ethereum.homestead.vm.gas
Ethereum Virtual Machine (EVM) Gas ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. contents:: Table of Contents :backlinks: none :local:
Introduction
EVM gas constants and calculators.
GAS_JUMPDEST
26 | GAS_JUMPDEST = Uint(1) |
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GAS_BASE
27 | GAS_BASE = Uint(2) |
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GAS_VERY_LOW
28 | GAS_VERY_LOW = Uint(3) |
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GAS_SLOAD
29 | GAS_SLOAD = Uint(50) |
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GAS_STORAGE_SET
30 | GAS_STORAGE_SET = Uint(20000) |
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GAS_STORAGE_UPDATE
31 | GAS_STORAGE_UPDATE = Uint(5000) |
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GAS_STORAGE_CLEAR_REFUND
32 | GAS_STORAGE_CLEAR_REFUND = Uint(15000) |
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GAS_LOW
33 | GAS_LOW = Uint(5) |
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GAS_MID
34 | GAS_MID = Uint(8) |
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GAS_HIGH
35 | GAS_HIGH = Uint(10) |
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GAS_EXPONENTIATION
36 | GAS_EXPONENTIATION = Uint(10) |
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GAS_EXPONENTIATION_PER_BYTE
37 | GAS_EXPONENTIATION_PER_BYTE = Uint(10) |
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GAS_MEMORY
38 | GAS_MEMORY = Uint(3) |
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GAS_KECCAK256
39 | GAS_KECCAK256 = Uint(30) |
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GAS_KECCAK256_WORD
40 | GAS_KECCAK256_WORD = Uint(6) |
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GAS_COPY
41 | GAS_COPY = Uint(3) |
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GAS_BLOCK_HASH
42 | GAS_BLOCK_HASH = Uint(20) |
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GAS_EXTERNAL
43 | GAS_EXTERNAL = Uint(20) |
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GAS_BALANCE
44 | GAS_BALANCE = Uint(20) |
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GAS_LOG
45 | GAS_LOG = Uint(375) |
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GAS_LOG_DATA
46 | GAS_LOG_DATA = Uint(8) |
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GAS_LOG_TOPIC
47 | GAS_LOG_TOPIC = Uint(375) |
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GAS_CREATE
48 | GAS_CREATE = Uint(32000) |
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GAS_CODE_DEPOSIT
49 | GAS_CODE_DEPOSIT = Uint(200) |
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GAS_ZERO
50 | GAS_ZERO = Uint(0) |
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GAS_CALL
51 | GAS_CALL = Uint(40) |
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GAS_NEW_ACCOUNT
52 | GAS_NEW_ACCOUNT = Uint(25000) |
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GAS_CALL_VALUE
53 | GAS_CALL_VALUE = Uint(9000) |
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GAS_CALL_STIPEND
54 | GAS_CALL_STIPEND = Uint(2300) |
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REFUND_SELF_DESTRUCT
55 | REFUND_SELF_DESTRUCT = Uint(24000) |
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GAS_ECRECOVER
56 | GAS_ECRECOVER = Uint(3000) |
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GAS_SHA256
57 | GAS_SHA256 = Uint(60) |
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GAS_SHA256_WORD
58 | GAS_SHA256_WORD = Uint(12) |
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GAS_RIPEMD160
59 | GAS_RIPEMD160 = Uint(600) |
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GAS_RIPEMD160_WORD
60 | GAS_RIPEMD160_WORD = Uint(120) |
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GAS_IDENTITY
61 | GAS_IDENTITY = Uint(15) |
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GAS_IDENTITY_WORD
62 | GAS_IDENTITY_WORD = Uint(3) |
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ExtendMemory
Define the parameters for memory extension in opcodes
cost
: ethereum.base_types.Uint
The gas required to perform the extension
expand_by
: ethereum.base_types.Uint
The size by which the memory will be extended
65 | @dataclass |
---|
class ExtendMemory:
cost
76 | cost: Uint |
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expand_by
77 | expand_by: Uint |
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MessageCallGas
Define the gas cost and stipend for executing the call opcodes.
cost
: ethereum.base_types.Uint
The non-refundable portion of gas reserved for executing the
call opcode.
stipend
: ethereum.base_types.Uint
The portion of gas available to sub-calls that is refundable
if not consumed
80 | @dataclass |
---|
class MessageCallGas:
cost
93 | cost: Uint |
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stipend
94 | stipend: Uint |
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charge_gas
Subtracts amount
from evm.gas_left
.
Parameters
evm : The current EVM. amount : The amount of gas the current operation requires.
def charge_gas(evm: Evm, amount: Uint) -> None:
98 | """ |
---|---|
99 | Subtracts `amount` from `evm.gas_left`. |
100 |
|
101 | Parameters |
102 | ---------- |
103 | evm : |
104 | The current EVM. |
105 | amount : |
106 | The amount of gas the current operation requires. |
107 |
|
108 | """ |
109 | evm_trace(evm, GasAndRefund(amount)) |
110 | |
111 | if evm.gas_left < amount: |
112 | raise OutOfGasError |
113 | else: |
114 | evm.gas_left -= U256(amount) |
calculate_memory_gas_cost
Calculates the gas cost for allocating memory to the smallest multiple of 32 bytes, such that the allocated size is at least as big as the given size.
Parameters
size_in_bytes : The size of the data in bytes.
Returns
total_gas_cost : ethereum.base_types.Uint
The gas cost for storing data in memory.
def calculate_memory_gas_cost(size_in_bytes: Uint) -> Uint:
118 | """ |
---|---|
119 | Calculates the gas cost for allocating memory |
120 | to the smallest multiple of 32 bytes, |
121 | such that the allocated size is at least as big as the given size. |
122 |
|
123 | Parameters |
124 | ---------- |
125 | size_in_bytes : |
126 | The size of the data in bytes. |
127 |
|
128 | Returns |
129 | ------- |
130 | total_gas_cost : `ethereum.base_types.Uint` |
131 | The gas cost for storing data in memory. |
132 | """ |
133 | size_in_words = ceil32(size_in_bytes) // 32 |
134 | linear_cost = size_in_words * GAS_MEMORY |
135 | quadratic_cost = size_in_words**2 // 512 |
136 | total_gas_cost = linear_cost + quadratic_cost |
137 | try: |
138 | return total_gas_cost |
139 | except ValueError: |
140 | raise OutOfGasError |
calculate_gas_extend_memory
Calculates the gas amount to extend memory
Parameters
memory : Memory contents of the EVM. extensions: List of extensions to be made to the memory. Consists of a tuple of start position and size.
Returns
extend_memory: ExtendMemory
def calculate_gas_extend_memory(memory: bytearray, extensions: List[Tuple[U256, U256]]) -> ExtendMemory:
146 | """ |
---|---|
147 | Calculates the gas amount to extend memory |
148 |
|
149 | Parameters |
150 | ---------- |
151 | memory : |
152 | Memory contents of the EVM. |
153 | extensions: |
154 | List of extensions to be made to the memory. |
155 | Consists of a tuple of start position and size. |
156 |
|
157 | Returns |
158 | ------- |
159 | extend_memory: `ExtendMemory` |
160 | """ |
161 | size_to_extend = Uint(0) |
162 | to_be_paid = Uint(0) |
163 | current_size = Uint(len(memory)) |
164 | for start_position, size in extensions: |
165 | if size == 0: |
166 | continue |
167 | before_size = ceil32(current_size) |
168 | after_size = ceil32(Uint(start_position) + Uint(size)) |
169 | if after_size <= before_size: |
170 | continue |
171 |
|
172 | size_to_extend += after_size - before_size |
173 | already_paid = calculate_memory_gas_cost(before_size) |
174 | total_cost = calculate_memory_gas_cost(after_size) |
175 | to_be_paid += total_cost - already_paid |
176 |
|
177 | current_size = after_size |
178 | |
179 | return ExtendMemory(to_be_paid, size_to_extend) |
calculate_message_call_gas
Calculates the gas amount for executing Opcodes CALL
and CALLCODE
.
Parameters
state :
The current state.
gas :
The amount of gas provided to the message-call.
to:
The address of the recipient account.
value:
The amount of ETH
that needs to be transferred.
Returns
message_call_gas: MessageCallGas
def calculate_message_call_gas(state: State, gas: Uint, to: Address, value: U256) -> MessageCallGas:
185 | """ |
---|---|
186 | Calculates the gas amount for executing Opcodes `CALL` and `CALLCODE`. |
187 |
|
188 | Parameters |
189 | ---------- |
190 | state : |
191 | The current state. |
192 | gas : |
193 | The amount of gas provided to the message-call. |
194 | to: |
195 | The address of the recipient account. |
196 | value: |
197 | The amount of `ETH` that needs to be transferred. |
198 |
|
199 | Returns |
200 | ------- |
201 | message_call_gas: `MessageCallGas` |
202 | """ |
203 | create_gas_cost = Uint(0) if account_exists(state, to) else GAS_NEW_ACCOUNT |
204 | transfer_gas_cost = Uint(0) if value == 0 else GAS_CALL_VALUE |
205 | cost = GAS_CALL + gas + create_gas_cost + transfer_gas_cost |
206 | stipend = gas if value == 0 else GAS_CALL_STIPEND + gas |
207 | return MessageCallGas(cost, stipend) |