From 7801f4387d96c19de6dedc518e45d3037d9c53fa Mon Sep 17 00:00:00 2001
From: Eric Lombrozo <elombrozo@gmail.com>
Date: Mon, 19 Oct 2015 08:25:29 -0400
Subject: [PATCH] Added fPowNoRetargeting field to Consensus::Params that
 disables nBits recalculation.

---
 src/chainparams.cpp    | 3 +++
 src/consensus/params.h | 1 +
 src/pow.cpp            | 3 +++
 3 files changed, 7 insertions(+)

diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 430b75683bb..52d818059e9 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -76,6 +76,7 @@ public:
         consensus.nPowTargetTimespan = 14 * 24 * 60 * 60; // two weeks
         consensus.nPowTargetSpacing = 10 * 60;
         consensus.fPowAllowMinDifficultyBlocks = false;
+        consensus.fPowNoRetargeting = false;
         /** 
          * The message start string is designed to be unlikely to occur in normal data.
          * The characters are rarely used upper ASCII, not valid as UTF-8, and produce
@@ -155,6 +156,7 @@ public:
         consensus.nPowTargetTimespan = 14 * 24 * 60 * 60; // two weeks
         consensus.nPowTargetSpacing = 10 * 60;
         consensus.fPowAllowMinDifficultyBlocks = true;
+        consensus.fPowNoRetargeting = false;
         pchMessageStart[0] = 0x0b;
         pchMessageStart[1] = 0x11;
         pchMessageStart[2] = 0x09;
@@ -217,6 +219,7 @@ public:
         consensus.nPowTargetTimespan = 14 * 24 * 60 * 60; // two weeks
         consensus.nPowTargetSpacing = 10 * 60;
         consensus.fPowAllowMinDifficultyBlocks = true;
+        consensus.fPowNoRetargeting = true;
 
         pchMessageStart[0] = 0xfa;
         pchMessageStart[1] = 0xbf;
diff --git a/src/consensus/params.h b/src/consensus/params.h
index c480a1cce19..efbbbed3525 100644
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -22,6 +22,7 @@ struct Params {
     /** Proof of work parameters */
     uint256 powLimit;
     bool fPowAllowMinDifficultyBlocks;
+    bool fPowNoRetargeting;
     int64_t nPowTargetSpacing;
     int64_t nPowTargetTimespan;
     int64_t DifficultyAdjustmentInterval() const { return nPowTargetTimespan / nPowTargetSpacing; }
diff --git a/src/pow.cpp b/src/pow.cpp
index bb53ad204bc..5ace3fbc9b5 100644
--- a/src/pow.cpp
+++ b/src/pow.cpp
@@ -52,6 +52,9 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
 
 unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params& params)
 {
+    if (params.fPowNoRetargeting)
+        return pindexLast->nBits;
+
     // Limit adjustment step
     int64_t nActualTimespan = pindexLast->GetBlockTime() - nFirstBlockTime;
     LogPrintf("  nActualTimespan = %d  before bounds\n", nActualTimespan);