96 lines
2.4 KiB
C
96 lines
2.4 KiB
C
/*
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* =======================================================================================
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*
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* Author: Jan Eitzinger (je), jan.eitzinger@fau.de
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* Copyright (c) 2020 RRZE, University Erlangen-Nuremberg
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*
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* This file is part of MD-Bench.
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*
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* MD-Bench is free software: you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published
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* by 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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* MD-Bench 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 A
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* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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* details.
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*
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* You should have received a copy of the GNU Lesser General Public License along
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* with MD-Bench. If not, see <https://www.gnu.org/licenses/>.
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* =======================================================================================
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*/
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#include <string.h>
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#include <util.h>
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/* Park/Miller RNG w/out MASKING, so as to be like f90s version */
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#define IA 16807
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#define IM 2147483647
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#define AM (1.0/IM)
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#define IQ 127773
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#define IR 2836
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#define MASK 123459876
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double myrandom(int* seed)
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{
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int k= (*seed) / IQ;
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double ans;
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*seed = IA * (*seed - k * IQ) - IR * k;
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if(*seed < 0) *seed += IM;
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ans = AM * (*seed);
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return ans;
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}
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void random_reset(int *seed, int ibase, double *coord)
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{
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int i;
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char *str = (char *) &ibase;
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int n = sizeof(int);
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unsigned int hash = 0;
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for (i = 0; i < n; i++) {
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hash += str[i];
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hash += (hash << 10);
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hash ^= (hash >> 6);
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}
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str = (char *) coord;
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n = 3 * sizeof(double);
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for (i = 0; i < n; i++) {
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hash += str[i];
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hash += (hash << 10);
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hash ^= (hash >> 6);
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}
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hash += (hash << 3);
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hash ^= (hash >> 11);
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hash += (hash << 15);
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// keep 31 bits of unsigned int as new seed
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// do not allow seed = 0, since will cause hang in gaussian()
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*seed = hash & 0x7ffffff;
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if (!(*seed)) *seed = 1;
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// warm up the RNG
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for (i = 0; i < 5; i++) myrandom(seed);
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//save = 0;
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}
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int str2ff(const char *string)
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{
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if(strncmp(string, "lj", 2) == 0) return FF_LJ;
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if(strncmp(string, "eam", 3) == 0) return FF_EAM;
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return -1;
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}
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const char* ff2str(int ff)
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{
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if(ff == FF_LJ) { return "lj"; }
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if(ff == FF_EAM) { return "eam"; }
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return "invalid";
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}
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