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https://git.gfz-potsdam.de/naaice/poet.git
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96 lines
2.5 KiB
C++
96 lines
2.5 KiB
C++
// Time-stamp: "Last modified 2023-04-24 23:20:55 mluebke"
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/*
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**-----------------------------------------------------------------------------
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** MurmurHash2 was written by Austin Appleby, and is placed in the public
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** domain. The author hereby disclaims copyright to this source code.
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**-----------------------------------------------------------------------------
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**
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** Copyright (C) 2018-2021 Alexander Lindemann, Max Luebke (University of
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** Potsdam)
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**
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** Copyright (C) 2018-2022 Marco De Lucia, Max Luebke (GFZ Potsdam)
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**
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** POET is free software; you can redistribute it and/or modify it under the
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** terms of the GNU General Public License as published by the Free Software
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** Foundation; either version 2 of the License, or (at your option) any later
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** version.
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**
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** POET is distributed in the hope that it will be useful, but WITHOUT ANY
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** WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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** A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License along with
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** this program; if not, write to the Free Software Foundation, Inc., 51
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** Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "HashFunctions.hpp"
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#if defined(_MSC_VER)
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#define BIG_CONSTANT(x) (x)
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// Other compilers
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#else // defined(_MSC_VER)
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#define BIG_CONSTANT(x) (x##LLU)
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#endif // !defined(_MSC_VER)
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//-----------------------------------------------------------------------------
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// MurmurHash2, 64-bit versions, by Austin Appleby
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// The same caveats as 32-bit MurmurHash2 apply here - beware of alignment
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// and endian-ness issues if used across multiple platforms.
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// 64-bit hash for 64-bit platforms
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// objsize: 0x170-0x321: 433
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uint64_t poet::Murmur2_64A(int len, const void *key) {
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const uint64_t m = BIG_CONSTANT(0xc6a4a7935bd1e995);
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const int r = 47;
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uint64_t h = HASH_SEED ^ (len * m);
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const uint64_t *data = (const uint64_t *)key;
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const uint64_t *end = data + (len / 8);
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while (data != end) {
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uint64_t k = *data++;
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k *= m;
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k ^= k >> r;
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k *= m;
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h ^= k;
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h *= m;
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}
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const unsigned char *data2 = (const unsigned char *)data;
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switch (len & 7) {
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case 7:
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h ^= uint64_t(data2[6]) << 48;
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case 6:
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h ^= uint64_t(data2[5]) << 40;
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case 5:
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h ^= uint64_t(data2[4]) << 32;
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case 4:
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h ^= uint64_t(data2[3]) << 24;
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case 3:
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h ^= uint64_t(data2[2]) << 16;
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case 2:
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h ^= uint64_t(data2[1]) << 8;
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case 1:
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h ^= uint64_t(data2[0]);
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h *= m;
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};
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h ^= h >> r;
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h *= m;
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h ^= h >> r;
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return h;
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}
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