MD-Bench/common/util.c

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/*
* Copyright (C) 2022 NHR@FAU, University Erlangen-Nuremberg.
* All rights reserved. This file is part of MD-Bench.
* Use of this source code is governed by a LGPL-3.0
* license that can be found in the LICENSE file.
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*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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#include <util.h>
/* Park/Miller RNG w/out MASKING, so as to be like f90s version */
#define IA 16807
#define IM 2147483647
#define AM (1.0/IM)
#define IQ 127773
#define IR 2836
#define MASK 123459876
double myrandom(int* seed) {
int k= (*seed) / IQ;
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double ans;
*seed = IA * (*seed - k * IQ) - IR * k;
if(*seed < 0) *seed += IM;
ans = AM * (*seed);
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return ans;
}
void random_reset(int *seed, int ibase, double *coord) {
int i;
char *str = (char *) &ibase;
int n = sizeof(int);
unsigned int hash = 0;
for (i = 0; i < n; i++) {
hash += str[i];
hash += (hash << 10);
hash ^= (hash >> 6);
}
str = (char *) coord;
n = 3 * sizeof(double);
for (i = 0; i < n; i++) {
hash += str[i];
hash += (hash << 10);
hash ^= (hash >> 6);
}
hash += (hash << 3);
hash ^= (hash >> 11);
hash += (hash << 15);
// keep 31 bits of unsigned int as new seed
// do not allow seed = 0, since will cause hang in gaussian()
*seed = hash & 0x7ffffff;
if (!(*seed)) *seed = 1;
// warm up the RNG
for (i = 0; i < 5; i++) myrandom(seed);
//save = 0;
}
int str2ff(const char *string) {
if(strncmp(string, "lj", 2) == 0) return FF_LJ;
if(strncmp(string, "eam", 3) == 0) return FF_EAM;
if(strncmp(string, "dem", 3) == 0) return FF_DEM;
return -1;
}
const char* ff2str(int ff) {
if(ff == FF_LJ) { return "lj"; }
if(ff == FF_EAM) { return "eam"; }
if(ff == FF_DEM) { return "dem"; }
return "invalid";
}
int get_num_threads() {
const char *num_threads_env = getenv("NUM_THREADS");
return (num_threads_env == NULL) ? 32 : atoi(num_threads_env);
}
void readline(char *line, FILE *fp) {
if(fgets(line, MAXLINE, fp) == NULL) {
fprintf(stderr, "readline(): Error: could not read line!\n");
exit(-1);
}
}