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authorJorge Timón <jtimon@jtimon.cc>2015-11-30 00:46:49 +0100
committerJorge Timón <jtimon@jtimon.cc>2016-01-12 13:43:14 +0100
commite86756193ebdbf71504e2a1a8db43e38d57f9673 (patch)
tree1048571b27029b21d33d889c3f37fb48c1798ad5 /src/chain.cpp
parent3cd836c1d855b92e7c73ab31979f471c4f8dad68 (diff)
MOVEONLY: non-consensus: from pow to chain:
- GetBlockProof - GetBlockProofEquivalentTime
Diffstat (limited to 'src/chain.cpp')
-rw-r--r--src/chain.cpp32
1 files changed, 32 insertions, 0 deletions
diff --git a/src/chain.cpp b/src/chain.cpp
index 3450ed6c3f..32f6480f84 100644
--- a/src/chain.cpp
+++ b/src/chain.cpp
@@ -110,3 +110,35 @@ void CBlockIndex::BuildSkip()
if (pprev)
pskip = pprev->GetAncestor(GetSkipHeight(nHeight));
}
+
+arith_uint256 GetBlockProof(const CBlockIndex& block)
+{
+ arith_uint256 bnTarget;
+ bool fNegative;
+ bool fOverflow;
+ bnTarget.SetCompact(block.nBits, &fNegative, &fOverflow);
+ if (fNegative || fOverflow || bnTarget == 0)
+ return 0;
+ // We need to compute 2**256 / (bnTarget+1), but we can't represent 2**256
+ // as it's too large for a arith_uint256. However, as 2**256 is at least as large
+ // as bnTarget+1, it is equal to ((2**256 - bnTarget - 1) / (bnTarget+1)) + 1,
+ // or ~bnTarget / (nTarget+1) + 1.
+ return (~bnTarget / (bnTarget + 1)) + 1;
+}
+
+int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& from, const CBlockIndex& tip, const Consensus::Params& params)
+{
+ arith_uint256 r;
+ int sign = 1;
+ if (to.nChainWork > from.nChainWork) {
+ r = to.nChainWork - from.nChainWork;
+ } else {
+ r = from.nChainWork - to.nChainWork;
+ sign = -1;
+ }
+ r = r * arith_uint256(params.nPowTargetSpacing) / GetBlockProof(tip);
+ if (r.bits() > 63) {
+ return sign * std::numeric_limits<int64_t>::max();
+ }
+ return sign * r.GetLow64();
+}