package keeper import ( "math/big" sdk "github.com/cosmos/cosmos-sdk/types" "github.com/ethereum/go-ethereum/common" "github.com/ethereum/go-ethereum/common/math" ) // CalculateBaseFee calculates the base fee for the current block. This is only calculated once per // block during BeginBlock. If the NoBaseFee parameter is enabled or below activation height, this function returns nil. // NOTE: This code is inspired from the go-ethereum EIP1559 implementation and adapted to Cosmos SDK-based // chains. For the canonical code refer to: https://github.com/ethereum/go-ethereum/blob/master/consensus/misc/eip1559.go func (k Keeper) CalculateBaseFee(ctx sdk.Context) *big.Int { params := k.GetParams(ctx) // Ignore the calculation if not enable if !params.IsBaseFeeEnabled(ctx.BlockHeight()) { return nil } consParams := ctx.ConsensusParams() // If the current block is the first EIP-1559 block, return the InitialBaseFee. if ctx.BlockHeight() == params.EnableHeight { return new(big.Int).SetInt64(params.InitialBaseFee) } // get the block gas used and the base fee values for the parent block. parentBaseFee := k.GetBaseFee(ctx) if parentBaseFee == nil { parentBaseFee = new(big.Int).SetInt64(params.InitialBaseFee) } parentGasUsed := k.GetBlockGasUsed(ctx) gasLimit := new(big.Int).SetUint64(math.MaxUint64) if consParams != nil && consParams.Block.MaxGas > -1 { gasLimit = big.NewInt(consParams.Block.MaxGas) } parentGasTargetBig := new(big.Int).Div(gasLimit, new(big.Int).SetUint64(uint64(params.ElasticityMultiplier))) if !parentGasTargetBig.IsUint64() { return new(big.Int).SetInt64(params.InitialBaseFee) } parentGasTarget := parentGasTargetBig.Uint64() baseFeeChangeDenominator := new(big.Int).SetUint64(uint64(params.BaseFeeChangeDenominator)) // If the parent gasUsed is the same as the target, the baseFee remains unchanged. if parentGasUsed == parentGasTarget { return new(big.Int).Set(parentBaseFee) } if parentGasUsed > parentGasTarget { // If the parent block used more gas than its target, the baseFee should increase. gasUsedDelta := new(big.Int).SetUint64(parentGasUsed - parentGasTarget) x := new(big.Int).Mul(parentBaseFee, gasUsedDelta) y := x.Div(x, parentGasTargetBig) baseFeeDelta := math.BigMax( x.Div(y, baseFeeChangeDenominator), common.Big1, ) return x.Add(parentBaseFee, baseFeeDelta) } // Otherwise if the parent block used less gas than its target, the baseFee should decrease. gasUsedDelta := new(big.Int).SetUint64(parentGasTarget - parentGasUsed) x := new(big.Int).Mul(parentBaseFee, gasUsedDelta) y := x.Div(x, parentGasTargetBig) baseFeeDelta := x.Div(y, baseFeeChangeDenominator) return math.BigMax( x.Sub(parentBaseFee, baseFeeDelta), common.Big0, ) }