ethereum.homestead.vm.gas

Ethereum Virtual Machine (EVM) Gas ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. contents:: Table of Contents :backlinks: none :local:

Introduction

EVM gas constants and calculators.

GAS_JUMPDEST

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GAS_JUMPDEST = Uint(1)

GAS_BASE

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GAS_BASE = Uint(2)

GAS_VERY_LOW

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GAS_VERY_LOW = Uint(3)

GAS_SLOAD

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GAS_SLOAD = Uint(50)

GAS_STORAGE_SET

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GAS_STORAGE_SET = Uint(20000)

GAS_STORAGE_UPDATE

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GAS_STORAGE_UPDATE = Uint(5000)

GAS_STORAGE_CLEAR_REFUND

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GAS_STORAGE_CLEAR_REFUND = Uint(15000)

GAS_LOW

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GAS_LOW = Uint(5)

GAS_MID

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GAS_MID = Uint(8)

GAS_HIGH

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GAS_HIGH = Uint(10)

GAS_EXPONENTIATION

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GAS_EXPONENTIATION = Uint(10)

GAS_EXPONENTIATION_PER_BYTE

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GAS_EXPONENTIATION_PER_BYTE = Uint(10)

GAS_MEMORY

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GAS_MEMORY = Uint(3)

GAS_KECCAK256

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GAS_KECCAK256 = Uint(30)

GAS_KECCAK256_WORD

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GAS_KECCAK256_WORD = Uint(6)

GAS_COPY

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GAS_COPY = Uint(3)

GAS_BLOCK_HASH

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GAS_BLOCK_HASH = Uint(20)

GAS_EXTERNAL

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GAS_EXTERNAL = Uint(20)

GAS_BALANCE

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GAS_BALANCE = Uint(20)

GAS_LOG

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GAS_LOG = Uint(375)

GAS_LOG_DATA

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GAS_LOG_DATA = Uint(8)

GAS_LOG_TOPIC

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GAS_LOG_TOPIC = Uint(375)

GAS_CREATE

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GAS_CREATE = Uint(32000)

GAS_CODE_DEPOSIT

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GAS_CODE_DEPOSIT = Uint(200)

GAS_ZERO

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GAS_ZERO = Uint(0)

GAS_CALL

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GAS_CALL = Uint(40)

GAS_NEW_ACCOUNT

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GAS_NEW_ACCOUNT = Uint(25000)

GAS_CALL_VALUE

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GAS_CALL_VALUE = Uint(9000)

GAS_CALL_STIPEND

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GAS_CALL_STIPEND = Uint(2300)

REFUND_SELF_DESTRUCT

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REFUND_SELF_DESTRUCT = Uint(24000)

GAS_ECRECOVER

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GAS_ECRECOVER = Uint(3000)

GAS_SHA256

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GAS_SHA256 = Uint(60)

GAS_SHA256_WORD

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GAS_SHA256_WORD = Uint(12)

GAS_RIPEMD160

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GAS_RIPEMD160 = Uint(600)

GAS_RIPEMD160_WORD

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GAS_RIPEMD160_WORD = Uint(120)

GAS_IDENTITY

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GAS_IDENTITY = Uint(15)

GAS_IDENTITY_WORD

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GAS_IDENTITY_WORD = Uint(3)

ExtendMemory

Define the parameters for memory extension in opcodes

cost: ethereum.base_types.Uint The gas required to perform the extension expand_by: ethereum.base_types.Uint The size by which the memory will be extended

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@dataclass
class ExtendMemory:

cost

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    cost: Uint

expand_by

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    expand_by: Uint

MessageCallGas

Define the gas cost and stipend for executing the call opcodes.

cost: ethereum.base_types.Uint The non-refundable portion of gas reserved for executing the call opcode. stipend: ethereum.base_types.Uint The portion of gas available to sub-calls that is refundable if not consumed

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@dataclass
class MessageCallGas:

cost

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    cost: Uint

stipend

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    stipend: Uint

charge_gas

Subtracts amount from evm.gas_left.

Parameters

evm : The current EVM. amount : The amount of gas the current operation requires.

def charge_gas(​evm: Evm, ​​amount: Uint​) -> None:
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    """
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    Subtracts `amount` from `evm.gas_left`.
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    Parameters
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    ----------
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    evm :
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        The current EVM.
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    amount :
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        The amount of gas the current operation requires.
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    """
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    evm_trace(evm, GasAndRefund(int(amount)))
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    if evm.gas_left < amount:
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        raise OutOfGasError
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    else:
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        evm.gas_left -= amount

calculate_memory_gas_cost

Calculates the gas cost for allocating memory to the smallest multiple of 32 bytes, such that the allocated size is at least as big as the given size.

Parameters

size_in_bytes : The size of the data in bytes.

Returns

total_gas_cost : ethereum.base_types.Uint The gas cost for storing data in memory.

def calculate_memory_gas_cost(​size_in_bytes: Uint​) -> Uint:
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    """
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    Calculates the gas cost for allocating memory
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    to the smallest multiple of 32 bytes,
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    such that the allocated size is at least as big as the given size.
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    Parameters
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    ----------
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    size_in_bytes :
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        The size of the data in bytes.
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    Returns
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    -------
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    total_gas_cost : `ethereum.base_types.Uint`
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        The gas cost for storing data in memory.
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    """
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    size_in_words = ceil32(size_in_bytes) // Uint(32)
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    linear_cost = size_in_words * GAS_MEMORY
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    quadratic_cost = size_in_words ** Uint(2) // Uint(512)
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    total_gas_cost = linear_cost + quadratic_cost
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    try:
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        return total_gas_cost
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    except ValueError:
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        raise OutOfGasError

calculate_gas_extend_memory

Calculates the gas amount to extend memory

Parameters

memory : Memory contents of the EVM. extensions: List of extensions to be made to the memory. Consists of a tuple of start position and size.

Returns

extend_memory: ExtendMemory

def calculate_gas_extend_memory(​memory: bytearray, ​​extensions: List[Tuple[U256, U256]]​) -> ExtendMemory:
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    """
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    Calculates the gas amount to extend memory
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    Parameters
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    ----------
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    memory :
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        Memory contents of the EVM.
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    extensions:
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        List of extensions to be made to the memory.
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        Consists of a tuple of start position and size.
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    Returns
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    -------
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    extend_memory: `ExtendMemory`
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    """
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    size_to_extend = Uint(0)
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    to_be_paid = Uint(0)
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    current_size = Uint(len(memory))
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    for start_position, size in extensions:
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        if size == 0:
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            continue
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        before_size = ceil32(current_size)
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        after_size = ceil32(Uint(start_position) + Uint(size))
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        if after_size <= before_size:
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            continue
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        size_to_extend += after_size - before_size
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        already_paid = calculate_memory_gas_cost(before_size)
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        total_cost = calculate_memory_gas_cost(after_size)
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        to_be_paid += total_cost - already_paid
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        current_size = after_size
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    return ExtendMemory(to_be_paid, size_to_extend)

calculate_message_call_gas

Calculates the gas amount for executing Opcodes CALL and CALLCODE.

Parameters

state : The current state. gas : The amount of gas provided to the message-call. to: The address of the recipient account. value: The amount of ETH that needs to be transferred.

Returns

message_call_gas: MessageCallGas

def calculate_message_call_gas(​state: State, ​​gas: Uint, ​​to: Address, ​​value: U256​) -> MessageCallGas:
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    """
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    Calculates the gas amount for executing Opcodes `CALL` and `CALLCODE`.
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    Parameters
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    ----------
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    state :
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        The current state.
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    gas :
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        The amount of gas provided to the message-call.
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    to:
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        The address of the recipient account.
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    value:
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        The amount of `ETH` that needs to be transferred.
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    Returns
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    -------
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    message_call_gas: `MessageCallGas`
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    """
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    create_gas_cost = Uint(0) if account_exists(state, to) else GAS_NEW_ACCOUNT
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    transfer_gas_cost = Uint(0) if value == 0 else GAS_CALL_VALUE
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    cost = GAS_CALL + gas + create_gas_cost + transfer_gas_cost
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    stipend = gas if value == 0 else GAS_CALL_STIPEND + gas
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    return MessageCallGas(cost, stipend)