github.com/SmartMeshFoundation/Spectrum@v0.0.0-20220621030607-452a266fee1e/core/vm/gas.go (about) 1 // Copyright 2015 The Spectrum Authors 2 // This file is part of the Spectrum library. 3 // 4 // The Spectrum 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 Spectrum 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 Spectrum library. If not, see <http://www.gnu.org/licenses/>. 16 17 package vm 18 19 import ( 20 "github.com/holiman/uint256" 21 ) 22 23 const ( 24 GasQuickStep uint64 = 2 25 GasFastestStep uint64 = 3 26 GasFastStep uint64 = 5 27 GasMidStep uint64 = 8 28 GasSlowStep uint64 = 10 29 GasExtStep uint64 = 20 30 ) 31 32 // calcGas returns the actual gas cost of the call. 33 // 34 // The cost of gas was changed during the homestead price change HF. To allow for EIP150 35 // to be implemented. The returned gas is gas - base * 63 / 64. 36 // The cost of gas was changed during the homestead price change HF. 37 // As part of EIP 150 (TangerineWhistle), the returned gas is gas - base * 63 / 64. 38 func callGas(isEip150 bool, availableGas, base uint64, callCost *uint256.Int) (uint64, error) { 39 if isEip150 { 40 availableGas = availableGas - base 41 gas := availableGas - availableGas/64 42 // If the bit length exceeds 64 bit we know that the newly calculated "gas" for EIP150 43 // is smaller than the requested amount. Therefore we return the new gas instead 44 // of returning an error. 45 if !callCost.IsUint64() || gas < callCost.Uint64() { 46 return gas, nil 47 } 48 } 49 if !callCost.IsUint64() { 50 return 0, ErrGasUintOverflow 51 } 52 return callCost.Uint64(), nil 53 }