[petsc-dev] PetscSF in Fortran

[Adrian Croucher]

hi


On 16/10/17 15:16, Jed Brown wrote:
> Adrian Croucher <a.croucher at auckland.ac.nz> writes:
>
>> So do you think the SF stuff in petsc/finclude/petscis.h should be taken
>> out, and put into a new petsc/finclude/petscsf.h ?
> I think that's desirable for symmetry with include/petscsf.h, but it
> isn't important for your contribution.

I have got Fortran bindings for PetscSFGetGraph() and PetscSFSetGraph() 
working. First I tried separating the existing SF stuff out of the IS 
modules, but ran into dependency problems in other modules. I wasn't too 
confident about the best way to resolve those without breaking things, 
so I tried it again just doing minimal changes to the existing SF stuff- 
essentially just adding Fortran wrappers for PetscSFGetGraph() and 
PetscSFSetGraph() into src/vec/f90-mod/petscis.h90- and that seemed to 
work fine. Maybe someone more familiar with the setup could separate out 
the SF stuff from IS sometime.


So, now I'm trying to add Fortran bindings for PetscSFBcastBegin() and 
PetscSFBcastEnd().

 From the C side I have added the following into 
src/vec/is/sf/interface/f90-custom/zsff90.c:

PETSC_EXTERN void PETSC_STDCALL petscsfbcastbegin_(PetscSF *sf, 
MPI_Datatype *unit, F90Array1d *rptr, F90Array1d *lptr , int *ierr 
PETSC_F90_2PTR_PROTO(rptrd) PETSC_F90_2PTR_PROTO(lptrd))
{
   PetscDataType ptype;
   const void* rootdata;
   void* leafdata;

   *ierr = PetscMPIDataTypeToPetscDataType(*unit, &ptype);if (*ierr) return;
   *ierr = F90Array1dAccess(rptr, ptype, (void**) &rootdata 
PETSC_F90_2PTR_PARAM(rptrd));if (*ierr) return;
   *ierr = F90Array1dAccess(lptr, ptype, (void**) &leafdata 
PETSC_F90_2PTR_PARAM(lptrd));if (*ierr) return;

   *ierr = PetscSFBcastBegin(*sf, *unit, rootdata, leafdata);

}

and similarly for petscsfbcastend_(). Does this look plausible?

Then some wrappers need to be added to src/vec/f90-mod/petscis.h90. I am 
not sure how to do those.

The difficulty is in declaring the arrays that are passed in, which can 
be of various types. In C they are declared as void*, but I'm not sure 
what to do with that in Fortran. I can't seem to find any other example 
wrappers in PETSc to model it on either. Any suggestions?

- Adrian

-- 
Dr Adrian Croucher
Senior Research Fellow
Department of Engineering Science
University of Auckland, New Zealand
email: a.croucher at auckland.ac.nz
tel: +64 (0)9 923 4611