ethereum.tangerine_whistle.vm.instructions.keccak
Ethereum Virtual Machine (EVM) Keccak Instructions ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. contents:: Table of Contents :backlinks: none :local:
Introduction
Implementations of the EVM keccak instructions.
keccak
Pushes to the stack the Keccak-256 hash of a region of memory.
This also expands the memory, in case the memory is insufficient to access the data's memory location.
Parameters
evm : The current EVM frame.
def keccak(evm: Evm) -> None:
32 | """ |
---|---|
33 | Pushes to the stack the Keccak-256 hash of a region of memory. |
34 |
|
35 | This also expands the memory, in case the memory is insufficient to |
36 | access the data's memory location. |
37 |
|
38 | Parameters |
39 | ---------- |
40 | evm : |
41 | The current EVM frame. |
42 |
|
43 | """ |
44 | # STACK |
45 | memory_start_index = pop(evm.stack) |
46 | size = pop(evm.stack) |
47 | |
48 | # GAS |
49 | words = ceil32(Uint(size)) // Uint(32) |
50 | word_gas_cost = GAS_KECCAK256_WORD * words |
51 | extend_memory = calculate_gas_extend_memory( |
52 | evm.memory, [(memory_start_index, size)] |
53 | ) |
54 | charge_gas(evm, GAS_KECCAK256 + word_gas_cost + extend_memory.cost) |
55 | |
56 | # OPERATION |
57 | evm.memory += b"\x00" * extend_memory.expand_by |
58 | data = memory_read_bytes(evm.memory, memory_start_index, size) |
59 | hash = keccak256(data) |
60 | |
61 | push(evm.stack, U256.from_be_bytes(hash)) |
62 | |
63 | # PROGRAM COUNTER |
64 | evm.pc += Uint(1) |