1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2018 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 <dogecoin.h>
#include <primitives/block.h>
#include <uint256.h>
unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params& params)
{
assert(pindexLast != nullptr);
unsigned int nProofOfWorkLimit = UintToArith256(params.powLimit).GetCompact();
// Dogecoin: 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
bool fNewDifficultyProtocol = (pindexLast->nHeight+1 >= 145000);
const int64_t difficultyAdjustmentInterval = fNewDifficultyProtocol
? 1
: params.DifficultyAdjustmentInterval();
const int64_t powTargetSpacing = fNewDifficultyProtocol
? 60
: params.nPowTargetSpacing;
if ((pindexLast->nHeight+1) % 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() + powTargetSpacing*2) {
return nProofOfWorkLimit;
}
else
{
// Return the last non-special-min-difficulty-rules-block
const CBlockIndex* pindex = pindexLast;
while (pindex->pprev && pindex->nHeight % 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 = difficultyAdjustmentInterval-1;
if ((pindexLast->nHeight+1) != difficultyAdjustmentInterval)
blockstogoback = 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 CalculateDogecoinNextWorkRequired(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;
}
|