1 files changed, 61 insertions, 0 deletions
diff --git a/src/dogecoin.cpp b/src/dogecoin.cpp
index 72a9f3cc5..e946acad6 100644
--- a/src/dogecoin.cpp
+++ b/src/dogecoin.cpp
@@ -5,7 +5,9 @@
 #include <boost/random/uniform_int.hpp>
 #include <boost/random/mersenne_twister.hpp>
 
+#include "arith_uint256.h"
 #include "dogecoin.h"
+#include "util.h"
 
 int static generateMTRandom(unsigned int s, int range)
 {
@@ -14,6 +16,65 @@ int static generateMTRandom(unsigned int s, int range)
     return dist(gen);
 }
 
+unsigned int CalculateDogecoinNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params& params)
+{
+    int nHeight = pindexLast->nHeight + 1;
+    bool fNewDifficultyProtocol = (nHeight >= 145000);
+    // bool fNewDifficultyProtocol = (nHeight >= params.GetDigiShieldForkBlock());
+    const int64_t retargetTimespan = fNewDifficultyProtocol
+                             ? 60 // params.DigiShieldTargetTimespan()
+                             : params.nPowTargetTimespan;
+
+    const int64_t nActualTimespan = pindexLast->GetBlockTime() - nFirstBlockTime;
+    int64_t nModulatedTimespan = nActualTimespan;
+    int64_t nMaxTimespan;
+    int64_t nMinTimespan;
+
+    if (fNewDifficultyProtocol) //DigiShield implementation - thanks to RealSolid & WDC for this code
+    {
+        // amplitude filter - thanks to daft27 for this code
+        nModulatedTimespan = retargetTimespan + (nModulatedTimespan - retargetTimespan) / 8;
+
+        nMinTimespan = retargetTimespan - (retargetTimespan / 4);
+        nMaxTimespan = retargetTimespan + (retargetTimespan / 2);
+    } else if (nHeight > 10000) {
+        nMinTimespan = retargetTimespan / 4;
+        nMaxTimespan = retargetTimespan * 4;
+    } else if (nHeight > 5000) {
+        nMinTimespan = retargetTimespan / 8;
+        nMaxTimespan = retargetTimespan * 4;
+    } else {
+        nMinTimespan = retargetTimespan / 16;
+        nMaxTimespan = retargetTimespan * 4;
+    }
+
+    // Limit adjustment step
+    if (nModulatedTimespan < nMinTimespan)
+        nModulatedTimespan = nMinTimespan;
+    else if (nModulatedTimespan > nMaxTimespan)
+        nModulatedTimespan = nMaxTimespan;
+
+    // Retarget
+    const arith_uint256 bnPowLimit = UintToArith256(params.powLimit);
+    arith_uint256 bnNew;
+    arith_uint256 bnOld;
+    bnNew.SetCompact(pindexLast->nBits);
+    bnOld = bnNew;
+    bnNew *= nModulatedTimespan;
+    bnNew /= retargetTimespan;
+
+    if (bnNew > bnPowLimit)
+        bnNew = bnPowLimit;
+
+    /// debug print
+    LogPrintf("GetNextWorkRequired RETARGET\n");
+    LogPrintf("params.nPowTargetTimespan = %d    nActualTimespan = %d\n", params.nPowTargetTimespan, nActualTimespan);
+    LogPrintf("Before: %08x  %s\n", pindexLast->nBits, bnOld.ToString());
+    LogPrintf("After:  %08x  %s\n", bnNew.GetCompact(), bnNew.ToString());
+
+    return bnNew.GetCompact();
+}
+
 CAmount GetDogecoinBlockSubsidy(int nHeight, const Consensus::Params& consensusParams, uint256 prevHash)
 {
     int halvings = nHeight / consensusParams.nSubsidyHalvingInterval;