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Correction for errata 152557

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This commit is contained in:
Andreas M. Antonopoulos 2016-01-02 12:04:38 -06:00
parent 419d2c0868
commit 0d050d01ab
1 changed files with 18 additions and 23 deletions
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@ -642,35 +642,30 @@ New Difficulty = Old Difficulty * (Actual Time of Last 2016 Blocks / 20160 minut
<<retarget_difficulty_code>> shows the code used in the Bitcoin Core client.
[[retarget_difficulty_code]]
.Retargeting the proof-of-work difficulty—GetNextWorkRequired() in pow.cpp, line 43
.Retargeting the proof-of-work difficulty — CalculateNextWorkRequired() in pow.cpp
====
[source,cpp]
----
// Go back by what we want to be 14 days worth of blocks
const CBlockIndex* pindexFirst = pindexLast;
for (int i = 0; pindexFirst && i < Params().Interval()-1; i++)
pindexFirst = pindexFirst->pprev;
assert(pindexFirst);
// Limit adjustment step
int64_t nActualTimespan = pindexLast->GetBlockTime() - nFirstBlockTime;
LogPrintf(" nActualTimespan = %d before bounds\n", nActualTimespan);
if (nActualTimespan < params.nPowTargetTimespan/4)
nActualTimespan = params.nPowTargetTimespan/4;
if (nActualTimespan > params.nPowTargetTimespan*4)
nActualTimespan = params.nPowTargetTimespan*4;
// Limit adjustment step
int64_t nActualTimespan = pindexLast->GetBlockTime() - pindexFirst->GetBlockTime();
LogPrintf(" nActualTimespan = %d before bounds\n", nActualTimespan);
if (nActualTimespan < Params().TargetTimespan()/4)
nActualTimespan = Params().TargetTimespan()/4;
if (nActualTimespan > Params().TargetTimespan()*4)
nActualTimespan = Params().TargetTimespan()*4;
// Retarget
const arith_uint256 bnPowLimit = UintToArith256(params.powLimit);
arith_uint256 bnNew;
arith_uint256 bnOld;
bnNew.SetCompact(pindexLast->nBits);
bnOld = bnNew;
bnNew *= nActualTimespan;
bnNew /= params.nPowTargetTimespan;
// Retarget
uint256 bnNew;
uint256 bnOld;
bnNew.SetCompact(pindexLast->nBits);
bnOld = bnNew;
bnNew *= nActualTimespan;
bnNew /= Params().TargetTimespan();
if (bnNew > Params().ProofOfWorkLimit())
bnNew = Params().ProofOfWorkLimit();
if (bnNew > bnPowLimit)
bnNew = bnPowLimit;
----
====