63 lines
1.7 KiB
C++
63 lines
1.7 KiB
C++
// Copyright (c) 2011-2016 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 "Common/int-util.h"
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#include "crypto/hash.h"
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#include "CryptoNoteConfig.h"
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#include "Difficulty.h"
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namespace CryptoNote {
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using std::uint64_t;
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using std::vector;
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#if defined(__SIZEOF_INT128__)
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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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#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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low = mul128(a, b, &high);
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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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bool check_hash(const Crypto::Hash &hash, difficulty_type difficulty) {
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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 *) &hash)[3]), difficulty, top, high);
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if (high != 0) {
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return false;
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}
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mul(swap64le(((const uint64_t *) &hash)[0]), difficulty, low, cur);
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mul(swap64le(((const uint64_t *) &hash)[1]), difficulty, 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 *) &hash)[2]), difficulty, 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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}
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