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fix_shear_history_omp.cpp
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Tue, May 14, 21:00

fix_shear_history_omp.cpp
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#include "string.h"
#include "stdio.h"
#include "fix_shear_history_omp.h"
#include "atom.h"
#include "comm.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "force.h"
#include "pair.h"
#include "update.h"
#include "modify.h"
#include "error.h"
#if defined(_OPENMP)
#include <omp.h>
#endif
using namespace LAMMPS_NS;
using namespace FixConst;
#define MAXTOUCH 15
/* ----------------------------------------------------------------------
copy shear partner info from neighbor lists to atom arrays
so can be exchanged with atoms
------------------------------------------------------------------------- */
void FixShearHistoryOMP::pre_exchange()
{
const int nlocal = atom->nlocal;
const int nghost = atom->nghost;
const int nall = nlocal + nghost;
const int nthreads = comm->nthreads;
int flag = 0;
#if defined(_OPENMP)
#pragma omp parallel default(none) shared(flag)
#endif
{
#if defined(_OPENMP)
const int tid = omp_get_thread_num();
#else
const int tid = 0;
#endif
// each thread works on a fixed chunk of local and ghost atoms.
const int ldelta = 1 + nlocal/nthreads;
const int lfrom = tid*ldelta;
const int lmax = lfrom +ldelta;
const int lto = (lmax > nlocal) ? nlocal : lmax;
const int gdelta = 1 + nghost/nthreads;
const int gfrom = nlocal + tid*gdelta;
const int gmax = gfrom + gdelta;
const int gto = (gmax > nall) ? nall : gmax;
int i,j,ii,jj,m,inum,jnum;
int *ilist,*jlist,*numneigh,**firstneigh;
int *touch,**firsttouch;
double *shear,*allshear,**firstshear;
// zero npartners for all current atoms
for (i = lfrom; i < lto; i++) npartner[i] = 0;
// copy shear info from neighbor list atoms to atom arrays
int *tag = atom->tag;
NeighList *list = pair->list;
inum = list->inum;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
firsttouch = list->listgranhistory->firstneigh;
firstshear = list->listgranhistory->firstdouble;
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
jlist = firstneigh[i];
allshear = firstshear[i];
jnum = numneigh[i];
touch = firsttouch[i];
for (jj = 0; jj < jnum; jj++) {
if (touch[jj]) {
j = jlist[jj];
j &= NEIGHMASK;
shear = &allshear[3*jj];
if ((i >= lfrom) && (i < lto)) {
if (npartner[i] < MAXTOUCH) {
m = npartner[i];
partner[i][m] = tag[j];
shearpartner[i][m][0] = shear[0];
shearpartner[i][m][1] = shear[1];
shearpartner[i][m][2] = shear[2];
}
npartner[i]++;
}
if ((j >= lfrom) && (j < lto)) {
if (npartner[j] < MAXTOUCH) {
m = npartner[j];
partner[j][m] = tag[i];
shearpartner[j][m][0] = -shear[0];
shearpartner[j][m][1] = -shear[1];
shearpartner[j][m][2] = -shear[2];
}
npartner[j]++;
}
if ((j >= gfrom) && (j < gto)) {
npartner[j]++;
}
}
}
}
// test for too many touching neighbors
int myflag = 0;
for (i = lfrom; i < lto; i++)
if (npartner[i] >= MAXTOUCH) myflag = 1;
if (myflag)
#if defined(_OPENMP)
#pragma omp atomic
#endif
++flag;
}
int flag_all;
MPI_Allreduce(&flag,&flag_all,1,MPI_INT,MPI_SUM,world);
if (flag_all) error->all(FLERR,"Too many touching neighbors - boost MAXTOUCH");
}

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