You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
94 lines
3.2 KiB
94 lines
3.2 KiB
// Copyright (c) 2009-2010 Satoshi Nakamoto |
|
// Copyright (c) 2009-2015 The Bitcoin Core developers |
|
// Distributed under the MIT software license, see the accompanying |
|
// file COPYING or http://www.opensource.org/licenses/mit-license.php. |
|
|
|
#include "pow.h" |
|
|
|
#include "arith_uint256.h" |
|
#include "chain.h" |
|
#include "primitives/block.h" |
|
#include "uint256.h" |
|
|
|
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.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 CalculateNextWorkRequired(pindexLast, pindexFirst->GetBlockTime(), params); |
|
} |
|
|
|
unsigned int CalculateNextWorkRequired(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.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; |
|
bnNew.SetCompact(pindexLast->nBits); |
|
bnNew *= nActualTimespan; |
|
bnNew /= params.nPowTargetTimespan; |
|
|
|
if (bnNew > bnPowLimit) |
|
bnNew = bnPowLimit; |
|
|
|
return bnNew.GetCompact(); |
|
} |
|
|
|
bool CheckProofOfWork(uint256 hash, unsigned int nBits, 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)) |
|
return false; |
|
|
|
// Check proof of work matches claimed amount |
|
if (UintToArith256(hash) > bnTarget) |
|
return false; |
|
|
|
return true; |
|
}
|
|
|