2014-08-13 10:38:35 +00:00
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// Copyright (c) 2012-2014, The CryptoNote developers, The Bytecoin developers
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//
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// This file is part of Bytecoin.
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//
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// Bytecoin is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Bytecoin is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with Bytecoin. If not, see <http://www.gnu.org/licenses/>.
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2014-03-03 22:07:58 +00:00
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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 "cryptonote_config.h"
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#include "difficulty.h"
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namespace cryptonote {
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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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2014-04-29 16:26:45 +00:00
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low = mul128(a, b, &high);
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2014-03-03 22:07:58 +00:00
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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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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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