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basefee.go
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basefee.go
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// Copyright 2021 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package misc
import (
"math/big"
"github.com/dominant-strategies/go-quai/common"
"github.com/dominant-strategies/go-quai/common/math"
"github.com/dominant-strategies/go-quai/core/types"
"github.com/dominant-strategies/go-quai/params"
)
// CalcBaseFee calculates the basefee of the header taking into account the basefee ceiling
func CalcBaseFee(config *params.ChainConfig, parent *types.Header) *big.Int {
calculatedBaseFee := calcBaseFee(config, parent)
ceiling := big.NewInt(params.MaxBaseFee)
if calculatedBaseFee.Cmp(ceiling) > 0 {
return ceiling
}
return calculatedBaseFee
}
// calcBaseFee calculates the basefee of the header.
func calcBaseFee(config *params.ChainConfig, parent *types.Header) *big.Int {
var (
parentGasTarget = parent.GasLimit() / params.ElasticityMultiplier
parentGasTargetBig = new(big.Int).SetUint64(parentGasTarget)
baseFeeChangeDenominator = new(big.Int).SetUint64(params.BaseFeeChangeDenominator)
)
// If the parent gasUsed is the same as the target, the baseFee remains unchanged.
if parent.GasUsed() == parentGasTarget {
return new(big.Int).Set(parent.BaseFee())
}
if parent.GasUsed() > parentGasTarget {
// If the parent block used more gas than its target, the baseFee should increase.
gasUsedDelta := new(big.Int).SetUint64(parent.GasUsed() - parentGasTarget)
x := new(big.Int).Mul(parent.BaseFee(), gasUsedDelta)
y := x.Div(x, parentGasTargetBig)
baseFeeDelta := math.BigMax(
x.Div(y, baseFeeChangeDenominator),
common.Big1,
)
return x.Add(parent.BaseFee(), baseFeeDelta)
} else {
// Otherwise if the parent block used less gas than its target, the baseFee should decrease.
gasUsedDelta := new(big.Int).SetUint64(parentGasTarget - parent.GasUsed())
x := new(big.Int).Mul(parent.BaseFee(), gasUsedDelta)
y := x.Div(x, parentGasTargetBig)
baseFeeDelta := x.Div(y, baseFeeChangeDenominator)
return math.BigMax(
x.Sub(parent.BaseFee(), baseFeeDelta),
common.Big0,
)
}
}