forked from lthn/blockchain
259 lines
9.4 KiB
C++
259 lines
9.4 KiB
C++
// Copyright (c) 2014-2018 Zano Project
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// Copyright (c) 2014-2018 The Louisdor Project
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// Copyright (c) 2012-2013 The Cryptonote developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <algorithm>
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#include <cassert>
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#include <cstddef>
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#include <cstdint>
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#include <vector>
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#include "misc_log_ex.h"
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#include "common/int-util.h"
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#include "crypto/hash.h"
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#include "currency_core/currency_config.h"
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#include "difficulty.h"
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#include "profile_tools.h"
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namespace currency {
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using std::size_t;
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using std::uint64_t;
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using std::vector;
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#if defined(_MSC_VER)
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//#include <windows.h>
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//#include <winnt.h>
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static inline void mul(uint64_t a, uint64_t b, uint64_t &low, uint64_t &high) {
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boost::multiprecision::uint128_t res = boost::multiprecision::uint128_t(a) * b;
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low = (res & 0xffffffffffffffffLL).convert_to<uint64_t>();
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high = (res >> 64).convert_to<uint64_t>();
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//low = _umul128(a, b, &high);
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//low = UnsignedMultiply128(a, b, &high);
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}
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#else
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static inline void mul(uint64_t a, uint64_t b, uint64_t &low, uint64_t &high) {
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typedef unsigned __int128 uint128_t;
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uint128_t res = (uint128_t)a * (uint128_t)b;
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low = (uint64_t)res;
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high = (uint64_t)(res >> 64);
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}
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#endif
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static inline bool cadd(uint64_t a, uint64_t b) {
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return a + b < a;
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}
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static inline bool cadc(uint64_t a, uint64_t b, bool c) {
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return a + b < a || (c && a + b == (uint64_t)-1);
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}
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#if defined(_MSC_VER)
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#ifdef max
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#undef max
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#endif
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#endif
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const wide_difficulty_type max64bit(std::numeric_limits<std::uint64_t>::max());
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const boost::multiprecision::uint256_t max128bit(std::numeric_limits<boost::multiprecision::uint128_t>::max());
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const boost::multiprecision::uint512_t max256bit(std::numeric_limits<boost::multiprecision::uint256_t>::max());
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bool check_hash(const crypto::hash &hash_, wide_difficulty_type difficulty)
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{
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//revert byte order
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crypto::hash h = {};
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for (size_t i = 0; i != sizeof(h); i++)
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{
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*(((char*)&h) + (sizeof(h) - (i + 1))) = *(((char*)&hash_) + i);
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}
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PROFILE_FUNC("check_hash");
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if (difficulty < max64bit)
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{ // if can convert to small difficulty - do it
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std::uint64_t dl = difficulty.convert_to<std::uint64_t>();
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uint64_t low, high, top, cur;
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// First check the highest word, this will most likely fail for a random hash.
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mul(swap64le(((const uint64_t *)&h)[3]), dl, top, high);
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if (high != 0)
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return false;
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mul(swap64le(((const uint64_t *)&h)[0]), dl, low, cur);
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mul(swap64le(((const uint64_t *)&h)[1]), dl, low, high);
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bool carry = cadd(cur, low);
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cur = high;
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mul(swap64le(((const uint64_t *)&h)[2]), dl, low, high);
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carry = cadc(cur, low, carry);
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carry = cadc(high, top, carry);
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return !carry;
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}
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// fast check
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if (((const uint64_t *)&h)[3] > 0)
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return false;
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// usual slow check
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boost::multiprecision::uint512_t hashVal = 0;
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for(int i = 0; i < 4; i++)
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{
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hashVal <<= 64;
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hashVal |= swap64le(((const uint64_t *) &h)[3-i]);
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}
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return (hashVal * difficulty <= max256bit);
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}
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uint64_t difficulty_to_boundary(wide_difficulty_type difficulty)
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{
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boost::multiprecision::uint256_t nominal_hash = std::numeric_limits<boost::multiprecision::uint256_t>::max();
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nominal_hash = nominal_hash / difficulty;
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uint64_t res = (nominal_hash >> 192).convert_to<std::uint64_t>();
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return res;
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}
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void difficulty_to_boundary_long(wide_difficulty_type difficulty, crypto::hash& result)
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{
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boost::multiprecision::uint256_t nominal_hash = std::numeric_limits<boost::multiprecision::uint256_t>::max();
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nominal_hash = nominal_hash / difficulty;
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static_assert(sizeof(uint64_t) * 4 == sizeof(result), "!");
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for (size_t i = 0; i < 4; ++i)
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{
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(reinterpret_cast<uint64_t*>(&result))[i] = nominal_hash.convert_to<uint64_t>();
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nominal_hash >>= 64;
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}
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}
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void get_cut_location_from_len(size_t length, size_t& cut_begin, size_t& cut_end, size_t REDEF_DIFFICULTY_WINDOW, size_t REDEF_DIFFICULTY_CUT_OLD, size_t REDEF_DIFFICULTY_CUT_LAST)
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{
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if (length <= REDEF_DIFFICULTY_WINDOW)
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{
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cut_begin = 0;
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cut_end = length;
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}
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else
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{
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cut_begin = REDEF_DIFFICULTY_WINDOW - REDEF_DIFFICULTY_CUT_LAST + 1;
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cut_end = cut_begin + (REDEF_DIFFICULTY_WINDOW - (REDEF_DIFFICULTY_CUT_OLD + REDEF_DIFFICULTY_CUT_LAST));
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}
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}
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void get_adjustment_zone(size_t length, size_t& cut_begin, size_t& cut_end, size_t REDEF_DIFFICULTY_WINDOW, size_t REDEF_DIFFICULTY_CUT_OLD, size_t REDEF_DIFFICULTY_CUT_LAST)
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{
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//cutoff DIFFICULTY_LAG
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if (length <= REDEF_DIFFICULTY_WINDOW - (REDEF_DIFFICULTY_CUT_OLD + REDEF_DIFFICULTY_CUT_LAST))
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{
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cut_begin = 0;
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cut_end = length;
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}
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else
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{
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cut_begin = REDEF_DIFFICULTY_CUT_LAST;
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cut_end = cut_begin + (REDEF_DIFFICULTY_WINDOW - (REDEF_DIFFICULTY_CUT_OLD + REDEF_DIFFICULTY_CUT_LAST));
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if (cut_end > length)
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cut_end = length;
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}
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CHECK_AND_ASSERT_THROW_MES(/*cut_begin >= 0 &&*/ cut_begin + 2 <= cut_end && cut_end <= length, "validation in next_difficulty is failed");
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}
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wide_difficulty_type get_adjustment_for_zone(vector<uint64_t>& timestamps_sorted, vector<wide_difficulty_type>& cumulative_difficulties, size_t target_seconds, size_t REDEF_DIFFICULTY_WINDOW, size_t REDEF_DIFFICULTY_CUT_OLD, size_t REDEF_DIFFICULTY_CUT_LAST)
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{
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size_t length = timestamps_sorted.size();
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size_t cut_begin = 0;
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size_t cut_end = 0;
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get_adjustment_zone(length, cut_begin, cut_end, REDEF_DIFFICULTY_WINDOW, REDEF_DIFFICULTY_CUT_OLD, REDEF_DIFFICULTY_CUT_LAST);
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uint64_t time_span = timestamps_sorted[cut_begin] - timestamps_sorted[cut_end - 1];
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if (time_span == 0)
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{
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time_span = 1;
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}
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wide_difficulty_type total_work = cumulative_difficulties[cut_begin] - cumulative_difficulties[cut_end - 1];
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boost::multiprecision::uint256_t res = (boost::multiprecision::uint256_t(total_work) * target_seconds + time_span - 1) / time_span;
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if (res > max128bit)
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return 0; // to behave like previous implementation, may be better return max128bit?
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return res.convert_to<wide_difficulty_type>();
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}
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wide_difficulty_type next_difficulty_1(vector<uint64_t>& timestamps, vector<wide_difficulty_type>& cumulative_difficulties, size_t target_seconds)
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{
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// timestamps - first is latest, back - is oldest timestamps
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if (timestamps.size() > DIFFICULTY_WINDOW)
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{
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timestamps.resize(DIFFICULTY_WINDOW);
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cumulative_difficulties.resize(DIFFICULTY_WINDOW);
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}
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size_t length = timestamps.size();
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CHECK_AND_ASSERT_MES(length == cumulative_difficulties.size(), 0, "Check \"length == cumulative_difficulties.size()\" failed");
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if (length <= 1)
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{
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return DIFFICULTY_STARTER;
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}
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static_assert(DIFFICULTY_WINDOW >= 2, "Window is too small");
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CHECK_AND_ASSERT_MES(length <= DIFFICULTY_WINDOW, 0, "length <= DIFFICULTY_WINDOW check failed, length=" << length);
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sort(timestamps.begin(), timestamps.end(), std::greater<uint64_t>());
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static_assert(2 * DIFFICULTY_CUT <= DIFFICULTY_WINDOW - 2, "Cut length is too large");
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wide_difficulty_type dif_slow = get_adjustment_for_zone(timestamps, cumulative_difficulties, target_seconds, DIFFICULTY_WINDOW, DIFFICULTY_CUT/2, DIFFICULTY_CUT/2);
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wide_difficulty_type dif_medium = get_adjustment_for_zone(timestamps, cumulative_difficulties, target_seconds, DIFFICULTY_WINDOW/3, DIFFICULTY_CUT / 8, DIFFICULTY_CUT / 12);
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wide_difficulty_type dif_fast = get_adjustment_for_zone(timestamps, cumulative_difficulties, target_seconds, DIFFICULTY_WINDOW/18, DIFFICULTY_CUT / 10, 2);
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uint64_t devider = 1;
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wide_difficulty_type summ = dif_slow;
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if (dif_medium != 0)
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{
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summ += dif_medium;
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++devider;
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}
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if (dif_fast != 0)
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{
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summ += dif_fast;
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++devider;
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}
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return summ / devider;
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}
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wide_difficulty_type next_difficulty_2(vector<uint64_t>& timestamps, vector<wide_difficulty_type>& cumulative_difficulties, size_t target_seconds)
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{
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// timestamps - first is latest, back - is oldest timestamps
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if (timestamps.size() > DIFFICULTY_WINDOW)
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{
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timestamps.resize(DIFFICULTY_WINDOW);
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cumulative_difficulties.resize(DIFFICULTY_WINDOW);
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}
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size_t length = timestamps.size();
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CHECK_AND_ASSERT_MES(length == cumulative_difficulties.size(), 0, "Check \"length == cumulative_difficulties.size()\" failed");
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if (length <= 1)
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{
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return DIFFICULTY_STARTER;
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}
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static_assert(DIFFICULTY_WINDOW >= 2, "Window is too small");
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CHECK_AND_ASSERT_MES(length <= DIFFICULTY_WINDOW, 0, "length <= DIFFICULTY_WINDOW check failed, length=" << length);
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sort(timestamps.begin(), timestamps.end(), std::greater<uint64_t>());
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static_assert(2 * DIFFICULTY_CUT <= DIFFICULTY_WINDOW - 2, "Cut length is too large");
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wide_difficulty_type dif_slow = get_adjustment_for_zone(timestamps, cumulative_difficulties, target_seconds, DIFFICULTY_WINDOW, DIFFICULTY_CUT / 2, DIFFICULTY_CUT / 2);
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wide_difficulty_type dif_medium = get_adjustment_for_zone(timestamps, cumulative_difficulties, target_seconds, DIFFICULTY_WINDOW / 3, DIFFICULTY_CUT / 8, DIFFICULTY_CUT / 12);
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uint64_t devider = 1;
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wide_difficulty_type summ = dif_slow;
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if (dif_medium != 0)
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{
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summ += dif_medium;
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++devider;
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}
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return summ / devider;
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}
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}
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