// 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 ( "math/big" ) // Gas costs const ( GasQuickStep uint64 = 2 GasFastestStep uint64 = 3 GasFastStep uint64 = 5 GasMidStep uint64 = 8 GasSlowStep uint64 = 10 GasExtStep uint64 = 20 ) // calcGas 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 *big.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. Therefor 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 }