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fix_python.cpp
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Tue, May 28, 11:38

fix_python.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.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing author: Richard Berger (Temple U)
------------------------------------------------------------------------- */
#include <Python.h>
#include <stdio.h>
#include <string.h>
#include "fix_python.h"
#include "atom.h"
#include "force.h"
#include "update.h"
#include "respa.h"
#include "error.h"
#include "python.h"
#include "python_compat.h"
using namespace LAMMPS_NS;
using namespace FixConst;
/* ---------------------------------------------------------------------- */
FixPython::FixPython(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg != 6) error->all(FLERR,"Illegal fix python command");
nevery = force->inumeric(FLERR,arg[3]);
if (nevery <= 0) error->all(FLERR,"Illegal fix python command");
// ensure Python interpreter is initialized
python->init();
if (strcmp(arg[4],"post_force") == 0) {
selected_callback = POST_FORCE;
} else if (strcmp(arg[4],"end_of_step") == 0) {
selected_callback = END_OF_STEP;
} else {
error->all(FLERR,"Unsupported callback name for fix/python");
}
// get Python function
PyGILState_STATE gstate = PyGILState_Ensure();
PyObject * pyMain = PyImport_AddModule("__main__");
if (!pyMain) {
PyGILState_Release(gstate);
error->all(FLERR,"Could not initialize embedded Python");
}
char * fname = arg[5];
pFunc = PyObject_GetAttrString(pyMain, fname);
if (!pFunc) {
PyGILState_Release(gstate);
error->all(FLERR,"Could not find Python function");
}
PyGILState_Release(gstate);
}
/* ---------------------------------------------------------------------- */
int FixPython::setmask()
{
return selected_callback;
}
/* ---------------------------------------------------------------------- */
void FixPython::end_of_step()
{
PyGILState_STATE gstate = PyGILState_Ensure();
PyObject * ptr = PY_VOID_POINTER(lmp);
PyObject * arglist = Py_BuildValue("(O)", ptr);
PyObject * result = PyEval_CallObject((PyObject*)pFunc, arglist);
Py_DECREF(arglist);
PyGILState_Release(gstate);
}
/* ---------------------------------------------------------------------- */
void FixPython::post_force(int vflag)
{
if (update->ntimestep % nevery != 0) return;
PyGILState_STATE gstate = PyGILState_Ensure();
PyObject * ptr = PY_VOID_POINTER(lmp);
PyObject * arglist = Py_BuildValue("(Oi)", ptr, vflag);
PyObject * result = PyEval_CallObject((PyObject*)pFunc, arglist);
Py_DECREF(arglist);
PyGILState_Release(gstate);
}

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