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core, miner: added difficulty bomb

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This commit is contained in:
Jeffrey Wilcke
2015-08-04 23:46:38 +02:00
parent 56219a5e7a
commit 71d32f54f7
6 changed files with 196 additions and 7 deletions
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20
core/chain_util.go
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@@ -30,14 +30,15 @@ import (
)
var (
blockHashPre = []byte("block-hash-")
blockNumPre = []byte("block-num-")
blockHashPre = []byte("block-hash-")
blockNumPre = []byte("block-num-")
expDiffPeriod = big.NewInt(100000)
)
// CalcDifficulty is the difficulty adjustment algorithm. It returns
// the difficulty that a new block b should have when created at time
// given the parent block's time and difficulty.
func CalcDifficulty(time, parentTime uint64, parentDiff *big.Int) *big.Int {
func CalcDifficulty(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)
@@ -52,8 +53,19 @@ func CalcDifficulty(time, parentTime uint64, parentDiff *big.Int) *big.Int {
diff.Sub(parentDiff, adjust)
}
if diff.Cmp(params.MinimumDifficulty) < 0 {
return params.MinimumDifficulty
diff = 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
}