1 files changed, 59 insertions, 0 deletions
diff --git a/src/timedata.h b/src/timedata.h
index 0e7bdc2c1f..d0c84b3183 100644
--- a/src/timedata.h
+++ b/src/timedata.h
@@ -6,9 +6,68 @@
 #define BITCOIN_TIMEDATA_H
 
 #include <stdint.h>
+#include <vector>
+#include <algorithm>
+#include <assert.h>
 
 class CNetAddr;
 
+/** Median filter over a stream of values.
+ * Returns the median of the last N numbers
+ */
+template <typename T> class CMedianFilter
+{
+private:
+    std::vector<T> vValues;
+    std::vector<T> vSorted;
+    unsigned int nSize;
+public:
+    CMedianFilter(unsigned int size, T initial_value):
+        nSize(size)
+    {
+        vValues.reserve(size);
+        vValues.push_back(initial_value);
+        vSorted = vValues;
+    }
+
+    void input(T value)
+    {
+        if(vValues.size() == nSize)
+        {
+            vValues.erase(vValues.begin());
+        }
+        vValues.push_back(value);
+
+        vSorted.resize(vValues.size());
+        std::copy(vValues.begin(), vValues.end(), vSorted.begin());
+        std::sort(vSorted.begin(), vSorted.end());
+    }
+
+    T median() const
+    {
+        int size = vSorted.size();
+        assert(size>0);
+        if(size & 1) // Odd number of elements
+        {
+            return vSorted[size/2];
+        }
+        else // Even number of elements
+        {
+            return (vSorted[size/2-1] + vSorted[size/2]) / 2;
+        }
+    }
+
+    int size() const
+    {
+        return vValues.size();
+    }
+
+    std::vector<T> sorted () const
+    {
+        return vSorted;
+    }
+};
+
 /* Functions to keep track of adjusted P2P time */
 int64_t GetTimeOffset();
 int64_t GetAdjustedTime();