github.com/ontio/ontology@v1.14.4/vm/evm/gas.go (about)

     1  // Copyright (C) 2021 The Ontology Authors
     2  // Copyright 2015 The go-ethereum Authors
     3  // This file is part of the go-ethereum library.
     4  //
     5  // The go-ethereum library is free software: you can redistribute it and/or modify
     6  // it under the terms of the GNU Lesser General Public License as published by
     7  // the Free Software Foundation, either version 3 of the License, or
     8  // (at your option) any later version.
     9  //
    10  // The go-ethereum library is distributed in the hope that it will be useful,
    11  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    12  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    13  // GNU Lesser General Public License for more details.
    14  //
    15  // You should have received a copy of the GNU Lesser General Public License
    16  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    17  
    18  package evm
    19  
    20  import (
    21  	"github.com/holiman/uint256"
    22  	"github.com/ontio/ontology/vm/evm/errors"
    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  // callGas returns the actual gas cost of the call.
    36  //
    37  // The cost of gas was changed during the homestead price change HF.
    38  // As part of EIP 150 (TangerineWhistle), the returned gas is gas - base * 63 / 64.
    39  func callGas(isEip150 bool, availableGas, base uint64, callCost *uint256.Int) (uint64, error) {
    40  	if isEip150 {
    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. Therefore 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, errors.ErrGasUintOverflow
    52  	}
    53  
    54  	return callCost.Uint64(), nil
    55  }