git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@4808 f3b2605a-c512-4ea7-a41b-209d697bcdaa

src/fix_external.cpp

@@ -0,0 +1,105 @@
+/* ----------------------------------------------------------------------
+   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 "stdio.h"
+#include "string.h"
+#include "fix_external.h"
+#include "atom.h"
+#include "update.h"
+#include "memory.h"
+#include "error.h"
+
+using namespace LAMMPS_NS;
+
+/* ---------------------------------------------------------------------- */
+
+FixExternal::FixExternal(LAMMPS *lmp, int narg, char **arg) :
+  Fix(lmp, narg, arg)
+{
+  if (narg != 3) error->all("Illegal fix external command");
+
+  callback = NULL;
+
+  nmax = 0;
+  fexternal = NULL;
+}
+
+/* ---------------------------------------------------------------------- */
+
+FixExternal::~FixExternal()
+{
+  memory->destroy_2d_double_array(fexternal);
+}
+
+/* ---------------------------------------------------------------------- */
+
+int FixExternal::setmask()
+{
+  int mask = 0;
+  mask |= POST_FORCE;
+  return mask;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixExternal::init()
+{
+  if (callback == NULL) error->all("Fix external callback function not set");
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixExternal::setup(int vflag)
+{
+  post_force(vflag);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixExternal::post_force(int vflag)
+{
+  if (atom->nlocal > nmax) {
+    memory->destroy_2d_double_array(fexternal);
+    nmax = atom->nmax;
+    fexternal = memory->create_2d_double_array(nmax,3,"external:fexternal");
+  }
+
+  // invoke the callback in driver program
+  // it will fill fexternal with forces
+
+  (this->callback)(ptr_caller,update->ntimestep,
+		   atom->nlocal,atom->tag,atom->x,fexternal);
+
+  // add forces from fexternal to atoms in group
+
+  double **f = atom->f;
+  int *mask = atom->mask;
+  int nlocal = atom->nlocal;
+
+  for (int i = 0; i < nlocal; i++)
+    if (mask[i] & groupbit) {
+      f[i][0] += fexternal[i][0];
+      f[i][1] += fexternal[i][1];
+      f[i][2] += fexternal[i][2];
+    }
+}
+
+/* ----------------------------------------------------------------------
+   external caller sets a callback function to invoke in post_force()
+------------------------------------------------------------------------- */
+
+void FixExternal::set_callback(FnPtr caller_callback, void *caller_ptr)
+{
+  callback = caller_callback;
+  ptr_caller = caller_ptr;
+}

src/fix_external.h

@@ -0,0 +1,49 @@
+/* ----------------------------------------------------------------------
+   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.
+------------------------------------------------------------------------- */
+
+#ifdef FIX_CLASS
+
+FixStyle(external,FixExternal)
+
+#else
+
+#ifndef LMP_FIX_EXTERNAL_H
+#define LMP_FIX_EXTERNAL_H
+
+#include "fix.h"
+
+namespace LAMMPS_NS {
+
+class FixExternal : public Fix {
+ public:
+  FixExternal(class LAMMPS *, int, char **);
+  ~FixExternal();
+  int setmask();
+  void init();
+  void setup(int);
+  void post_force(int);
+
+  typedef void (*FnPtr)(void *, int, int, int *, double **, double **);
+  void set_callback(FnPtr, void *);
+
+ private:
+  FnPtr callback;
+  void *ptr_caller;
+  int nmax;
+  double **fexternal;
+};
+
+}
+
+#endif
+#endif