make the legacy fortran wrapper work (again)

examples/COUPLE/fortran/README

@@ -1,7 +1,7 @@
-libfwrapper.c is a C file that wraps the LAMMPS library API
+libfwrapper.c is a C file that wraps a few functions of the LAMMPS
-in src/library.h so that it can be called from Fortran.
+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
+See the couple/simple/simple_f77.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

examples/COUPLE/fortran/libfwrapper.c

@@ -29,14 +29,7 @@
 
 void lammps_open_(MPI_Fint *comm, int64_t *ptr)
 {
-    void *obj;
+    *ptr = (int64_t) lammps_open_fortran(0,NULL,*comm);
-    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. */
@@ -107,30 +100,3 @@ void lammps_get_natoms_(int64_t *ptr, MPI_Fint *natoms)
     *natoms = lammps_get_natoms(obj);
 }
 
-/* wrapper to copy coordinates from lammps to fortran */
-
-/* NOTE: this is now out-of-date, needs to be updated to lammps_gather_atoms()
-
-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 */
-
-/* NOTE: this is now out-of-date, needs to be updated to lammps_scatter_atoms()
-
-void lammps_put_coords_(int64_t *ptr, double *coords)
-{
-    void *obj;
-    obj = (void *) *ptr;
-
-    lammps_put_coords(obj,coords);
-}
-
-*/

examples/COUPLE/simple/README

@@ -7,18 +7,21 @@ code to perform a coupled calculation.
 
 simple.cpp     is the C++ driver
 simple.c       is the C driver
-simple.f90     is the Fortran driver
+simple.f90     is the Fortran driver using the new Fortran module
+simple_f77.f90 is the Fortran driver using the legacy Fortran wrapper
 
-The 3 codes do the same thing, so you can compare them to see how to
+The 4 codes do the same thing, so you can compare them to see how to
 drive LAMMPS from each language.  See python/example/simple.py
-to do something similar from Python.  The Fortran driver requires a
+to do something similar from Python.  The new Fortran driver requires
-Fortran module that uses the Fortran 03 ISO_C_BINDING module to
+a Fortran module that uses the Fortran 03 ISO_C_BINDING module to
 interface the LAMMPS C library functions to Fortran.
 
 First build LAMMPS as a library (see examples/COUPLE/README), e.g.
 
 make mode=shlib mpi
 
+or via CMake through settings -DBUILD_SHARED_LIBS=on
+
 You can then build any of the driver codes with compile lines like
 these, which include paths to the LAMMPS library interface, and
 linking with FFTW (only needed if you built LAMMPS as a library with
@@ -27,22 +30,27 @@ its PPPM solver).
 This builds the C++ driver with the LAMMPS library using the mpicxx
 (C++) compiler:
 
-mpicxx -I/home/sjplimp/lammps/src -c simple.cpp
+mpicxx -I${HOME}/lammps/src -c simple.cpp
-mpicxx -L/home/sjplimp/lammps/src simple.o -llammps -o simpleCC
+mpicxx -L${HOME}/lammps/src simple.o -llammps -o simpleCC
 
 This builds the C driver with the LAMMPS library using the mpicc (C)
 compiler:
 
-mpicc -I/home/sjplimp/lammps/src -c simple.c
+mpicc -I${HOME}/lammps/src -c simple.c
-mpicc -L/home/sjplimp/lammps/src simple.o -llammps -o simpleC
+mpicc -L${HOME}/lammps/src simple.o -llammps -o simpleC
 
 This builds the Fortran module and driver with the LAMMPS library
 using the mpifort (Fortran) compilers, using the Fortran module from
 the fortran directory:
 
-mpifort -L/home/sjplimp/lammps/src ../../../fortran/lammps.f90 simple.f90 -llammps -o simpleF
+mpifort -L${HOME}/lammps/src ../../../fortran/lammps.f90 simple.f90 -llammps -o simpleF
 
-You then run simpleCC, simpleC, or simpleF on a parallel machine
+This builds the legacy Fortran wrapper and driver with the LAMMPS library
+using the mpifort (Fortran) MPI compiler wrapper (assuming GNU gfortran).
+
+mpifort -std=legacy -L${HOME}/lammps/src ../fortran/libfwrapper.c simple.f90 -llammps -o simpleF77
+
+You then run simpleCC, simpleC, simpleF, or simpleF77 on a parallel machine
 on some number of processors Q with 2 arguments:
 
 % mpirun -np Q simpleCC P in.lj

examples/COUPLE/simple/simple.f90

@@ -29,7 +29,7 @@ PROGRAM f_driver
 
   REAL (kind=8), ALLOCATABLE :: x(:)
   REAL (kind=8), PARAMETER   :: epsilon=0.1
-  
+
   CHARACTER (len=64)   :: arg
   CHARACTER (len=1024) :: line
 

examples/COUPLE/simple/simple_f77.f90

@@ -0,0 +1,125 @@
+!  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.
+
+! f_driver = simple example of how an umbrella program
+!            can invoke LAMMPS as a library on some subset of procs
+! Syntax: simpleF 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
+
+PROGRAM f_driver
+  IMPLICIT NONE
+  INCLUDE 'mpif.h'
+
+  INTEGER, PARAMETER :: fp=20
+  INTEGER :: n, narg, ierr, me, nprocs, natoms
+  INTEGER :: lammps, nprocs_lammps, comm_lammps
+  INTEGER (kind=8) :: ptr
+
+  REAL (kind=8), ALLOCATABLE :: x(:)
+  REAL (kind=8), PARAMETER   :: epsilon=0.1
+
+  CHARACTER (len=64)   :: arg
+  CHARACTER (len=1024) :: line
+
+  ! 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)
+
+  CALL mpi_init(ierr)
+
+  narg = command_argument_count()
+
+  IF (narg /= 2) THEN
+     PRINT *, 'Syntax: simpleF P in.lammps'
+     CALL mpi_abort(MPI_COMM_WORLD,1,ierr)
+  END IF
+
+  CALL mpi_comm_rank(MPI_COMM_WORLD,me,ierr);
+  CALL mpi_comm_size(MPI_COMM_WORLD,nprocs,ierr);
+
+  CALL get_command_argument(1,arg)
+  READ (arg,'(I10)') nprocs_lammps
+
+  IF (nprocs_lammps > nprocs) THEN
+     IF (me == 0) THEN
+        PRINT *, 'ERROR: LAMMPS cannot use more procs than available'
+        CALL mpi_abort(MPI_COMM_WORLD,2,ierr)
+     END IF
+  END IF
+
+  lammps = 0
+  IF (me < nprocs_lammps) THEN
+     lammps = 1
+  ELSE
+     lammps = MPI_UNDEFINED
+  END IF
+
+  CALL mpi_comm_split(MPI_COMM_WORLD,lammps,0,comm_lammps,ierr)
+
+  ! open LAMMPS input script on rank zero
+
+  CALL get_command_argument(2,arg)
+  OPEN(UNIT=fp, FILE=arg, ACTION='READ', STATUS='OLD', IOSTAT=ierr)
+  IF (ierr /= 0) THEN
+     PRINT *, 'ERROR: Could not open LAMMPS input script'
+     CALL mpi_abort(MPI_COMM_WORLD,3,ierr);
+  END IF
+
+  ! 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 */
+
+  IF (lammps == 1) CALL lammps_open(comm_lammps,ptr)
+
+  n = 0
+  DO
+     IF (me == 0) THEN
+        READ (UNIT=fp, FMT='(A)', IOSTAT=ierr) line
+        n = 0
+        IF (ierr == 0) THEN
+           n = LEN(TRIM(line))
+           IF (n == 0 ) THEN
+              line = ' '
+              n = 1
+           END IF
+        END IF
+     END IF
+     CALL mpi_bcast(n,1,MPI_INTEGER,0,MPI_COMM_WORLD,ierr)
+     IF (n == 0) EXIT
+     CALL mpi_bcast(line,n,MPI_CHARACTER,0,MPI_COMM_WORLD,ierr)
+     IF (lammps == 1) CALL lammps_command(ptr,line,n)
+  END DO
+  CLOSE(UNIT=fp)
+
+  ! run 10 more steps followed by a single step */
+
+  IF (lammps == 1) THEN
+     CALL lammps_command(ptr,'run 10',6)
+
+     CALL lammps_get_natoms(ptr,natoms)
+     print*,'natoms=',natoms
+
+     CALL lammps_command(ptr,'run 1',5);
+  END IF
+
+  ! free LAMMPS object
+
+  IF (lammps == 1) CALL lammps_close(ptr);
+
+  ! close down MPI
+
+  CALL mpi_finalize(ierr)
+
+END PROGRAM f_driver