NAME¶
MPI_File_get_type_extent - Returns the extent of the data type in a file.
SYNTAX¶
C Syntax
#include <mpi.h>
int MPI_File_get_type_extent(MPI_File fh, MPI_Datatype
datatype, MPI_Aint *extent)
Fortran Syntax (see FORTRAN 77 NOTES)¶
INCLUDE 'mpif.h'
MPI_FILE_GET_TYPE_EXTENT( FH, DATATYPE, EXTENT, IERROR)
INTEGER FH, DATATYPE, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) EXTENT
C++ Syntax¶
#include <mpi.h>
MPI::Aint MPI::File::Get_type_extent(const MPI::Datatype&
datatype) const
- fh
- File handle (handle).
- datatype
- Data type (handle).
OUTPUT PARAMETERS¶
- extent
- Data type extent (integer).
- IERROR
- Fortran only: Error status (integer).
DESCRIPTION¶
MPI_File_get_type_extent can be used to calculate
extent for
datatype in the file. The extent is the same for all processes
accessing the file associated with
fh. If the current view uses a
user-defined data representation, MPI_File_get_type_extent uses the
dtype_file_extent_fn callback to calculate the extent.
FORTRAN 77 NOTES¶
The MPI standard prescribes portable Fortran syntax for the
EXTENT
argument only for Fortran 90. FORTRAN 77 users may use the non-portable syntax
INTEGER*MPI_ADDRESS_KIND EXTENT
where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the length of
the declared integer in bytes.
NOTES¶
If the file data representation is other than "native," care must be
taken in constructing etypes and file types. Any of the data-type constructor
functions may be used; however, for those functions that accept displacements
in bytes, the displacements must be specified in terms of their values in the
file for the file data representation being used. MPI will interpret these
byte displacements as is; no scaling will be done. The function
MPI_File_get_type_extent can be used to calculate the extents of data types in
the file. For etypes and file types that are portable data types, MPI will
scale any displacements in the data types to match the file data
representation. Data types passed as arguments to read/write routines specify
the data layout in memory; therefore, they must always be constructed using
displacements corresponding to displacements in memory.
ERRORS¶
Almost all MPI routines return an error value; C routines as the value of the
function and Fortran routines in the last argument. C++ functions do not
return errors. If the default error handler is set to
MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will
be used to throw an MPI:Exception object.
Before the error value is returned, the current MPI error handler is called. For
MPI I/O function errors, the default error handler is set to
MPI_ERRORS_RETURN. The error handler may be changed with
MPI_File_set_errhandler; the predefined error handler MPI_ERRORS_ARE_FATAL may
be used to make I/O errors fatal. Note that MPI does not guarantee that an MPI
program can continue past an error.