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#!/usr/bin/python3
# Copyright (c) 2014, The Monero Project
#
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification, are
# permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice, this list of
# conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright notice, this list
# of conditions and the following disclaimer in the documentation and/or other
# materials provided with the distribution.
#
# 3. Neither the name of the copyright holder nor the names of its contributors may be
# used to endorse or promote products derived from this software without specific
# prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
# THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
# THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
from random import randint
DIFFICULTY_TARGET = 120
DIFFICULTY_WINDOW = 720
DIFFICULTY_LAG = 15
DIFFICULTY_CUT = 60
UINT_MAX = (1 << 64) - 1
def difficulty():
times = []
diffs = []
while True:
if len(times) <= 1:
diff = 1
else:
begin = max(len(times) - DIFFICULTY_WINDOW - DIFFICULTY_LAG, 0)
end = min(begin + DIFFICULTY_WINDOW, len(times))
length = end - begin
assert length >= 2
if length <= DIFFICULTY_WINDOW - 2 * DIFFICULTY_CUT:
cut_begin = 0
cut_end = length
else:
excess = length - (DIFFICULTY_WINDOW - 2 * DIFFICULTY_CUT)
cut_begin = (excess + 1) // 2
cut_end = length - excess // 2
assert cut_begin + 2 <= cut_end
wnd = times[begin:end]
wnd.sort()
dtime = wnd[cut_end - 1] - wnd[cut_begin]
assert 0 <= dtime <= UINT_MAX
dtime = max(dtime, 1)
ddiff = sum(diffs[begin + cut_begin + 1:begin + cut_end])
assert 0 < ddiff <= UINT_MAX
assert dtime <= ddiff * DIFFICULTY_TARGET + dtime - 1 <= UINT_MAX
diff = (ddiff * DIFFICULTY_TARGET + dtime - 1) // dtime
assert 0 < diff <= UINT_MAX
times.append((yield diff))
diffs.append(diff)
time = 1000
gen = difficulty()
diff = next(gen)
for i in range(1000):
power = 10 if i < 100 else 10000 if i < 500 else 1000000
time += randint(-diff // power - 10, 3 * diff // power + 10)
assert 0 <= time <= UINT_MAX
print(time, diff)
diff = gen.send(time)
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