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// Copyright (c) 2015-2017 The Dogecoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <boost/random/uniform_int.hpp>
#include <boost/random/mersenne_twister.hpp>
#include <arith_uint256.h>
#include <dogecoin.h>
#include <pow.h>
#include <util.h>
int static generateMTRandom(unsigned int s, int range)
{
boost::mt19937 gen(s);
boost::uniform_int<> dist(1, range);
return dist(gen);
}
// Dogecoin: Normally minimum difficulty blocks can only occur in between
// retarget blocks. However, once we introduce Digishield every block is
// a retarget, so we need to handle minimum difficulty on all blocks.
bool AllowDigishieldMinDifficultyForBlock(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params& params)
{
// check if the chain allows minimum difficulty blocks
if (!params.fPowAllowMinDifficultyBlocks)
return false;
// check if the chain allows minimum difficulty blocks on recalc blocks
if (pindexLast->nHeight < 157500)
// if (!params.fPowAllowDigishieldMinDifficultyBlocks)
return false;
// Allow for a minimum block time if the elapsed time > 2*nTargetSpacing
return (pblock->GetBlockTime() > pindexLast->GetBlockTime() + params.nPowTargetSpacing*2);
}
unsigned int CalculateDogecoinNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params& params)
{
int nHeight = pindexLast->nHeight + 1;
bool fNewDifficultyProtocol = (nHeight >= 145000);
// bool fNewDifficultyProtocol = (nHeight >= params.GetDigiShieldForkBlock());
const int64_t retargetTimespan = fNewDifficultyProtocol ? 60 // params.DigiShieldTargetTimespan()
:
params.nPowTargetTimespan;
const int64_t nActualTimespan = pindexLast->GetBlockTime() - nFirstBlockTime;
int64_t nModulatedTimespan = nActualTimespan;
int64_t nMaxTimespan;
int64_t nMinTimespan;
if (fNewDifficultyProtocol) //DigiShield implementation - thanks to RealSolid & WDC for this code
{
// amplitude filter - thanks to daft27 for this code
nModulatedTimespan = retargetTimespan + (nModulatedTimespan - retargetTimespan) / 8;
nMinTimespan = retargetTimespan - (retargetTimespan / 4);
nMaxTimespan = retargetTimespan + (retargetTimespan / 2);
} else if (nHeight > 10000) {
nMinTimespan = retargetTimespan / 4;
nMaxTimespan = retargetTimespan * 4;
} else if (nHeight > 5000) {
nMinTimespan = retargetTimespan / 8;
nMaxTimespan = retargetTimespan * 4;
} else {
nMinTimespan = retargetTimespan / 16;
nMaxTimespan = retargetTimespan * 4;
}
// Limit adjustment step
if (nModulatedTimespan < nMinTimespan)
nModulatedTimespan = nMinTimespan;
else if (nModulatedTimespan > nMaxTimespan)
nModulatedTimespan = nMaxTimespan;
// Retarget
const arith_uint256 bnPowLimit = UintToArith256(params.powLimit);
arith_uint256 bnNew;
arith_uint256 bnOld;
bnNew.SetCompact(pindexLast->nBits);
bnOld = bnNew;
bnNew *= nModulatedTimespan;
bnNew /= retargetTimespan;
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();
}
bool CheckAuxPowProofOfWork(const CBlockHeader& block, const Consensus::Params& params)
{
/* Except for legacy blocks with full version 1, ensure that
the chain ID is correct. Legacy blocks are not allowed since
the merge-mining start, which is checked in AcceptBlockHeader
where the height is known. */
if (!block.IsLegacy() && params.fStrictChainId
&& block.GetChainId() != params.nAuxpowChainId)
return error("%s : block does not have our chain ID"
" (got %d, expected %d, full nVersion %d)",
__func__, block.GetChainId(),
params.nAuxpowChainId, block.nVersion);
/* If there is no auxpow, just check the block hash. */
if (!block.auxpow) {
if (block.IsAuxpow())
return error("%s : no auxpow on block with auxpow version",
__func__);
if (!CheckProofOfWork(block.GetPoWHash(), block.nBits, params))
return error("%s : non-AUX proof of work failed", __func__);
return true;
}
/* We have auxpow. Check it. */
if (!block.IsAuxpow())
return error("%s : auxpow on block with non-auxpow version", __func__);
if (!block.auxpow->check(block.GetHash(), block.GetChainId(), params))
return error("%s : AUX POW is not valid", __func__);
if (!CheckProofOfWork(block.auxpow->getParentBlockPoWHash(), block.nBits, params))
return error("%s : AUX proof of work failed", __func__);
return true;
}
CAmount GetDogecoinBlockSubsidy(int nHeight, const Consensus::Params& consensusParams, uint256 prevHash)
{
int halvings = nHeight / consensusParams.nSubsidyHalvingInterval;
if (nHeight < 145000) // && !consensusParams.SimplifiedRewards())
{
// Old-style rewards derived from the previous block hash
const std::string cseed_str = prevHash.ToString().substr(7, 7);
const char* cseed = cseed_str.c_str();
char* endp = NULL;
long seed = strtol(cseed, &endp, 16);
CAmount maxReward = (1000000 >> halvings) - 1;
int rand = generateMTRandom(seed, maxReward);
return (1 + rand) * COIN;
} else if (nHeight < (6 * consensusParams.nSubsidyHalvingInterval)) {
// New-style constant rewards for each halving interval
return (500000 * COIN) >> halvings;
} else {
// Constant inflation
return 10000 * COIN;
}
}
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