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- // Copyright 2015 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 vm
- import (
- "github.com/holiman/uint256"
- )
- // Gas costs
- const (
- GasQuickStep uint64 = 2
- GasFastestStep uint64 = 3
- GasFastStep uint64 = 5
- GasMidStep uint64 = 8
- GasSlowStep uint64 = 10
- GasExtStep uint64 = 20
- )
- // callGas returns the actual gas cost of the call.
- //
- // The cost of gas was changed during the homestead price change HF.
- // As part of EIP 150 (TangerineWhistle), the returned gas is gas - base * 63 / 64.
- func callGas(isEip150 bool, availableGas, base uint64, callCost *uint256.Int) (uint64, error) {
- if isEip150 {
- availableGas = availableGas - base
- gas := availableGas - availableGas/64
- // If the bit length exceeds 64 bit we know that the newly calculated "gas" for EIP150
- // is smaller than the requested amount. Therefore we return the new gas instead
- // of returning an error.
- if !callCost.IsUint64() || gas < callCost.Uint64() {
- return gas, nil
- }
- }
- if !callCost.IsUint64() {
- return 0, ErrGasUintOverflow
- }
- return callCost.Uint64(), nil
- }
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