101 lines
3.4 KiB
C++
101 lines
3.4 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2015 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include "pow.h"
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#include "arith_uint256.h"
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#include "chain.h"
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#include "primitives/block.h"
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#include "uint256.h"
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#include "util.h"
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#include <stdio.h>
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static arith_uint256 GetTargetLimit(int64_t nTime, const Consensus::Params& params, bool fProofOfStake)
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{
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uint256 nLimit;
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if (fProofOfStake) {
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if (params.IsProtocolV2(nTime))
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nLimit = params.posLimitV2;
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else
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nLimit = params.posLimit;
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} else {
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nLimit = params.powLimit;
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}
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return UintToArith256(nLimit);
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}
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unsigned int GetNextTargetRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params& params, bool fProofOfStake)
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{
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unsigned int nTargetLimit = GetTargetLimit(pindexLast->GetBlockTime(), params, fProofOfStake).GetCompact();
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// Genesis block
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if (pindexLast == NULL)
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return UintToArith256(params.powLimit).GetCompact();
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const CBlockIndex* pindexPrev = GetLastBlockIndex(pindexLast, fProofOfStake);
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if (pindexPrev->pprev == NULL)
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return nTargetLimit; // first block
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const CBlockIndex* pindexPrevPrev = GetLastBlockIndex(pindexPrev->pprev, fProofOfStake);
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if (pindexPrevPrev->pprev == NULL)
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return nTargetLimit; // second block
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return CalculateNextTargetRequired(pindexPrev, pindexPrevPrev->GetBlockTime(), params, fProofOfStake);
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}
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unsigned int CalculateNextTargetRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params& params, bool fProofOfStake)
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{
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if (fProofOfStake) {
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if (params.fPoSNoRetargeting)
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return pindexLast->nBits;
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} else {
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if (params.fPowNoRetargeting)
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return pindexLast->nBits;
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}
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int64_t nTargetSpacing = params.IsProtocolV2(pindexLast->GetBlockTime()) ? params.nTargetSpacing : params.nTargetSpacingV1;
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int64_t nActualSpacing = pindexLast->GetBlockTime() - nFirstBlockTime;
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// Limit adjustment step
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if (pindexLast->GetBlockTime() > params.nProtocolV1RetargetingFixedTime && nActualSpacing < 0)
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nActualSpacing = nTargetSpacing;
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if (pindexLast->GetBlockTime() > params.nProtocolV3Time && nActualSpacing > nTargetSpacing*10)
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nActualSpacing = nTargetSpacing*10;
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// retarget with exponential moving toward target spacing
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const arith_uint256 bnTargetLimit = GetTargetLimit(pindexLast->GetBlockTime(), params, fProofOfStake);
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arith_uint256 bnNew;
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bnNew.SetCompact(pindexLast->nBits);
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int64_t nInterval = params.nTargetTimespan / nTargetSpacing;
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bnNew *= ((nInterval - 1) * nTargetSpacing + nActualSpacing + nActualSpacing);
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bnNew /= ((nInterval + 1) * nTargetSpacing);
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if (bnNew <= 0 || bnNew > bnTargetLimit)
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bnNew = bnTargetLimit;
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return bnNew.GetCompact();
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}
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bool CheckProofOfWork(uint256 hash, unsigned int nBits, const Consensus::Params& params)
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{
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bool fNegative;
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bool fOverflow;
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arith_uint256 bnTarget;
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bnTarget.SetCompact(nBits, &fNegative, &fOverflow);
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// Check range
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if (fNegative || bnTarget == 0 || fOverflow || bnTarget > UintToArith256(params.powLimit))
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return false;
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// Check proof of work matches claimed amount
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if (UintToArith256(hash) > bnTarget)
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return false;
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return true;
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}
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