1 files changed, 59 insertions, 0 deletions
diff --git a/src/chain.cpp b/src/chain.cpp
new file mode 100644
index 0000000000..bcb497b2d4
--- /dev/null
+++ b/src/chain.cpp
@@ -0,0 +1,59 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2014 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "chain.h"
+
+using namespace std;
+
+// CChain implementation
+
+CBlockIndex *CChain::SetTip(CBlockIndex *pindex) {
+    if (pindex == NULL) {
+        vChain.clear();
+        return NULL;
+    }
+    vChain.resize(pindex->nHeight + 1);
+    while (pindex && vChain[pindex->nHeight] != pindex) {
+        vChain[pindex->nHeight] = pindex;
+        pindex = pindex->pprev;
+    }
+    return pindex;
+}
+
+CBlockLocator CChain::GetLocator(const CBlockIndex *pindex) const {
+    int nStep = 1;
+    std::vector<uint256> vHave;
+    vHave.reserve(32);
+
+    if (!pindex)
+        pindex = Tip();
+    while (pindex) {
+        vHave.push_back(pindex->GetBlockHash());
+        // Stop when we have added the genesis block.
+        if (pindex->nHeight == 0)
+            break;
+        // Exponentially larger steps back, plus the genesis block.
+        int nHeight = std::max(pindex->nHeight - nStep, 0);
+        if (Contains(pindex)) {
+            // Use O(1) CChain index if possible.
+            pindex = (*this)[nHeight];
+        } else {
+            // Otherwise, use O(log n) skiplist.
+            pindex = pindex->GetAncestor(nHeight);
+        }
+        if (vHave.size() > 10)
+            nStep *= 2;
+    }
+
+    return CBlockLocator(vHave);
+}
+
+const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {
+    if (pindex->nHeight > Height())
+        pindex = pindex->GetAncestor(Height());
+    while (pindex && !Contains(pindex))
+        pindex = pindex->pprev;
+    return pindex;
+}