1 files changed, 54 insertions, 10 deletions

diff --git a/src/chain.cpp b/src/chain.cpp
index e76073674..2ce98818f 100644
--- a/src/chain.cpp
+++ b/src/chain.cpp
@@ -1,30 +1,30 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2014 The Bitcoin Core developers
+// Copyright (c) 2009-2016 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 "chain.h"
-
-#include "main.h"
+#include "validation.h"
 
 using namespace std;
 
 /* Moved here from the header, because we need auxpow and the logic
    becomes more involved.  */
-CBlockHeader CBlockIndex::GetBlockHeader() const
+CBlockHeader CBlockIndex::GetBlockHeader(const Consensus::Params& consensusParams) const
 {
     CBlockHeader block;
 
+    block.nVersion       = nVersion;
+
     /* The CBlockIndex object's block header is missing the auxpow.
        So if this is an auxpow block, read it from disk instead.  We only
        have to read the actual *header*, not the full block.  */
-    if (nVersion.IsAuxpow())
+    if (block.IsAuxpow())
     {
-        ReadBlockHeaderFromDisk(block, this);
+        ReadBlockHeaderFromDisk(block, this, consensusParams);
         return block;
     }
 
-    block.nVersion       = nVersion;
     if (pprev)
         block.hashPrevBlock = pprev->GetBlockHash();
     block.hashMerkleRoot = hashMerkleRoot;
@@ -78,6 +78,9 @@ CBlockLocator CChain::GetLocator(const CBlockIndex *pindex) const {
 }
 
 const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {
+    if (pindex == NULL) {
+        return NULL;
+    }
     if (pindex->nHeight > Height())
         pindex = pindex->GetAncestor(Height());
     while (pindex && !Contains(pindex))
@@ -85,6 +88,13 @@ const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {
     return pindex;
 }
 
+CBlockIndex* CChain::FindEarliestAtLeast(int64_t nTime) const
+{
+    std::vector<CBlockIndex*>::const_iterator lower = std::lower_bound(vChain.begin(), vChain.end(), nTime,
+        [](CBlockIndex* pBlock, const int64_t& time) -> bool { return pBlock->GetBlockTimeMax() < time; });
+    return (lower == vChain.end() ? NULL : *lower);
+}
+
 /** Turn the lowest '1' bit in the binary representation of a number into a '0'. */
 int static inline InvertLowestOne(int n) { return n & (n - 1); }
 
@@ -109,13 +119,15 @@ CBlockIndex* CBlockIndex::GetAncestor(int height)
     while (heightWalk > height) {
         int heightSkip = GetSkipHeight(heightWalk);
         int heightSkipPrev = GetSkipHeight(heightWalk - 1);
-        if (heightSkip == height ||
-            (heightSkip > height && !(heightSkipPrev < heightSkip - 2 &&
-                                      heightSkipPrev >= height))) {
+        if (pindexWalk->pskip != NULL &&
+            (heightSkip == height ||
+             (heightSkip > height && !(heightSkipPrev < heightSkip - 2 &&
+                                       heightSkipPrev >= height)))) {
             // Only follow pskip if pprev->pskip isn't better than pskip->pprev.
             pindexWalk = pindexWalk->pskip;
             heightWalk = heightSkip;
         } else {
+            assert(pindexWalk->pprev);
             pindexWalk = pindexWalk->pprev;
             heightWalk--;
         }
@@ -133,3 +145,35 @@ 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();
+}