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-rw-r--r--src/chain.cpp19
1 files changed, 19 insertions, 0 deletions
diff --git a/src/chain.cpp b/src/chain.cpp
index 8d4c4e7dea..ffd58d471d 100644
--- a/src/chain.cpp
+++ b/src/chain.cpp
@@ -148,3 +148,22 @@ int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& fr
}
return sign * r.GetLow64();
}
+
+/** Find the last common ancestor two blocks have.
+ * Both pa and pb must be non-NULL. */
+const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb) {
+ if (pa->nHeight > pb->nHeight) {
+ pa = pa->GetAncestor(pb->nHeight);
+ } else if (pb->nHeight > pa->nHeight) {
+ pb = pb->GetAncestor(pa->nHeight);
+ }
+
+ while (pa != pb && pa && pb) {
+ pa = pa->pprev;
+ pb = pb->pprev;
+ }
+
+ // Eventually all chain branches meet at the genesis block.
+ assert(pa == pb);
+ return pa;
+}