evm

v0.1.14

evm v0.1.14 EVM.Gas

Functions for interacting wth gas and costs of opscodes.

Link to this section Summary

Types

gas_price()
t()

Functions

cost(machine_state, exec_env)

Returns the cost to execute the given a cycle of the VM. This is defined in Appenix H of the Yellow Paper, Eq.(220) and is denoted C

g_transaction()

Paid for every transaction

g_txcreate()

Paid by all contract-creating transactions after the Homestead transition

g_txdata(data)

Returns the gas cost for G_txdata{zero, nonzero} as defined in Appendix G (Fee Schedule) of the Yellow Paper

memory_cost(arg1, arg2, machine_state)
memory_expansion_cost(machine_state, offset, length)
memory_expansion_value(active_words, offset, length)
operation_cost(operation \\ nil, inputs \\ nil, machine_state \\ nil, exec_env \\ nil)

Returns the cost of a call to sstore. This is defined in Appenfix H.2. of the Yellow Paper under the definition of SSTORE, referred to as C_SSTORE

quadratic_memory_cost(a)

Link to this section Types

Link to this type gas_price() 
gas_price() :: EVM.Wei.t

Link to this section Functions

Link to this function cost(machine_state, exec_env) 
cost(EVM.MachineState.t, EVM.ExecEnv.t) :: t | nil

Returns the cost to execute the given a cycle of the VM. This is defined in Appenix H of the Yellow Paper, Eq.(220) and is denoted C.

Examples 

# TODO: Figure out how to hand in state
iex> EVM.Gas.cost(%EVM.MachineState{}, %EVM.ExecEnv{})
0
Link to this function g_transaction() 
g_transaction() :: t

Paid for every transaction.

Link to this function g_txcreate() 
g_txcreate() :: t

Paid by all contract-creating transactions after the Homestead transition.

Link to this function g_txdata(data) 
g_txdata(binary) :: t

Returns the gas cost for G_txdata{zero, nonzero} as defined in Appendix G (Fee Schedule) of the Yellow Paper.

This implements g_txdatazero and g_txdatanonzero

Examples 

iex> EVM.Gas.g_txdata(<<1, 2, 3, 0, 4, 5>>)
5 * 68 + 4

iex> EVM.Gas.g_txdata(<<0>>)
4

iex> EVM.Gas.g_txdata(<<0, 0>>)
8

iex> EVM.Gas.g_txdata(<<>>)
0
Link to this function memory_cost(arg1, arg2, machine_state)
Link to this function memory_expansion_cost(machine_state, offset, length)
Link to this function memory_expansion_value(active_words, offset, length)
Link to this function operation_cost(operation \\ nil, inputs \\ nil, machine_state \\ nil, exec_env \\ nil) 
operation_cost(atom, [EVM.val], EVM.state, EVM.MachineState.t) ::
  t |
  nil

Returns the cost of a call to sstore. This is defined in Appenfix H.2. of the Yellow Paper under the definition of SSTORE, referred to as C_SSTORE.

Examples

iex> address = 0x0000000000000000000000000000000000000001 iex> account_interface = EVM.Interface.Mock.MockAccountInterface.new() iex> exec_env = %EVM.ExecEnv{address: address, account_interface: account_interface} iex> EVM.Gas.operation_cost(:sstore, [0, 0], %EVM.MachineState{}, exec_env) 5000 iex> EVM.Gas.operation_cost(:sstore, [0, 2], %EVM.MachineState{}, exec_env) 20000

Link to this function quadratic_memory_cost(a)