def compute_difficulty(bomb_delay: int, parent_header: BlockHeader,
timestamp: int) -> int:
"""
https://github.com/ethereum/EIPs/issues/100
"""
parent_timestamp = parent_header.timestamp
validate_gt(timestamp, parent_timestamp, title="Header.timestamp")
parent_difficulty = parent_header.difficulty
offset = parent_difficulty // DIFFICULTY_ADJUSTMENT_DENOMINATOR
has_uncles = parent_header.uncles_hash != EMPTY_UNCLE_HASH
adj_factor = max(
((2 if has_uncles else 1) - ((timestamp - parent_timestamp) //
BYZANTIUM_DIFFICULTY_ADJUSTMENT_CUTOFF)),
-99,
)
difficulty = max(parent_difficulty + offset * adj_factor,
min(parent_header.difficulty, DIFFICULTY_MINIMUM))
num_bomb_periods = (max(
0,
parent_header.block_number + 1 - bomb_delay,
) // BOMB_EXPONENTIAL_PERIOD) - BOMB_EXPONENTIAL_FREE_PERIODS
if num_bomb_periods >= 0:
return max(difficulty + 2**num_bomb_periods, DIFFICULTY_MINIMUM)
else:
return difficulty
def compute_homestead_difficulty(parent_header: BlockHeader, timestamp: int) -> int:
"""
Computes the difficulty for a homestead block based on the parent block.
"""
parent_tstamp = parent_header.timestamp
validate_gt(timestamp, parent_tstamp, title="Header.timestamp")
offset = parent_header.difficulty // DIFFICULTY_ADJUSTMENT_DENOMINATOR
sign = max(
1 - (timestamp - parent_tstamp) // HOMESTEAD_DIFFICULTY_ADJUSTMENT_CUTOFF,
-99)
difficulty = int(max(
parent_header.difficulty + offset * sign,
min(parent_header.difficulty, DIFFICULTY_MINIMUM)))
num_bomb_periods = (
(parent_header.block_number + 1) // BOMB_EXPONENTIAL_PERIOD
) - BOMB_EXPONENTIAL_FREE_PERIODS
if num_bomb_periods >= 0:
return max(difficulty + 2**num_bomb_periods, DIFFICULTY_MINIMUM)
else:
return difficulty
def compute_frontier_difficulty(parent_header: BlockHeader,
timestamp: int) -> int:
"""
Computes the difficulty for a frontier block based on the parent block.
"""
validate_gt(timestamp, parent_header.timestamp, title="Header timestamp")
offset = parent_header.difficulty // DIFFICULTY_ADJUSTMENT_DENOMINATOR
# We set the minimum to the lowest of the protocol minimum and the parent
# minimum to allow for the initial frontier *warming* period during which
# the difficulty begins lower than the protocol minimum.
difficulty_minimum = min(parent_header.difficulty, DIFFICULTY_MINIMUM)
if timestamp - parent_header.timestamp < FRONTIER_DIFFICULTY_ADJUSTMENT_CUTOFF:
base_difficulty = max(
parent_header.difficulty + offset,
difficulty_minimum,
)
else:
base_difficulty = max(
parent_header.difficulty - offset,
difficulty_minimum,
)
# Adjust for difficulty bomb.
num_bomb_periods = (
(parent_header.block_number + 1) //
BOMB_EXPONENTIAL_PERIOD) - BOMB_EXPONENTIAL_FREE_PERIODS
if num_bomb_periods >= 0:
difficulty = max(
base_difficulty + 2**num_bomb_periods,
DIFFICULTY_MINIMUM,
)
else:
difficulty = base_difficulty
return difficulty
def test_validate_gt(value, minimum, is_valid):
if is_valid:
validate_gt(value, minimum)
else:
with pytest.raises(ValidationError):
validate_gt(value, minimum)
