This directory hosts an early draft for a Coarray run-time
libarary on MPI basis.

------------------ IDEA -------------------
Calls to a wrapper run-time library will be generated; the
first implementation will use MPI; library is available as
source thus the local MPI can be used. The wrapper calls are
enabled using some option like
 -fcoarray=library/lib/...

Possible extensions:
* An option to enable direct thread support
  (rather than, e.g., an implementation, which uses the
   wrapper-library ABI):
  -fcoarray=thread/shared/openmp/...

* A debug version, which generates checks by passing more
  information to the wrapper library, e.g.
  -fcoarray=lib-debug

* An option to preset the number of images, which allows some
  optimizations in the compiler, but must be checked at
  run-time (if not setable by the CAF program).
  -fcoarray-num-images=<n>, n >= 0 (0 = run-time determined)

Example usage:
  mpicc -c libgfortran_coarray_mpi.c
  gfortran -fcoarray=library -c myFort*.f90
  mpif90 myFort*.o libgfortran_coarray_mpi.o

(If needed, one can still use "ar" to create a lib*.a to place
it into $SYSLIBDIR)


------------------ REFERENCES -------------------

For more details, have a look at
http://users.physik.fu-berlin.de/~tburnus/coarray/README.txt
and http://gcc.gnu.org/ml/fortran/2010-04/msg00168.html


------------------ IMPLEMENTATION ---------------

The library should be written to be compatible with MPIv1.x
or with MPIv2.1/MPIv2.2; if possible compatible to both with
#ifdefs. Similarly, there should be optional error checks.

MPI standard, see http://www.mpi-forum.org/docs/docs.html

MPI tutorial for mere beginners ;-)
 https://computing.llnl.gov/tutorials/mpi/