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MPI_Register_datarep(3OpenMPI)                                                MPI_Register_datarep(3OpenMPI)



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 identi-fier identifier
       fier (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 pro-vided provided
       vided 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.




Open MPI 1.2                                   September 2006                 MPI_Register_datarep(3OpenMPI)