From 010d757e2e69c3196f78722096e74cc0be317fdf Mon Sep 17 00:00:00 2001
From: Julian Yap <julianokyap@gmail.com>
Date: Fri, 2 Dec 2016 22:23:20 -1000
Subject: [PATCH] Remove calcDifficultyFrontier

---
 core/block_validator.go | 39 ---------------------------------------
 1 file changed, 39 deletions(-)

diff --git a/core/block_validator.go b/core/block_validator.go
index dbc98c88a7..6eac3d5133 100644
--- a/core/block_validator.go
+++ b/core/block_validator.go
@@ -259,14 +259,6 @@ func ValidateHeader(config *params.ChainConfig, pow pow.PoW, header *types.Heade
 // the difficulty that a new block should have when created at time
 // given the parent block's time and difficulty.
 func CalcDifficulty(config *params.ChainConfig, time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
-	if config.IsHomestead(new(big.Int).Add(parentNumber, common.Big1)) {
-		return calcDifficultyHomestead(time, parentTime, parentNumber, parentDiff)
-	} else {
-		return calcDifficultyFrontier(time, parentTime, parentNumber, parentDiff)
-	}
-}
-
-func calcDifficultyHomestead(time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
 	// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.mediawiki
 	// algorithm:
 	// diff = (parent_diff +
@@ -315,37 +307,6 @@ func calcDifficultyHomestead(time, parentTime uint64, parentNumber, parentDiff *
 	return x
 }
 
-func calcDifficultyFrontier(time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
-	diff := new(big.Int)
-	adjust := new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor)
-	bigTime := new(big.Int)
-	bigParentTime := new(big.Int)
-
-	bigTime.SetUint64(time)
-	bigParentTime.SetUint64(parentTime)
-
-	if bigTime.Sub(bigTime, bigParentTime).Cmp(params.DurationLimit) < 0 {
-		diff.Add(parentDiff, adjust)
-	} else {
-		diff.Sub(parentDiff, adjust)
-	}
-	if diff.Cmp(params.MinimumDifficulty) < 0 {
-		diff.Set(params.MinimumDifficulty)
-	}
-
-	periodCount := new(big.Int).Add(parentNumber, common.Big1)
-	periodCount.Div(periodCount, ExpDiffPeriod)
-	if periodCount.Cmp(common.Big1) > 0 {
-		// diff = diff + 2^(periodCount - 2)
-		expDiff := periodCount.Sub(periodCount, common.Big2)
-		expDiff.Exp(common.Big2, expDiff, nil)
-		diff.Add(diff, expDiff)
-		diff = common.BigMax(diff, params.MinimumDifficulty)
-	}
-
-	return diff
-}
-
 // CalcGasLimit computes the gas limit of the next block after parent.
 // The result may be modified by the caller.
 // This is miner strategy, not consensus protocol.