evm v0.1.14 EVM.Functions

Set of functions defined in the Yellow Paper that do not logically fit in other modules.

Link to this section Summary

Functions

is_exception_halt?(machine_state, exec_env)

Returns whether or not the current program is in an exceptional halting state. This may be due to running out of gas, having an invalid instruction, having a stack underflow, having an invalid jump destination or having a stack overflow

is_normal_halting?(machine_state, exec_env)

Returns whether or not the current program is halting due to a return or terminal statement

max_stack_depth()

Link to this section Functions

is_exception_halt?(machine_state, exec_env)

is_exception_halt?(EVM.MachineState.t, EVM.ExecEnv.t) ::
  :continue |
  {:halt, String.t}

This is defined as Z in Eq.(126) of the Yellow Paper.

Examples

# TODO: Once we add gas cost, make this more reasonable
# TODO: How do we pass in state?
iex> EVM.Functions.is_exception_halt?(%EVM.MachineState{program_counter: 0, gas: 0xffff}, %EVM.ExecEnv{machine_code: <<0xfe>>})
{:halt, :undefined_instruction}

iex> EVM.Functions.is_exception_halt?(%EVM.MachineState{program_counter: 0, gas: 0xffff, stack: []}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:add)>>})
{:halt, :stack_underflow}

iex> EVM.Functions.is_exception_halt?(%EVM.MachineState{program_counter: 0, gas: 0xffff, stack: [5]}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:jump)>>})
{:halt, :invalid_jump_destination}

iex> EVM.Functions.is_exception_halt?(%EVM.MachineState{program_counter: 0, gas: 0xffff, stack: [1]}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:jump), EVM.Operation.encode(:jumpdest)>>})
:continue

iex> EVM.Functions.is_exception_halt?(%EVM.MachineState{program_counter: 0, gas: 0xffff, stack: [1, 5]}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:jumpi)>>})
{:halt, :invalid_jump_destination}

iex> EVM.Functions.is_exception_halt?(%EVM.MachineState{program_counter: 0, gas: 0xffff, stack: [1, 5]}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:jumpi), EVM.Operation.encode(:jumpdest)>>})
:continue

iex> EVM.Functions.is_exception_halt?(%EVM.MachineState{program_counter: 0, gas: 0xffff, stack: (for _ <- 1..1024, do: 0x0)}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:stop)>>})
:continue

iex> EVM.Functions.is_exception_halt?(%EVM.MachineState{program_counter: 0, gas: 0xffff, stack: (for _ <- 1..1024, do: 0x0)}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:push1)>>})
{:halt, :stack_overflow}

is_normal_halting?(machine_state, exec_env)

is_normal_halting?(EVM.MachineState.t, EVM.ExecEnv.t) ::
  nil |
  binary

Returns whether or not the current program is halting due to a return or terminal statement.

Examples

iex> EVM.Functions.is_normal_halting?(%EVM.MachineState{program_counter: 0}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:add)>>})
nil

iex> EVM.Functions.is_normal_halting?(%EVM.MachineState{program_counter: 0}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:mul)>>})
nil

iex> EVM.Functions.is_normal_halting?(%EVM.MachineState{program_counter: 0}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:stop)>>})
<<>>

iex> EVM.Functions.is_normal_halting?(%EVM.MachineState{program_counter: 0}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:suicide)>>})
<<>>

iex> EVM.Functions.is_normal_halting?(%EVM.MachineState{stack: [0, 1], memory: <<0xabcd::16>>}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:return)>>})
<<0xab>>

iex> EVM.Functions.is_normal_halting?(%EVM.MachineState{stack: [0, 2], memory: <<0xabcd::16>>}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:return)>>})
<<0xab, 0xcd>>

iex> EVM.Functions.is_normal_halting?(%EVM.MachineState{stack: [1, 1], memory: <<0xabcd::16>>}, %EVM.ExecEnv{machine_code: <<EVM.Operation.encode(:return)>>})
<<0xcd>>

max_stack_depth()