evm

v0.1.14

evm v0.1.14 EVM.VM

The core of the EVM which runs operations based on the opcodes of a contract during a transfer or message call.

Link to this section Summary

Types

output()

Functions

cycle(machine_state, sub_state, exec_env)

Runs a single cycle of our VM returning the new state, defined as O in the Yellow Paper, Eq.(131)

exec(machine_state, sub_state, exec_env)

Runs a cycle of our VM in a recursive fashion, defined as X, Eq.(122) of the Yellow Paper. This function halts when return is called or an exception raised

run(gas, exec_env)

This function computes the Ξ function Eq.(116) of the Section 9.4 of the Yellow Paper. This is the complete result of running a given program in the VM

Link to this section Types

Link to this type output() 
output() :: binary

Link to this section Functions

Link to this function cycle(machine_state, sub_state, exec_env) 
cycle(EVM.MachineState.t, EVM.SubState.t, EVM.ExecEnv.t) :: {EVM.world_state, EVM.MachineState.t, EVM.SubState.t, EVM.ExecEnv.t}

Runs a single cycle of our VM returning the new state, defined as O in the Yellow Paper, Eq.(131).

Examples 

iex> EVM.VM.cycle(%EVM.MachineState{program_counter: 0, gas: 5, stack: [1, 2]}, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:add])})
{%EVM.MachineState{program_counter: 1, gas: 2, stack: [3]}, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:add])}}
Link to this function exec(machine_state, sub_state, exec_env) 
exec(EVM.MachineState.t, EVM.SubState.t, EVM.ExecEnv.t) :: {EVM.MachineState.t, EVM.SubState.t, EVM.ExecEnv.t, output}

Runs a cycle of our VM in a recursive fashion, defined as X, Eq.(122) of the Yellow Paper. This function halts when return is called or an exception raised.

Examples 

iex> EVM.VM.exec(%EVM.MachineState{program_counter: 0, gas: 5, stack: [1, 2]}, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:add])})
{%EVM.MachineState{program_counter: 2, gas: 2, stack: [3]}, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:add])}, <<>>}

iex> EVM.VM.exec(%EVM.MachineState{program_counter: 0, gas: 9, stack: []}, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:push1, 3, :push1, 5, :add])})
{%EVM.MachineState{program_counter: 6, gas: 0, stack: [8]}, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:push1, 3, :push1, 5, :add])}, ""}

iex> EVM.VM.exec(%EVM.MachineState{program_counter: 0, gas: 24, stack: []}, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:push1, 3, :push1, 5, :add, :push1, 0x00, :mstore, :push1, 32, :push1, 0, :return])})
{%EVM.MachineState{active_words: 1, memory: <<0x08::256>>, gas: 0, program_counter: 13, stack: []}, %EVM.SubState{logs: "", refund: 0, suicide_list: []}, %EVM.ExecEnv{machine_code: <<96, 3, 96, 5, 1, 96, 0, 82, 96, 32, 96, 0, 243>>}, <<8::256>>}
Link to this function run(gas, exec_env) 
run(EVM.Gas.t, EVM.ExecEnv.t) :: {EVM.Gas.t, EVM.SubState.t, EVM.ExecEnv.t, output}

This function computes the Ξ function Eq.(116) of the Section 9.4 of the Yellow Paper. This is the complete result of running a given program in the VM.

Note: We replace returning state with exec env, which in our implementation contains the world state.

Examples 

# Full program
iex> EVM.VM.run(24, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:push1, 3, :push1, 5, :add, :push1, 0x00, :mstore, :push1, 32, :push1, 0, :return])})
{0, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:push1, 3, :push1, 5, :add, :push1, 0x00, :mstore, :push1, 32, :push1, 0, :return])}, <<0x08::256>>}

# Program with implicit stop
iex> EVM.VM.run(9, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:push1, 3, :push1, 5, :add])})
{0, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.     compile([:push1, 3, :push1, 5, :add])}, ""}

# Program with explicit stop
iex> EVM.VM.run(5, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:push1, 3, :stop])})
{2, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:push1, 3, :stop])}, ""}

# Program with exception halt
iex> EVM.VM.run(5, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:add])})
{5, %EVM.SubState{}, %EVM.ExecEnv{machine_code: EVM.MachineCode.compile([:add])}, ""}