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Modify diff algo for Callisto

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This commit is contained in:
Yohan Graterol 2017-12-14 22:25:33 -05:00
parent e22f4696f4
commit 071261edfd
1 changed files with 52 additions and 1 deletions
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53
consensus/ethash/consensus.go
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@ -292,6 +292,8 @@ func (ethash *Ethash) verifyHeader(chain consensus.ChainReader, header, parent *
func CalcDifficulty(config *params.ChainConfig, time uint64, parent *types.Header) *big.Int {
next := new(big.Int).Add(parent.Number, big1)
switch {
case config.IsCallisto(next):
return calcDifficultyCallisto(time, parent)
case config.IsByzantium(next):
return calcDifficultyByzantium(time, parent)
case config.IsHomestead(next):
@ -304,6 +306,7 @@ func CalcDifficulty(config *params.ChainConfig, time uint64, parent *types.Heade
// Some weird constants to avoid constant memory allocs for them.
var (
expDiffPeriod = big.NewInt(100000)
expDiffPeriodCallisto = big.NewInt(300000)
big1 = big.NewInt(1)
big2 = big.NewInt(2)
big9 = big.NewInt(9)
@ -312,6 +315,54 @@ var (
big2999999 = big.NewInt(2999999)
)
// calcDifficultyCallisto is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time given the
// parent block's time and difficulty. No bomb.
func calcDifficultyCallisto(time uint64, parent *types.Header) *big.Int {
// For Callisto the periodCount is modified each 300k blocks
// diff = (parent_diff +
// (parent_diff / 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))
// ) + 2^(periodCount - 2)
bigTime := new(big.Int).SetUint64(time)
bigParentTime := new(big.Int).Set(parent.Time)
// holds intermediate values to make the algo easier to read & audit
x := new(big.Int)
y := new(big.Int)
// 1 - (block_timestamp - parent_timestamp) // 10
x.Sub(bigTime, bigParentTime)
x.Div(x, big10)
x.Sub(big1, x)
// max(1 - (block_timestamp - parent_timestamp) // 10, -99)
if x.Cmp(bigMinus99) < 0 {
x.Set(bigMinus99)
}
// (parent_diff + parent_diff // 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))
y.Div(parent.Difficulty, params.DifficultyBoundDivisor)
x.Mul(y, x)
x.Add(parent.Difficulty, x)
// minimum difficulty can ever be (before exponential factor)
if x.Cmp(params.MinimumDifficulty) < 0 {
x.Set(params.MinimumDifficulty)
}
// for the exponential factor
periodCount := new(big.Int).Add(parent.Number, big1)
periodCount.Div(periodCount, expDiffPeriodCallisto)
// the exponential factor, commonly referred to as "the bomb"
// diff = diff + 2^(periodCount - 2)
if periodCount.Cmp(big1) > 0 {
y.Sub(periodCount, big2)
y.Exp(big2, y, nil)
x.Add(x, y)
}
return x
}
// calcDifficultyByzantium is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time given the
// parent block's time and difficulty. The calculation uses the Byzantium rules.
@ -561,7 +612,7 @@ func AccumulateRewards(config *params.ChainConfig, state *state.StateDB, header
if config.IsCallisto(header.Number) {
reward.Sub(reward, treasuryReward)
state.AddBalance(common.HexToAddress("SET ADDRESS IN SETTINGS"), treasuryReward)
state.AddBalance(config.CallistoTreasuryAddress, treasuryReward)
}
state.AddBalance(header.Coinbase, reward)