hi
On 19/10/17 06:45, Matthew Knepley wrote:
On Tue, Oct 17, 2017 at 11:35 PM, Adrian Croucher
<[email protected] <mailto:[email protected]>> wrote:
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?
I think this is working now by just declaring those void* C variables as
type(*) in the Fortran interface, e.g.:
Interface
Subroutine PetscSFBcastBegin(sf,unit,rarray,
& larray,ierr)
use petscisdef
PetscSF :: sf
PetscInt :: unit
type(*) :: rarray(:)
type(*) :: larray(:)
PetscErrorCode :: ierr
End Subroutine PetscSFBcastBegin
End Interface
The only difficulty I have left with this is in the MPI_Datatype
variable. I'd forgotten that these datatypes are all different in C and
Fortran as well.
I amended the C interface code to the following, to convert the Fortran
MPI datatype (actually an integer) to a C MPI_Datatype:
PETSC_EXTERN void PETSC_STDCALL petscsfbcastbegin_(PetscSF *sf, MPI_Fint
*unit, F90Array1d *rptr, F90Array1d *lptr , int *ierr
PETSC_F90_2PTR_PROTO(rptrd) PETSC_F90_2PTR_PROTO(lptrd))
{
PetscDataType pdtype;
MPI_Datatype dtype;
const void* rootdata;
void* leafdata;
dtype = MPI_Type_f2c(*unit);
*ierr = PetscMPIDataTypeToPetscDataType(dtype, &pdtype);if (*ierr)
return;
*ierr = F90Array1dAccess(rptr, pdtype, (void**) &rootdata
PETSC_F90_2PTR_PARAM(rptrd));if (*ierr) return;
*ierr = F90Array1dAccess(lptr, pdtype, (void**) &leafdata
PETSC_F90_2PTR_PARAM(lptrd));if (*ierr) return;
*ierr = PetscSFBcastBegin(*sf, dtype, rootdata, leafdata);
}
The problem is this only seems to work if I declare the datatype in the
calling Fortran code to be of the appropriate C MPI datatype, e.g.
MPI_INT, rather than the corresponding Fortran datatype, e.g.
MPI_INTEGER (which causes PetscMPIDataTypeToPetscDataType() to fail, as
something weird gets passed in for dtype).
I was expecting the opposite to be true. It doesn't seem right to have
to use the C datatypes in Fortran code (confusing if the Fortran
datatypes are used elsewhere). So I suspect I've messed something up.
Anyone have any ideas?
- Adrian
--
Dr Adrian Croucher
Senior Research Fellow
Department of Engineering Science
University of Auckland, New Zealand
email: [email protected]
tel: +64 (0)9 923 4611
