def exp(evm: Evm) -> None:
"""
Exponential operation of the top 2 elements. Pushes the result back on
the stack.
Parameters
----------
evm :
The current EVM frame.
Raises
------
StackUnderflowError
If `len(stack)` is less than `2`.
"""
base = Uint(pop(evm.stack))
exponent = Uint(pop(evm.stack))
gas_used = GAS_EXPONENTIATION
if exponent != 0:
# This is equivalent to 1 + floor(log(y, 256)). But in python the log
# function is inaccurate leading to wrong results.
exponent_bits = exponent.bit_length()
exponent_bytes = (exponent_bits + 7) // 8
gas_used += GAS_EXPONENTIATION * exponent_bytes
evm.gas_left = subtract_gas(evm.gas_left, gas_used)
result = U256(pow(base, exponent, U256_CEIL_VALUE))
push(evm.stack, result)
def mulmod(evm: Evm) -> None:
"""
Modulo multiplication of the top 2 elements with the 3rd element. Pushes
the result back on the stack.
Parameters
----------
evm :
The current EVM frame.
Raises
------
StackUnderflowError
If `len(stack)` is less than `3`.
OutOfGasError
If `evm.gas_left` is less than `8`.
"""
evm.gas_left = subtract_gas(evm.gas_left, GAS_MID)
x = Uint(pop(evm.stack))
y = Uint(pop(evm.stack))
z = Uint(pop(evm.stack))
if z == 0:
result = U256(0)
else:
result = U256((x * y) % z)
push(evm.stack, result)
def test_uint_to_be_bytes32_max_value() -> None:
encoded = Uint(2**256 - 1).to_be_bytes32()
assert encoded == bytes([
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
0xFF,
])
def test_uint_rpow_modulo() -> None:
value = Uint.__rpow__(Uint(2), 4, 3)
assert isinstance(value, int)
assert value == 1
def test_uint_from_be_bytes_empty() -> None:
value = Uint.from_be_bytes(b"")
assert value == 0
def test_uint_rsub_too_big() -> None:
with pytest.raises(ValueError):
6 - Uint(7)
def test_uint_rsub_float() -> None:
value = (6.0) - Uint(5)
assert not isinstance(value, int)
assert value == 1.0
def test_uint_iadd() -> None:
value = Uint(5)
value += 4
assert isinstance(value, Uint)
assert value == 9
def test_uint_iadd_float() -> None:
value = Uint(5)
value += 1.0 # type: ignore
assert not isinstance(value, int)
assert value == 6.0
def test_uint_to_be_bytes_zero() -> None:
encoded = Uint(0).to_be_bytes()
assert encoded == bytes([])
def test_uint_new() -> None:
value = Uint(5)
assert isinstance(value, int)
assert isinstance(value, Uint)
assert value == 5
def test_uint_ipow_modulo() -> None:
value = Uint(4).__ipow__(2, 3)
assert isinstance(value, Uint)
assert value == 1
def test_uint_ipow_modulo_negative() -> None:
with pytest.raises(ValueError):
Uint(4).__ipow__(2, -3)
def test_uint_ipow_negative() -> None:
value = Uint(3)
with pytest.raises(ValueError):
value **= -2
def test_uint_ipow() -> None:
value = Uint(3)
value **= 2
assert isinstance(value, Uint)
assert value == 9
def test_uint_rpow_modulo_negative() -> None:
with pytest.raises(ValueError):
Uint.__rpow__(Uint(2), 4, -3)
def test_uint_from_be_bytes_one() -> None:
value = Uint.from_be_bytes(bytes([1]))
assert value == 1
def test_uint_to_be_bytes_one() -> None:
encoded = Uint(1).to_be_bytes()
assert encoded == bytes([1])
def test_uint_from_be_bytes_is_big_endian() -> None:
value = Uint.from_be_bytes(bytes([0xAB, 0xCD]))
assert value == 0xABCD
def test_uint_to_be_bytes_is_big_endian() -> None:
encoded = Uint(0xABCD).to_be_bytes()
assert encoded == bytes([0xAB, 0xCD])
def test_uint_add_float() -> None:
value = Uint(5) + (1.0)
assert not isinstance(value, int)
assert value == 6.0
def test_uint_to_be_bytes32_zero() -> None:
encoded = Uint(0).to_be_bytes32()
assert encoded == bytes([0] * 32)
def test_uint_iadd_negative() -> None:
value = Uint(5)
with pytest.raises(ValueError):
value += -4
def test_uint_to_be_bytes32_one() -> None:
encoded = Uint(1).to_be_bytes32()
assert encoded == bytes([0] * 31 + [1])
def test_uint_rsub() -> None:
value = 6 - Uint(5)
assert isinstance(value, Uint)
assert value == 1
def test_uint_rpow() -> None:
value = 3**Uint(2)
assert isinstance(value, Uint)
assert value == 9
def test_uint_rsub_negative() -> None:
with pytest.raises(ValueError):
(-4) - Uint(5)
def test_uint_add_negative() -> None:
with pytest.raises(ValueError):
Uint(5) + (-4)
def test_uint_sub() -> None:
value = Uint(5) - 4
assert isinstance(value, Uint)
assert value == 1
def test_uint_rpow_negative() -> None:
with pytest.raises(ValueError):
(-3)**Uint(2)