github.com/dominant-strategies/go-quai@v0.28.2/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  	"github.com/holiman/uint256"
    21  )
    22  
    23  // Gas costs
    24  const (
    25  	GasQuickStep   uint64 = 2
    26  	GasFastestStep uint64 = 3
    27  	GasFastStep    uint64 = 5
    28  	GasMidStep     uint64 = 8
    29  	GasSlowStep    uint64 = 10
    30  	GasExtStep     uint64 = 20
    31  )
    32  
    33  // callGas returns the actual gas cost of the call.
    34  func callGas(availableGas, base uint64, callCost *uint256.Int) (uint64, error) {
    35  	availableGas = availableGas - base
    36  	gas := availableGas - availableGas/64
    37  	// If the bit length exceeds 64 bit we know that the newly calculated "gas"
    38  	// is smaller than the requested amount. Therefore we return the new gas instead
    39  	// of returning an error.
    40  	if !callCost.IsUint64() || gas < callCost.Uint64() {
    41  		return gas, nil
    42  	}
    43  
    44  	return callCost.Uint64(), nil
    45  }