return bnNew.GetCompact();
}
unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params& params)
{
const arith_uint256 powLimit = UintToArith256(params.powLimit);
unsigned int nProofOfWorkLimit = powLimit.GetCompact();
// Genesis block
if (pindexLast == NULL)
return nProofOfWorkLimit;
if (params.fPowNoRetargeting)
return pindexLast->nBits;
const int height = pindexLast->nHeight + 1;
//okay, maybe not this line
if (height < 14640)
return GetNextWorkRequired_OLD(pindexLast, params);
//hardcoded switch to 256.0 difficulty at block 14639
if (height == 14640)
return 0x1C00FFFF;
// Only change once per interval
const int64_t nInterval = params.DifficultyAdjustmentInterval();
const int64_t nTargetSpacing = params.nPowTargetSpacing;
if ((pindexLast->nHeight+1) % nInterval != 0)
{
// Special difficulty rule for testnet:
if (params.fPowAllowMinDifficultyBlocks)
{
// If the new block's timestamp is more than 2* 10 minutes
// then allow mining of a min-difficulty block.
if (pblock->nTime > pindexLast->nTime + nTargetSpacing*2)
return nProofOfWorkLimit;
else
{
// Return the last non-special-min-difficulty-rules-block
const CBlockIndex* pindex = pindexLast;
while (pindex->pprev && pindex->nHeight % nInterval != 0 && pindex->nBits == nProofOfWorkLimit)
pindex = pindex->pprev;
return pindex->nBits;
}
}
return pindexLast->nBits;
}
// This fixes an issue where a 51% attack can change difficulty at will.
// Go back the full period unless it's the first retarget after genesis. Code courtesy of Art Forz
// Patch modified from Litecoin.
int blockstogoback = nInterval-1;
if (height >= 150000 && height != nInterval)
blockstogoback = nInterval;
// Go back by what we want to be 14 days worth of blocks
const CBlockIndex* pindexFirst = pindexLast;
for (int i = 0; pindexFirst && i < blockstogoback; i++)
pindexFirst = pindexFirst->pprev;
assert(pindexFirst);
// Limit adjustment step
const int64_t nTargetTimespan = params.nPowTargetTimespan;
int64_t nActualTimespan = pindexLast->GetBlockTime() - pindexFirst->GetBlockTime();
// assymmetric retarget (slow difficulty rise / fast difficulty drop) can be
// abused to make a 51% attack more profitable than it should be,
// therefore we adopt (starting at block 895000) a symmetric algorithm based
// on bitcoin's algorithm.
//
// we retarget at most by a factor of 4^(120/2016) = 1.086
if (height < 895000) { // use the old retarget algorithm
const int64_t nTwoPercent = nTargetTimespan/50;
if (nActualTimespan < nTargetTimespan) //is time taken for a block less than 3minutes?
{
//limit increase to a much lower amount than dictates to get past the pump-n-dump mining phase
//due to retargets being done more often it also needs to be lowered significantly from the 4x increase
if(nActualTimespan<(nTwoPercent*16)) //less than a minute?
nActualTimespan=(nTwoPercent*45); //pretend it was only 10% faster than desired
else if(nActualTimespan<(nTwoPercent*32)) //less than 2 minutes?
nActualTimespan=(nTwoPercent*47); //pretend it was only 6% faster than desired
else
nActualTimespan=(nTwoPercent*49); //pretend it was only 2% faster than desired
//int64 nTime=nTargetTimespan-nActualTimespan;
//nActualTimespan = nTargetTimespan/2;
}
else if (nActualTimespan > nTargetTimespan*4) nActualTimespan = nTargetTimespan*4;
} else { // new algorithm
// use integer aritmmetic to make sure that
// all architectures return the exact same answers,
// so instead of:
//
// foo < bar/1.086 we do foo < (1000*bar)/1086
// foo = bar/1.086 we do foo = (1000*bar)/1086
// foo > bar*1.086 we do foo > (1086*bar)/1000
// foo = bar*1.086 we do foo = (1086*bar)/1000
//
// (parentheses to stress desired operator precedence)
//
// risk of overflow? no way; bar is quite small and
// we have it under control, it is defined as 3*60*60
if (nActualTimespan < (1000*nTargetTimespan)/1086)
nActualTimespan = (1000*nTargetTimespan)/1086;
else if (nActualTimespan > (1086*nTargetTimespan)/1000)
nActualTimespan = (1086*nTargetTimespan)/1000;
}
// Retarget
arith_uint256 bnNew;
bnNew.SetCompact(pindexLast->nBits);
bnNew *= nActualTimespan;
bnNew /= nTargetTimespan;
if (bnNew > powLimit)
bnNew = powLimit;
/// debug print
LogPrintf("GetNextWorkRequired RETARGET\n");
LogPrintf("nTargetTimespan = %ld nActualTimespan = %ld\n", nTargetTimespan, nActualTimespan);
LogPrintf("Before: %08x\n", pindexLast->nBits);
LogPrintf("After: %08x\n", bnNew.GetCompact());
return bnNew.GetCompact();
}
