Merge pull request ethereum#5 from expanse-project/test-difficulty-ad…

…justment

merge difficulty adjustment branch

core/chain_util.go

@@ -40,7 +40,14 @@ var (
 // given the parent block's time and difficulty.
 func CalcDifficulty(time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
 	diff := new(big.Int)
-	adjust := new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor)
+    adjust := new(big.Int)
+
+	if parentNumber.Cmp(params.HardFork1) < 0 {
+	    adjust = new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor)
+	} else {
+	    adjust = new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor2)
+	}
+
 	bigTime := new(big.Int)
 	bigParentTime := new(big.Int)
 

params/protocol_params.go

@@ -30,6 +30,8 @@ var (
 	TxGas                  = big.NewInt(21000)  // Per transaction. NOTE: Not payable on data of calls between transactions.
 	TxDataZeroGas          = big.NewInt(4)      // Per byte of data attached to a transaction that equals zero. NOTE: Not payable on data of calls between transactions.
 	DifficultyBoundDivisor = big.NewInt(2048)   // The bound divisor of the difficulty, used in the update calculations.
+	DifficultyBoundDivisor2 = big.NewInt(512)   // Difficulty should adjust faster.
+	HardFork1               = big.NewInt(23000) // fork at this block number
 	QuadCoeffDiv           = big.NewInt(512)    // Divisor for the quadratic particle of the memory cost equation.
 	GenesisDifficulty      = big.NewInt(131072) // Difficulty of the Genesis block.
 	DurationLimit          = big.NewInt(60)     // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.