forked from lijiext/lammps
117 lines
3.3 KiB
C
117 lines
3.3 KiB
C
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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www.cs.sandia.gov/~sjplimp/lammps.html
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Steve Plimpton, sjplimp@sandia.gov, Sandia National Laboratories
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Copyright (2003) Sandia Corporation. Under the terms of Contract
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DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
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certain rights in this software. This software is distributed under
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the GNU General Public License.
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See the README file in the top-level LAMMPS directory.
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------------------------------------------------------------------------- */
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/* c_driver = simple example of how an umbrella program
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can invoke LAMMPS as a library on some subset of procs
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Syntax: c_driver P in.lammps
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P = # of procs to run LAMMPS on
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must be <= # of procs the driver code itself runs on
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in.lammps = LAMMPS input script
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See README for compilation instructions */
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#include "stdio.h"
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#include "stdlib.h"
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#include "string.h"
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#include "mpi.h"
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#include "library.h" /* this is a LAMMPS include file */
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int main(int narg, char **arg)
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{
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/* setup MPI and various communicators
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driver runs on all procs in MPI_COMM_WORLD
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comm_lammps only has 1st P procs (could be all or any subset) */
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MPI_Init(&narg,&arg);
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if (narg != 3) {
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printf("Syntax: c_driver P in.lammps\n");
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exit(1);
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}
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int me,nprocs;
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MPI_Comm_rank(MPI_COMM_WORLD,&me);
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MPI_Comm_size(MPI_COMM_WORLD,&nprocs);
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int nprocs_lammps = atoi(arg[1]);
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if (nprocs_lammps > nprocs) {
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if (me == 0)
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printf("ERROR: LAMMPS cannot use more procs than available\n");
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MPI_Abort(MPI_COMM_WORLD,1);
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}
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int lammps;
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if (me < nprocs_lammps) lammps = 1;
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else lammps = MPI_UNDEFINED;
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MPI_Comm comm_lammps;
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MPI_Comm_split(MPI_COMM_WORLD,lammps,0,&comm_lammps);
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/* open LAMMPS input script */
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FILE *fp;
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if (me == 0) {
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fp = fopen(arg[2],"r");
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if (fp == NULL) {
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printf("ERROR: Could not open LAMMPS input script\n");
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MPI_Abort(MPI_COMM_WORLD,1);
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}
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}
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/* run the input script thru LAMMPS one line at a time until end-of-file
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driver proc 0 reads a line, Bcasts it to all procs
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(could just send it to proc 0 of comm_lammps and let it Bcast)
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all LAMMPS procs call lammps_command() on the line */
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void *ptr;
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if (lammps == 1) lammps_open(0,NULL,comm_lammps,&ptr);
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int n;
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char line[1024];
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while (1) {
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if (me == 0) {
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if (fgets(line,1024,fp) == NULL) n = 0;
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else n = strlen(line) + 1;
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if (n == 0) fclose(fp);
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}
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MPI_Bcast(&n,1,MPI_INT,0,MPI_COMM_WORLD);
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if (n == 0) break;
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MPI_Bcast(line,n,MPI_CHAR,0,MPI_COMM_WORLD);
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if (lammps == 1) lammps_command(ptr,line);
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}
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/* run 10 more steps
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get coords from LAMMPS
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change coords of 1st atom
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put coords back into LAMMPS
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run a single step with changed coords */
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if (lammps == 1) {
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lammps_command(ptr,"run 10");
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int natoms = lammps_get_natoms(ptr);
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double *x = (double *) malloc(3*natoms*sizeof(double));
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lammps_gather_atoms(lmp,"x",1,3,x);
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double epsilon = 0.1;
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x[0] += epsilon;
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lammps_scatter_atoms(lmp,"x",1,3,x);
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free(x);
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lammps_command(ptr,"run 1");
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}
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if (lammps == 1) lammps_close(ptr);
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/* close down MPI */
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MPI_Finalize();
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}
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