ethereum.vm.interpreter

Ethereum Virtual Machine (EVM) Interpreter

Introduction

A straightforward interpreter that executes EVM code.

Module Contents

Functions

process_call

Executes a call from the caller to the target in a new EVM instance.

Module Details

process_call

ethereum.vm.interpreter.process_call(caller: ethereum.eth_types.Address, target: ethereum.eth_types.Address, data: bytes, value: ethereum.base_types.U256, gas: ethereum.base_types.U256, depth: ethereum.base_types.Uint, env: ethereum.vm.Environment) → Tuple[ethereum.base_types.U256, List[ethereum.eth_types.Log]]

Executes a call from the caller to the target in a new EVM instance.

Parameters

• caller – Account which initiated this call.

• target – Account whose code will be executed.

• data – Array of bytes provided to the code in target.

• value – Value to be transferred.

• gas – Gas provided for the code in target.

• depth – Number of call/contract creation environments on the call stack.

• env – External items required for EVM execution.

Returns

output – The tuple (gas_left, logs), where gas_left is the remaining gas after execution, and logs is the list of eth1spec.eth_types.Log generated during execution.

Return type

Tuple[U256, List[eth1spec.eth_types.Log]]

def process_call(
    caller: Address,
    target: Address,
    data: bytes,
    value: U256,
    gas: U256,
    depth: Uint,
    env: Environment,
) -> Tuple[U256, List[Log]]:
    evm = Evm(
        pc=Uint(0),
        stack=[],
        memory=bytearray(),
        code=env.state[target].code,
        gas_left=gas,
        current=target,
        caller=caller,
        data=data,
        value=value,
        depth=depth,
        env=env,
        refund_counter=Uint(0),
    )

    logs: List[Log] = []

    if evm.value != 0:
        evm.env.state[evm.caller].balance -= evm.value
        evm.env.state[evm.current].balance += evm.value

    while evm.pc < len(evm.code):
        op = evm.code[evm.pc]
        op_implementation[op](evm)
        evm.pc += 1

    gas_used = gas - evm.gas_left
    refund = min(gas_used // 2, evm.refund_counter)

    return evm.gas_left + refund, logs