ethereum.forks.bpo1.vm.instructions.memory
Ethereum Virtual Machine (EVM) Memory Instructions.
.. contents:: Table of Contents :backlinks: none :local:
Introduction
Implementations of the EVM Memory instructions.
mstore ¶
Stores a word to memory. This also expands the memory, if the memory is insufficient to store the word.
Parameters
evm : The current EVM frame.
def mstore(evm: Evm) -> None:
| 26 | <snip> |
|---|---|
| 37 | # STACK |
| 38 | start_position = pop(evm.stack) |
| 39 | value = pop(evm.stack).to_be_bytes32() |
| 40 | |
| 41 | # GAS |
| 42 | extend_memory = calculate_gas_extend_memory( |
| 43 | evm.memory, [(start_position, U256(len(value)))] |
| 44 | ) |
| 45 | |
| 46 | charge_gas(evm, GasCosts.OPCODE_MSTORE_BASE + extend_memory.cost) |
| 47 | |
| 48 | # OPERATION |
| 49 | evm.memory += b"\x00" * extend_memory.expand_by |
| 50 | memory_write(evm.memory, start_position, value) |
| 51 | |
| 52 | # PROGRAM COUNTER |
| 53 | evm.pc += Uint(1) |
mstore8 ¶
Stores a byte to memory. This also expands the memory, if the memory is insufficient to store the word.
Parameters
evm : The current EVM frame.
def mstore8(evm: Evm) -> None:
| 57 | <snip> |
|---|---|
| 68 | # STACK |
| 69 | start_position = pop(evm.stack) |
| 70 | value = pop(evm.stack) |
| 71 | |
| 72 | # GAS |
| 73 | extend_memory = calculate_gas_extend_memory( |
| 74 | evm.memory, [(start_position, U256(1))] |
| 75 | ) |
| 76 | |
| 77 | charge_gas(evm, GasCosts.OPCODE_MSTORE8_BASE + extend_memory.cost) |
| 78 | |
| 79 | # OPERATION |
| 80 | evm.memory += b"\x00" * extend_memory.expand_by |
| 81 | normalized_bytes_value = Bytes([value & U256(0xFF)]) |
| 82 | memory_write(evm.memory, start_position, normalized_bytes_value) |
| 83 | |
| 84 | # PROGRAM COUNTER |
| 85 | evm.pc += Uint(1) |
mload ¶
Loads a word from memory.
Parameters
evm : The current EVM frame.
def mload(evm: Evm) -> None:
| 89 | <snip> |
|---|---|
| 98 | # STACK |
| 99 | start_position = pop(evm.stack) |
| 100 | |
| 101 | # GAS |
| 102 | extend_memory = calculate_gas_extend_memory( |
| 103 | evm.memory, [(start_position, U256(32))] |
| 104 | ) |
| 105 | charge_gas(evm, GasCosts.OPCODE_MLOAD_BASE + extend_memory.cost) |
| 106 | |
| 107 | # OPERATION |
| 108 | evm.memory += b"\x00" * extend_memory.expand_by |
| 109 | value = U256.from_be_bytes( |
| 110 | memory_read_bytes(evm.memory, start_position, U256(32)) |
| 111 | ) |
| 112 | push(evm.stack, value) |
| 113 | |
| 114 | # PROGRAM COUNTER |
| 115 | evm.pc += Uint(1) |
msize ¶
Pushes the size of active memory in bytes onto the stack.
Parameters
evm : The current EVM frame.
mcopy ¶
Copies the bytes in memory from one location to another.
Parameters
evm : The current EVM frame.
def mcopy(evm: Evm) -> None:
| 142 | <snip> |
|---|---|
| 151 | # STACK |
| 152 | destination = pop(evm.stack) |
| 153 | source = pop(evm.stack) |
| 154 | length = pop(evm.stack) |
| 155 | |
| 156 | # GAS |
| 157 | words = ceil32(Uint(length)) // Uint(32) |
| 158 | copy_gas_cost = GasCosts.OPCODE_COPY_PER_WORD * words |
| 159 | |
| 160 | extend_memory = calculate_gas_extend_memory( |
| 161 | evm.memory, [(source, length), (destination, length)] |
| 162 | ) |
| 163 | charge_gas( |
| 164 | evm, |
| 165 | GasCosts.OPCODE_MCOPY_BASE + copy_gas_cost + extend_memory.cost, |
| 166 | ) |
| 167 | |
| 168 | # OPERATION |
| 169 | evm.memory += b"\x00" * extend_memory.expand_by |
| 170 | value = memory_read_bytes(evm.memory, source, length) |
| 171 | memory_write(evm.memory, destination, value) |
| 172 | |
| 173 | # PROGRAM COUNTER |
| 174 | evm.pc += Uint(1) |