evm v0.1.8 EVM.MachineState

Module for tracking the current machine state, which is roughly equivilant to the VM state for an executing contract.

This is most often seen as µ in the Yellow Paper.

Link to this section Summary

Functions

After a memory operation, we may have incremented the total number of active words. This function takes a memory offset accessed and updates the machine state accordingly

Increments the program counter

Pops n values off the stack

Push a values onto the stack

Returns a new execution environment less the amount of gas specified

Link to this section Types

Link to this type memory()
memory() :: binary
Link to this type pc()
pc() :: integer
Link to this type t()
t() :: %EVM.MachineState{active_words: integer, gas: EVM.Gas.t, memory: memory, pc: pc, previously_active_words: term, stack: EVM.Stack.t}

Link to this section Functions

Link to this function maybe_set_active_words(machine_state, last_word)
maybe_set_active_words(t, EVM.val) :: t

After a memory operation, we may have incremented the total number of active words. This function takes a memory offset accessed and updates the machine state accordingly.

Examples

iex> %EVM.MachineState{active_words: 2, previously_active_words: 1} |> EVM.MachineState.maybe_set_active_words(1)
%EVM.MachineState{active_words: 2, previously_active_words: 2}

iex> %EVM.MachineState{active_words: 2, previously_active_words: 1} |> EVM.MachineState.maybe_set_active_words(3)
%EVM.MachineState{active_words: 3, previously_active_words: 2}

iex> %EVM.MachineState{active_words: 2, previously_active_words: 1} |> EVM.MachineState.maybe_set_active_words(1)
%EVM.MachineState{active_words: 2, previously_active_words: 2}
Link to this function next_pc(machine_state, operation)

Increments the program counter

Examples

iex> EVM.MachineState.next_pc(%EVM.MachineState{pc: 9}, :add)
%EVM.MachineState{pc: 10}

Pops n values off the stack

Examples

iex> EVM.MachineState.pop_n(%EVM.MachineState{stack: [1, 2, 3]}, 2)
{[1 ,2], %EVM.MachineState{stack: [3]}}

Push a values onto the stack

Examples

iex> EVM.MachineState.push(%EVM.MachineState{stack: [2, 3]}, 1)
%EVM.MachineState{stack: [1, 2, 3]}
Link to this function subtract_gas(machine_state, gas)
subtract_gas(t, EVM.Gas.t) :: t

Returns a new execution environment less the amount of gas specified.

Examples

iex> %EVM.MachineState{gas: 5} |> EVM.MachineState.subtract_gas(4)
%EVM.MachineState{gas: 1}