From c5eb32a85beeec07dc4ebea3788a63da23df9dff Mon Sep 17 00:00:00 2001
From: Jannis Froese <s9jafroe@stud.uni-saarland.de>
Date: Sat, 22 Mar 2014 07:33:44 +0100
Subject: [PATCH] updated to Dogecoin 1.6 protocol

(cherry picked from commit d6dbaf412e2331426d5012d1c10b7749b6821b82)
---
 src/main.cpp | 34 ++++++++++++++++++++++++++++++----
 src/main.h   |  4 ++++
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index f4159e269..2cfe9a6e3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1184,9 +1184,12 @@ int64_t GetBlockValue(int nHeight, int64_t nFees, uint256 prevHash)
 }
 
 static const int64_t nTargetTimespan = 4 * 60 * 60; // DogeCoin: every 4 hours
+static const int64_t nTargetTimespanNEW = 60 ; // DogeCoin: every 1 minute
 static const int64_t nTargetSpacing = 60; // DogeCoin: 1 minute
 static const int64_t nInterval = nTargetTimespan / nTargetSpacing;
 
+static const int64_t nDiffChangeTarget = 145000; // Patch effective @ block 145000
+
 //
 // minimum amount of work that could possibly be required nTime after
 // minimum work required was nBase
@@ -1217,6 +1220,18 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
 {
     unsigned int nProofOfWorkLimit = Params().ProofOfWorkLimit().GetCompact();
 
+    int nHeight = pindexLast->nHeight + 1;
+    bool fNewDifficultyProtocol = (nHeight >= nDiffChangeTarget);
+    
+    int64_t retargetTimespan = nTargetTimespan;
+    int64_t retargetSpacing = nTargetSpacing;
+    int64_t retargetInterval = nInterval;
+    
+    if (fNewDifficultyProtocol) {
+        retargetInterval = nTargetTimespanNEW / nTargetSpacing;
+        retargetTimespan = nTargetTimespanNEW;
+    }
+    
     // Genesis block
     if (pindexLast == NULL)
         return nProofOfWorkLimit;
@@ -1257,15 +1272,23 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
 
     // Limit adjustment step
     int64_t nActualTimespan = pindexLast->GetBlockTime() - pindexFirst->GetBlockTime();
-    //printf("  nActualTimespan = %"PRI64d"  before bounds\n", nActualTimespan);
-    if(pindexLast->nHeight+1 > 10000)
+    LogPrintf("  nActualTimespan = %d  before bounds\n", nActualTimespan);
+    
+    if (fNewDifficultyProtocol) //DigiShield implementation - thanks to RealSolid & WDC for this code
     {
+        // amplitude filter - thanks to daft27 for this code
+        nActualTimespan = retargetTimespan + (nActualTimespan - retargetTimespan)/8;
+        printf("DIGISHIELD RETARGET\n");
+        if (nActualTimespan < (retargetTimespan - (retargetTimespan/4)) ) nActualTimespan = (retargetTimespan - (retargetTimespan/4));
+        if (nActualTimespan > (retargetTimespan + (retargetTimespan/2)) ) nActualTimespan = (retargetTimespan + (retargetTimespan/2));
+    }
+    else if (pindexLast->nHeight+1 > 10000) {
         if (nActualTimespan < nTargetTimespan/4)
             nActualTimespan = nTargetTimespan/4;
         if (nActualTimespan > nTargetTimespan*4)
             nActualTimespan = nTargetTimespan*4;
     }
-    else if(pindexLast->nHeight+1 > 5000)
+    else if (pindexLast->nHeight+1 > 5000)
     {
         if (nActualTimespan < nTargetTimespan/8)
             nActualTimespan = nTargetTimespan/8;
@@ -1549,7 +1572,10 @@ bool CheckInputs(const CTransaction& tx, CValidationState &state, CCoinsViewCach
 
             // If prev is coinbase, check that it's matured
             if (coins.IsCoinBase()) {
-                if (nSpendHeight - coins.nHeight < COINBASE_MATURITY)
+                int minDepth = COINBASE_MATURITY;
+                if(coins.nHeight >= COINBASE_MATURITY_SWITCH)
+                    minDepth = COINBASE_MATURITY_NEW;
+                if (nSpendHeight - coins.nHeight < minDepth)
                     return state.Invalid(
                         error("CheckInputs() : tried to spend coinbase at depth %d", nSpendHeight - coins.nHeight),
                         REJECT_INVALID, "bad-txns-premature-spend-of-coinbase");
diff --git a/src/main.h b/src/main.h
index 29015b2bc..96cd8733f 100644
--- a/src/main.h
+++ b/src/main.h
@@ -61,6 +61,10 @@ static const int64_t DUST_SOFT_LIMIT = 100000000;
 static const int64_t DUST_HARD_LIMIT = 1000000;
 /** Coinbase transaction outputs can only be spent after this number of new blocks (network rule) */
 static const int COINBASE_MATURITY = 30;
+/** Coinbase maturity after block 145000 **/
+static const int COINBASE_MATURITY_NEW = 60*4;
+/** Block at which COINBASE_MATURITY_NEW comes into effect **/
+static const int COINBASE_MATURITY_SWITCH = 145000;
 /** Threshold for nLockTime: below this value it is interpreted as block number, otherwise as UNIX timestamp. */
 static const unsigned int LOCKTIME_THRESHOLD = 500000000; // Tue Nov  5 00:53:20 1985 UTC
 /** Maximum number of script-checking threads allowed */