From 1f7ee4af70ece8759f7a4e6d8df9c39284bb1482 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Thu, 4 Oct 2018 23:26:05 +0100
Subject: [PATCH] Rename min-difficulty flag to remove off-by-one in the name

---
 src/chainparams.cpp    | 6 +++---
 src/consensus/params.h | 2 +-
 src/miner.cpp          | 4 ++--
 src/pow.cpp            | 6 ++++--
 4 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 25f9f45f3..8ebf04c6f 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -95,7 +95,7 @@ public:
         consensus.nPowMaxAdjustDown = 32; // 32% adjustment down
         consensus.nPowMaxAdjustUp = 16; // 16% adjustment up
         consensus.nPowTargetSpacing = 2.5 * 60;
-        consensus.nPowAllowMinDifficultyBlocksFromHeight = boost::none;
+        consensus.nPowAllowMinDifficultyBlocksAfterHeight = boost::none;
         consensus.vUpgrades[Consensus::BASE_SPROUT].nProtocolVersion = 170002;
         consensus.vUpgrades[Consensus::BASE_SPROUT].nActivationHeight =
             Consensus::NetworkUpgrade::ALWAYS_ACTIVE;
@@ -272,7 +272,7 @@ public:
         consensus.nPowMaxAdjustDown = 32; // 32% adjustment down
         consensus.nPowMaxAdjustUp = 16; // 16% adjustment up
         consensus.nPowTargetSpacing = 2.5 * 60;
-        consensus.nPowAllowMinDifficultyBlocksFromHeight = 299187;
+        consensus.nPowAllowMinDifficultyBlocksAfterHeight = 299187;
         consensus.vUpgrades[Consensus::BASE_SPROUT].nProtocolVersion = 170002;
         consensus.vUpgrades[Consensus::BASE_SPROUT].nActivationHeight =
             Consensus::NetworkUpgrade::ALWAYS_ACTIVE;
@@ -393,7 +393,7 @@ public:
         consensus.nPowMaxAdjustDown = 0; // Turn off adjustment down
         consensus.nPowMaxAdjustUp = 0; // Turn off adjustment up
         consensus.nPowTargetSpacing = 2.5 * 60;
-        consensus.nPowAllowMinDifficultyBlocksFromHeight = 0;
+        consensus.nPowAllowMinDifficultyBlocksAfterHeight = 0;
         consensus.vUpgrades[Consensus::BASE_SPROUT].nProtocolVersion = 170002;
         consensus.vUpgrades[Consensus::BASE_SPROUT].nActivationHeight =
             Consensus::NetworkUpgrade::ALWAYS_ACTIVE;
diff --git a/src/consensus/params.h b/src/consensus/params.h
index 4e6f7b86a..26288f243 100644
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -93,7 +93,7 @@ struct Params {
     NetworkUpgrade vUpgrades[MAX_NETWORK_UPGRADES];
     /** Proof of work parameters */
     uint256 powLimit;
-    boost::optional<uint32_t> nPowAllowMinDifficultyBlocksFromHeight;
+    boost::optional<uint32_t> nPowAllowMinDifficultyBlocksAfterHeight;
     int64_t nPowAveragingWindow;
     int64_t nPowMaxAdjustDown;
     int64_t nPowMaxAdjustUp;
diff --git a/src/miner.cpp b/src/miner.cpp
index 960ac60de..b76226ecc 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -103,7 +103,7 @@ void UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams,
     pblock->nTime = std::max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());
 
     // Updating time can change work required on testnet:
-    if (consensusParams.nPowAllowMinDifficultyBlocksFromHeight) {
+    if (consensusParams.nPowAllowMinDifficultyBlocksAfterHeight) {
         pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, consensusParams);
     }
 }
@@ -727,7 +727,7 @@ void static BitcoinMiner()
                 // Update nNonce and nTime
                 pblock->nNonce = ArithToUint256(UintToArith256(pblock->nNonce) + 1);
                 UpdateTime(pblock, chainparams.GetConsensus(), pindexPrev);
-                if (chainparams.GetConsensus().nPowAllowMinDifficultyBlocksFromHeight)
+                if (chainparams.GetConsensus().nPowAllowMinDifficultyBlocksAfterHeight)
                 {
                     // Changing pblock->nTime can change work required on testnet:
                     hashTarget.SetCompact(pblock->nBits);
diff --git a/src/pow.cpp b/src/pow.cpp
index 7bc2fa79f..82c817efb 100644
--- a/src/pow.cpp
+++ b/src/pow.cpp
@@ -25,8 +25,10 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
         return nProofOfWorkLimit;
 
     {
-        if (params.nPowAllowMinDifficultyBlocksFromHeight &&
-            pindexLast->nHeight >= params.nPowAllowMinDifficultyBlocksFromHeight.get())
+        // Comparing to pindexLast->nHeight with >= because this function
+        // returns the work required for the block after pindexLast.
+        if (params.nPowAllowMinDifficultyBlocksAfterHeight &&
+            pindexLast->nHeight >= params.nPowAllowMinDifficultyBlocksAfterHeight.get())
         {
             // Special difficulty rule for testnet:
             // If the new block's timestamp is more than 6 * 2.5 minutes