path: root/GasMeter.cpp

/*
    This file is part of cpp-ethereum.

    cpp-ethereum is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    cpp-ethereum 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file GasMeter.cpp
 * @author Christian <c@ethdev.com>
 * @date 2015
 */

#include "GasMeter.h"
#include <libevmcore/Params.h>

using namespace std;
using namespace dev;
using namespace dev::eth;

GasMeter::GasConsumption& GasMeter::GasConsumption::operator+=(GasConsumption const& _other)
{
    isInfinite = isInfinite || _other.isInfinite;
    if (isInfinite)
        return *this;
    bigint v = bigint(value) + _other.value;
    if (v > std::numeric_limits<u256>::max())
        isInfinite = true;
    else
        value = u256(v);
    return *this;
}

GasMeter::GasConsumption GasMeter::estimateMax(AssemblyItem const& _item)
{
    switch (_item.type()) {
    case Push:
    case PushTag:
        return runGas(Instruction::PUSH1);
    case Tag:
        return runGas(Instruction::JUMPDEST);
    case Operation:
    {
        GasConsumption gas = runGas(_item.instruction());
        switch (_item.instruction())
        {
        case Instruction::SSTORE:
            // @todo logic can be improved
            gas += c_sstoreSetGas;
            break;
        case Instruction::SLOAD:
            gas += c_sloadGas;
            break;
        case Instruction::MSTORE:
        case Instruction::MSTORE8:
        case Instruction::MLOAD:
        case Instruction::RETURN:
        case Instruction::SHA3:
        case Instruction::CALLDATACOPY:
        case Instruction::CODECOPY:
        case Instruction::EXTCODECOPY:
        case Instruction::LOG0:
        case Instruction::LOG1:
        case Instruction::LOG2:
        case Instruction::LOG3:
        case Instruction::LOG4:
        case Instruction::CALL:
        case Instruction::CALLCODE:
        case Instruction::CREATE:
        case Instruction::EXP:
            // @todo logic can be improved
            gas = GasConsumption::infinite();
            break;
        default:
            break;
        }
        return gas;
        break;
    }
    default:
        break;
    }

    return GasConsumption::infinite();
}

GasMeter::GasConsumption GasMeter::runGas(Instruction _instruction)
{
    if (_instruction == Instruction::JUMPDEST)
        return GasConsumption(1);

    int tier = instructionInfo(_instruction).gasPriceTier;
    return tier == InvalidTier ? GasConsumption::infinite() : c_tierStepGas[tier];
}