github.com/sberex/go-sberex@v1.8.2-0.20181113200658-ed96ac38f7d7/core/vm/gas.go (about)

     1  // This file is part of the go-sberex library. The go-sberex library is 
     2  // free software: you can redistribute it and/or modify it under the terms 
     3  // of the GNU Lesser General Public License as published by the Free 
     4  // Software Foundation, either version 3 of the License, or (at your option)
     5  // any later version.
     6  //
     7  // The go-sberex library is distributed in the hope that it will be useful, 
     8  // but WITHOUT ANY WARRANTY; without even the implied warranty of
     9  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser 
    10  // General Public License <http://www.gnu.org/licenses/> for more details.
    11  
    12  package vm
    13  
    14  import (
    15  	"math/big"
    16  
    17  	"github.com/Sberex/go-sberex/params"
    18  )
    19  
    20  const (
    21  	GasQuickStep   uint64 = 2
    22  	GasFastestStep uint64 = 3
    23  	GasFastStep    uint64 = 5
    24  	GasMidStep     uint64 = 8
    25  	GasSlowStep    uint64 = 10
    26  	GasExtStep     uint64 = 20
    27  
    28  	GasReturn       uint64 = 0
    29  	GasStop         uint64 = 0
    30  	GasContractByte uint64 = 200
    31  )
    32  
    33  // calcGas returns the actual gas cost of the call.
    34  //
    35  // The cost of gas was changed during the homestead price change HF. To allow for EIP150
    36  // to be implemented. The returned gas is gas - base * 63 / 64.
    37  func callGas(gasTable params.GasTable, availableGas, base uint64, callCost *big.Int) (uint64, error) {
    38  	if gasTable.CreateBySuicide > 0 {
    39  		availableGas = availableGas - base
    40  		gas := availableGas - availableGas/64
    41  		// If the bit length exceeds 64 bit we know that the newly calculated "gas" for EIP150
    42  		// is smaller than the requested amount. Therefor we return the new gas instead
    43  		// of returning an error.
    44  		if callCost.BitLen() > 64 || gas < callCost.Uint64() {
    45  			return gas, nil
    46  		}
    47  	}
    48  	if callCost.BitLen() > 64 {
    49  		return 0, errGasUintOverflow
    50  	}
    51  
    52  	return callCost.Uint64(), nil
    53  }