typedef int MPI_Datarep_extent_function(MPI_Datatype datatype, MPI_Aint *file_extent, void *extra_state);
SUBROUTINE DATAREP_EXTENT_FUNCTION(DATATYPE, EXTENT, EXTRA_STATE, IERROR)INTEGER DATATYPE, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) EXTENT, EXTRA_STATE
typedef MPI::Datarep_extent_function(const MPI::Datatype& datatype, MPI::Aint& file_extent, void* extra_state);
The function dtype_file_extent_fn must return, in file_extent, the number of bytes required to store datatype in the file representation. The function is passed, in extra_state, the argument that was passed to the MPI_REGISTER_DATAREP call. MPI-/ will only call this routine with predefined datatypes employed by the user.
MPI-Standard for MARMOT