github.com/core-coin/go-core/v2@v2.1.9/core/vm/energy.go (about)

     1  // Copyright 2023 by the Authors
     2  // This file is part of the go-core library.
     3  //
     4  // The go-core 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-core 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-core library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package vm
    18  
    19  import (
    20  	"github.com/core-coin/uint256"
    21  )
    22  
    23  // Energy costs
    24  const (
    25  	EnergyQuickStep   uint64 = 2
    26  	EnergyFastestStep uint64 = 3
    27  	EnergyFastStep    uint64 = 5
    28  	EnergyMidStep     uint64 = 8
    29  	EnergySlowStep    uint64 = 10
    30  	EnergyExtStep     uint64 = 20
    31  )
    32  
    33  // callEnergy returns the actual energy cost of the call.
    34  //
    35  // The returned energy is energy - base * 63 / 64.
    36  func callEnergy(availableEnergy, base uint64, callCost *uint256.Int) (uint64, error) {
    37  	availableEnergy = availableEnergy - base
    38  	energy := availableEnergy - availableEnergy/64
    39  	// If the bit length exceeds 64 bit we know that the newly calculated "energy" for CIP150
    40  	// is smaller than the requested amount. Therefore we return the new energy instead
    41  	// of returning an error.
    42  	if !callCost.IsUint64() || energy < callCost.Uint64() {
    43  		return energy, nil
    44  	}
    45  	if !callCost.IsUint64() {
    46  		return 0, ErrEnergyUintOverflow
    47  	}
    48  
    49  	return callCost.Uint64(), nil
    50  }