76 lines
1.6 KiB
C
76 lines
1.6 KiB
C
/*
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Copyright (c) 2019 tevador
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This file is part of RandomX.
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RandomX is free software: you can redistribute it and/or modify
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it under the terms of the GNU 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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RandomX 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 General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with RandomX. If not, see<http://www.gnu.org/licenses/>.
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*/
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/*
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Based on the original idea by SChernykh:
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https://github.com/SChernykh/xmr-stak-cpu/issues/1#issuecomment-414336613
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*/
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#include <stdint.h>
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#if !defined(_M_X64) && !defined(__x86_64__)
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typedef struct {
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uint64_t lo;
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uint64_t hi;
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} uint128_t;
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#define LO(x) ((x)&0xffffffff)
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#define HI(x) ((x)>>32)
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static inline uint128_t square128(uint64_t x) {
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uint64_t xh = HI(x), xl = LO(x);
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uint64_t xll = xl * xl;
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uint64_t xlh = xl * xh;
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uint64_t xhh = xh * xh;
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uint64_t m1 = 2 * LO(xlh) + HI(xll);
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uint64_t m2 = 2 * HI(xlh) + LO(xhh) + HI(m1);
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uint64_t m3 = HI(xhh) + HI(m2);
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uint128_t x2;
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x2.lo = (m1 << 32) + LO(xll);
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x2.hi = (m3 << 32) + LO(m2);
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return x2;
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}
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#undef LO(x)
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#undef HI(x)
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inline uint64_t squareHash(uint64_t x) {
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x += 1613783669344650115;
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for (int i = 0; i < 42; ++i) {
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uint128_t x2 = square128(x);
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x = x2.lo - x2.hi;
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}
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return x;
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}
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#else
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#if defined(__cplusplus)
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extern "C" {
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#endif
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uint64_t squareHash(uint64_t);
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#if defined(__cplusplus)
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}
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#endif
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#endif |