git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@8604 f3b2605a-c512-4ea7-a41b-209d697bcdaa

examples/COUPLE/fortran/README

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+libfwrapper.c is a C file that wraps the LAMMPS library API
+in src/library.h so that it can be called from Fortran.
+
+See the couple/simple/simple.f90 program for an example
+of a Fortran code that does this.
+
+See the README file in that dir for instructions
+on how to build a Fortran code that uses this
+wrapper and links to the LAMMPS library.

examples/COUPLE/fortran/libfwrapper.c

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+/* ----------------------------------------------------------------------
+   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.
+------------------------------------------------------------------------- */
+
+/* libwrapper = fortran wrappers for LAMMPS library functions.
+   See README for compilation instructions */
+
+#include "mpi.h"
+#include "stdio.h"
+#include "stdlib.h"
+#include "string.h"
+#include "stdint.h"
+#include "library.h"        /* this is a LAMMPS include file */
+
+/* wrapper for creating a lammps instance from fortran.
+   since fortran has no simple way to emit a c-compatible
+   argument array, we don't support it. for simplicity,
+   the address of the pointer to the lammps object is
+   stored in a 64-bit integer on all platforms. */
+
+void lammps_open_(MPI_Fint *comm, int64_t *ptr)
+{
+    void *obj;
+    MPI_Comm ccomm;
+
+    /* convert MPI communicator from fortran to c */
+    ccomm = MPI_Comm_f2c(*comm);
+
+    lammps_open(0,NULL,ccomm,&obj);
+    *ptr = (int64_t) obj;
+}
+
+/* no-MPI version of the wrapper from above. */
+
+void lammps_open_no_mpi_(int64_t *ptr)
+{
+    void *obj;
+
+    lammps_open_no_mpi(0,NULL,&obj);
+    *ptr = (int64_t) obj;
+}
+
+/* wrapper for shutting down a lammps instance from fortran. */
+
+void lammps_close_(int64_t *ptr)
+{
+    void *obj;
+    obj = (void *) *ptr;
+
+    lammps_close(obj);
+}
+
+/* wrapper for passing an input file to lammps from fortran.
+   since fortran strings are not zero terminated, we have
+   to pass the length explicitly and make a copy that is. */
+
+void lammps_file_(int64_t *ptr, char *fname, MPI_Fint *len)
+{
+    void *obj;
+    char *cpy;
+
+    obj = (void *) *ptr;
+
+    cpy = (char *)calloc(*len + 1,sizeof(char));
+    memcpy(cpy,fname,*len);
+
+    lammps_file(obj,cpy);
+    free(cpy);
+}
+
+/* wrapper for passing a line input to lammps from fortran.
+   since fortran strings are not zero terminated, we have
+   to pass the length explicitly and make a copy that is. */
+
+void lammps_command_(int64_t *ptr, char *line, MPI_Fint *len)
+{
+    void *obj;
+    char *cpy;
+
+    obj = (void *) *ptr;
+
+    cpy = (char *)calloc(*len + 1,sizeof(char));
+    memcpy(cpy,line,*len);
+
+    lammps_command(obj,cpy);
+    free(cpy);
+}
+
+/* fortran wrapper to get the number of atoms from lammps.
+   return values require an interface in fortran, so we 
+   make the wrapper into a procedure. */
+
+void lammps_get_natoms_(int64_t *ptr, MPI_Fint *natoms)
+{
+    void *obj;
+    obj = (void *) *ptr;
+
+    *natoms = lammps_get_natoms(obj);
+}
+
+/* wrapper to copy coordinates from lammps to fortran */
+
+void lammps_get_coords_(int64_t *ptr, double *coords)
+{
+    void *obj;
+    obj = (void *) *ptr;
+
+    lammps_get_coords(obj,coords);
+}
+
+/* wrapper to copy coordinates from fortran to lammps */
+
+void lammps_put_coords_(int64_t *ptr, double *coords)
+{
+    void *obj;
+    obj = (void *) *ptr;
+
+    lammps_put_coords(obj,coords);
+}
+