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npair_half_size_bin_newton_omp.cpp
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Thu, May 2, 12:19

npair_half_size_bin_newton_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 "npair_half_size_bin_newton_omp.h"
#include "npair_omp.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "atom.h"
#include "atom_vec.h"
#include "my_page.h"
#include "error.h"
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
NPairHalfSizeBinNewtonOmp::NPairHalfSizeBinNewtonOmp(LAMMPS *lmp) :
NPair(lmp) {}
/* ----------------------------------------------------------------------
size particles
binned neighbor list construction with full Newton's 3rd law
each owned atom i checks its own bin and other bins in Newton stencil
every pair stored exactly once by some processor
------------------------------------------------------------------------- */
void NPairHalfSizeBinNewtonOmp::build(NeighList *list)
{
const int nlocal = (includegroup) ? atom->nfirst : atom->nlocal;
const int history = list->history;
const int mask_history = 3 << SBBITS;
NPAIR_OMP_INIT;
#if defined(_OPENMP)
#pragma omp parallel default(none) shared(list)
#endif
NPAIR_OMP_SETUP(nlocal);
int i,j,k,m,n,nn,ibin;
double xtmp,ytmp,ztmp,delx,dely,delz,rsq;
double radi,radsum,cutsq;
int *neighptr;
double **x = atom->x;
double *radius = atom->radius;
tagint *tag = atom->tag;
int *type = atom->type;
int *mask = atom->mask;
tagint *molecule = atom->molecule;
int *ilist = list->ilist;
int *numneigh = list->numneigh;
int **firstneigh = list->firstneigh;
// each thread has its own page allocator
MyPage<int> &ipage = list->ipage[tid];
ipage.reset();
for (i = ifrom; i < ito; i++) {
n = 0;
neighptr = ipage.vget();
xtmp = x[i][0];
ytmp = x[i][1];
ztmp = x[i][2];
radi = radius[i];
// loop over rest of atoms in i's bin, ghosts are at end of linked list
// if j is owned atom, store it, since j is beyond i in linked list
// if j is ghost, only store if j coords are "above and to the right" of i
for (j = bins[i]; j >= 0; j = bins[j]) {
if (j >= nlocal) {
if (x[j][2] < ztmp) continue;
if (x[j][2] == ztmp) {
if (x[j][1] < ytmp) continue;
if (x[j][1] == ytmp && x[j][0] < xtmp) continue;
}
}
if (exclude && exclusion(i,j,type[i],type[j],mask,molecule)) continue;
delx = xtmp - x[j][0];
dely = ytmp - x[j][1];
delz = ztmp - x[j][2];
rsq = delx*delx + dely*dely + delz*delz;
radsum = radi + radius[j];
cutsq = (radsum+skin) * (radsum+skin);
if (rsq <= cutsq) {
if (history && rsq < radsum*radsum)
neighptr[n++] = j ^ mask_history;
else
neighptr[n++] = j;
}
}
// loop over all atoms in other bins in stencil, store every pair
ibin = atom2bin[i];
for (k = 0; k < nstencil; k++) {
for (j = binhead[ibin+stencil[k]]; j >= 0; j = bins[j]) {
if (exclude && exclusion(i,j,type[i],type[j],mask,molecule)) continue;
delx = xtmp - x[j][0];
dely = ytmp - x[j][1];
delz = ztmp - x[j][2];
rsq = delx*delx + dely*dely + delz*delz;
radsum = radi + radius[j];
cutsq = (radsum+skin) * (radsum+skin);
if (rsq <= cutsq) {
if (history && rsq < radsum*radsum)
neighptr[n++] = j ^ mask_history;
else
neighptr[n++] = j;
}
}
}
ilist[i] = i;
firstneigh[i] = neighptr;
numneigh[i] = n;
ipage.vgot(n);
if (ipage.status())
error->one(FLERR,"Neighbor list overflow, boost neigh_modify one");
}
NPAIR_OMP_CLOSE;
list->inum = nlocal;
}

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