git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@4695 f3b2605a-c512-4ea7-a41b-209d697bcdaa

2010-09-06 16:44:27 +00:00
parent 6fd6931b7f
commit 8279ef5170
4 changed files with 327 additions and 0 deletions
--- a/examples/COUPLE/c_driver.c
+++ b/examples/COUPLE/c_driver.c
@ -0,0 +1,116 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   www.cs.sandia.gov/~sjplimp/lammps.html
+   Steve Plimpton, sjplimp@sandia.gov, Sandia National Laboratories
+
+   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.
+------------------------------------------------------------------------- */
+
+/* c_driver = simple example of how an umbrella program
+              can invoke LAMMPS as a library on some subset of procs
+   Syntax: c_driver P in.lammps
+           P = # of procs to run LAMMPS on
+               must be <= # of procs the driver code itself runs on
+           in.lammps = LAMMPS input script
+   See README for compilation instructions */
+
+#include "stdio.h"
+#include "stdlib.h"
+#include "string.h"
+#include "mpi.h"
+#include "library.h"        /* this is a LAMMPS include file */
+
+int main(int narg, char **arg)
+{
+  /* setup MPI and various communicators
+     driver runs on all procs in MPI_COMM_WORLD
+     comm_lammps only has 1st P procs (could be all or any subset) */
+
+  MPI_Init(&narg,&arg);
+
+  if (narg != 3) {
+    printf("Syntax: c_driver P in.lammps\n");
+    exit(1);
+  }
+
+  int me,nprocs;
+  MPI_Comm_rank(MPI_COMM_WORLD,&me);
+  MPI_Comm_size(MPI_COMM_WORLD,&nprocs);
+
+  int nprocs_lammps = atoi(arg[1]);
+  if (nprocs_lammps > nprocs) {
+    if (me == 0)
+      printf("ERROR: LAMMPS cannot use more procs than available\n");
+    MPI_Abort(MPI_COMM_WORLD,1);
+  }
+
+  int lammps;
+  if (me < nprocs_lammps) lammps = 1;
+  else lammps = MPI_UNDEFINED;
+  MPI_Comm comm_lammps;
+  MPI_Comm_split(MPI_COMM_WORLD,lammps,0,&comm_lammps);
+
+  /* open LAMMPS input script */
+
+  FILE *fp;
+  if (me == 0) {
+    fp = fopen(arg[2],"r");
+    if (fp == NULL) {
+      printf("ERROR: Could not open LAMMPS input script\n");
+      MPI_Abort(MPI_COMM_WORLD,1);
+    }
+  }
+
+  /* run the input script thru LAMMPS one line at a time until end-of-file
+     driver proc 0 reads a line, Bcasts it to all procs
+     (could just send it to proc 0 of comm_lammps and let it Bcast)
+     all LAMMPS procs call lammps_command() on the line */
+
+  void *ptr;
+  if (lammps == 1) lammps_open(0,NULL,comm_lammps,&ptr);
+
+  int n;
+  char line[1024];
+  while (1) {
+    if (me == 0) {
+      if (fgets(line,1024,fp) == NULL) n = 0;
+      else n = strlen(line) + 1;
+      if (n == 0) fclose(fp);
+    }
+    MPI_Bcast(&n,1,MPI_INT,0,MPI_COMM_WORLD);
+    if (n == 0) break;
+    MPI_Bcast(line,n,MPI_CHAR,0,MPI_COMM_WORLD);
+    if (lammps == 1) lammps_command(ptr,line);
+  }
+
+  /* run 10 more steps
+     get coords from LAMMPS
+     change coords of 1st atom
+     put coords back into LAMMPS
+     run a single step with changed coords */
+
+  if (lammps == 1) {
+    lammps_command(ptr,"run 10");
+
+    int natoms = lammps_get_natoms(ptr);
+    double *x = (double *) malloc(3*natoms*sizeof(double));
+    lammps_get_coords(ptr,x);
+    double epsilon = 0.1;
+    x[0] += epsilon;
+    lammps_put_coords(ptr,x);
+    free(x);
+
+    lammps_command(ptr,"run 1");
+  }
+
+  if (lammps == 1) lammps_close(ptr);
+
+  /* close down MPI */
+
+  MPI_Finalize();
+}