From d64eef48a45d1bbbbab5adf39d6ba1fe4537cea1 Mon Sep 17 00:00:00 2001
From: coblee <chocobo@alum.mit.edu>
Date: Fri, 17 May 2013 00:57:05 -1000
Subject: Add getnetworkhashps to get the calculated network hashrate

---
 src/rpcmining.cpp | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

(limited to 'src/rpcmining.cpp')

diff --git a/src/rpcmining.cpp b/src/rpcmining.cpp
index 25111d3787..ca768ad71f 100644
--- a/src/rpcmining.cpp
+++ b/src/rpcmining.cpp
@@ -27,6 +27,59 @@ void ShutdownRPCMining()
     delete pMiningKey; pMiningKey = NULL;
 }
 
+// Return average network hashes per second based on the last 'lookup' blocks,
+// or from the last difficulty change if 'lookup' is nonpositive.
+// If 'height' is nonnegative, compute the estimate at the time when a given block was found.
+Value GetNetworkHashPS(int lookup, int height) {
+    CBlockIndex *pb = pindexBest;
+
+    if (height >= 0 && height < nBestHeight)
+        pb = FindBlockByHeight(height);
+
+    if (pb == NULL || !pb->nHeight)
+        return 0;
+
+    // If lookup is -1, then use blocks since last difficulty change.
+    if (lookup <= 0)
+        lookup = pb->nHeight % 2016 + 1;
+
+    // If lookup is larger than chain, then set it to chain length.
+    if (lookup > pb->nHeight)
+        lookup = pb->nHeight;
+
+    CBlockIndex *pb0 = pb;
+    int64 minTime = pb0->GetBlockTime();
+    int64 maxTime = minTime;
+    for (int i = 0; i < lookup; i++) {
+        pb0 = pb0->pprev;
+        int64 time = pb0->GetBlockTime();
+        minTime = std::min(time, minTime);
+        maxTime = std::max(time, maxTime);
+    }
+
+    // In case there's a situation where minTime == maxTime, we don't want a divide by zero exception.
+    if (minTime == maxTime)
+        return 0;
+
+    uint256 workDiff = pb->nChainWork - pb0->nChainWork;
+    int64 timeDiff = maxTime - minTime;
+
+    return (boost::int64_t)(workDiff.getdouble() / timeDiff);
+}
+
+Value getnetworkhashps(const Array& params, bool fHelp)
+{
+    if (fHelp || params.size() > 2)
+        throw runtime_error(
+            "getnetworkhashps [blocks] [height]\n"
+            "Returns the estimated network hashes per second based on the last 120 blocks.\n"
+            "Pass in [blocks] to override # of blocks, -1 specifies since last difficulty change.\n"
+            "Pass in [height] to estimate the network speed at the time when a certain block was found.");
+
+    return GetNetworkHashPS(params.size() > 0 ? params[0].get_int() : 120, params.size() > 1 ? params[1].get_int() : -1);
+}
+
+
 Value getgenerate(const Array& params, bool fHelp)
 {
     if (fHelp || params.size() != 0)
@@ -93,6 +146,7 @@ Value getmininginfo(const Array& params, bool fHelp)
     obj.push_back(Pair("generate",         GetBoolArg("-gen", false)));
     obj.push_back(Pair("genproclimit",     (int)GetArg("-genproclimit", -1)));
     obj.push_back(Pair("hashespersec",     gethashespersec(params, false)));
+    obj.push_back(Pair("networkhashps",    getnetworkhashps(params, false)));
     obj.push_back(Pair("pooledtx",         (uint64_t)mempool.size()));
     obj.push_back(Pair("testnet",          TestNet()));
     return obj;
-- 
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