github.com/hxy-daniel/soda-study@v0.0.0-20210825114314-29b7dcb300f1/SODA_code/go-ethereum/core/vm/gas.go (about) 1 // Copyright 2015 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 package vm 18 19 import ( 20 "math/big" 21 22 "github.com/ethereum/go-ethereum/params" 23 ) 24 25 // Gas costs 26 const ( 27 GasQuickStep uint64 = 2 28 GasFastestStep uint64 = 3 29 GasFastStep uint64 = 5 30 GasMidStep uint64 = 8 31 GasSlowStep uint64 = 10 32 GasExtStep uint64 = 20 33 ) 34 35 // calcGas returns the actual gas cost of the call. 36 // 37 // The cost of gas was changed during the homestead price change HF. To allow for EIP150 38 // to be implemented. The returned gas is gas - base * 63 / 64. 39 func callGas(gasTable params.GasTable, availableGas, base uint64, callCost *big.Int) (uint64, error) { 40 if gasTable.CreateBySuicide > 0 { 41 availableGas = availableGas - base 42 gas := availableGas - availableGas/64 43 // If the bit length exceeds 64 bit we know that the newly calculated "gas" for EIP150 44 // is smaller than the requested amount. Therefor we return the new gas instead 45 // of returning an error. 46 if !callCost.IsUint64() || gas < callCost.Uint64() { 47 return gas, nil 48 } 49 } 50 if !callCost.IsUint64() { 51 return 0, errGasUintOverflow 52 } 53 54 return callCost.Uint64(), nil 55 }