ad49c256c3
Split up util.cpp/h into: - string utilities (hex, base32, base64): no internal dependencies, no dependency on boost (apart from foreach) - money utilities (parsesmoney, formatmoney) - time utilities (gettime*, sleep, format date): - and the rest (logging, argument parsing, config file parsing) The latter is basically the environment and OS handling, and is stripped of all utility functions, so we may want to rename it to something else than util.cpp/h for clarity (Matt suggested osinterface). Breaks dependency of sha256.cpp on all the things pulled in by util.
121 lines
4.1 KiB
C++
121 lines
4.1 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2014 The Bitcoin developers
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// Distributed under the MIT/X11 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 "chainparams.h"
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#include "core.h"
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#include "main.h"
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#include "uint256.h"
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#include "util.h"
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unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock)
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{
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unsigned int nProofOfWorkLimit = Params().ProofOfWorkLimit().GetCompact();
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// Genesis block
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if (pindexLast == NULL)
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return nProofOfWorkLimit;
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// Only change once per interval
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if ((pindexLast->nHeight+1) % Params().Interval() != 0)
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{
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if (Params().AllowMinDifficultyBlocks())
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{
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// Special difficulty rule for testnet:
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// If the new block's timestamp is more than 2* 10 minutes
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// then allow mining of a min-difficulty block.
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if (pblock->GetBlockTime() > pindexLast->GetBlockTime() + Params().TargetSpacing()*2)
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return nProofOfWorkLimit;
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else
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{
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// Return the last non-special-min-difficulty-rules-block
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const CBlockIndex* pindex = pindexLast;
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while (pindex->pprev && pindex->nHeight % Params().Interval() != 0 && pindex->nBits == nProofOfWorkLimit)
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pindex = pindex->pprev;
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return pindex->nBits;
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}
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}
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return pindexLast->nBits;
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}
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// Go back by what we want to be 14 days worth of blocks
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const CBlockIndex* pindexFirst = pindexLast;
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for (int i = 0; pindexFirst && i < Params().Interval()-1; i++)
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pindexFirst = pindexFirst->pprev;
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assert(pindexFirst);
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// Limit adjustment step
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int64_t nActualTimespan = pindexLast->GetBlockTime() - pindexFirst->GetBlockTime();
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LogPrintf(" nActualTimespan = %d before bounds\n", nActualTimespan);
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if (nActualTimespan < Params().TargetTimespan()/4)
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nActualTimespan = Params().TargetTimespan()/4;
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if (nActualTimespan > Params().TargetTimespan()*4)
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nActualTimespan = Params().TargetTimespan()*4;
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// Retarget
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uint256 bnNew;
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uint256 bnOld;
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bnNew.SetCompact(pindexLast->nBits);
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bnOld = bnNew;
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bnNew *= nActualTimespan;
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bnNew /= Params().TargetTimespan();
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if (bnNew > Params().ProofOfWorkLimit())
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bnNew = Params().ProofOfWorkLimit();
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/// debug print
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LogPrintf("GetNextWorkRequired RETARGET\n");
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LogPrintf("Params().TargetTimespan() = %d nActualTimespan = %d\n", Params().TargetTimespan(), nActualTimespan);
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LogPrintf("Before: %08x %s\n", pindexLast->nBits, bnOld.ToString());
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LogPrintf("After: %08x %s\n", bnNew.GetCompact(), bnNew.ToString());
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return bnNew.GetCompact();
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}
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bool CheckProofOfWork(uint256 hash, unsigned int nBits)
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{
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bool fNegative;
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bool fOverflow;
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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 > Params().ProofOfWorkLimit())
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return error("CheckProofOfWork() : nBits below minimum work");
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// Check proof of work matches claimed amount
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if (hash > bnTarget)
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return error("CheckProofOfWork() : hash doesn't match nBits");
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return true;
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}
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//
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// minimum amount of work that could possibly be required nTime after
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// minimum work required was nBase
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//
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unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime)
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{
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const uint256 &bnLimit = Params().ProofOfWorkLimit();
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// Testnet has min-difficulty blocks
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// after Params().TargetSpacing()*2 time between blocks:
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if (Params().AllowMinDifficultyBlocks() && nTime > Params().TargetSpacing()*2)
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return bnLimit.GetCompact();
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uint256 bnResult;
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bnResult.SetCompact(nBase);
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while (nTime > 0 && bnResult < bnLimit)
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{
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// Maximum 400% adjustment...
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bnResult *= 4;
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// ... in best-case exactly 4-times-normal target time
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nTime -= Params().TargetTimespan()*4;
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}
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if (bnResult > bnLimit)
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bnResult = bnLimit;
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return bnResult.GetCompact();
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}
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