MPI_Register_datarep(3)            Open MPI            MPI_Register_datarep(3)



NAME
       MPI_Register_datarep - Defines data representation.




SYNTAX
       C Syntax
           #include <mpi.h>
           int MPI_Register_datarep(char *datarep,
                  MPI_Datarep_conversion_function *read_conversion_fn,
                  MPI_Datarep_conversion_function *write_conversion_fn,
                  MPI_Datarep_extent_function *dtype_file_extent_fn,
                  void *extra_state)

       Fortran Syntax
           INCLUDE 'mpif.h'
           MPI_REGISTER_DATAREP(DATAREP, READ_CONVERSION_FN,
            WRITE_CONVERSION_FN, DTYPE_FILE_EXTENT_FN,
            EXTRA_STATE, IERROR)
                 CHARACTER*(*) DATAREP
                 EXTERNAL READ_CONVERSION_FN, WRITE_CONVERSION_FN,
                          DTYPE_FILE_EXTENT_FN
                 INTEGER   IERROR
                 INTEGER(KIND=MPI_ADDRESS_KIND) EXTRA_STATE


C++ Syntax
       #include <mpi.h>
       void MPI::Register_datarep(const char* datarep,
            MPI::Datarep_conversion_function* read_conversion_fn,
            MPI::Datarep_conversion_function* write_conversion_fn,
            MPI::Datarep_extent_function* dtype_file_extent_fn,
            void* extra_state)


INPUT PARAMETERS
       datarep   Data representation identifier (string).

       read_conversion_fn
                 Function invoked to convert from file representation to
                 native representation (function).

       write_conversion_fn
                 Function invoked to convert from native representation to
                 file representation (function).

       dtype_file_extent_fn
                 Function invoked to get the extent of a data type as
                 represented in the file (function).

       extra_state
                 Extra state.


OUTPUT PARAMETER
       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPI_Register_datarep defines a data representation. It associates the
       data representation's identifier (a string) with the functions that
       convert from file representation to the native representation and vice
       versa, with the function that gets the extent of a data type as
       represented in the file, as well as with "extra state," which is used
       for passing arguments. Once a data representation has been registered
       using this routine, you may specify its identifier as an argument to
       MPI_File_set_view, causing subsequent data-access operations to call
       the specified conversion functions.

       The call associates read_conversion_fn, write_conversion_fn, and
       dtype_file_extent_fn with the data representation identifier datarep.
       datarep can then be used as an argument to MPI_File_set_view, causing
       subsequent data access operations to call the conversion functions to
       convert all data items accessed between file data representation and
       native representation. MPI_Register_datarep is a local operation and
       only registers the data representation for the calling MPI process. If
       datarep is already defined, an error in the error class
       MPI_ERR_DUP_DATAREP is raised using the default file error handler. The
       length of a data representation string is limited to the value of
       MPI_MAX_DATAREP_STRING. MPI_MAX_DATAREP_STRING must have a value of at
       least 64. No routines are provided to delete data representations and
       free the associated resources; it is not expected that an application
       will generate them in significant numbers.


NOTES
       The Fortran version of each MPI I/O routine includes a final argument,
       IERROR, which is not defined in the PARAMETERS sections. This argument
       is used to return the error status of the routine in the manner typical
       for Fortran library routines.

       The C version of each routine returns an error status as an integer
       return value.

       Error classes are found in mpi.h (for C), mpif.h (for Fortran), and
       mpi++.h (for C++).


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.




1.4.1                            Jan 14, 2010          MPI_Register_datarep(3)
